RC India

Hi everyone,

Some of you may remember the ‘1st Chuck’ from July 2018
http://www.rcindia.org/kites-trains-free-flight-and-all-others/1st-chuck/

It’s time for the 2nd Chuck.
This time it’s a Lunchbox, an 8” span hand launch glider, designed by John Oldenkamp, a well known American designer, in 1975.

Plans are available here:
https://outerzone.co.uk/download_file.asp?planID=11309&FileType=Plan&Filename=Lunchbox_oz11309.pdf

I didn’t print the plan. Just saved it as a pic on my iPad.
Then adjusted the size for 8” span and saved a screenshot.
Then copied it and made a paper template.

Then took a foam dinner plate I got for Rs2!
And cut the wing and tail parts from it

Then made a fuselage from a piece of 3mm x 5mm x 10” piece ofscrap balsa.
And added a bit of plasticine for nose weight...

And it flies!

https://m.youtube.com/watch?v=MAvgYe_-Xo0

So now I can build a few kits in balsa for the ‘Next Contest’

Maybe a few more of you will join!

This build took 1 hour.
Including a 30 minute walk with the dog!

Nice going Mr.Iyer  ;D

Thanks.
Perhaps you may like to join the ‘Next Contest’, as a participant, or a sponsor...

i want to  :) but no time too much of work  :'(

If things get better i can be the surprise entry  ;D

I’m surprised at how busy people are!
This kit needs 5 minutes to assemble. A few more if you wish to sand the wings.
Of course you’ll need an hour in the park on Sunday to fly it!
Sponsorship however needs no time at all!
Regards

I will also be participating sir,but will be using a paper aeroplane style launcher...What is the required flight time?
https://www.youtube.com/watch?v=RVgemKXnhM

Sir , is it 1mm or 2mm balsa?

Queries about model on this thread please. Had to move this query.
On the ‘Next Contest’ thread, only contest queries please.

Pl see the plan.
It says 3/32 for wing, 1/8 hard for fuselage, 1/32 for empennage.
I’ve used 2.2mm for wing, 2x2.2mm for fuselage, 1.5mm sanded to 0.75mm for empennage

I’m not clear about the reason for this query  ???

Regards

Some problem with the video you posted.

Contest Guidelines since posted in ‘Next Contest’ thread

Regards

In case you are not able to access the plan via the link in the first post, do this:

Go to outerzone.co.uk
Select search
Enter ‘Lunchbox’

You’ll get the plan.

Thanks to R C GUY for pointing out the error

Sir , I have some balsa sheets with me ( 2mm ) So I wanted to know whether that would suffice . Thanks for clarifying.

Made 5 kits

The 5 kits together weigh 30gms.
Or 6 gms each without nose weight.
Or probably 8-9gms with nose weight for balance.

If someone can get the AUW down to 5gms, it’ll be a wortwhile achievement.
And the difference in performance will show.

For comparison, the foamy version weighs nothing according to my scale!

The foamy version I built weighs 2.5 gms  ( with nose weight - glue ) . I thought I’ll have some test flights and training on trimming /launch etc before the contest :)

2.5gms if fine for a start.
Please post a video here of your test flights.
Regards

Should I sir ? :) Before the contest ? ;)

Ok sir , here’s a very short video . It glides smoothly , inside the room . Since it’s raining outside in most of the evenings ( predicted to continue for 4 more days) , I need to find a less windy day for more testing . Am I allowed to throw it from the balcony ? :) From the rules , I think I have to launch it from the ground itself , isn’t it sir?

https://youtu.be/EDep3rEq5RM

Excellent!
Just reduce nose weight a bit.
That will induce a slight stall.
Correct it by giving very slight left rudder.

No elevated launch. Otherwise the guy at the tallest building wil win  ;D
Regards


Post a pic of the model too.

Yes.
This is the build thread.
All pics and videos of builds, test flights etc are most welcome.
Might even inspire others.

Later you can post your duration flight videos as entries in the Next Contest thread.

Regards

Sir newbie here,

For foam I understand that you have to cut it using hot wire but how to go about Balsa? how to cut the wing profile on it or even the foam. Any easy way for foam without hotwire?

@turbo20,

1mm foam (disposable dinner plate) can be cut with scissors

Depron sheets and balsa can be cut with a razor blade, but safer to use surgical blades #11 or #24 with matching handle.

For balsa 5mm and above, (and plywood) you need a baby saw or razor saw.

Thermocol upto about 1” thick can be cut with a new razor blade.

Hot wire cutter is needed only if you want to cut curved profiles, like wing aerofoil.

Hope this helps.
Regards

Materials for balsa kit build

The plan says 3/32” for wing, 1/8” hard for fuselage and 1/32” for stab and fin.
In the kit I’m using 2.2mm for wing, 2x2.2mm for fuselage and 1.5mm sanded to 0.75mm for tail.

The wings are already sanded to an airfoil section, though not as sharp as in the plan, as it would have made the wings too delicate.
The wing centre is already beveled for dihedral.
The fuselage has an extension below the nose for the catapult, and a 1/2” extension at the back for pulling back in catapult launch.
All parts already doped and finish sanded with 600 grit sandpaper as specified in the plan article.
Included is a small Feviquik, pin and thread for balancing, plasticine for nose weight and some rubber bands for an initial catapult.

So it can actually be ready to fly in 5-10 minutes. (However see wing fuselage joint reinforcement in a following post)

Edit:
Not able to load pics for some reason.
Will post assembly instructions and pics tomorrow

Here’s a pic of the kit contents

Assembly

Use a grid, graph paper or at least draw two perpendicular lines to ensure that the stab is perpendicular to the fuselage in top view.

Hold the fuselage in place with the plasticine. Ensure fuselage and fin are perpendicular to stab.

Put a few dots of Feviquik on both sides.
Wait and check if everything is square.
Then put a small amount of Feviquik on both sides.

The wings are temporarily taped at the bottom, and BEVELED AT THE TOP OF THE JOINT to accomodate the bend for the dihedral.

Thank you sir for the detailed instructions! And we expect more on launch , trimming etc .

Place one wing flat with the other tip raised 3”

Put some Feviquik down the joint.

After a few seconds, pick it up and put some Feviquik down the bottom of the joint.

Now we have fuselage with the tail parts, and a wing with dihedral.

And we have stick them together.
IN PROPER ALIGNMENT!

For once I see several guys watching this thread...

So let’s finish the assembly...

Mark a point at the top of the fuselage 2” from the nose.

This is where the leading edge of the wing will be.

Set the wing on the fuselage with packing under each wing.

The wing has to be DEAD SQUARE to the fuselage
and its center line should be DEAD CENTRE on the fuselage
And both wingtips at equal height.

See pics.

Does it look okay?

Actually the alignment is NOT GOOD ENOUGH

So I’ll adjust it till it’s as accurate as I can get it.

Once aligned as best as possible, put a dot of Feviquik at the leading edge and trailing edge.

Wait a few seconds, then pick it up to check alignment.

If not satisfied, the wing can be removed easily as it is stuck at only two points, and realigned.

When satisfied, pick it up and run a bead of Feviquik on either side of the wing/ fuselage joint under the wing.

ASSEMBLY COMPLETE !  ;D

Okay sir , understood .Thanks .And where should be it’s CG ( with the plasticine)?

Sir , one doubt here . Should we glue the whole fin on top or on one side of the fuselage? If fully glued , how to trim the rudder ?

Balancing

Start by putting enough plasticine (~1gm) on the nose, to balance it 1.75” from the leading edge.

Then test glide. Add or reduce nose weight till you get a floating glide, with no dive and no stall.
(BTW, this is harder than it sounds!)

In the kit it’s already stuck on top.
If you make it a bit taller, you can stick it to one side.

Very little rudder is required, soyou can still bend it in.

Like this

Ipad battery down.
So bye till tomorrow
Regards to everyone

Yes! That’s the most difficult part ! :) Now every step is crystal clear ! Thank you!

Took a bit of trial and error to get it to fly properly in my drawing room.

Then I tried it with 2 x 2” rubber bands.
Wow. What a surprise!

For testing with 2 x 2” rubber bands, you’ll need at least a tennis court size area.

With more rubber bands and more pull, you’ll need a football field!

Be warned. Don’t fly it in a restricted space...

Best wishes

Query from aspersid

If possible can you also add some rubberbands to the kit? The long ones especially or the tan sport ones if you have them, I don't think they are available where I am currently. I'm willing to pay extra for them.

Reply

Included.
Didn’t you see the pic of the kit contents?

I was surprised at the performance with 2x 2” rubber bands.
With 4x2” rubber bands, I think 30 seconds is possible.

Tan rubber, eh?
I’m not sure, but I think a 9” loop of 1/8” Tan super Sport is the standard for catapult launch gliders.

I have some, but not enough to distribute to all participants...

I have some Tan Super Sport rubber, but not enough to supply to all participants as part of the kit.

Freeflight has agreed to limit himself to office use rubber bands and not use Tan.

The prototype and the first four kits weighed 8gms with nose weight.

In the next four, I’m trying to get it down to 7gms. I can skip the dope finish (0.5gms), but I don’t want to do that. Plus I’m planning to use silicon polish!

The next 4 wings are 2.5gms each.

The balsa one is 8 gms
The foamy is 1 gm (shows zero on my kitchen scale)

Their performance is identical!
In test glides in the drawing room.

The difference will show up when the speed increases.
As in full power hand launch or catapult launch...

Wonder if anyone would be interested in this TLG LAUNCH SPEED ESTIMATE, posted by me 6 yrs ago...

http://www.rcindia.org/kites-trains-free-flight-and-all-others/tlg-launch-speed-estimate/

Twelve stop action shots here

http://www.rcindia.org/kites-trains-free-flight-and-all-others/for-the-5th-sweepstakes-first-model-k-k-iyer/msg181491/#msg181491

4 kits sent
6 kits under way
4 booked.
2 available

Freeflight has built and flown his Lunchbox.

Wait for his build pics and flight videos.
If he posts today (USA), we’ll see it tomorrow

The Lunchbox CLG ( Catapult Launch Glider) a design by a famous free flighter is ready. Here is the video for your review. Built it to 7 grams, used stationary (office) rubber bands. Hope you like it.

https://www.youtube.com/watch?v=sbzfiVNPQoU&t=56s

Dear All,
 Nice to meet you in this great forum thread. I do not know your background in free flight CLG flying. I assume this is your first CLG build and contest. If not let me know.

CLG flying is the most fun type flying that does not make noise, not expensive either. You do not have to drive to a flying field as any good grassy (?) public park would do. The joy to watch your glider in thermal when launched with simple rubber band is just awesome.

I want all of you to hit the 20 second mark and definitely have "fun" doing so.

These are the tools that I used to build the CLG. Note:  I built from scratch via the plans.
Nothing fancy, regular items around the house or a quick trip to the stationary mart.

PS: Just re read Mr. Iyer build on the pages before. What you are getting is a wonderful ARF with glue and balancer.

A few things below will be helpful in your build:

1)A good matchbox with good wood. These will be used as trimming pieces during flying. Talk more about it when the time comes.

2) Nail file sticks , one side rough , other side fine. Also good to have is the sponge / foam type nail polisher to to give an overall smooth finish.

3) Color pen markers (definitelynot water base) I used RED but you can use orange for top of the wing,  however, black or dark navy blue is a must for the bottom of the wing.

4)A good ruler.

6)A small plastic set square.

7) Glue: Mr. Iyer has supplied you feviquick (?) CA glue. So get a nice reputable  company glue stick that you will also carry to the field with feviquick.  

8 )  Coffee stirrer sticks from your favorite coffee shop . Need one or two.  

9) A good 6 mm round stick that is no more than 6 inches long to make a launcher out of it.

10) For sure  two or three thin produce plastic bags to save your working surface,  table . Make sure they are clean and dry.

11) You need a very flat surface to work from. Make sure it is flat.

You need the kit from Mr. Iyer.

So until all of you have got your kits, get your tool box ready and print out the plans and go over it.

We will take you to the 20 second mark in three steps. An accurate build (trimming starts here), the launch and transition and lastly the glide.

I wait for all of you to confirm that you have got the kit by mail. We start together, except for the more experienced guys who can and perhaps will start right away.

In the second lot of kits, I’ve included a wedge shaped strip of balsa.
Don’t throw it away!
1cm pieces cut from this strip are used to adjust the flight pattern during your trimming flights.

What does that mean?

During your test flights, you may find that you need a little rudder, or a little elevator, or a bit of aileron to correct a spiral dive.
The traditional method was to bend the trailing edge of the rudder, stab, wing a bit, or attach a small tab made of card. Both are subject to unintended change.
Much better to use a 1cm wedge at the trailing edge of the flying surface concerned.
Stick it on with a glue stick, add or reduce as required.

Sharp edge facing forward and square edge flush with the trailing edge of the flying surface.

More details of how to use when Freeflight talks about trimming...

BTW, I’ve not included a handle for the catapult, since you can use a half used pencil  ;D

Thank you for allowing me to share with you my Lunchbox build. Many books and blog on the internet (most of them good) on how to go about doing this, but this is how I built it.

No matter what you do, please make sure of the following:
A) Take your time, measure, remeasure, then when satisfied stick glue. Critical trims should be built in, that should prevent you from having to squeeze the balsa, breathe hard on it and bend, put tabs etc. It took me 4 hours to build it. There is no prize for the quickest builder.
B) You need to use enough glue not too much.

The critical dimensions in the build are the following , no compromise or close enough will do.
1) The center line of the the wing and stab must be on the center line of the fuselage. Cannot have even 1 mm more to the right or left. Both the wing and stab must be at right angle to the fuselage, no skewed attachment.
2) Building dihedral must be exact.
3) When you glue the wing to the fuselage, make sure both tips are at exactly at the same height.
4) The distance from the wing TE to the stab LE (TMA) is exactly 3.5 inches. This should bring you wing LE exactly 2 inches from the nose(NMA).

plan shows Stab TE on the right up by 1/32", rudder 1/32" left, WASHIN on the left wing by 1/32 inch. We will accurately build these in.

Regarding #4, position of wing and stab marked on the fuselage in the kit.

that is great , thanks Mr. Iyer.

Step one:
I had to glue the rudder on. Use a set square to assure that the parts are glued on perpendicular to the fuse and that the wing plus stab are square to the fuse. Use such techniques throughout, please.

OK, I am having issues attaching the photos as small as possible .I have 21 photos to share, taking you step by step, shows how to build in the 1/32 trims, use the glue stick and feviquick with toothpicks so on and so forth. It will take you to a square accurate build.

Suggestions? or I try and post on some photo album that all of you can access. Latter being the fastest way.

Take pics with your iPad (it has far less resolution than phones)
When adding pics, it has a size option.
Select small or medium.
This is what I’ve been doing.

Lets try:

No go. Took photos on my iPad too to begin with.

I am at the smallest size saved on my iPad.

Check perpendicular and side wise each time. No skew

Also side should be square as shown here on the wing to the fuse. This is an example. Use this to check all alignment, stab, rudder , wings etc.

Ok now let's fix the stab. First arrange it correctly. As Mr. Iyer suggested, draw perpendicular on paper or use cutting mat. Make sure stab is equal on either side and that fuse is perpendicular to floor. I used rectangular magnets as I had them. Make sure everything is taped (blue) down so it does not move on you.

above you see that I used three business cards (M) on the left side of the stab that gives the needed tilt. But the fuse is perpendicular to the matt or paper. Note: a stab tilt is very vital in gliding. A little less stab tilt is better than more. Aim for the 1/32" tilt.

Once you have confirmed everything it is time to glue the stab.

Now make two or three swipes on the fuse where the stab will be installed with the glue stick. Not too much, at all.

The glue stick gives you ample time to position everything back together and re check all alignment, tilt etc. Now put a drop of feviquick on a tooth pick and apply it to the LE and TE of the stab on both sides of the fuse. Give it 2 minutes to cure. Once cured, remove from board and apply feviquick to the remainder of the stab only after you , yes, reconfirmed all is attached correctly.

Your stab is now installed with the tilt. So now is the time to tie a thread to the nose and install sandpaper grip to the back end of the fuse. The tread is needed so the launch hook does not detach after so many flights. The sand paper is needed at the back to give you a consistent launch. Apply feviquick to both the thread and the sand paper to attach / Again use sparingly with toothpick, enough but not too much.

So this is how it looks when complete.

Now we need to put the 1/32 left on the rudder. So take your matchstick and cut it with a new sharp blades. You can make the tab as 2mm wide, 7 mm long and 1 mm thick. Do not cut longer than 7 mm as it will give you issues in trimming. Glue it to the left side of the bottom of the rudder with a GLUE STICK ONLY as it may have to be modified later. You need this tab on the left side to hold the launch angle to the top as soon as you let it go with rubber band.

Picture: Black marks show dimensions and location

Tomorrow we will complete the glider.
Please give me a feedback :
a) ok
b) too easy , I knew it all, waste of time.
c) helpful?
d) any other feedback, please

modified thread reply #66

A CLARIFICATION

STAB TILT

I had not mentioned this so far, as in the initial stages I feel it is more important that the tail parts are perpendicular to each other, than to incorporate more advanced features.

However, since it has been mentioned, let me explain.

Stab tilt means the stab is installed on the fuselage with one tip higher than the other (say 1/8” for this size). It makes the model turn towards the higher tip during glide.

