RC India

Learnt a lot from the free flight TLG.
So decided to make a larger one capable of carrying RC.
Got small lipo, ESC and servos.
Made proper patterns in hardwood for the airfoil shape (AG03 root, AG11 tip)

Hunted through Harveer's stock for light balsa.
Found one 5/16x4x48 that was 96gms. That is 6lb/cft, ie contest grade.
Cut into 4 panels for polyhedral, and ease of sanding.
Each panel took 2 hours of sanding (don't have a razor plane).
After collecting a cupful of balsa dust (never know when you'll need it!), threw away rest.
Result was worth the effort. (Pinholes in section are for epoxy to grip well in the panel joints)
Weight of 4 panels 72gms.
With lipo, servos, ESC at 30g, Rx 4g, boom 15g, tail est 7g, pod est 10g, targeting AUW under 150gms.
Hope no extra nose weight is needed, so that wing loading does not exceed 4oz/sqft.
(FF TLG is 3.5 oz/sqft loading)

For anyone interested in the technical details:
Aspect ratio is 12. Rather high. Hope it won't flutter on full power launch.
Estimate Reynolds Number of around 100,000 at launch and around 25,000 in glide.
At 25k Re, it will need Cl of about 1 to support 150gms. This is clearly wishful thinking, but what's the harm in trying?
Have reduced the tail volume coefficients to about 2/3rd of what was used in the FF TLG, as the need for stability is reduced with RC...
Replacing Y tail with cruciform, as 4gm Rx has only 4 channels, so no mixing available.

Edit: No mixing? Wrong. Only Ch 2&4 required. So used to thinking flaperon that i forgot V tail doesn't need Ch 5 or 6. Well one lives and learns...

G Great

Great Aerofoil achieved sir

Completed wing seems too fragile due to high aspect ratio and low (6%) thickness laminar flow airfoil.
Can't think of any alternative except to glass the entire wing, as i have no CF rovings or tape.
Started with top of one tip panel. May have to rip it off if it adds too much weight.
1 side of 1 tip has added 4gms. Hence 32gms will be added to my 72gm wing :banghead:
Still better than breaking on the first tip first landing...
Should have measured the bending resistance without glass, for comparison...

Excellence at its best ....

Thanks Abhay, Manoj and DocNayeem.

Decided to make a last minute attempt to complete by tomorrow!
Fibre glassed the entire wing. Weight increased from 72gms to 100.
Pics of bulkheads with hole for CF boom, and V tail with torsion springs for elevons.
(No pushrod, only pulling by string against torsion spring)
Bulkhead for wing mounting bolt needed a shallow to accomodate centre dihedral.
Going to make the fuselage pod now...

good job , wing finish is very good craftsmanship :bow:
 :goodjob::goodjob::goodjob::goodjob::goodjob::goodjob::goodjob::goodjob::goodjob:

that is expected from you sir

i want to say is it right or wrong

as seen in the photo that you are using some weight at the nose in place of it place battery at the nose could reduce some extra weight of the airplane.

and for minor adjustment of c.g place very small weight near the  leading edge .
and replace it position so as to fly it fast or slow which ever is needed.

Where did you see the nose? On the free flight TLG?
RCTLG fuselage is still under construction.

Looking good, sir. You have some very good sanding skills. :thumbsup:

I'm guessing, you're using the ESC for the BEC, I think you could cut down on a few grams using a UBEC instead (If you have one ATM).

Do you coat the bare wing with epoxy, lay the FG and apply epoxy again over the glass? I had attempted to glass a small balsa wing, the wood absorbed a bit more epoxy than I had anticipated and weight increased by more than twice, it was a loss. :-\

@anjanbabu
Since you mentioned it, i decided to look at just what i have.
Being satisfied with the performance, size and weight of the 10a ESC in the HK Donkey combo, i got an HK 10a ESC from Adiboy and one from another forum member.
Now i see that they don't say 10a ESC. They say 10a UBEC!

If you know what's the difference, pl advise.
No time to research just now as RCTLG waiting to be completed.
Progress so far till 1130pm in pic below.

BTW lovely British Racing Green on your trike. And i would have expected a tail wheel trike to oversteer under power...

Edit: Forgot to answer your question. No epoxy on bare wood. First laid glass cloth then dribbled epoxy and spread with a credit card. I realise now that nearly all the epoxy can be scraped away with the card. Did not try soaking up epoxy with tissue towels, as RC Aunt warned that we will end up with bits of tissue all over the wing. I still dont think the wing is strong enough. Have just one day to complete and test fly. Maybe a tow launch. Tomorrow will see if i have the guts for a discus launch before i get carbon fibre/ kevlar reinforcement.