Normally we would use rudder to turn (in a model without ailerons)
This works ok on a chuck or hand launch glider.
In a catapult glider, the launch speed is several times the glide speed.
So the rudder offset required for turn in the glide has excessive effect at launch speed.

What we need is a method to have a turn in the glide without excessive turn at launch.
This achieved with stab tilt.
In the glide, the speed is low, so to remain aloft, the model flies at a high angle of attack.
Actually the model is in a more or less horizonal attitude. But because it is descending, the airflow is not head on, but slightly from below. When this upward airflow hits a tilted stab, it produces a small sideways component. A stab with left tip higher will move to the right, causing the model to turn left.
This is used for turn during glide.

In the launch, the speed is high, so the model needs only a small angle of attack.
The airflow is therefore nearly head on, and the sideways effect of the tilted stab is negligible.

In a nutshell, stab tilt is a way to have a turn in the glide without excessive turn at launch.

 As Mr. Iyer concludes "In a nutshell, stab tilt is a way to have a turn in the glide without excessive turn at launch.".

So, in a CLG, rudder is effective during launch at high speeds and stab tilt is effective at low gliding speeds. So the piece of ruder tab cannot be too big. The dimensions given are first guess. Hence stuck with glue stick, not CA. You may have to modify it.

In a CLG, to glide well in circles (turn) , it has been known not to depend on the rudder as it can lead to spiral in.

Wing Dihedral is very vital, make sure you get it exact. your dihedral angles are already made by Mr. Iyer.

Lay the the two halves very close on a tape. Make a carboard piece three inches tall. Before adding any glue just move one half up and assure that it bends to exact 3 inches while the other is flat on the table. I would tape the flat piece so it does not move on you.

At this time please observe that when you prop the the wing halves together at 3", THERE is no visible gap between the two halves which will now be glued. They must mate to a single joint, see photo below.

When happy glue the leading edges and trailing edge with CA and make sure the upper half is still sitting at 3 inches. When satisfied, glue the mid portion of the wing and let the CA cure for about 2 minutes. Your dihedral is complete, gently remove the tape from the wing

Photos:

Now we have to install the wing onto the fuse. But your wing has a V shape and needs to be glued onto a flat fuse. So tape a nail file on the table and move the wing gently back and forth on it to produce a flat at the V. Be gentle and check several times that you are not removing too much wood. You just want a flat that you can feel on your finger tips. Go very slow on this step and check often. The photo below may give an illusion that on half of the wing is flat on the table. Both halves are off the table, you sanding with the wing perpendicular (straight up on the V ) on the table.

Producing a flat:

Now comes a very vital gluing of the wing to the fuse. Trace the fuselage on a thick carboard. NOW is the TIME to measure the fuse height ( from bottom to top) where the leading edge and trailing edge will be glued. They must be EQUAL. If at all, the trailing edge maybe a bit lower than the LE height, BUT not by much, a difference about the thickness of a hair. In no case the fuse height at LE on the fuse be higher than TE height.

Add 1 and 1/2 inch to the traced fuse (dihedral is 1.5 inches on each tip). Cut out the template, then cut it at the center so you get two, one for each tip.

Make sure the fuse is again taped perpendicular  to your flat building board or mat. Use a glue stick and rub it two or three swipes on the the fuse between where the LE and TE will be glued. Mount the wing on the fuse. Use the toothpick method to put CA on the TE and LE of the wing. Let it cure. See photo below

A GOOD TIME TO CHECK AND MAKE SURE THAT THE DISTANCE BETWEEN THE WING LE AND STAB TE IS 3.5 INCHES.

Mr Iyer has already marked these on your fuse.

Photos:

After the glue is set at the both the LE and TE , remove the glider from mat. Now put CA at the remainder of the wing from the bottom. This is called fillet,  Your glue stick glue should hold the wing correctly.

Now the time has come to install the Washin on LEFT SIDE OF THE WING ONLY.

From your good match sticks cut a piece gently that is 2 cms long, 2 mm wide and about 1 mm thick. Use the glue stick again and glue it away from fuse at a distance of 6 cm from the fuse. Again, vital that you use the glue stick as it may have to be modified in the trimming and gliding phase.

Balance the plane.

Mr. Iyer has included (I think) a pin with a thread on it. Pierce the pin at the CG location which is exactly 1 and 1/8 inch from the wing TE. Take a bit of clay and roll it into a cylinder. Place the clay on TOP of  the fuse nose. Add and subtract as needed small amounts of clay so that the glider balances with a slight nose downwards about a couple degrees, NOT Much more that.

This is also the time to assure that one half of the wing is not heavier than the other. If the left side is slightly down, that maybe OK. If the right side is heavy make a note of it. I am sure it will balance horizontally from wing tip to wing tip flat.

It is important that you put the clay so that it does not touch lower end of the fuse. During gliding and testing or even normal flying, when the glider touches the ground, the clay will either pick up dust  or rub off and you will wonder why the glider is no longer flying correctly.

Also, adjust the CG by putting the clay a bit behind the nose as seen in the photo. During glide test adjusting, if you need more nose weight, just move the clay 1 mm forward each time. If it dives, move the clay 1 mm in each step to the back. This way you are not guessing how much is too much, add or subtract. Adding and subtracting clay can be a frustrating experience, but here you are just moving the clay pillow back and forth.

Congratulation.

You have now completed building your glider with the stab tilt, washin, rudder off set and correct CG.

Next we get into gliding and trimming.

Hope you took the time for your build and measured each critical dimensions correctly and that using the glue stick and toothpick for CA initially has helped you to get a light and true plane which will be easier to trim and glide.

PS : Resist the urge to glide the model inside your house. You will ding it or worst break it.

You can wrap around clay with cello tape to keep clay in place  even during hard landing.  You can do this after you are satisfied with the balancing.

@ Dreamliner: Excellent idea and a  good point. That will definitely do it. But we are trying to keep overall weight down and fewer parts too.

My glider took 0.5 grams of clay to balance it. So very small quantities will be needed in Mr. Iyer's kit.

CLARIFICATION

In elucidating the build process in detail, some new issues have gotten introduced, that I had not mentioned earlier.

So let me put the concepts into a logical sequence.

1. For a newcomer to the hobby, a chuck glider is the most inexpensive introduction
2. It should be based on a known successful design
3. A kit is easier than building from scratch
4. An ARF kit saves the newcomer a lot of work, and can be ready in a few minutes

My kit meets these criteria.

Now we come to assembly, which involves:

5. Sticking the wing halves together at the correct dihedral angle. In the kit, the joining surfaces have already been sanded to the correct angle. And the wing halves are temporarily taped at the bottom. All that is required is to keep one panel flat, lift the other tip 3”, and glue the joint.

6. Attaching fin to fuselage, ensuring that it is upright and dead straight. Already done in the kit.

7. Attaching the stab to the fuselage. I’ve recommended that it be perpendicular to the fuselage/fin.
No need for stab tilt at this stage. (More on this later)

8. Attaching wings to fuselage.
You can sand a little flat at the bottom of the wing centre, to increase the contact area.
Align the wing centre line accurately with the fuselage (ie, centered on the fuselage and trailing edge perpendicular to fuselage.
Glue initially only at leading edge and trailing edge with small drops of Feviquik.
Check alignment.
Then run a bead of glue down the bottom of the wing fuselage joint.
I had suggested Feviquik, but due to lack of contact area, Allfix (from Fevicol) or Fevicol may be better.

9. Balance. Stick a pin into the top of the wing centre 1.75” back fromthe leading edge, same as 1.25” ahead of the trailing edge. Add nose weight (with clay provided in kit) till it balances level.

Now its ready for a test glide

Next: How to test glide

Much later: use of trim tab wedges, stab tilt, washin etc.
As these are things that come into play only after the test glide is satisfactory.

 

Hi all,

Very comprehensive and clear build and trim instructions by Free Flight and further concept elucidation and applicability of instructions to the kit by KK.
I learnt quite a few things too regarding CLGs.
It can't get better than this.
And this is what any forum should be about - sharing expertise and experience.
Reminds me of how I was struggling in getting even 15 secs on rubber powered models - and was the mentored by Bill Gowen - one of the masters of indoor on the Hippocketaeronautics forum - for almost 4 months -  at the end of which there was that eureka moment when it all came together.
Kudos to KK and Free Flight.
I sincerely hope this effort triggers at least a few to delve deeper into HLG and CLG - which is a world by itself.
Regards

Wow! Learned a LOT ! stab tilt , washin etc ... - new insights . Very thankful  for properly guiding us .

Thanks Glidiator and S174 for the your kind words. So let's have fun flying this plane.

I have made an assumption (sorry) that all of you are right handed. If you are left handed, your changes will be the opposite. Right and left as discussed  are from the pilot's point of view ( In any model flying). Assume you are the pilot sitting in the cockpit facing the nose. Your right is the glider right.

In a CLG flight there are 3 steps :
1) The launch with the rubber band that goes at extremely high speeds. Small wraps will have a distinct effect here.  This called the launch phase.
2) Once the glider reaches to the top called apex, it will slide its left wing down ( so called roll out) . This called transition.
3) Start gliding at a much lower speed. This the glide phase.

So how does this all look when all is said and done. See my video below. When you play it on Youtube, go to "Full Screen" and in setting put the "playback speed" at 0.25 lowest setting and watch the short video. You will see the glider shoots up to the right , transitions or falls on the left wing level and starts the glide with left turn. All this WITHOUT loosing height. That is vital

This called a right-left CLG flying for a right handed person. For a left handed person it will be a left-right CLG flying.

PS : Notice in the video that the bottom of my wing is colored BLACK. This so that it stands out clear in its attitude against a sunny sky. The red color on top of the wing is so that it visible clearly on ground and I can find it. Do not go heavy on the color , just smartly with a non water based marker pen. Keep that weight down on the glider.

https://www.youtube.com/watch?v=xt5lFggMzJs

Hold on guys. One more step before you go out for the glide test. At home, check once again that :
1) No warps have been introduced in the wing, stab and rudder
2) Balance on pin and thread. Assure the CG is correct !

Now make a small box to carry : a) extra clay b) Feviquick and a GLUE Stick for sure , c) small match  sticks already cut in similar dimensions as in build d) An extra set of rubber bands e) The nail file or sandpaper on a popsicle ( ice cream) stick. I would advise you carry the plane to the field in a box as I have broken it once just carrying it to the field . Very upsetting.

Pick a good place to fly. Prefer a good open park with few or no  trees.  The field must be grassy, not concrete, gravel, stones or black road top (asphalt) . Our planes do not like hard ground to come down upon. I only know Mumbai. So I would go to either Mahalaxmi race course, gym khanna grounds, Azad or Oval maidan ( next to the university tower) or similar places.

Finally, pick a very calm day, hardly any wind. Your first glide test must be in the late evening . When you get to the field, drop a leaf or bundle of grass from the ground from shoulder height. It must fall within 4 feet of you. Note the direction in which it fell. That is where the gentle breeze is coming from. You WILL LAUNCH directly into the gentle breeze.

A free flight pilot must develop to be patient. I watch the weather everyday, when it is calm , I pack my box and go to fly.

READY ! Let us go.

The Glide Test :

1) Face the breeze to test glide, i.e., launch the glider directly into the wind.
2) Raise the glider to eye level , so you can see that you are launching it at a correct angle nose down and WINGS LEVEL..
3) Aim a point about 30 feet away from you and push the glider gently with your arm , do not flick it with your wrist. PRACTICE.
4) When launching make sure that the nose is VERY slightly down , definitely not up.

If all goes well. you should see that the glider is " floating" down gently and perhaps a little turn to the left. As you launch it gently the glider will perhaps raise it nose VERY slightly as it is going forward.  That is good, means you have enough decalage (more on that later).

Your glider should land about 30 to 40 feet away from you. Less is not so good, but longer means your glider is very close to being ready for launch trims.

If that happens, you have successfully completed your test glide. It has never happened to me ever on the first glide even though , say, I have built Tich CLG about 5 times in my life.  

NOW : Very Vital :  Do not make judgements based on a single glide. Repeat this test glide , I do it 5 times, each time expecting the same glide pattern. Do not make changes based on a SINGLE GLIDE. Moreover, make only one change at a time. Else you do not know what worked or if the change was correct or ENOUGH.

Attached below is the link for Glider testing. This one is for the indoor CLG ( Where the indoor guys call it ELG or Elastic Launch Gliders) and they fly Right-Right. We want a left turn as we will fly outdoors RIGHT-LEFT pattern outside.  But the video  shows what a stall is, what a dive is and why.

In this Video They adjust wing differently than we will. Plus you have no Stab tilt as instructed by Mr. Iyer. Your left turn will be adjusted by a clay on the left wing tip. DISREGARD those parts of the video.

https://www.youtube.com/watch?v=8SmWT-5Ypbs

So like me, you did not get a perfect glide. That is OK.

1)If the glider stalled , add a bit of clay to the nose , each time about the size of a pin head. ( Remember : Patience Development). If you used my technique in the build, slide the clay to the front to the nose, about 1 mm at a time. Each time confirm the glide, that is you made the correct change and got the same response several times.

2) If the glider dived, remove a small bit of clay (again about a pin head) and re establish the glide.
 
3) It is diving to the right or left at once. Not good. Talk to us and we can have another discussion on that.  Probably a warp has developed mainly at the rudder, rarely at the wings as Mr. Iyer has doped and finished your wings. ALSO CHECK : Make sure that the WASHIN wedge we put on the left wing with a glue stick has NOT FALLEN OFF.

Now our glider needs to have a gentle LEFT turn as we fly Right-Left. This will be achieved by putting a very small amount of clay on the lower side of the left wing tip. Start with about 2 pin head size and re establish the glide. At the end of say 20 to 30 feet are you getting a gentle left turn with a nice floaty glide?

If the answer is yes Congratulations on the GLIDE Test Part.

Please note : GLIDE Test is essential to move forward. But a good glide test is only the beginning and NO GARUNTEE that the CLG will fly good. So next we work on the launch Phase. More on that tomorrow as you digest and practice this. 

So all said and done this how it all looks: Turns gently to the left at a distance of 30 feet from your launch.
If it turns to the left to sharp, remove clay from left wing tip that you put to create the turn. Not enough left turn, put a pin head amount of clay more at the wing tip lower part.

CLARIFICATION- TEST GLIDE

Getting complicated? Let’s simplify.

Freeflight is helping you set up for circling flight, which is the ultimate objective. Else it’ll fly away.

However, one of my objectives is to introduce newcomers to setting up a model for straight flight, before anything else. Because many of them are building electric powered depron models with RC and having problems due to not getting the fundamentals right.

Let’s get to the test glide.
What is it for?
To ensure that it flies straight down the glide slope, neither climbing nor diving, neither turning left nor right.

Glide slope? What’s that?
My prototype Lunchbox, launched from eye level (5’ or 1.5m) goes about 22’/7m before landing on the sofa (1.5’/0.5m)
So it goes 7m for 1m drop in height, or L/D of 7.

If all is well, from an eye level launch, it’ll go 30-35 feet.

Hold it under the wing a bit behind the CG, or a bit ahead of the wing trailing edge.
Point it at a point on the ground about 30-35 ft away.
And launch it.

But at what speed?
Slightly less than what you’d use to throw a marble (kuncha) the same distance.

If you have balanced it fore and aft at 1.75” behind the wing LE, this is what will happen:

1. It climbs above eye level. Either launched nose up or speed too high
2. Dives and lands too soon. Launch too slow
3. Correct launch speed is when it doesn’t dive, and doesn’t climb above eye level

4. If it still dives, reduce nose weight
5. If it noses up, and then dives, add nose weight
6. Adjust nose weight till it flies down the glide slope.

Meanwhile it may turn left or right, due to slight misalignment of fin, or because the wing is not centered on or square to the fuselage.

If the turn is drastic, you’ll have to recheck the alignment of the fin and/or wing

If the turn is mild, let it be, for now.

At this stage you should get a 3-4 second flight going straight or a bit to one side, for 30-40 ft

I’ll tell you more when you cross this stage.

@freeflight

Please delay catapult launch techniques till I’m done with test glide and hand launch.

Only 4 have received kits.
5 more being despatched tomorrow, so they won’t be ready to fly till the Sunday after this.

So a week of lull, perhaps

Regards

Mr. Iyer, Will do.

I am busy till next Tuesday anyways, so this helps.

Iyer sir , let him complete it in a stretch . All basic lessons in one thread ! And I’ll bookmark this page forever ! I think I’ll carry my training  with this glider even after this competition is over . So we will read his posts and yours and go forward . I missed my chance for the stab tilt this time because I had glued mine before reading his post on that .

@Freeflight,

1. I’ll try to make a short video on test glide trimming. That will conclude the test glide phase.

2. After seeing your catapult launches, I doubt if there’d be much interest in hand launch. So I’ll defer that.

3. Rest of the kits sent, and should arrive in 2-3 days.

So it would be great if you can continue with the catapult launch guidance during this weekend if you have the time.

Regards

Dear Iyer sir,

Definitely will do. Seeing both my kids who have come home after a very long time, so busy this weekend. Will start again as soon as my Sunday evening comes along.

Thanks for making the glide test video.

Best Regards,

@Freeflight , please post a video of hand launch of your glider and the trimming you do . Thanks.

@ S174. Will make a video of my test glide and the launch. Will show the launch angle and bank very close. This week it is very cold and extremely windy (gust up to 25 mph) . So the first chance to make a video is Friday or Saturday this week.

Regarding your request for hand launch the glider. Since a few years I am launching with rubber band only as my arm gets pain after a few flights. But you youngsters should definitely try it. Before that, go to the gym and work up your arms. You need to give it a massive power launch to get the glider up about 100 feet.

 Ok , before we go for the first launch, re check that a) Glide test is correct , in the sense when you point the glider a bit down and do a hard push, your glider will raise it nose and then go into a nice (not sharp) left circle. b) CG is correct c) no warp has developed in the wing , stab and rudder.

Preliminary rubber pull test : Before you actually catapult the glider (for a right handed person), hold the glider by its tail, hook the rubber at the nose, holding the launch stick in your left hand. Then assure that  the nose is  level to the horizon/ground  and assure that the wings are horizontal, not banked. Pull back only about 1 to 2 inches and let go. You should observe the glider at first raise its nose and turn gently (not sharp) to the the left.  It should not stall, dive or spiral in. If it does any of the the stall/dive/etc, go back and restart the glide test. DO NOT PROCEED WITH A FULL BLOWN LAUNCH  TILL YOU SEE A PERFECT GLIDE FROM THE HORIZONTAL LAUNCH.

Finally : The CLG Launch: there are three parts to this flight:
1) The Launch phase, will take around 2 seconds to reach the top maximum height. Here you launch with the nose high (about 70 degrees from the ground/horizon) and the right wing banked towards the ground.  
2) The Transition : You are launching the glider nose up (called the launch angle) and the right wing banked to the ground (called the bank angle). It is banked to compensate all the things you have built-in  to turn gently left, stab-tilt or small clay on the left wing, rudder off-set tab to the left and the washin-in wedge on the left wing. Once the glider reaches the top, it will do a half roll (meaning, the left wing will drop to level) and the glider should not loose any height.
The transition is fast, blink of an eye, shortest of all three phases. (you colored the bottom of your wings black, yes?).
3) The glide phase to the left. All your glide test hard work should pay-off now. This is the longest phase. (you colored the top of the wing red or orange, yes? to help you find it on the ground)

Analysis: So from your 20 second flight, you have about 2 seconds to reach the top, fraction of a second to transition, then the rest 18 seconds are in the glide phase. If you luckily happen to "pick the air" (means you launched it in a thermal) the glide phase will be much longer and maybe perhaps loose it out of sight (OOS) or your offering to the Thermal Gods (Hoong).  

See the diagrams below.

The Flight:

A Video Paints a Thousand Words:

I am posting a link to J&H  trimming video. Best trimming video I have seen ( though many good ones out there).  Couple thing: Your launch hook is behind the stab not below, he talks about lead, you have clay. See his analysis : Hand glide, then horizontal rubber pull, then the banked launch. He shows transition very well and what to do when it is not exact. You did put sandpaper at the tail for consistent launch, yes? Consistent launch is the key. Once your glider is flying correctly, write down on the wing the launch angle and bank angle.

Observe his launch angle and bank angle. Yours will be similar not exact same, but not too far either. You need to experiment with both the launch angle and bank angle. If you build 2 gliders at the same time, their angles will be slightly different.

He also shows you how to make and attach trim tabs (Remember: matchsticks, blade, glue stick etc.)

https://www.youtube.com/watch?v=meOx8_TSsnE

Next thing I will do is post my video of the Lunchbox. We will go through trimming situations there. After that I can post cause & effect table : If the glider does this look for that etc.

Please let me know if all of you are in the build phase, and ready for the glide phase.

Build light, but enough glue to be strong and build it accurate.

Take your time, please ask questions that you may have.

Please remind me later to go through the discussion as to things like :
a) Do I adjust CG or give more elevator?
B) Should I give less rudder or more washin ?
c) My favorite (took me a while to understand), my glider launches great, great transition but always flies straight, no turns. I have a rudder off set. What gives?  

Is this okay ?

 I feel there is a slight stab tilt correctly on the left side (right side of photo). If so, then it is good.  Looks like a slight gap between the wing and fuse. May want to assure you have enough CA there so it does not come off. What is the weight in grams?

Looks good for sure.

PS: Looking forward to see everyone's initial photo.

@Freeflight , initial weight ( without clay ) 7.6 gms. There’s not much tilt , even if ; it’s meagre :( . There was a minimal gap bw fuse & wings , but applied enough CA and it’s well bound now .

@S174: My first one weighs 7.2 grams that includes clay nose weight. Your glider will have good penetration in the breeze, it will not be easily blown away. However it will glider much faster. As the glider spends most of its  time  in the glide phase, your challenge is to get the glider as high as possible with a good transition, that is no loss in height at transition.

A meager stab tilt to the left  (left stab higher) when viewed from back is better than more. The plan calls for only 1/32" of tilt, very small.

How is everyone else doing? Any photos to share, please? weights?

@dreamliner,

Received kit?

@S174: contacted a couple of my free flight friends. They clearly recall loosing the Lunchbox a few years ago at 8 grams flying weight. Catches thermals well at that weight too. You should be ok.

Ok, thanks for the comforting words .

Since Freeflight is providing most of the input, what can I contribute?

Instructions in HINDI, as preferred by some!

TERMS
1. LE, leading edge, wing ke aage ka kinara
2. TE, trailing edge, wing ke peeche ka kinara
3. Fin, poonch ke oopar ka hissa
4. Stab, stabilizer, poonch ke neeche ka hissa
5. CG, centre of gravity. Jahaan balance karna hai
6. Trim tab. Tikoni dandi ka 1-2cm tukda. Flight ki disha modne ke liye. Aur mudhe samay andar wale wing ko sahaara dene ke liye
7. Trim. Ichcha anusaar udne ke liye adjust karna.

TEST GLIDE
1. Model ko CG aur TE ke beech neeche se pakdain
2. Model ko aankh ki level pe rakhain.
3. Fursh par lagbhag 30 ft ki doori pe nishana lagayen
4. Yaad rahe ki model ki naak uupar ki aur na ho, thodi neeche.
5. Ek kanche ko 30 ft phenkna ho to jidna dum lagega, usse thoda kum dum lagayain.

Seedha 25-30 ft gaya?

Nahin gaya to batayen ki kya hua.
Phir elaj bataunga...

Can’t understand why Dreamliner has not received his kit, sent on Monday morning.

Everyone else has received.

Since assembly needs only 5 minutes, hope everyone has assembled their models.

So far, only seen SI74’s pic.

Look forward to build pics and testflight videos. Over the weekend perhaps?

Very good sir i like, i hope also some one like in hindi  :hatsoff:

Aapne bahot sahi tarike se samjaya he
Thank you sir

@Freeflight:  Your efforts are appreciable.  {:)} I didn't knew that a chuck glider needs so much trimming. 
Good that I haven't started assembling my glider.  I am totally new as far as chuck glider is concern.
Thank you for your guidance and keep it up.

Will post pictures of my "Lunchbox" soon.     

@KK
What have you used for doping the parts?

Being more in indoor ultralight rubber -- have never needed doping ..
Regards

@WeekendFlyer. Thanks and you are welcome.

Looking forward to everyone's photos and videos.

I see everyone is building. So yesterday I made a trimming video even though it was very windy. You should do all your trimming , glide test etc.  in no breeze conditions, probably late evening.

Anyways, this is a raw video. But I have tried to explain all the key concepts.

Once you think you are ready for the catapult launch, play with the launch and bank angle. One combination of the launch and bank angle will be correct for your glider. I cannot predict it for you are myself either. This is called trimming.

Video Error: in the bank angle, I kept saying 45 degrees, but did a 90 degree angle. Sorry, my error as I was trimming the second glider at that time. So try a 70 degree launch angle and 45 degree bank, not a full bank as shown in video.

PLEASE ASK QUESTIONS. I have gone over the basics in the build and trimming. But when you ask questions, I can hopefully answer them and you can start enjoying the CLG.

You have got an EXCELLENT kit from Mr. Iyer. As they say, I fully suspect that your glider from his kit will fly right of the drawing board.

https://www.youtube.com/watch?v=GOjHBd875FQ

Once upon a time in India you could get Dope from India’s Hobby Center

Thereafter, NC Clear Lacquer, usually Duco, from car painters.
The key is to use Duco NC thinner, not hardware store thinner, which is apparently methanol+water!

Ok , thanks for the video . So for a hand launch , are these (same) angles that should be followed ?

@SI74,

In case you haven’t seen my Aug 2018 post in the ‘1st Chuck’ thread, here’s a copy:

On reaching the second test of Chuck Glider flying,
Having crossed the first test (finding an approximate CG and getting a smooth glide of 30-40 feet, without stalls and dives). You did pass that test, no? Else you return to stage one!

The second test, or stage, is how to avoid looping in a full power launch.
This has two parts
How to launch
How to avoid looping.

The launch for the first stage is from shoulder height, model held just behind the CG, nose pointed slightly down, aimed at a spot on the ground about 50’ away, and pushed gently straight, without your hand describing an arc.

The power launch is utterly different except for holding the model at the same place, ie, just behind CG.
(I’m assuming you are right handed)
Hold the model lightly.
Keep your wrist loose. Don’t cock it.
Swing your LEFT hand up about 45degrees, while swinging your RIGHT hand down as low and as far back as you can.
Are you holding the model loosely? Is your wrist loose and not cocked?
If so, the model should be banked RIGHT A LOT MORE THAN 90 degrees and pointing UP ~45 deg.
The action is like a discuss throw.
NO ELBOW BEND. ALL JOINTS OF RIGHT HAND LOOSE, FROM SHOULDER TO FINGERS.
Stand facing the wind, wind up your torso till your left hand points into the wind and 45 deg high.
The right hand will be more than 180 deg away, behind your back.
To launch, swing your whole upper body hard left, release the model when your right hand is about horizontal. At release the model should be banked right about 45 deg and pointed up about 45 deg, and going a little to the right of the incoming wind..

This is the way to launch, and enter the second stage of how to cure the looping!

Ok , got it . Thanks.

@SI74,

How to cure looping in full power hand launch

Since it is premature to discuss this on this thread, I’ve sent you a PM.

Will discuss on this thread later, after everyone has crossed the test glide stage...

Thanks. Will try that
Regards

Just popped by to see how things were and the first thing that I see is this beauty of a thread!

@VC,
Welcome back.
Nearly 2 years since your last post.

See the ‘Next Contest’ thread.
Look forward to your entry as an honorary participant with your Flika perhaps?
Or maybe there’s even a Lunchbox in your fleet...

Warm regards

A few very short videos of test gliding the Lunchbox...

https://m.youtube.com/watch?v=gl8G5B6bWc4

https://m.youtube.com/watch?v=ubP_c3xXkR4

https://m.youtube.com/watch?v=aEVDaUkwPmc

https://m.youtube.com/watch?v=6axuWiRiTLA

Got a surprise today.
A participant was unable to get his test glides right.
Because he was trying for 10 seconds, not realising that the test glide is only meant to get the model flying correctly

I think this is a result of too many instructions too soon.

And is the reason why no test glide posts are coming.

Please, folks, do your test glides, and get it to fly 20-30ft straight with no climb or dive, and maybe a slight turn.

Please see my test glide videos, and copy.

Yes, I too thought so initially! That was why I repeatedly asked how to do a hand launch ! I too was looking for 10 sec flight during test glides ! Thanks Iyer sir for the correction.

Yes, there are three separate stages.

1. Test glide from shoulder height, slightly downwards and not fast, to a point 20-25 ft away on the ground. Flight time 2-3 seconds. Please see my test glide videos.

2. Full power handlaunch, for those want to take advantage of the multiple allowed (10 second hand launch equivalent to 20 second by catapult). Instructions below (*)

3. Catapult launch (see instructions/videos by Freeflight)

* Hand launch
I’m repeating contents of an old post on my ‘1st Chuck’ thread.

The launch for the first stage is from shoulder height, model held just behind the CG, nose pointed slightly down, aimed at a spot on the ground about 50’ away, and pushed gently straight, without your hand describing an arc.

The power launch is utterly different except for holding the model at the same place, ie, just behind CG.
(I’m assuming you are right handed)
Hold the model lightly.
Keep your wrist loose. Don’t cock it.
Swing your LEFT hand up about 45degrees, while swinging your RIGHT hand down as low and as far back as you can.
Are you holding the model loosely? Is your wrist loose and not cocked?
If so, the model should be banked RIGHT A LOT MORE THAN 90 degrees and pointing UP ~45 deg.
The action is like a discuss throw.
NO ELBOW BEND. ALL JOINTS OF RIGHT HAND LOOSE, FROM SHOULDER TO FINGERS.
Stand facing the wind, wind up your torso till your left hand points into the wind and 45 deg high.
The right hand will be more than 180 deg away, behind your back.
To launch, swing your whole upper body hard left, release the model when your right hand is about horizontal. At release the model should be banked right about 45 deg and pointed up about 45 deg, and going a little to the right of the incoming wind..

Please ask all the questions you may have. Enjoy flying the glider and best wishes for the contest.

I am yet to fix the CG, but here is a time lapse of the complete build process. Will share proper build video soon.
https://youtu.be/oVfOjtepiBM


Sent from my AC2001 using Tapatalk

My glider is almost ready. 
However, it seems tail heavy, will have to put more weight on nose to balance it.

Any suggestions ????

Obviously so, as there’s more wood behind the CG than ahead of it  ;D

That’s why plasticine was included for nose weight!

If I put more plasticine the overall weight will increase.
Please guide me. 

@Weekend Flyer. Will not increase by much. CG is very vital to make it fly.  I had a Lunchbox at 8 grams, no issues in a good flight.

Great photos and videos. Enjoyed seeing them. More to come,  I hope.

It’s not extra weight, it is necessary weight.
Can’t fly till it’s balanced.
Please put plasticine on the nose till it balances at 1.75” behind the leading edge of the wing.
This is the starting point for the CG.
As you do test glides, the nose weight may need to be increased/ decreased slightly.

1. Please balance as suggested.
2. Please test glide as suggested. These will last 2-4 seconds only. They are not full hand launches.
3. See my test glide videos, and copy how I launch, with the nose pointing down to the ground about 20-30 ft away, and slow enough to avoid climb at launch.
4. See test glide videos of Hitesh Kher and Karthick. You’ll have to share your phone number with them to see their videos on Whatsapp

@Weekend Flyer brought up a good point to discuss. the topic is Wing Loading.

Wing Loading = Weight of glider in grams divided by the wing area in Square inches. For almost all free flight models , one needs to build light so we are below 0.5 grams per square inch. The experts here go to 0.4 grams per square inch, but not lower than that for outdoor planes.

A very rough calculations on Lunchbox gave me 13 square inches of it's wing area. Please someone check my estimate, I could be wrong. So at 8 grams it gives 0.6 grams per square inch of wing loading. Not too far, for a first time builder, pretty good.

Another point, start with CG location shown on the plan. That is where the designers recommends to begin with. My two Lunchboxes, one is right at the location, other is a 2.0 mm ahead of the shown. You have seen my videos. Both fly well.

Use the technique Mr. Iyer suggested and get the glide correct. See his videos to make the point clear. You may then have to add or subtract clay to get the glides he shows.

Looks like Mr. Iyer and I had same thoughts, posted together. Nice.
Would love to see your videos. Can you guys post it on YouTube? Or can we make a WhatsApp group. Call it "ILC" : Mr. Iyer's first Lunchbox  glider contest for beginners in IN.

@KK Iyer: Thanks for all your instructions.  I have flown towline glider and have idea about the glide test.  I think it is more or less same with chuck glider.  Will go thru the test glide phase tomorrow.

@Free Flight:  Thank you.  I have built (to say correctly, "assembled") this chuck glider, not only this, a chuck glider for first time and this was just a sort of challenge for myself. But its good to learn new skill.  But more important is that the guidance ("that too FREE") we are getting thru this forum.

Thank you all.

Did some test glide of my glider.  But the flights were in afternoon and also, there was little breeze, which was affecting the glide. 
So postponed the test glide till evening.
Sorry no videos captured, as I was all by myself.

The glider was flying well and am getting flight time of 2-3 seconds but its banking right.

Will try out after warping the rudder / fin a little bit in the opposite direction.

See you later !!!

In the Whatsapp videos sent by Hitesh Kher and Karthick, the models dived downwards despite being balanced at the specified position. Subsequently cured by adding a small tab/wedge for up elevator.

The culprit is (lack of) decalage.

Decalage is difference between the angles of incidence of the wing and stab.

1. Zero zero when both are parallel (pic 1)
2. Positive when wing is at higher incidence than stab (pic 2)
3. Negative when wing is at lower incidence than stab (pic 3)

Negative decalage is like down elevator and makes the model dive despite correct CG. Reducing nose weight will not cure it. This is what had been happening with your models.

My experience is that a small amount (< 1 degree) of positive decalage is required for longitudinal stability.

Freeflight once mentioned to me that he uses zero zero setup. Probably adds a small up elevator wedge.

@WeekendFlyer : "The glider was flying well and am getting flight time of 2-3 seconds but its banking right.

Will try out after warping the rudder / fin a little bit in the opposite direction."