If you're talking about the one placed on the weighing scale in the first post, that's definitely an ESC because it has motor connection wires on them.
ESCs come with built in UBEC/SBEC to provide 5v to the Rx. I was talking about just an external BEC that only provides power for Rx, like this one-- http://www.rcbazaar.com/products/807-hobbywing-switchable-u-bec-3a-56v.aspx (http://www.rcbazaar.com/products/807-hobbywing-switchable-u-bec-3a-56v.aspx)

I had blue in mind, but can't beat the BRG when it comes to showing off raw power.  :giggle:
I'll be building an aeroplane some time soon, tailwheel drifting on that. ;D

I noticed that if I don't wet the wing surface with epoxy before laying the FG, the adhesion is very poor and surface is not smooth at all. I use a 360gsm cloth, that could be the problem.

I never had success with DLGs, hopefully, I can learn some bits here. ;D

360gms? Wow.
What i'm using is under 30!

Forget 3oz/sqft loading. Now only hoping not to exceed 4.5oz/sqft.
Guess one should count one's blessings. At least i wont have add ballast. Wind here >15kmph all day.

I mentioned the FG cloth density as 360gsm (grams/meter). ;D

Glider looking nice, good luck for tomorrow's fight.  :thumbsup:

@anjanbabu
Thanks.
My glass skin is under 30gms/sqmtr!
Looks like this.

Build status at 2:20am!
Second pic shows wedge inserted in V and sanded round to improve contact with boom.

Nose length increased to avoid having to add nose weight.
To compensate for additional side area ahead of CG, have to add sub-fin to add yaw damping.
(This will add 2gms to tail, to compensate for which i will add 8gms to the nose. AAARGGGHHH)

Is there a formula to calculate optimum nose and tail length for HLG/DLG?

@anjanbabu
The stability in pitch and yaw imparted by the stab and fin is a function of their size (area) and moment arm (ie, distance from aerodynamic centre of the wing, generally taken as being at 25% of the chord from the wing leading edge)
It also depends on the wing area, wing chord and wing span.
This is measured as (horizontal/vertical) tail volume coefficients.
The value varies for different types of models like glider, trainer, aerobatic, 3D, jet etc.
In addition you have to decide how much of something called 'margin of static stability' you want.

But since much of our 'design' of models is based on TLAR (that looks about right), a reasonable thumb rule is 3-4 times the wing chord for wing TE to tail LE, and about 1-1.5 times the wing chord from wing LE to nose.

Hope this was of some help. Unless you are interested in aerodynamics for its own sake, the time tested method is to find a successful design and copy it with cosmetic changes!

Pic shows build status at 3:25 am!

Completed at last. But it is too dark to test fly (1245am).
Worked whole of yesterday night.
Hope i get up early enough to test fly and shoot video to post before 10am deadline.

Pic 1 Complete except for stickers
Pic 2 Note pull thread instead of pushrod

Best of luck to all participants.

Good Morning Mr. Iyer

- How did you do the Rudder , elevator linkages ?? Did you load the
opposite side of the surface with a spring / rubberband ?

Could you post a picture ??

@ Saikat sir,
Guitar E string.
First tried '[' shape (like a staple). Spine 2cm, arms 1cm each.
Elevator folded back flat on stab, one arm each pushed into stab and elevator.
Too strong.
Increased spine length to 4cm, arms 1cm.
Instead of staple shape, in which there is 180 degree torsion at neutral, made a crank shape like aileron torque rod, so that torsion is only 90degree at neutral.

Managed a test flight video in the nick of time. Test glide from shoulder height went over 60 meters!

www.youtube.com/watch?feature=youtube_gdata_player&v=ie2thgI193A (http://)

Very nice sir  {:)} {:)} {:)}

No RC? Disqualified  >:D >:D >:D

@sanjayrai55,
One FF glider
One RC glider
Covered both bets. Tarzan and Son of Tarzan, haha.
Needed to built about 10 more (like you  ;D) to stand a chance.
Never got around to completing Fanjet...

W {:)} W !!

Great efforts put sir.

This is a real GLIDER. Great  :bow:  :thumbsup:  :hatsoff:  :salute:  {:)}
 5ft to 60mtrs. .... what is the glide ratio? Try launching it from a 20 storey building. RC will be a real requirement otherwise it will cover 60*20*(10/5) =2400mtrs
Think seriously of settling down in Bangalore. I am inviting you again. How long do you plan to be in Indore?