Very Good. Now that is a step in the right direction. I am glad that you made a decision to fly later when the breeze is not there. Very good.

Notes:
1) the photographs posted above by Mr. Iyer are terrific. Clearly shows the concept . Please ask questions that you may have.
2) Yes, i do build Zero-Zero. Then I adjust with tabs see photos below. See my video on trimming in the previous page the first full minute where I show my tabs.
3) i used to bend stab, rudder etc. but gave up on it as these bends are not permanent. They can change in as little as few minutes or the next time you go out to fly.
4) I use small pieces of matchstick to make the stab. I glue them on with a glue stick, as it is easy to remove and adjust if needed. Usually i just sand it at the field, if it too big a tab, with a nail file. This becomes a more dependable and permanent adjustment.
5) I have shown examples of my jet glider Canberra. It came out exactly zero zero and need more left rudder. So I put the tabs on the stab to prevent it from diving and a left rudder tab to make it glide to the left. These are very small tabs, about two playing cards thick. The second photo shows tabs at the bottom of my Lunchbox as I had too much positive decalage (Mr. Iyer photo #2).It used to loop so I had to put it on the bottom. If it is diving, put it on top .
6) Please see the video again on reply #111. He shows very clearly as to how he makes the tab and attaches it to the glider. He is an expert, so he uses CA right away. I use glue stick so if I made an error, I can remove it and put a new one.

Kindly requesting again: Can one of you make a WhatsApp group so I too can enjoy seeing you trim and fly. Would very much like to see your videos. Else as I suggested, put it on YouTube.

So much looking forward to your flying videos.

Found some good articles in my box Hopefully it will help you understand trimming better. What to do when ...?
This was for paper glider so he talks about bending. In your case, attaching tabs will be more consistent!

@Freeflight,

I have a small Whatsapp group ‘Iyer’s Young Aero Friends’ but members seem to prefer interacting with me personally rather than in the group.

The problem with putting this Lunchbox build and contest in a Whatsapp group is that it becomes private and is no longer available to others on RCINDIA.

On the other hand, if everyone posts all their test flight on RCINDIA via YouTube, we will be swamped, and end up confusing onlookers.

Here’s a suggestion for a via media:

1. Participants can post Youtube videos here selectively
2. They can send all their videos via Whatsapp to you and/or me.
3. My wife, the RC AUNT, has a Youtube channel - ‘andiyerlko’ where we post all our videos. (Her name is Anandi, and LKO is for Lucknow, where we stayed for many years. Hence andiyerlko)
4. From the Whatsapp videos I receive, I can select the relevant ones, post them on YouTube, and post the link here on RCINDIA.
5. You could do the same, selecting some to illustrate your point.

I’ll try tonight/tomorrow

Regards

Hitesh Kher intial flight, and flight after trimming.

https://m.youtube.com/watch?v=X3ZDIq7YMKw


https://m.youtube.com/watch?v=z3L9-HVxZ5w

Karthick Ashwath, initial flight and flight after trimming

https://m.youtube.com/watch?v=JJvS52cBwEQ

https://m.youtube.com/watch?v=FU6UOKYUt1s

Dear All,
Wonderful guys. great job. So happy and enjoying seeing these. Thanks so much Mr. Iyer for posting.

@Hitesh, terrific glide test. You are ready for the catapult launch. Others: See his video, very nice and try for that glide. Hard push and nice glide. I am not sure if you pushed the glider to right. Try again, but this time push it a little bit to the left. It should turn left.

Also in your first video, it appears that you launched it too high. Keep the same bank angle and launch a little lower. That perhaps will get rid of the stall. Try again and let us see your video. See hand sketch, upper one on reply # 110.
Looks like you are trying hand launch. Work on your launch angle and I am sure you will get a very long flight.

@Karthick: Congratulations. Perfect lunch and bank angle. Very Very good transition You got it. You will hit a minute on this. Couple of recommendations, if I may please. After transition, now is the time to start tuning the glide phase. What it appears to me is that it is diving fast, and too the right. Based on the video , you need to put a small tab on your rudder, left side, you had called it correct. Then try again, as it should make the glider turn left after transition. You want right climb, you got it, left glide. Try it and give us another video. After you get the left glide, if it is still gliding fast, then remove a bit of clay, about the size of a pin head. Keep removing such small amount of clay every time, until your glider is gliding with the nose slightly up in glide phase. I am sure your glider will float.

So happy to see your progress. Enjoy!

Others, looking forward to see your trim videos.
Best Regards,

Wow! Cool ! Congrats Hitesh .

Just got a few videos from SI74.

Will upload on YouTube and post here tomorrow

@S174. Looking forward to your video too.

Quote from Mr Iyer’s message:

"Here’s a suggestion:

1. Participants can post YouTube videos here selectively
2. They can send all their videos via WhatsApp to you and/or me.
3. My wife, the RC AUNT, has a YouTube channel - ‘andiyerlko’ where we post all our videos. (Her name is Anandi, and LKO is for Lucknow, where we stayed for many years. Hence andiyerlko)
4. From the WhatsApp videos I receive, I can select the relevant ones, post them on YouTube, and post the link here on RCINDIA.
5. You could do the same, selecting some to illustrate your point."

Like your suggestion. Contestants, please send me a PM and I will give you my cell number to send the videos. Then we do as Mr. Iyer suggests.

SI74’s test flight progress:

Initial flights - diving

https://m.youtube.com/watch?v=g38dhi7yAXc


Next. Launch too high. Still diving.

https://m.youtube.com/watch?v=iovHC-tZBt4


Then. Correct launch for test glide. Still a bit nose heavy.

https://m.youtube.com/watch?v=SjPUnj5HD-g

Yes sir , I corrected it .

@Glidiator sir,

I know you’re watching   ;D

Await comments

Regards

Found two cans of this stuff while rummaging in the garage. Actually used for sealing watercolor or charcoal paintings. Can be used for crafts also . More important- water repellant.
Used it on trial on a piece of balsa 3sq cms. Original weight  0.10 GM's - after one coat - 0.16 GM's.
Will try it on the lunchbox - parts ready - will be assembled tomorrow.

@S174 : "Yes sir , I corrected it ." yes you did very well. Yes diving a bit.  But good throw and curves to the left.

So for everyone : In his case should he start moving CG back or put just a little more tab on the stab?

You have to think about it. If your CG is at the correct location, I would put a slight more "up" tab on the elevator. See if it cures diving and if it stalls very slightly at that time. If that slight stall is there, go for your horizontal catapult and then full launch up .

your goal now is to dial in the exact launch and bank angle to give you a smooth transition to glide. Then work on the glide.

As mentioned before, you will have to experiment with a good launch angle and bank angle. I would start where Karthick did in his second video.

This is so enjoyable to see you guys succeeding so well right away. You are doing well and you have an excellent kit from Mr. Iyer who did all the sanding and roughing part.

@KK
My connectivity is on  almost 24x7 either thru wifi or direct data connection
Yes have been watching the progress of various participants.
Free Flight and you are doing a great mentoring job.
Too many cooks will spoil the broth.
Moreover my practical experience in CLG is limited.
Will be fun to see how well Iam able to fly the model.
Anant

Something I should share that everyone experts agree.

To get the correct launch and transition, just adjust Stab incidence and rudder left stab, Leave every thing else alone.

Then work on the glide by ONLY adjusting the CG and tail tilt. In the case you did not add the tail tilt, put clay on the left wing to make a smaller (30 to 40 foot) circle. if the circle is too small, put a little clay at the right wing tip, it will open up the circle.

If it spirals (going in tighter circles) to the left in glide, increase the washin tab.

All adjustments made very small. Remember the free flight will develop your patience, not rush hurriedly and make mistakes. Also now is the time to recall that you do not make an adjustment based on one flight. Fly it 4 or 5 times, if it does the same thing, go ahead and adjust.

"Will be fun to see how well I am able to fly the model." looking forward to your flights .

"Remember the free flight will develop your patience, not rush hurriedly and make mistakes"

This is the most important lesson learnt through free flight.
Also one correction at a time so you are sure what change caused what difference in flight.

Free Flight -- Can stab tilt be created by giving a slight twist to the tail end of the fuselage. This is done in indoor rubber where ofcourse the tail boom is very thin and flexible. Though this correction won't be permanent.
Regards

@Freeflight, thanks for the encouraging words .  I was referring to the excess nose weight of my glider, which I corrected. When I sent my test flight videos to Iyer sir , he had pointed out the same . Now I think, will have to do more trimming  ,for a near perfect glide as Hitesh , by your suggestions. Thanks.

@S174: your last video is quite good. I am of the opinion that you need more up stab not CG. Your glider rises a bit when thrown and turn very good left.

Experiment and you will be your own teacher as you gain experience.

All three of you have done very well for the first glider ever in your career of model airplanes.

"Free Flight -- Can stab tilt be created by giving a slight twist to the tail end of the fuselage. This is done in indoor rubber where ofcourse the tail boom is very thin and flexible. Though this correction won't be permanent."

yes most definitely, but your keyword is : not permanent.

But the rest of you guys can experiment what Glidiator suggest. Experiment!

Yes , I am gonna do that .

All has been quite for a while. Eagerly awaiting to hear of your experiences and video ,though videos are a lot of work for Mr. Iyer. Thanks so much, Mr. Iyer. Meanwhile, Perhaps contestants can posts photos, yes?

Hello everyone,this is Karthick Ashwath with a long overdue post.

First of all, thank you to K K Iyer sir and Freeflight sir for giving so much input. (not to mention the kit)  :bow:
The actual build with mistakes and then corrections of alignment took me over 1 hour. But I spent about 45 minutes making the box jigs for the wings.

Now I would like to make a confession. I was not aware that Iyer sir and Freeflight sir were giving guidelines for different launch styles and flight profiles. I thought they were both talking about the same thing and implemented a mix of both in my model. For some reason it flies well.(I implemented stab tilt,but went for a 45 degree launch with no circling during launch). It would have been better if someone had mentioned this.

During the basic build and during subsequent trimming, I made the mistake of using fevi quik everywhere. Now that prevents me from changing decalage for trimming. I also put on my elevator tabs with fevi quik. Then I thought next time will use fevicol. And even that is hard to remove. Should use fevi stick for the tabs in the future as recommended by Freeflight sir.

After the basic build, the model was performing exceptionally badly. So I added some nose weight and did some outdoor hand launches. There I noticed that my launch technique was poor and the model had to correct for it aerodynamically. So I went for catapult launch to reduce the number of variables.

In my first catapult launch, I was holding onto it form the CG and not from the tail. So I damaged the leading edge of the elevator. Beginner mistake. Post that launch Iyer sir recommended that I put some up elevator.

The model started flying very well after that. The maximum test flight time that I achieved was 9 sec.

Here are links to the 1080P version of the videos uploaded by Iyer sir. (Iyer sir's version is so pixellated due to whatsapp file compression)
1.Slow motion videohttps://youtu.be/P9WQ3iQq5Oo (https://youtu.be/P9WQ3iQq5Oo)
2.9 second test flight: https://youtu.be/XyGyc_xAfdY (https://youtu.be/XyGyc_xAfdY)
I have also documented every step of the process on video. If there's anyone here who wants to see the build video do subscribe to my youtube channel. https://www.youtube.com/c/KarthickAshwath/ (https://www.youtube.com/c/KarthickAshwath/)Will upload it there.

Hi Karthick,

Good attempts. A few comments after seeing your good slow motion videos:* This applies to everyone trying to get the fine glide:

1) The building technique between Mr. Iyer and me are different. But the flying technique with a catapult has to be the same. If you are a right hander, your glider should climb to the right and glide to the left. This is the only way to start getting duration.

2) In your first video slow motion, at 15 seconds mark you clearly see that your glider is on its back. You do not want that. Just slight past the 90 degree mark. In your glider you have too much incidence. Reduce it. If you gave incidence by putting a tab, sand it down little each time so that when you launch it it just goes a little past the vertical, not much.

3) Your glider after transition always circles to the right and dives down. The way to counter that is to put a tab giving a small left rudder. If the tab is too much to the left, it will dive to the left. Then take little left rudder tab out, till you get a nice left glide.

4) Keep the same angle of launch and bank. In your first video you have a big launch angle and little bank. In your second video you have low launch angle and too much bank. Try and be consistent. That is one difficult part that needs practice.

Karthick, post a close up photo of the back of your glider as it is now . Then after your modification. Perhaps I can see something to recommend.

Hope you have the washin wedge on the left wing, that helps the transition also while it prevents spiral down in the glide.

Looking forward to see your next video.

Dear All,

There are many great YouTube videos on CLG flying. In the search you can type CLG Glider. Others have shown similar to my methods of trimming and launching. Today I found this great video where he trims and flies a glider that is probably the Lunchbox.

 Most important point: right climb, left glide upon transition to get duration. You can go right and right, but it will be inconsistent flights and if you get a thermal in launch, you may get a long flight. But then, can you do it again?

See S174 video #2 in reply # 161. nice glide and turns left. That is what you want. Also very second video from Hitesh, Reply #155,but he needs to have his glider go the left, not right.

https://www.youtube.com/watch?v=XOJ2Be1WSFw&t=4s

As see in all the experts videos, must do a gentle horizontal rubber launch, slight down. I hope you all have done that and you see your glider go with a slight nose up, turn left and nice glide. let us see your videos of the harizontal launch. We can tell a lot by those videos.

Watch again my trim video on page 6. See the horizontal launch.

Then you are ready for the full launch on rubber.

Print this page and take it your flying field to remember right - left flight. Written by  expert Frank Zaic.

@Freeflight ,Given up tab and left rudder . Is that glide okay ? 
https://youtu.be/m1-lLEW1YLM

S174: very nice: hard throw straight, nose rises and turns left. Good.
Do a horizontal launch, no banking wings,  pulling the rubber about 2 inches. See if you get a similar flight. (may want to see my trim video again on page 6, I think)

If yes, go for the full launch. Start with a 70 degree launch angle and 45 degree bank. do it on a calm , no breeze evening. I am afraid that the glider may get caught in the trees. Can you find a more open space ?

 I am very hopeful for your glider,
Videos soon, I hope? Go for it.

S174: Can you post a close up photo of your trim tabs , back of the glider? Thanks

To all the seniors here who are guiding us here, I have a doubt. When I want to reduce the amount of up elevator that I have implemented in my glider, should I sand it down or should I reduce its area? And should I reduce area through chord reduction or span reduction?
By the way, my glider weighs 9-10 gm now.

Here are some photos of the glider:
https://iiitaphyd-my.sharepoint.com/:f:/g/personal/karthick_ashwath_students_iiit_ac_in/Er0lhxbNO_1Euempr6s9OZUBdboP7pTdUmZ6PGw6W8xwQQ?e=SCP4xq (https://iiitaphyd-my.sharepoint.com/:f:/g/personal/karthick_ashwath_students_iiit_ac_in/Er0lhxbNO_1Euempr6s9OZUBdboP7pTdUmZ6PGw6W8xwQQ?e=SCP4xq)
In one of the photos, the elevator tab is double the width of that in other photos. I reduced its chord by half as it was doing loop the loops. Then realised that it was a Cg issue.
Here's the build video of my glider:
https://youtu.be/x57k6oPaaUU (https://youtu.be/x57k6oPaaUU)
Complete chuck glider playlist:
https://www.youtube.com/playlist?list=PLcliCjJxS5BY6_1q2iCCbGhjDtKtRIsU6 (https://www.youtube.com/playlist?list=PLcliCjJxS5BY6_1q2iCCbGhjDtKtRIsU6)
@Freeflight: No sir, yet to implement washin. Will do it soon.

Karthick: you got the idea. A few suggestions. Keep the original design of spans, chord  . Mr. Oldenkemp, designer of this glider was an expert and many time winner. this is one of his famous glider that has been made around the world.

Thankyou for posting the pictures. You got the correct concept.  I understand now what you are experiencing.

First, your tab is too heavy. Can you instead use a matchstick? Secondly to remove loopiness, cut down the tab  length wise. Cut equal amount on both sides, little by little (as you cannot stick it correctly back again) until it no longer loops. See my photograph of my tab in the previous page, reply 151. The tab is about 4 playing cards thick and only a few mm in length. A light matchstick so thin, attached with glue pen lightly should not affect CG much.

Put the washin wedge for sure. In your case, put a left rudder tab. That should give you the gentle left turn. Based on your previous videos, once you reconfirm the glide and horizontal rubber launch, you too should be good to go.

Keep up the good work. You will get there soon.

Don't worry about the weight now. Your goal is to get it flying good.

PS : See the video I posted in reply # 177 .He talks abut how small the tabs are.

I am using a wooden coffee stirrer for a tab...it doesn't loop now after I added noseweight.

Coffee Stirrer. Yes I had mentioned it before, but that was to make the launch peg bigger, not tab.

Anyways, do not worry, keep it and redo the glide test, followed by horizontal launch and then full launch. Good luck.

Karthick: Just started watching your build video. Bravo, excellent job. So happy to see it. Thumbs up !

Will do in a few days sir..need to travel to flight testing location from build location.

My lunchbox.
Need to go to an open space to do test glides. Problem is open spaces near by are on a height not far from the sea so there is always a stiff breeze. Ideal for slope soaring.
Will have to get up early morning an see if things are calm then.
Weight 5.35 gms
Have attached nose hook after taking these pics.

@Freeflight , This is it . Throw was hard since I was in a hurry :) since it was 7:45 morning ;) . Here last few days it was raining and it’s dark by 6 PM , so not able to shoot . And yes , when I launched it (by hand) stuck to tree and somehow I managed to find it ( very dark by 7PM) If I want to take videos , it should be in the morning , but too sleepy in the morning to get up from bed - and since I ‘ll have to sacrifice my precious evening hours :) then . Most of the large grounds have restricted entry -since school grounds and I am afraid what local people might think of me if I fly early in the morning - here I haven’t seen anyone else flying . That’s why I am waiting for a perfect time to test a full glide . Unlike US , our state is so overpopulated , and plain lands are not easy to find . But I’ll try to take a video of my CLG by this weekend .

 :) Iyer sir , that was quick ! ;)  Point noted .
@Karthink , excellent build video , I wish I had seen this before my build , too good , explains how and what should be taken care of .

It’s afternoon and my Lunchbox is ready for maiden.  Gave less dihedral than recommended in anticipation of better lift.  Turns slightly left on indoor launches which hardly noticeable.  Glides good (perhaps it is amongst the many lucky pcs that will require less trimming).  Will check outdoors.

Still tempted for indoor test flights :) Hard to resist , isn’t it ? , even after @Freeflight’s warnings :)

Yes very tempting - but the wing will surely get dents and dings.

Finally got down to hand launch test flights in a place with no gusting beeeze.
Good floating glide with good low sink rate- no hint of stall . No videos as it was getting pretty dark. Will get some asap.
Tendency to go right in but some chucks some goes left. Was it due to faulty chucks? tab on rudder and a spot of clay on left wing plus wash in.
Will try some horizontal catapult launch and see flight path.

Free flight - your comments will be appreciated
Anant

Thank you for your feedback Sunil sir.

Great amount of  catch up read for me today. Got busy today, so comments are late. Sorry.

S174: Ok I see your tab. that is a very big tab. Usually it is only 0.5 to 1 mm long, 2 mm wide and 1mm thick. Will repost a picture below. This time my rudder tab is colored black in the photo for contrast. That small tab is enough to hold in the launch and put it to start for a left glide. You should put it very close to the end of the rudder, not a bit away from it. If you stuck your rudder tab with a glue stick only, remove it and put one like mine. Then restart glide test, horizontal tests.
The reason  of my asking you to make this change is that if the rudder tab is too big like yours, it becomes very difficult to trim in catapult. Everyone : Moment to observe from S174: At very high speeds, a small deviation like the rudder tab, has a huge , very huge effect. At low speed (glide test) it may  have a deceptive small an effect. Hence all the tabs shown in the original plan call for 1/32" bend. Very very small.  The CLG IS THE  FORM OF FREE FLIGHT FLYING , WHERE YOU GO FROM ALMOST 70 MILES PER HOUR LAUNCH TO AROUND 5 miles per hour in  GLIDING SPEED. Be aware of that.  This rudder stab acts as an elevator in the launch, kind of holding the glider in a knife edge. We can discuss this later, but just take the recommendation. Same on your elevator tab. But I see you did it correct, diving, so put the up tab on stab on the right hand side. Congrats that is a correct move on your part.

Dreamline: Hopefully you have not taken out too much dihedral. Mr. John Olednkemp was a master of free flight who designed it. I am not sure (not an aero engineer) about less dihedral giving more lift, but dihedral gives stability, which we are after. So lets see what happens, specially if your dihedral is just a very little less.
Turns very slightly left in hand toss / glide test. Hopefully a lower power hand launch. Then , that is very good. Your glider looks good and happy to hear that it has wonderfully passed the glide test. Eager to see your video.

Mr. Glidiator: Great glider at 5.5 grams, sir.
"Tendency to go right in but some chucks some goes left. Was it due to faulty chucks? tab on rudder and a spot of clay on left wing plus wash in. Will try some horizontal catapult launch and see flight path"
 Yes it most probably in the chuck, I do it so many times. All: repeating: do not make adjustment based on a single glide or flight. Make sure it happens all the time before you make an adjustment.
Please put  a washin tab not  clay on the left wing to begin with. Eventually if your turn is too wide (because of less stab tilt), then a bit of clay on left wing will help make a more desirable smaller circle. Left circle better controlled by modifying rudder tab, just a little bit. Clay will diminish some of the washin tab effect, could spiral in. So, if I were you, no clay, just a washin  on the leftwing. Both my Lunchbox's had NO CLAY ON THE PORT WING. All in all, you are on the right track. Eagerly awaiting your video.

Wow: cannot wait to get up in the morning and see more of everyone's post, photos and videos.

Ciao.. talk soon.

Regards

PS: Remember the Mantra" right climb, left glide" for all of the right handed guys like me. Left handed, go opposite, and looks great flight too.

 

Rudder & Elevator tabs. Small! Also see photos in reply#151 , previous page.
If the tab is not quite effective as you want it, then go a little thicker versus longer. If it is too much effective, use nail file and sand it a small amount each flight.

After each adjustment, start again with the glide test, to assure nothing else has happened.

Please Note: I hope all of you will get beautiful flights. I do not wish you guys to just one or two good long flights, but a good long flight for always. Hence a little "sticky" in my comments, sorry.

Question for all to think about: Please let me know your answer / opinion / thoughts so we can discuss.
Q) What happens if your washin tab is too big? I bet the glider will fly good, but what would you expect in the glide phase of the flight?

Do not be shy, please answer, thanks.

Points noted. Will correct and test fly. Will get some videos.
A basic doubt - To achieve the 1/32 stab tilt effect using tabs - are the tabs on port side top or stbd side top?

@Glidiator sir,

Stab tilt effect cannot be achieved with trim tabs.
Tabs become more effective at higher speeds.
Stab tilt becomes more effective at lower speed (ie, higher angle of attack)

Regards

Sir I can confirm that lesser dihedral will produce more lift, but it will obviously reduce the self correction capacity of the plane.
Also sir what is the need to have a turn during climb? Can't we have straight climb then turning glide?

@Dreamliner
@Karthick Ashwath
@Freeflight

REDUCTION OF DIHEDRAL

Assume total dihedral reduced from 3” to 2”, or from 1.5” to 1” per 4” semi span.

The effects are:
1. Horizontally projected wing area (representing Lift) is increased by 4.6%
2. Vertically projected side area of wing (representing roll stability) is reduced by 33%

In other words, the gain in lift is negligible, but the loss of roll stability is drastic.

@KK
Thanks for the clarification.
Will have to ensure sufficient stab tilt to created turn. Will be evident in horizontal catapult launch.
Anant

Hi everyone,

You may have noticed that Freeflight has been emphasising two things:
1. Stab tilt
2. A right climb, left glide flight pattern

I’ve already explained how stab tilt works.

Now here’s the theory behind getting that right climb, left glide pattern.

1. Put a small wedge/ trim tab under the trailing edge of the left wing, near the tip.

2. This (wash in) increases the left wing tip’s angle of attack compared to the right wing.

3. We don’t know by how much, but with a small wedge/tab, let us assume it’s 1 or 2 degrees.

4. Now let’s see the effect at different speeds. The gliding speed of my Lunchbox is about 2-3 m/sec.
The launch speed may be 10 times higher. (Proof in an old thread of mine called ‘Estimating Launch Speed’ or something similar)

5. At such high speeds, the necessary lift can be generated at very low angles of attack, say 1 degree
(I can give proof, but it’s beyond the scope of this thread)

6. In the glide you want maximum duration. Or minimum sink / highest coefficient of lift.
This occurs at an angle of attack close to the stalling angle. Typically at say around 15 degrees.

7. In other words, the model flies at low angle of attack at launch, and at high angle of attack in the glide.

8. This is not apparent due to the fuselage level (or slight nose down) attitude of the model in glide.
The high angle of attack is not due to flying nose high.
It’s due to the descending path of the model that the airflow is hitting the wing at an angle from below, not head on.

9. We now have a model with a slight wash in on the left wing.
The left wingtip is therefore at a slightly higher angle of attack than the right wing.

10. The effect of this is different at different speeds. SEE ATTACHED PIC.

11. At high speed (ie, low angle of attack), a small difference in angle of attack leads to little difference in the drag of the left and right wing.
But the lift of the left wing is significantly higher than the right wing.
SO THE MODEL ROLLS RIGHT AT LAUNCH

12. At low speed (ie, high angle of attack), there’s hardly any difference in lift, but the drag of the left wing is significantly higher than the right wing.
SO THE MODEL TURNS LEFT IN THE GLIDE

13. Once the model settles into a left circle in glide, there’s a second order effect.
The right wing is describing a slightly larger circle.
So it’s flying a bit faster than the left wing.
Accordingly generating a bit more lift than the left wing, that could lead to a left spiral.
But this is counteracted by the fact that the left wingtip is flying at a slightly higher angle of attack due to its wash in.

Perhaps now it may be apparent why I’m not in favour of budding aeromodellers jumping head first into RC Models. There’s enough learning material in simple 8” span, 8gm chuck gliders!

Please let me know if such detailed theoretical explanations are of interest or not.
Then I’ll know whether to continue or not.

Regards to everyone.

Iyer

Very interesting and clear cut explanation! Please enlighten us , the underprivileged (in Aero modelling )

Mr. Iyer,
Thanks for the good explanation. I have learnt from experience, but nice to understand theory behind it.

Please do as before, such as this and dihedral effects on lift and stability etc.

Dear Karthick,
"Also sir what is the need to have a turn during climb? Can't we have straight climb then turning glide?"

Very good questions, others may benefit. In the CLG we strive not to climb in circles. My concept is that I want to get as high as possible to make the glide phase as long as possible, of course, assuming that the transition went well, i.e.. you did not loose height. When climbing in circles, my experience shows that happens with too much incidence, you are loosing all the rubber power climbing in circles. So a maximum height is not attained.

See my sketches carefully in reply# 110 . you are climbing almost vertical. At transition point, the glider nose is slightly (emphasis on slightly) pass the 90 degree angle to the ground. If it goes too back, it is approaching a loop.

You are climbing almost vertically. For a fraction of a second, less than the time you blink your eye, it flops to transition for the glide phase. Now at low speed in glide, the rudder tab is ineffective and the stab tilt is very effective to make the circles.

Why glide in circles? Well, for one reason, you want to keep the glider in your field. But not really, I have almost a 1 mile in field. We want the glider to catch a thermal. Thermals moves in circles, hopefully the glider enters the thermal circle versus going straight and out of the the lift (thermal) that nature provides. All the expert CLG winners know how to "pick the air" i.e. launch in a thermal.

So we choose to put a tiny amount of clay on either wing tips. If the thermals are not small, they are in a bigger circle, so you want a larger glide circle. Put the clay on the right wing. If you get a smaller diameter but strong thermal, you want to glide in smaller circles. So then, you put the clay on the left wing. At every contest day, weather is different. Have to adjust both the CG ( slightly forward on windy days) and glide circle with clay on wing tip as the stab tilt is fixed.

Understanding the trimming is very vital. Every contest day brings a different weather. Need to learn how to take advantage of what nature brings.

Here is an excellent website to bookmark. See how this expert explains: Of course he is talking about hand launch, but CLG is similar process. Study his sketches as to what is desirable, what is not

http://www.f4bscale.co.uk/launch.htm

Excellent elaboration of theory and practice by KK and Free Flight.
Even the most simple paper airplane teaches a lot of aerodynamics.
In fact with respect to very slow forward speeds in indoor FF ( especially rubber power) - very little study has been done of the effects of very low Reynolds numbers
Stab tilt - if it is seen to be insufficient in test flights - not sufficient left turn effect - Twisting tail boom is not permanent - and fuse is pretty stiff - chances of cracking it if one is not careful. So how does one increase it permanently so trim is set once and for all.

Here is one very good video of CLG trimming. He starts with trimming by moving CG back
(remove clay from nose) then goes back to original CG with a little up elevator. He bends, but we go permeant with tabs.

https://www.youtube.com/watch?v=lDsu29TQUDk&feature=emb_rel_end

Dear Glidiator:
"Stab tilt - if it is seen to be insufficient in test flights - not sufficient left turn effect - Twisting tail boom is not permanent - and fuse is pretty stiff - chances of cracking it if one is not careful. So how does one increase it permanently so trim is set once and for all."

great question. I have struggled with this question as there is no way on the field you remove the tail and re fix it. You are not close to being accurate and may affect the incidence (established correct before) too.

So here is my approach. A little less stab tilt is better than a little more. I only build CLG's that have been designed by great experts like in this case. They have gone through a lot of  experiments, before publishing a winning plan. So, I start what the designers recommends, get it as exact as you can.

Now on the field, I use the clay on the wing tip. Left side for smaller circle, right side for make the larger circle.

Last year I competed in AMA nationals, spent the whole day with experts. They use the same clay technique on the wing.

As I said before, every flying day brings a different weather. So cannot be adjusting the stab tilt each time, but start with the recommended one and use wing tip clay.

Let’s get back to basics for a moment, and go step by step.

Step 1. Build everything straight. No rudder offset, no stab tilt, no wash in, no wedge, no trim tab.

Step 2. The designer has specified the CG position after trials. Let us balance our model at the specified CG first.

Step 3. Try to get a straight glide slope from say 5 feet high to a point about 30 ft away on the ground.
This approximates the glide slope of the model

Step 4. Launch your test glide a bit nose down, pointing at a point on the ground about 30 ft away.

Step 5. How fast to throw? A bit slower than you’d throw a marble at the same target.

Got a straight flight of 3-4 seconds, neither climbing nor diving, neither turning left nor right?

If it turns a bit left or right, let it be for the present.

If it dives, add an up elevator trim tab. This is a half cm piece of the supplied triangular wedge, or a a similar piece of matchstick.

If it climbs, add a tiny bit of plasticine to the nose and try again.

THE OBJECTIVE IS TO GET A STRAIGHT GLIDE FROM A 5-6 FOOT LAUNCH TO A POINT ABOUT 30 FEET AWAY ON THE GROUND.

Step 6. Now we want it to turn left on glide.
So we twist in a little left rudder.
And it glides nicely in a slow left turn in the glide.
But when catapulted at high speed, it makes it spiral dive to the left...

Perhaps this left rudder is not such a good idea...

Maybe worth looking at reply #204

@Dreamliner
@Karthick Ashwath
@Freeflight

Any response?
Anyone tried to check/ replicate the maths?

Sir,

When one wing flat on the ground, then tip of the other wing is 2” from the floor.

@dreamliner

Now you know what to expect!

Mr. Iyer,

Agreed with your first statement. not sure how to calculate the vertically projected side area in statement #2 that reduces stability by 33%.

Dreamliner : When one wing flat on the ground, then tip of the other wing is 2” from the floor.

Then part 2 , make sure when you glue it to the fuse, both wings are of equal height from the glider fuse (floor) and that the center line of the wing is exactly on the center line of the fuselage.

Simple.
In side view chord remains unchanged.
Height reduced from 1.5” to 1”, ie area reduced by 33%
(Strictly speaking, it applies rigorously to a rectangular wing...)

Did you verify the math for the lift?

Just looking at flat span , it is 8.5 inches. With dihedral , one wing on floor and other at 3 inches, or 1.5 inch equally, the projected span is exactly 8 inches. So reduced effective wing area due to dihedral.
Basically : Area= Projected span * MAC. 

@Freeflight ,Is this okay ?And  CG is perfect . So what else should be taken care of ? Should I do a trial CLG launch by less pull before the full stretch launch ?

I sought an opinion about this thread from some experienced aeromodellers.

One feedback was:

“There is an overdose of information now on this.
Forget a newbie; an experienced modeller will get scared off“

I agree. Yes, there is something called overdose!

So I’ve decided to back off. And not post anything more on this thread till after the Contest.

It’s high time we started getting some competitive flight videos on the Contest thread...

So see you guys there. Remember the Contest closes with videos posted on RCINDIA till 9pm on 30th.
One Sunday and one weekend left.

Gentlemen, start your engines!
May the best man win...

Was wondering why even Hitesh didnt post a  CLG video yet .

Can the deadline be extended by one or two week ??
I think more time is required to process the information and put it into action.

Thanks

Hope this works for me .

 https://youtu.be/2AVhcZlztjI

Perfect gliding is not an easy task ! unlike RC (or even rubber powered !)

@weekendflyer /Glidiator /Dreamliner , could you post your test flights too ?

I will have to hire somebody to do the video shooting  ;D
Just joking !!!!!!

I will do so shortly, will have to ask somebody to join me early morning.
Still trimming the glider

Not sure if that’s a good move from your part . Almost all of us are newbies in this sort of gliders . So I think learning is more important than competing. I don’t care who wins . But I am sure I learned a whole lot after I was involved in this . Even test gliding seems fun ! CLG should be thrilling , I am sure . Please let us take time and improve . Competition spirit is there , but that comes when we are sort of “experts” in this field . So please don’t leave us in the desert :)

Yes, big problems there  What I learned so far ( from the mentors and practice about trimming - and the mistakes I repeatedly did - balance the glider in its correct CG ( and forget about it unless there is loss of clay on landing ) Next focus on elevator tab and rudder tab/ washin during test flights . Rest of it - I don’t know .

S174: Perfect video. That is ideal glide test. Hard push, nose rises up, gentle curve / turn to the left.