Wow!!!! That's some glide Iyer Sir,  seemed like forever. Did it land finally? could not see it in the video clearly.  ;D

Nice build.  :thumbsup: :thumbsup:  {:)} {:)}

Thanks Sanjay sir, Sandy sir, Ashok, Ahmed, Manoj, Anjan.

Wind dropped today after many weeks. Time to check out tow launch of my RCTLG.
Short (25m) line, almost nil wind.

www.youtube.com/watch?v=oTk_zad4SeI&feature=youtube_gdata_player (http://)

First tow by Ahmed, launch by Harveer.
All went well till base leg. Hit pole as i was afraid of over control.
Surprised at lack of damage. Not even a ding!
Never knew that 0.75oz glass adds such strength. 40% wt penalty forgiven...
(Intake of breath is by RC Aunt...)
http://m.youtube.com/watch?v=D631xtTaeP4&feature=youtube_gdata_player (http://m.youtube.com/watch?v=D631xtTaeP4&feature=youtube_gdata_player)

Wow! Just WOW!  {:)}

P.S: All your videos are @240p max :(

 

Thanks Sidewinder
Can you believe that the iPad camera is one mega pixel?
RC Aunt uses it because it is easy.
Maybe she should use my Samsung phone, whose camera is 8mp.
All this while we've been using low resolution to reduce upload size.
Hope next sunday pics/videos are higher resolution.

What happens when you try to discus launch a high aspect ratio rc towline glider...

http://m.youtube.com/watch?feature=youtube_gdata_player&v=0tI2lGnxYqQ (http://m.youtube.com/watch?feature=youtube_gdata_player&v=0tI2lGnxYqQ)

A soft nose helps, especially when backed up by glass cloth!

 {:)} {:)} {:)}

Really very good sir  :hatsoff: :hatsoff:

very good glide never seen such glide before  :salute:

wing finish is woow

No news on Sweepstakes.
Continuing experiments.
Desi Jugaad HiStart
First in India?

http://m.youtube.com/watch?feature=youtube_gdata_player&v=KCUOcwIxKxE (http://m.youtube.com/watch?feature=youtube_gdata_player&v=KCUOcwIxKxE)

www.youtube.com/watch?feature=youtube_gdata_player&v=KCUOcwIxKxE (http://)

Good that you built one. You have been longing to have one for quite some time.

Your clarifications on
Type of rubber tubing used
Length of rubber tubing,
length of string,
rubber tubing pulled by what extent,
approx height gained by the glider,
do you put a stake at one end or someone holds the end.

This would help others in replicating a histart.

Next you should experiment on launching the glider using a winch. You can use a glow engine starter for the winch motor. A few pullies and you should have a winch working.

Did it over 40 years ago on a Yellow Bird  >:D >:D ;D

Used about 3 feet length, of which 1 foot was surgical rubber tubing. It was tied to  a wooden post. but if we used to much pull, it would go crazy ;)

@sanjayrai55 sir,
Not RC, hence doesn't count. ;D haha, Gotcha >:D

Crazy launch.
Result of release without wings level. Got a real shock!

http://m.youtube.com/watch?feature=youtube_gdata_player&v=glLQMmUoIk8 (http://m.youtube.com/watch?feature=youtube_gdata_player&v=glLQMmUoIk8)

www.youtube.com/watch?feature=youtube_gdata_player&v=glLQMmUoIk8 (http://)

Iyer sir; 40+ years ago the Radio Sets were single Channel, and had wires and valves not transistors and ICs :D

Sir,
Just joking. No offense meant.

None expected. None accepted. None taken. None given.

 ;D ;D ;D

Iyer Sir, your build skills and knowledge levels are extraordinary  :hatsoff:

@sanjayrai55 sir,
This reminds me of an incident in about 1970.
We were flying in the Polo Ground near President's Estate, which was for the use of the President's Bodyguard.
One immaculate Bodyguard on a horse taller than me turned up to investigate.
He rode up to me and asked with ultimate politeness:
'Aapki tareef?' (Instead of 'Who the hell are you')
Fortunately I had enough Urdu for an appropriate reply:
'Kaash ki hum tareef layak hote...'

You were lucky!

In circa 1986, we guys were flying there, and this giant Sardar Cop comes along, says "Tvada Boss kithe?" and I was shoved in front  :o :o

He gave us 5 minutes to get out of there! This of course was after Mrs. Gandhi's assassination!  8-) 8-)

what a talk

Hope this is of use to other experimenters. Please note I was using under 1kg tension, as my RCTLG weighs only 200gms.
Edit:
Since RCTLG was barely moving forward in level flight into wind, and the theoretical stall speed is about 5m/s, i estimate that the wind was about 15kmph during the videos.