Your photographs of the elevator stab, rudder stab is good. A lot thicker than mine. But your glide test is good. So for now do not make any changes.

Go for a horizontal launch, that is plane is held level, wings level, pull back rubber about 2 inches and let go. It should do better than your glide test video. If that is true, go for a full pull launch. As I had said in the trim video, never do a partial pull on the rubber when you are ready for the catapult flight. Always pull back all the way. No partials. Your rubber band will break, take extra rubber bands.

Full Launch Pull: Launch angle say 70 degrees, bank angle 45 degrees, full pull let go. Do not look at the glider, aim to some point in the sky. If it loops back, sand your elevator tabs evenly on both sides, till loop goes away and you have an almost straight-up flight.
Let us see your video and can recommend something else, ONLY if needed.  Remember, if not satisfied ,play with launch and bank angle. Study the sketches in reply #110 on page 5 one more time to see how the flight should go.

Good luck, waiting to see your video.

Dear KK Iyer sir, sad to read your latest post Rely #220. A few contestants, at least, those posting videos and photos are doing real good. Proud of them catching on and asking real good questions. Other than indoor flying, CLG is the most difficult flights one can have, I am sure you agree. I think, after they master this, the expensive RC where you have to go to a special field to fly will be easy for them to grasp.

PS: Sweet but sad feeling today since I lost my first Lunchbox and right after that a Tip Launch Glider. Even when it is cold here today ( 7 deg. C)  thermals are quite strong and happened to launch both the gliders into it. We chased the Lunchbox for well over a mile and half in a golf cart. But kept on going up and up and then away, out of sight. Both the flights were just awesome. Today's Lost Lunchbox was catapulted with FAI tan sports rubber 1/4" and it was the first flight pulled on this rubber.

I am hoping that soon you guys will enjoy such moments too. It is a joy.

Thank goodness, had built the second Lunchbox

Will post some videos asap. Seriously thinking of getting a mobile head mount/ or make one with Velcro strips- then one is independent of assistant for taking videos.

There will always be two sides to the coin in terms of how much info / tech stuff is too much. My opinion -  nothing is too much - it’s for the other side to assimilate and digest - or read and ignore.

Free Flight- put your mobile number on the models and say “ Reward for Return”.
May be lucky to get it back. Model going off into outer space is “sweet agony” - happy it was trimmed perfectly - but sad to lose it.

Now to get down to some actual competitive flights.

yes, I do have my name and phone number on the glider. From so many I have lost over the past 3 years in  strong thermals, only two came back as some modeler was searching for his plane and found mine. By then, the model could not weather the rains, dirt, little bugs etc, were not flyable again, but was sweet to see them again. Funny, when searching for my glider found another of a colleague of ours, who lost it a year ago.

Anyways, back to the topic now. Looking forward to hear and see everyone's Lunchbox experience.

Went out to the open space nearby - the place with a gusting stiff breeze- no choice.
My Lunchbox in hand chucks neatly turning left. Horizontal catapult launch - CG corrected - now model climbs and starts turns in left circles - fights the headwind and keeps trying to turn left while breeze drifts it sideways.
In such conditions got approx15 sec flights. Angle of launch about 60 degs. Will give steeper angle when testing in calm conditions.
Stab tilt given by twisting tail boom - was not set during construction.
Will drag son along next outing to get some videos.

Awesome! Looking forward to your video.

Realised that a lot depends on a proper launch in terms of bank and angle of release - both angle relative to ground horizontal and angle relative to wind direction.
Learning a lot with what is usually dismissed erroneously as a simple model - model may be simple - but the aerodynamics remains the same as a complicated model.
Very humbling to go back to basics and realise there is a lot you don’t know.

My lunchbox with wings all decked out - full test flights with video scheduled for later this evening.

Looks pretty with all the tabs and coloring of the wings. Looking forward to your videos!

Got ditched by the videographer (son) as he got tied up in another commitment. Must get that head band stuff. Flew the lunchbox anyway - quite happy with the way it is behaving .
No loop on full launch. Added a wee bit of clay as there was a hint of a stall. Was doing right turn to transition and left turn glides.
A single video will be worth more than all these words.
The orange colour on wings was a great help in finding and retrieving the model from the tall dry grass.
Video coming soon. Competition closure date also round the corner.
Don’t see competition flight videos from any others.

" Was doing right turn to transition and left turn glides" Perfect.

Any flight times. Without good air, I speculate 40 + seconds for your glider.

Yes, looking forward to everyone's video.

Will time flights tomorrow. Now got the hang of launching it so I confident it stays within the field - the field abuts the airport boundary wall - if the model drifts across its lost. I don’t think flights are touching 40 secs - that’s an eternity- anything  closer to 30 secs will be satisfying.
Since there always a smart wind that is gusting- some flights I observed when model glides and is headed directly into the wind it is almost stationary at the same height for some time and when the gust dies down the model continues on it left circles path downwards.
A good lesson that speed of air flowing over wings is what is important for lift - not ground speed.
Will get those videos asap.

Closing date almost there -- still await performance videos from bonafide participants.

Rummaged thru my aeromodelling goodies rack - have some original CLG kits procured very long ago from IHC.
All pre cut parts with catapult handle - Ply doublers for nose.
 (rubber bands have deteriorated with age).

Propose incentive for participants in addition to prize announced by KK

Winner -- Yellow bird kit

2nd Place - Tailwind kit

All others who post performance videos of the models made by kits sent by KK --- Tiny Tot Kit

Above offer subject to approval by Competition Administrator.

Regards

Wonderful! (Especially #3)

@ K K Iyer sir please please consider extending the deadline by 2 weeks. I am very busy now with college endsem exams and a national level robotics competition so I am not able to give the hobby the time it deserves. I also don't have the luxury of having an open area near my own house so I travel to my cousin's house to do that. This increases time needed. Please sir. Kindly extend the deadline by 2 weeks.

Extension is often just another name for procrastination.

However due to the current situation, it’s quite reasonable to extend the deadline to say 9pm on Monday, 14th Dec, (or as long as desired) if there’s no objection from other participants.

Just let me know. 14/12? Or 31/12?

(Even though it means my next contest has to be deferred till 1st Jan  ;D)

@KK
Thanks for approval of my incentive proposal.
How many’s kits involved in competition?
Regards

Thank you sir. Will make it by 14/12. How many rubber bands(the ones that you provided) in series are allowed for the catapult launch?

2 for initial tests.

Thereafter no limit.

Only Freeflight, Glidiator and I have restrictions - we can’t use our TAN Super Sport rubber!

KIT and/or CONTESTANT

1. Weekendflyer
2. Rooster
3. SI74
4. Sanjayrai55 (Kit only, Honorary contestant?)
5. Aspersid
6. Hitesh Kher
7. Prabal276
8. Karthick Ashwath
9. Freeflight (No kit, Honorary contestant)
10. Glidiator (No kit, Honorary contestant)
11. Alex Bessie
12. Girish Madhavan
13. Dreamliner (only kit, not contesting?)

So 9contestants for 4 prizes.

I had proposed an extension before, however, that post got lost somewhere, no issues.
An extension will be appreciated for better competition.
14/12 is fine with me.
 

Saw it only today.
Missed earlier probably as I had taken a break from this thread...

Early Bird Incentive

A Tiny Tot kit for those who post at least one performance video by 30th Nov 9pm?

So get into action.

Nitya’s test glide

https://m.youtube.com/watch?v=6FWyRFo6mAc

Nitya: nice glide test. I am thinking the video is from a few days back? By now you have probably put a rudder tab on the left side to make it glide the same way but to the left. Also I do not see a rubber hook in the video at the front of the fuselage. I guess you are planning to hand launch. That is very good. Same principles apply.

Tiny Tot: come on guys, this is as the golfers say this is a "Give Me" . Very nice of Glidiator to offer it and also the other model for prize. Tiny Tot is a great model too. Satisfy the condition layed out and collect yours.

Am glad that an extension was approved. Very much looking forward to your photos and videos.

For all those preparing for exams, wish you the best.

All of you Lunchbox builders,

A few of you sent me videos on Whatsapp, some of which I posted here via YouTube.

During this coming weekend, if any of you manage to take videos and share with me on Whatsapp, I’ll be happy to post them here via YouTube.

Even if you don’t have any videos yet, I request you to post at least a photo of yourself with your model

This Lunchbox group is somewhat like a family now, and it would be nice to see the face and model of the members. (So far we don’t even know each other’s name!)

Just a thought. OK?
I realise that some may not like to share their own photos, but there should not be any problem in sharing photos of their model.

NOTE: Videos of competitive flights you have to post by yourself on the contest thread.

Finally got some flight videos. After being used to the very slow flight speeds of indoor rubber power where video recording is easy - taking good videos of a small fast CLG was a challenge.
Some observations in trying to get a decent video from launch to touchdown
1) Very difficult to follow the model at launch to the point of transition as launch speed is very high and model is quite small and following it is tough - rather impossible
2) So after getting launch on record  slowly pan mobile towards model by which time it would have reached the apex of launch and commenced glide
3) Pick up the model with naked eye keeping the centre of the top edge of the mobile just below the model - following model with naked eye - not on mobile screen where it may not even be visible properly..
4) Once you have picked up the model in glide and are able to follow it - can tap zoom to 2x to get better view of model
One will need a very wide angle camera with high zoom to actually keep the model in frame from launch to transition point.

The flights I managed to record decently were in the 30+ sec duration - as I mentioned after recording launch it takes a few secs to get the model back in sight and properly in frame.

In Flight 1 - had an interesting situation as a swallow got curious and flew around the model inspecting it.

In Flight 2 the model did not take left circle and went rather straight. My analysis is that since at that time the wind had died down completely- the stab tilt that was effective when wind was blowing/ gusting was not having enough turning effect in zero wind. So trimming  for different wind conditions will vary. Or the stab tilt that was given by twisting the tail boom had slowly gone back to being straight over multiple launches -  so no turn effect was created.

In slow motion launch video I am using right hand to hold catapult( as a left handed person would do) but banked model to right as for right handed launch as trimming is for right handed launch. This was because I realised I couldn’t straighten my left hand completely holding catapult due to a frozen shoulder I’m recovering from.

Lots to learn from a “Simple Model”.

Flight 1

https://youtu.be/22EnFwUmkhU

Flight 2

https://youtu.be/wvp0EctwK_c

Launch in slow motion - mobile automatically stops after recording after few secs

http://www.youtube.com/shorts/LJfgPkrrxIM

@Glidiator sir,

Wonderful stuff.

I’m glad you’re only an ‘honorary’ participant.

But what an inspiration to the others!

Regards

Edit:
That slo-mo of the left handed launch was great!

Congratulation Glidiator sir, Both flights approaching the 40 second mark ( not an eternity for sure) in still air. Terrific. Very good slow motion launch video. Really helps with someone filming it.

Probably the fuse twist must have gone back to original so the glider went straight. However I have found that a bigger than needed washin wedge produces the same effect. Hence all my tabs are put on the glider with a glue stick, so it is easy to remove or adjust.

Very nice seeing your flights. Enjoy.

Hitesh Kher has damaged his model by repeated crashes!

I offered to send him spare balsa, or a new kit, or a ready to fly model. For free, of course.

After some hesitation he opted for a kit.

If anyone else needs a replacement, please let me know. Quickly, latest tomorrow night.
So I can prepare on Sunday and despatch on Monday.

Free, but any contribution towards cost, effort, postage is welcome!

Regards

thank you so much sir :hatsoff:

Glidiator : Your photo on the previous page clearly shows a elevator tab and the washin wedge tab. Also looking close on the first photo, you have installed the rudder with a slant ( LE of rudder more to right of the Center line of the fuse). If that is so, terrific. That is the coolest way to do it. I do the same. This way it may not require the rudder tab to the left.  So do you have a rudder tab on the left?

All other contestant: Follow the simple build process and you too will get a near 40 second flight. But work on your transition to assure that you do not loose height after you reach the maximum height. To assure good transition, experiment with your launch and bank angles. Start with what both I and Glidiator suggested in the discussions above.

Thanks KK for the appreciation. Have built and flown many HLG / CLG- but they were just for fun flying with accurate construction and basic balancing. Frankly this was my first serious competitive CLG trimming and flying session. Thanks to Free Flight’s detailed trimming instructions - learnt a lot.
CLG as a category can be very engrossing and satisfying as flights are sufficiently long. Will now aim for that minute mark. If AUW is reduced the sink rate will surely reduce and give longer duration. The trade off is between strength / stiffness of components and weight. This is where carbon fuselage helps.

Free Flight - this is what my model has
Washin tab on port wing TE
Small Elevator tab
Rudder is fixed on right side of fuselage- not on top centreline. Giving the rudder a bit of an offset angle is done in rubber power too. There is a small rudder tab on left too.
Stab tilt was given by twisting tail boom. Now have a good idea how much tilt to give - when viewed from front - the stab  tilt is visible clearly — just that little up is all that seems to work well.

Also realised trim that works well for strong wind conditions may not be ideal in still air.

Lot of scope to experiment - learn - and improve.

Glidiator, you are most welcome. I am glad that the trimming details were helpful. You will hit close to a minute very soon, similar to my prediction of your 40 second flights. Since, you are not competing for prize, experiment with the FAI rubber that you have. Suggest 2 loops of 1/8 rubber only 7 inches long. Pull to the full strength. Watch what height it gets to, where the thermals are present.

Something to think about: Unlike indoor flying where weight is almost half the battle, there is a minimum weight that outdoor models need. The winner champions here ( 6 flights in succession at max which is two minutes) are all around 0.4 grams per wing square inch area. Much lower wing loading (lighter model) is only good for still air flights. Of course, on the day of competition, the winds are almost (Murphy's Law) around 5 to 9 miles per hour. Very light CLG almost get blown away like a potato chip in a windstorm.

All of the competitors that I have had the pleasure to talk and fly with, say to now concentrate on one thing: Learn to "pick the air" . Must launch in a thermal. That can be a new thread several pages long, and I ALWAYS stumble. The trick they showed me was, launch when the experts launch, as they have sensed the thermal. 

Thought I would share my experience.

Yes FF— lot of basic physics in action. You need that minimum weight to translate the catapult force into acceleration. — which is why you can throw a tennis ball further than a ball of cotton - though the force is same - the mass is required.
Learning to read and pick the air can only come with on field experience
Will use TAN rubber and see performance.
Have a bunch of CLGs - never seriously trimmed and flown. -  used as models to display at workshops.
Will get them in the air now that the taste of CLG has triggered a new addiction.
Will also repair an old IHC Interceptor - folding wing CLG - and fly.
A good way to be airborne since indoor spaces are restricted and difficult to access due to Corona.

All participants - 48 hrs to go to get that Early Bird kit.
Just Do It!!!!!!

"Have a bunch of CLGs - never seriously trimmed and flown. -  used as models to display at workshops.
Will get them in the air now that the taste of CLG has triggered a new addiction.
Will also repair an old IHC Interceptor - folding wing CLG - and fly."

Glad you caught this bug.

All other contestants: I am sure you too will catch the bug. Post a quick video and pick up the Tiny Tot. Most of all enjoy.

Replacement kit for Hitesh ready. 6gms!

I thought my entry would the last , as if so , I would stand a chance to win in terms of duration ;) . But since no one has dared yet , I thought , why not be the first ? :) instead . ( And I could not resist the additional perks offered by Glidiator :) ) And here it is -23 Sec from the top ( the guy who shot the video didn’t take launch and transition , my bad ) So it may be counted as 1-2 Sec more :) right ? Iyer sir ? Anyways , I think I deserve a prize as the first contestant to post ;) . Thanks Iyer sir and Freeflight for the proper guidance . Used only 3 rubber bands as I couldnot stretch my arms beyond that .

https://youtu.be/8K-4KsgzZro

Another shot
https://youtu.be/_RzQGwZUWIg

Congratulations to the student who learned so well from the teachers who guided so wisely  :salute:

I think similar results will follow.

We will have some good competition amongst us.

Weekendflyer sent a msg ‘glides ok but dives under full power’

Asked him to add a 1cm piece of matchstick as shown in the pic.

Anyone having trimming problems, please msg me on Whatsapp, preferably with a short video clip showing the model’s behaviour.

S174: Congratulations. Wonderful job. So you passed the 20 second mark in both the videos. Your glider looks good in the photo. Very nice design on the wing. So are you having fun? Enjoying?

Looks like you need a very tiny tiny bit of clay on the nose. Start very small, as the stall is quite evident. If your CG is in the correct location, then, I would have sanded the the elevator tab just a bit with a nail file. But that is tricky, you too can do it after you gain some experience. For now just start adding very small amount amount of clay at nose, size of a black ant, Fly each time and see if it takes out the stall. Then let us see your new video.

I am so happy to see your flights.  Congratulations once again. Glad you took the first stab of a full launch video.  

S174: Very happy to hear you say " Used only 3 rubber bands as I could not stretch my arms beyond that" .  Brilliant !
You are now gaining experience. Correct move.  We are allowed 9 inches of maximum rubber length when we compete. But all of us use anywhere from 6 to 7.5 inches only for the same reason.

Another thing to note is that I take at least three  to five rubber band sticks to the field. After about 5 or 6 launches, rubber gets "tired" so you do not get a full height. So I use the next rubber band stick.

After you stall is corrected, may want to experiment with a thicker rubber band. Or use two loops of rubber band in parallel. Will post a picture.

If you guys  had the tan rubber, your launch height would increase by 50 percent. But for this competition, you are not to use it as  it has to be same for everyone.

Dear All: Looking forward to your videos. I will be very happy when all of you cross the 20 second mark and as much as Glidiator and my videos reaching the 40 second mark.

Welcome to the world of CLG flying.

Here’s SI74’s latest video of his test glide.
The BEST test glide I’ve seen.
Better than mine  :banghead:

It is 12+ seconds, or equivalent to a 24+ seconds catapult flight.
And it’s just a simple test glide, not even a full power hand launch!
Just correct CG, correct trim, correct launch angle, correct launch speed.

At last I’m starting to see the results of my years of effort to popularise Chuck Gliders as the ideal introduction to this hobby.

Thank you, Doc!

https://m.youtube.com/watch?v=e0d85HIbRcI

That is a truly good glide video. Your glide test is correct, raises the nose a bit and turns left. This is the first step before catapulting. Then only you are ready to catapult. In the catapult video, you have a clear stall. So even though your glide is GREAT, NOW  starts trimming in glide portion of the catapult launch. Keep at it as suggested above and cross that 40 second mark.

To all: you must rejoice with your hard work paying off. But remember, you will see that in your work life, todays Outstanding work is tomorrows Expected. Do not stop even you cross 20 second mark. go for 40 seconds, then 60 seconds then what we call here a MAX, 120 seconds. Do not stop.  Aim higher and be the best you can be. Good Luck wishes to you all.

Can you imagine that there was NOT A SINGLE FLIGHT OF 10+ seconds in the last 4-5 years, despite my Rs 1000 prize offer?

Last month, frustrated with lack of results, I increased the prize to Rs 5000.
And it was taken within 24 hours!
By Imperial Fire.
With a paper model!

Boy, did you guys lose a real opportunity!

But don’t worry. New opportunities are coming.

Hope to launch the next project on 15th Dec, after this contest ends.
Maybe a new Contest in the New Year?

Thank you for appreciating my effort . Yes , it was tough for me too . Being a newbie , it was never easy to perfectly trim as Iyer sir did even after he and freeflight told everything behind - physics , practical tips etc etc . I was depressed and worried whether I could make it before the last date . So I thought let you guys win this time . But I kept on trying , reading this forum again and again . Took some time to identify what is wrong with my glider . I knew my glider was not perfect when I sent glide video to Iyer sir . But his reply changed everything . He told me to read the post of decalage again , and that was it! Mine was negative ! That's why whatever I do , be it is perfect CG , elevator tab , rudder etc wont do any good ! And once I changed it to a positive degree , result was obvious ! Perfect test glides! As if the glider wanted to fly on and on (sadly my frontyard was not enough !) And I needed a simple push , not as hard as seen previously ( that Freeflight commented on it) . So guys , do post your videos here or send to Iyer sir or freeflight . They understand what's wrong and will guide you . I had many specators in the field appreciating the smooth glides and one man came to me with a business invitation ! I asked him why and he told he has notbseen it before and wanted to sell it as a kit in his shop :) I told him that I am not into business and its just a hobby . I am the only person doing this here and so people are surprised and enjoys watching it glide in circles . Most of them wants to know whether I bought it or built by myself . Anyways , it's thouroghly enjoyable and I look forward to your videos too . I know there is tough competition as I saw Hitesh , Nitya and Karthik who did better than me in initial test glides . Very happy that I learned a lot more than just building an RC plane which  is lot more easier since we have the remote with us after launch and timely correctons are possible . Thanks everyone !

Hi everyone,

Just because it’s page 12, don’t skip the previous page.

There’s a lot of good stuff on page 11...

For example, see this by Glidiator. Never seen an Indian catapult launch video before...

https://m.youtube.com/watch?v=LJfgPkrrxIM

That is truly a great video by Glidiator of launching. Not seen any such clean video launch in the world wide web.

One thing that must come through in the second, third .., contest is that you competitors from that point onwards, try and think of your own solutions. Ask here if you are unsure of your OWN solutions. That is when by teaching yourself to analyze cause and effects, you gain experience to excel. Experiment, see your results. Did that change help or hurt? Are you heading in the right path to get better flights? For example: A roll and then a dive. Should you look for for a rudder offset or elevator? Both? Why? What did you observe? What is the first thing you will modify, knowing to make only one change at a time?

For the first set of competition such as this, it is both OK and correct to ask for guidance. Remember, to experiment by yourself to gain knowledge, what works, what does not and why.

I am looking forward to see your wonderful CLG videos a YEAR FROM NOW, how wonderful you have got.

Mr. Iyer, , in my opinion, the reason you did not get a bite in the first go around, is truly but sad speculation that no one was ever motivated to go through. But this time these kids are wonderful and have the desire to learn and enjoy. That clearly shows.

The MOST important reason for such good flights and participation  this time is the fact that YOU Mr. Iyer made all the superb kits that is giving them a chance to be successful.  Your contribution here is very well noted and worthy. Thank you for doing that. Most kids would give up just sanding the wing aerofoil. But you provided the correct tools for them to be set up for success. Congratulation to you, Mr. Iyer.

Well said FF.
Second your appreciation of KK’s efforts to promote interest in Gen next.

As mentioned the greatest teacher is experience. Learning by doing is the best way to reach excellence.
There are no short cuts. If you are an Aeromodeller- the proof of the pudding is your flight performance.

And I always say - “ Failure teaches you more than success”.
Analysing and finding out what went wrong adds to your expertise.

Here’s Weekendflyer’s problem

My guess is that he went to the catapult stage without first settling the glide phase.

What do you guys think?

https://m.youtube.com/watch?v=FrtX19rNi9I

Then one day I got a suggestion that I should provide kits and make it a one design contest.

That is what made this Lunchbox build/contest so lively.

The person who made that suggestion is actually a member of this Lunchbox group, but has fastidiously maintained a scrupulous silence.

A big thank you to SANJAYRAI55!  :hatsoff:

In case you didn’t know, he is the author of the largest number of model build threads in RCINDIA!

I played the Weekend Flyer video in slow motion and full screen. The launch angle, bank angle and the climb is all correct. Almost there, Weekend Flyer. Good height too. Then it appears that the model  tries to go for transition but rolls over hard to the right . Cannot recover, so straight down. Model Needs to climb right and as seen in your video which is Correct, but roll and transition to the left into glide phase. BUT Your glider kept going to the right.

My suggestion would be a) Make sure your wing is installed straight on the fuselage  that is not skewed to the right at all. If it is skewed to the right even a small bit, there is perhaps another option for you only. b) Launch exactly the same way as in your above video making sure you do not have any rudder to the right and just a bit rudder tab  to the left to solve the right roll issue. b)  Once the hard roll issue is solved and then if it still dives straight down, add a bit of up elevator tab on the right side of the elevator only. This is based on the best I can see in the video.

 Experiment one change at a time and see.

Looking forward to your next video. Congrats on getting a smooth very good height and right climb based on the buildings on the background.

PS Weekend Flyer: Very good call to have your friend film the flight from behind you. This way we got a good perspective of you launch, transition and glide.

Everyone Else: can you have your friend making your flight video do the same ? Would be nice.

Iyer sir, sorry for the silence. Someone in the family is very ill, and I have been quite tied up. I hope to actively participate soon

@Weekendflier ,my suggestion would be to  read this post before attempting catapult . Only after I was satisfied with the test flight ( it took 3 weeks!) I went for CLG.

Go step by step . You can’t go forward without clearing the previous step . That is how I proceeded . Regards.

On catapult launch, model goes straight up.
And then goes straight down.

This is a well known typical problem.

What this flight pattern means is that the decalage is not enough!

The correct solution is to remove the stab, and sand the place where it is mounted, to give about 0.5-1deg negative incidence, ie, stab leading edge lower than it’s trailing edge.

Since this is difficult to measure, aim for a 0.1” slope at the bottom of a 10” long fuselage.

What to do if the stab is already stuck on with Feviquik and can’t be removed?

Somehow we have to add a little UP elevator effect.

For this you have to make a wedge. About 10mm long, 5mm wide, 1mm high at the back, sharp at the front. (As provided in kit #5 onwards)
And stick it above the trailing edge of the stabiliser. You may need more or less length.

Since I’m not a catapult glider expert, I went by the advice of Freeflight, who prefers zero zero setting.
In other words, the wing and stab parallel to each other. Or NIL decalage. This gives a very high straight up launch

This is how the first 11 kits were set up. So all of them dive despite correct CG, and need some UP elevator.

Kits #12 onwards have about 0.5deg decalage built into the fuselage.

So they will probably glide nicely, but may loop under power.

But curing a loop under power is easier than curing a death dive from the top of a high launch  ;D

Will tackle looping at full power in a subsequent post.

And the difference between a wedge and 1x1mm matchstick if anyone is curious enough!

Don’t know if this is the correct way to do it ; but this is what I did . Inserted a thin piece (sanded to less than 1mm) of match stick under the LE of wing .

Yes. Correct.
Same as lowering the leading edge of the stab.

 Just re clarifying:

In a Catapult flight we have three different but all vital phases of flight. The launch (2 seconds) , the transition (fraction of a second) and lastly the glide where most of the time is spent( goal here is 2 minutes glide with help of thermals).

So you want to get as high as possible so you can glide for a long time. Hence the Zero-Zero built-in decalage. All CLG's need a bit of (mind you , very small) decalage so you do not go up and straight down, you transition to the left and glide to the left.

When I said to use a matchstick, I assumed most of you do not have access to 1/32 or 1/64 balsa. You need to sand it down or split it with a sharp blade. I call this a tab. See my first Lunchbox video, very second pull had nearly 27 second flight, second flight based on these principles. In that Lunchbox I used a matchstick as I wanted to prove it to myself before recommending. These were all trimming flights, flight 1 , 2 and 3 . All using a an intentionally build heavy (7 gram ) glider with office rubber bands.

So go for the maximum height to increase the glide time. Once I trimmed, to fly slower, I lost the Lunchbox. We chased it for one and half mile but kept rising and went over the woods after which we did not see it.

There are many roads that leads to Rome. Eventually, the goal of a HLG or CLG  is to get a floaty glide and the stop watch is your judge. If you build in any decalage, other than zero, you will not climb as high.

 My goal was to share my experiences so that you guys come as close to a 40 second flight in your first glider, perhaps loose it. In my opinion that might entice you to join the wild and beautiful world of CLG, cost effective, not special model airports, but you have to put time into it.

“Perhaps lose it “ @Freeflight , that’s my worst dream :) And so I have asked Iyer sir for two more kits ;) But surely will try your suggestions on my next glides - sand up tabs , less decalage etc are in my lists (experiments) . I found matchsticks a better idea than balsa for perfect adjustments (from your valuable suggestions) since it’s strong enough , easily sanded and lightweight .

Decalage depends on where you apply the glue first - at the LE or TE of the wing (midline) - right?

I think there’s a fundamental difference between how we historically learnt to fly HLG/CLG in India, and how CLGs are typically flown in the US.

In India, (lacking good rubber) we started with HLGs, launched not javelin style, but with a straight arm bowling throw (no elbow bend).
Released 45deg nose up, 45deg right bank.
Resulting in a right spiral climb and left circle glide.
This required some decalage and some left rudder.
This technique probably got carried over to CLGs.

I used to be amazed at CLG videos from the US, showing nearly vertical launches, going almost out of sight straight up. Then a little flop for transition, and off she goes on a floating glide.
Never saw such steep, straight launches, only spiral climbs.
Glidiator’s recent launch slo-mo was an eye opener!

So when I insist on decalage, I guess I’m historically compelled, ie, old fashioned ;D

No.

Mr. Iyer, I too had started the same way in HLG and CLG too. What changed for me was the Tich article with full size plan by the designer in the Indian Modeler magazine.  Next it was the original Yellowbird 13, where I got introduced to stab tilt, washin on the inner wing, adjusting decalage by -1/64 on the stab, wing at zero, left rudder tab, right launch and left glide etc. Had also built Arora Canberra that one day it took off from Breach Candy , Mumbai with friends in a low 30 foot high thermal. We ran after it for about a one km to the Mahalaxmi temple area (just 14 or 15 years old). Lost it in the high buildings. So got introduced to Thermals and Out of Sight flights. 45 years later rebuilt the Canberra and Tich CLG's, posted on RCI . Has been an enjoyable journey.

http://www.rcindia.org/kites-trains-free-flight-and-all-others/tich-the-article-in-indian-modeler-magazine/

http://www.rcindia.org/kites-trains-free-flight-and-all-others/the-flight-of-the-canberra/

videos are on YouTube, so play it in full screen and lowest speed in the setting. Straight up, flop to the left and glide. These are only trimming flights not competitive flying. No one has time for videos in competition, only for trimming flight so you can go home and study it.

Contestants: See the videos there. Hopefully a video paints a thousand words. This is what the Lunchbox also does. Unfortunately offered mine to Hung, the thermal God before any  videos.

Back to the topic.

So the trick is to gain as much height as possible, to get maximum glide time. Assuming you have a well built and trimmed glider (most of you are very close based on your reports and videos) what else can you do? As mentioned before , I take serval rubber band launch sticks with me as rubber gets tired and we think the trim changed.
Next ,  to stay within the competition rules,  many of us build a rubber band launch stick with two sets of parallel  rubbers as in photo below. This seems to take the glider even higher, at least for me. Give it a try after you are happy with the flight. Then get ready for sweet but sad flight that like a bird just flies away. A flight you will both enjoy and cherish.

PS : notice that I keep clay on my stick, just in case I need to add to the nose or right or left wing tip based on the weather that day. Too windy, and I still want to fly, add nose clay , move your CG just a bit forward.

For this Contest You can Only USE Office Type Rubber bands , like my Lunchbox videos.

Always PULL the RUBBER BAND to the maximum. If you pull a little, then little more, you have to retrim each time. So pull to the MAXIMUM right from the START.

OK here is my prize for the contestants.

For the first person who gets 40 seconds plus flight, three flights in a row , on the same day, and you show it all in a video. l will mail you an unopened packet of the original  1/16 FAI Tan rubber (16 feet long) that I have saved for years. Since you guys are enjoying this contest, I am happy to present this prize to you. I have two such packets, one for me, the other is the prize for you.

Will include a good kit, firm light balsa CLG too. Should be able to mail it in an envelope with no custom duty on your part, I hope.

Go for it, I know you can do it. You are very close, bravo for your experience on a first model. :salute:

Let me reclarify regarding match sticks and test glides.

Match sticks tabs: These are very small. I always attach it with glue stick so I can remove it at the field or sand it down if needed.  Glue stick has enough power to stick to the glider

A) For Rudder tab : See reply #73 and 74. Very small and close to the rudder, dimensions are given based on my glider. Yours maybe smaller or bigger, every glider is different. But you get the point
B) Elevator Tab : See Reply # 151 again very close to the fuselage. Again very thin and small. Use your nail file if too big.
If the model dives put a tab on the Right Side of the upper elevator.
If the model loops put a tab on the LOWER side of Left elevator.
c) Washin Tab : See Reply# 86 and dimensions are given as the first guess. This is the biggest tab. If your tab is too long, then the glider will launch, transition and keep going straight, no turns. Keep cutting the washin tab little by little until it glides turns gentlyto the  left without the left wing dropping in a circles. you are looking for 40 to 50 foot circles.

Glide test:

Glide test should prove that the the model is safe enough to catapult. It does not dive and has a gentle turn to the left.

You should throw it, very slightly pointed down and wings level at the speed at which the model will glide, not a  gentle push as your model will never see such low glides in its CLG flight.  This IS VERY DIFFICULT and needs a lot of Experience. But needed. Practice !

The model should glide smooth, raise its nose up ( shows you have incidence enough that it will not dive back to earth) and a gentle turn to the left. Not too sharp turn to the left. See Photo in Reply# 100.

See the videos as the experts explain in  Reply # 117 first and then Reply # 111. These are 15 minute videos wonderfully made. Study it before you go out next time. It is time well spent

This is how we go almost straight up , flop and glide to the left.

Deleted. info included above. Sorry

Your points are well taken . Why no other entries so far (other than Karthik & Hitesh ) I think everyone is waiting for more offers from Glidiator & Freeflight :) Or is it that everyone is waiting for the final day ?

Indoors with a gentle catapult.

Perfect flight with a nil height loss, straight.  Distance covered about 20ft.

Lunchbox Glide test outdoors.

Winds almost nil.  

My Chuck glider formed more or less a parabolic flight path with a hand launch.  It tracked straight. Climb seemed to be normal.  After top of climb, the half of descent seems to be little fast but last half was like a meteor falling off in starry starry night.  Distance covered about 60 ft.

Unable to attach the video as file size is large.

Dreamliner:

"Indoors with a gentle catapult.

Perfect flight with a nil height loss, straight.  Distance covered about 20ft." Wonderful must be a good sight

Lunchbox Glide test outdoors.

Winds almost nil.  Good.

"My Chuck glider formed more or less a parabolic flight path with a hand launch.  It tracked straight on yaw. Climb seemed to be normal.  After top of climb, the half of descent seems to be little fast but last half was like a meteor falling off in starry starry night.  Distance covered about 60 ft." I do not understand when you say tracked straight on "yaw" . Generally speaking yaw means to have a gentle turn. So did it fly smooth with a gentle left turn?

When you say "top of climb, the half descent seems a little fast... " That to me it means you have a gentle stall. If I have understood it correctly, put a little clay ( always very small and repeat as needed) till you get a very slight nose-up and smooth glide. Let us all know.

Sorry for the mix-up.  It tracked straight on outdoor glide test.

Upto, 40 feet, the climb angle was normal.  After that, It started nose diving from top climb which became steeper with descent.

Thanks for your feedback, will try different approach again as suggested by you.

"After that, It started nose diving from top climb which became steeper with descent."

That description is of a classic stall. The glider went up, the wing no longer generated lift, so it came down fast trying to regain flight but the ground was very close, looks like dive.

Looking forward to your flights in experiments.

Regarding CG :

Dear all : always start testing at the CG shown on the plan. But that was the designers glider. Your correct CG maybe a a couple mm forwards or backwards. In the lunchbox that I lost, my CG was 1.5 mm behind the the one shown on plan. It took a backward CG for MY glider to fly slow with just a hint of stall, nose very slightly up during entire glide phase while circling to the left.

So do not worry so much of adding weight to cure stall, make it glide well.

For some time this thread was on first or second place, on the homepage, due to the interaction regarding "Lunchbox".

I personally kept on checking this thread for new updates and more guidance.

Same here. Me too, . Looking forward to all your videos.

एस ,  all of us were waiting for your updates and videos . Did you try all the corrections @Freeflight suggested ? Results ?

I’m quiet.
But I’m watching!

Got free from some personal work, now will give time to this contest.
I haven't tested yet, but will be doing in a couple of days. 

Watch out

Just a couple more points to share:

1) when trimming the glider, always pick no wind days, in the evenings. Mornings are good too, but the dew on the ground is not good for your glider. Now that your glider is ready, try to fly between 10 AM  and 1 PM. these are the times that thermals are produced and should give you extra flight times.

2) When you pick up your glider after the flight, always try and a) pick it up from the nose just behind the clay. You pick it up from say wing, stab or even worse rudder, you have a good chance of affecting your trims. b) always pick up the plane yourself and walk back to fly again from the same place you launched before.

Really eager to see your flight videos.

One more glider trimming and flying video by the expert. Very well made video.
He talks about stab tilt by bending the fuse (same as Glidiator talked above), left rudder etc. Notice how hard he launches for the glide test ( slow push glide test is not representative of the actual glide speeds). I recommend you watch this about 8 minute video as he encapsulates all the major points that I have discussed above.You will gain a lot of knowledge from it. Enjoy.

https://www.youtube.com/watch?v=d2yFo9iRsnc

Very nice, despite getting banked at launch.

A very slight reduction of nose weight (say 2 pinheads of plasticine), a touch of left rudder, and it’s ready for the catapult.

https://m.youtube.com/watch?v=u8v_SPW7bUY

Beautiful. For the first catapult launch, fly as it is. Looking forward to seeing everyone's videos !!!

No update. Where are you guys?

Weekendflyer
Rooster
Aspersid
Prabal276
Karthick Ashwath
Alex Bessie
Girish Madhavan

No update from even Glidiator!
Come on Sir. You’re one of the motivators...

https://youtu.be/zsAlaym8oh0

Congratulations Hitesh. a job well done. Your glide is very good, so your CG came out just right. Keep experimenting to cross that 60 second mark . You are so close. You have a good big flying field.  :salute:

I just noticed. Very good Hitesh: You are right handed as seen in your second video post reply # 155. your glider in glide test went to the right. Yet in your latest wonderful video Rely # 317 you launch the glider holding in your left hand and rubber on your right. Result is that it climbs to the left and glides to the right. Perfect and good flight. Kudos to you to figure this out. Very nice !
Bravo

All Lunchbox builders,

Please watch the Lunchbox Contest thread too.

It shows the leader board, and the additional prizes offered by Glidiator and Free Flight!

http://www.rcindia.org/free-donations-and-sweepstakes/next-contest-20second-flight/msg311037/#msg311037

Sir very excited about the prospect of laying hands on FAI rubber. ;D

So, I finally did some new testing in a much smaller space with a different photographer(primary photographer not available)
1.Initially the elevator tab was too big (some people said so) and it was almost doing a loop in the transition phase.
2.So today I cut the span of each elevator tab by half
3.Then I realised that as a result of this now its very nose heavy. So I Kept removing nose weight
4.After a point it started looping so i added some weight.
5. Now it shows some very weird behaviour which I am not able to understand at all. It climbs well, then dives very fast. after this it recovers,pitches up too much and somewhat glides. When I do it from an altitude of 22.5m(5 storeys) it gets sufficient time to pick up speed so glides fairly well after that. I will be going back to my cousin's place so that I have a much larger flying field for some serious testing.

This is much worse than it what it was earlier. :banghead: :help:

I collected some data. With this poor performance and trimming, it travels 51.5m for 22.5 m of altitude drop.
I have made a collection of the better videos of today's lot. Uploaded on my youtube channel. https://youtu.be/ZM2IfXrW08k (https://youtu.be/ZM2IfXrW08k)

I had earlier posted all the above in a not so clear fashion along with a mish mash of videos brashly uploaded from field to our whatsapp group for this contest. Based on that, Iyer sir gave me some recommendations :hatsoff:, which I have some trouble comprehending. ???

I am sharing those recommendations here, hope Iyer sir won't mind.

Failure to recover from a dive is SURE indication of lack of decalage (ie, having no up elevator at all or perhaps even having slight down elevator).
Suggestions:
1. Remove all trim tabs/wedges
2. If possible, check that there is no down elevator built in.
3. Balance at the suggested CG location. If more than 2-3mm away, it has static imbalance, which is possibly being compensated by some dynamic (airflow) imbalance at some speeds, but not at other speeds.
3. Please change your launch technique for test glide.
4. I've explained many times the correct way to do the test glide to establish the trim for proper glide. See for example SI74's reply #286 on Lunchbox thread.
5. PUSH the model towards a point ON THE GROUND about 30' away. POINT THE NOSE IN THE DIRECTION OF FLIGHT. It has to be in the gliding attitude, ie slightly nose down, and at gliding speed. (That means slow enough to avoid climbing above launch height, and fast enough to avoid landing in say 20' or less.
You are launching it nose high with downward force. So it starts with very high angle of attack, not representative of the glide phase.
6. All this will take only a few minutes.
7. Then try a horizontal catapult launch with say 2 rubber bands pulled to twice their length.
8. You'll soon be UP, UP and AWAY!
Best wishes.

It would be very nice if Iyer sir further extends the deadline, so that I can do some real testing when cousin comes back to station on Thursday, Dec 17 2020.
Its a very humble request sir. I was a bit busy with college endsems till yesterday and multiple other competitions.

Karthick: Sharing a few observations from my point of view:

1) Per your videos, Your glider has no transition. Goes up and comes down.  If it fails to do a transition, then glider goes up and down may not be related to incidence at all. You must bank the right wing and see if the left transition occurs. The way I see your video, you have almost no or hardly any  bank angle when catapulting your glider. Need to bank the right wing , say, start at 30 degrees .Then experiment for your glider if you need more bank or les, all for the same launch angle. Change one thing at a time ONLY. See Hitesh's video for launch and bank angle.

2) Lunchbox is a world famous glider design specially for new comers. The designers knows the wing and stab areas. For this glider Mr. John has correctly calculated TVo, tail volume coefficient. It is all related to the ratio of the stab and wing area and the moment arm versus  MAC. In short, take his word for it, never cut down the wing or stab areas. When you put the tabs on the stab , it looped. Very good ! Expected. Now the tab is either  too long or thick. So  you can make  it short , 1 mm at a time, or sand it down with a nail file to thin it. Keep catapulting and sanding until the loop is just out, not too much.

3) CG affects only the glide phase. Your glider may need a bit ahead or slight behind.  Till you get the launch and transition correct, just keep the CG as shown on the plan.

I suggest put the correct stab on back again, and the tabs are 1/32 inch thick only about 6 mm long. My glider just needed that much only. Try it .

In Reply # 318 please see the comments in Blue just modified after observing all of Hitesh's video.

Please make a note of it, may help you in future if your glider just want to glide right. Very helpful, what he did.

You may have the left stab tilt and yet your glider wants to glide right. In that case, do as Hitesh did. Reverse your launch hands, glider in the left hand and rubber in the right hand.

A slight skewed  LE of the wing the right (very tiny bit off the fuse center line) will negate all stab tilts. Also if your washin tab is too thick or long, you may experience similar  right glides. In this case, best thing to do is reverse your launch hand as Hitesh did.

PS: In such a case, left climb and right glide, you may have to put the washin on the right wing  should your glider spin in during the glide phase to the right. Remove the left washin in this case too.

Good to hear that. I know you can do it.

Sir I think I failed to communicate properly again.
I am aware of the fact that Iyer sir has chosen a classic and beginner friendly design for this competition. Also, I am not making any changes whatsoever to the basic construction. I am just adjusting trim tabs and nose weight. I will check reply number 318 once more sir. Also. the elevator tab that I am using has roughly the same dimensions as what you recommended. Its 8mm long on each side and is about 1.5 mm wide.

Karthick: How are you coming along?

Very badly sir. Need to trust my intuition more. Will be doing more tests today in a larger field.

Thank you sir i will try for 60 sec up ..

Best thing , trust your intuition. Wish you the best. Post your flight videos

Hitesh: "Thank you sir i will try for 60 sec up .." Great. I am sure you will reach it.

@Free Flight,

Hitesh is left handed.

So I set up his models for left hand launch...

Regards

In his videos Reply # 155, the first video, a bad stall chuck he uses his left hand. Then in same reply second video he gets a good glide with his right hand. Then his full catapult launches are left handed. Led me to believe he is right handed. Perhaps I saw  the video wrong.

Thanks for setting him up for the left hand pull.

Anyways, bottom line is that he is getting good flights and enjoying. Aiming for a minute that I hope he can soon get it. And all this with an office rubber band, no Super Sport Tan rubber joy here.  {:)}

Free Flight sir,

Fooled me too.
Later he told me the right handed long test glide was by an experienced aeromodeller friend! Who helped him with the initial trimming.

Today he told me to donate half his prize money!
A nice gesture.  {:)}

Regards

"Today he told me to donate half his prize money!
A nice gesture." Agreed .

Thanks Mr. Iyer

Respected memebers of the forum, herewith I have shared the HD version of my latest videos. Has some analysis sfrom my side. One thing that Sunil sir has told me is that I need to launch more vertically. Will do that. I reached 12 sec and 18 sec flight time in the videos. There is also a slow motion shot in there.
https://youtu.be/NesEPyKWCPk (https://youtu.be/NesEPyKWCPk)

Congratulations Karthick. A job well done. Another delightful video from you. Your analysis is good in the video. A few questions that YOU have to find answers to: Why use a very long rubber band instead of more power from two short but parallel rubber band?  You correctly observed and stated that the glider is moving too fast with nose down, not floaty. You went to the right correction of removing clay to move the CG back. But could more be removed? The way to tell that is to keep removing clay till the glider no longer does any transition. Then add back small clay. Do you think it would help to float more if your stab tabs were thicker but very short very near the fuse. These are the experiments to think and do. I am sure you will cross the 40 seconds mark soon by questioning yourself.

In one of your replies you said "Need to follow MY intuition" good, keep at it. That is the key.

Good progress and happy to see the joy on you in the video. Having fun while learning is what matters.

The Lunchbox Contest thread is now closed.

But this thread is still open for comments.

Dear All,

The time has come for you to reach a slightly higher goals of consistent 1 minute flights that is the capability of this model. You guys are now hovering around 40 seconds a little plus or minus and am sure others will soon be there.

I had promised a tan rubber for the utmost three consecutive flights of 40 seconds on a single day with Tan rubber. But your hard work, makes me feel that I will award each of you you who actively participated with the 1/8 inch thick Tan rubber to send your gliders even higher and reach the minute flight.

Working on how to get it to you so please be a bit patient. So Hitesh, S174, Karthick, Weekendflyer, RC Guy please PM me your Email address so I can get in touch with you.

This is a wonderful beginning for you, but you can and will excel soon.

Now then, I have a recommendation for you, if I may please. You have to practice, so you need to build more of the SAME glider. I suggest the following way without balsa except the fuselage.

The technique was created by the world famous Japanese, Dr. Yasuaki Nimoya the inventor of the White Wings Paper Glider. I just made the Lunchbox ( LB from now on) using his techniques and  test glided in my basement. Near my house we have 14 inches of snow so not sure when I will maiden it outside.

 The advantage is that it will a)Most important it will continue to teach you trimming techniques by bending the paper easily and bend it back if it did not work or you are experimenting b) You can build it very fast as all you need is a balsa fuselage, a Manila folder ( available also in India for INR7 or so)  and the manila folder should weigh between 175 to 200 grams per square cms ( Divide weight by area)plus Feviquick and glue Stick  c)With the wing, stab and rudder of Manila Folder , balsa fuse and CLAY weight is around 7.3 grams, not much heavier than your balsa glider today .So the wing loading is very similar.  

I taught myself to fly competitive CLG using his building plus flying technique and have lost many in the thermals. They fly good and will teach you in a relaxed way.

I can volunteer a WhatsApp Video meeting on any Sunday morning my time  ( Sunday evening your time) where I can go over with you the details  quickly (very easy), better than typing many posts here, so you can start immediately.  One of you guys will have to take charge and create this video meeting.


 Next post I am attaching my two videos and two for the White Wings.

Let me know.

Ciao,

The Videos :

https://www.youtube.com/watch?v=pZLwlBVuqE0

https://www.youtube.com/watch?v=8j5_Y8AFRXo

https://www.youtube.com/watch?v=RAhDLuhFFBk

 This site has two such famous plans that you can download and build later or now. Both capable of 1 minute flights.

https://www.ssa.org/Youth?show=blog&id=3438

@Free Flight sir,

Excellent suggestions.

Here’s a Lunchbox with wings and tail parts made from a disposable dinner plate!

Regards

@Iyer Sir, Thanks.

Will get in touch with you and everyone who furnished their email very soon.

The foamies are excellent !

A Very good Question was asked: Can Manila folder gliders be reliable?  Yes very reliable no flex. Proof is in the 10 minute video below. Japanese HLG meet. See how hard they throw, see the launching style and how high they get. No flexing of wings etc. Even the senior guys are throwing hard, no complains from them (Note to myself : do not complain of bad arms).

Talk soon on the Card Paper flying!

https://www.youtube.com/watch?v=eNfvwwQNG9I

A final recommendation. As discussed, if built correctly, learn to trim and transition well. Then tune out the glide. Last, but very very vital,  learn to "pick the air" .

Here the same Lunchbox CLG  made from card paper and balsa fuse. I used a Manila folder for card paper for just proof of concept. Optimization needs to be done . AUW 7.3 grams, can and must  go lower. Card Paper airplanes are good to learn CLG trimming concepts. Once the trimming concepts are understood well, need to learn to pick the air. Finally move to balsa airplane for some awesome CLG fun.

The CLG Mantra: Climb almost vertical, transition with NO loss in height, glide slow with nose slightly up. For right handed people, climb right and glide left.

https://www.youtube.com/watch?v=JblP8VwUx3A

@ Free Flight,

Great transitions in the video with no loss of height.

Wonder if people noticed that one of my Lunchboxes is of balsa, and the other has the wing and tail parts made of disposable dinner plates of foam!

Regards and thanks once again for your invaluable contributions.

Dear Mr. Iyer,
Thanks for your kind words.

Personally this has been very enjoyable. I think, I learnt more here because of the very good questions asked by the actively participating contestants. These guys made me think differently, that helped me to grow in the world of CLG.

First set of gifts arrived from @FreeFlight ( Malav sir) . Thank you !

Great news!

Meanwhile, I got this stuff for you guys...

Looking good!

Let's start a Bobni contest. Must ROG, stay with the original design, must use ordinary packaging tissue, use the same diameter prop, must be plastic prop and not home built prop, use the great rubber as shown in the photo. This model was built by most seniors when they were young. and they got started in model airplanes by probably it being their first kit.

To level the field, minimum weight without the rubber at 8 grams.

Thank you Freeflight sir and Madhav sir for the tan super sport rubber and thank you Iyer sir for this great thread

Regards

Welcome guys. Enjoy the beauty of the competitive rubber launch. Want all of you to have fun in CLG.

@Freeflight

Thank you very much for your complimentary gift of tan rubber
Your guidance have given participants like me very good insight into flying chuckglider.

@KKIyer

Thank you very much for organizing Lunchbox contest.  Awaiting for the next challenge.

DJ

Benefits of participating in a contest .... more surprises , more prizes ...  :thumbsup: Thank you so much @Glidiator ( Anant sir ) . It was a surprise for me to see the YouTube video of “Folding fliers “ from Madhav Khare sir . YouTube link : https://youtu.be/WZjSFi6yD00   .Thank you Anant sir for this invaluable gift ! And for TinyTot &Tailwind ... .

First outdoor trip of my Lunchbox

https://m.youtube.com/watch?v=kXD5EW3WcSk

And it disappeared in the clouds ? :) Which building sir , in the background?