On 15th June RCTLG dived into the ground at full speed from about 20ft during histart launch. The others said the towline wound itself around the wing. Hard to believe. Maybe the line was tangled in the wing before release. Most probably the line must have hung up on a bush, making the line pull the model down.

RCTLG appeared to EXPLODE. It was shocking.

However the damage was surprisingly little. Underfin came off. One side tailplane came off. Servos uprooted but undamaged. Wing retaining bolt (plastic) snapped. Ply bulkhead at leading edge position broke in half. Not even a scratch on the wing. Fibreglass skin really works. The wing does not even have any dihedral brace!

Lack of serious damage to fuselage attributable to:
1. Carbon fibre tube goes all the way to the front
2. Pod is glass skinned
3. Nose block is of ordinary thermocole with glass skin. This compressed absorbing the shock.

RCTLG since repaired and flown yesterday (in over 25kmph wind!)

welcome back sir

waiting for next aircraft  build

Good Show  :thumbsup: :thumbsup:

Launcher needs to launch, not just open fingers!
How do you like the zoooom at the top?
Missed capturing the landing on video.

https://m.youtube.com/watch?feature=youtube_gdata_player&v=II75F6T8wDo (https://m.youtube.com/watch?feature=youtube_gdata_player&v=II75F6T8wDo)

www.youtube.com/watch?feature=youtube_gdata_player&v=II75F6T8wDo (http://)

Beautiful Iyer sir, that bird is just standing in air

45' of 3/16 surgical ( 20 pieces knotted together)
Height achieved presumably 200'
Best duration so far 90sec in 20km wind
Haven't been able to do 2min yet
Probable moral is that the AG03 airfoil can handle high winds,
but isn't the best of floaters at 5oz/sqft loading
http://m.youtube.com/watch?v=ulHKF3SsLHg&feature=youtube_gdata_player (http://m.youtube.com/watch?v=ulHKF3SsLHg&feature=youtube_gdata_player)
www.youtube.com/watch?v=ulHKF3SsLHg&feature=youtube_gdata_player (http://)

 Great  {:)}

Admin (and all members)
In 70 days, less than 50 responses, but more than 6000 views.
Ie, over 80 views every day!
Hard to believe that that 5-6000 people saw the thread.
Is this for real, or is something like the Google Spider that is increasing the count?

Sirjee, that is because we love to come back and visit this thread to admire at your exploits, rather than put useless comments.. ;D atleast this is my take. Maybe this is the case with others too!  :thumbsup:

Eight months after reply #55 (1min 40 sec flight),
Indore RCTLG flew again.
For some reason, needed extra 13gms nose weight.
And managed only 1 min.
Looks like the rubber is getting old...

www.youtube.com/watch?v=IPW8qQQ9KNs&feature=youtu.be (http://)

 {:)}  {:)}

You are tempting me to go home and hunt for bits of my glider built in Hyd (if you remember). Surely after all these years of transfers the glider would need big repairs!!!

A mos excellent build  :thumbsup:

That's Really Good Sir.:)
Regards,
Aman. :)

Iyer sir , still 1 min is very good time.

Thank you manoj, aman, Rai saheb and Ashok.
This Sunday i plan to try out Hobbyking rubber.
I fear it may be too much, as it can take models upto 3kg - mine is only 200gms.
And the rubber is only 10m.
$3.69 cost me Rs 850 due to shipping!

Frank Zaic first mentioned HiStart in 1938!
In a 1944 article, he said something that i think is of utmost importance to anyone trying a HiStart.
He said 'Use the minimum power required'

Having successfully crossed that stage (using 7 times the glider weight as against the recommended 4-5 times), i'm wondering what will happen with a shorter length of stronger rubber. I would have preferred a longer length of weaker rubber.

Response of anyone with first hand experience requested.

Iyer sir, you are going to love this  8-)

The rubber acts as a spring

Springs are chartacterised in their behaviour by the linear equation F=kx, where F is force, k is the spring co-efficient (a constant for a given spring) and x is the displacement

The first integral of Force yields Work or equivalent energy imparted

E = 1/2 k x²

Your interest is the amount of energy put in to the launch. Thus displacement (squared) is the defining factor.

So, a longer length, even of lower stiffness, will impart more energy to the plane (and have a smoother take-off incidentally)

 ;D

Thanks. Must have realised this instinctively!
"I would have preferred a longer length of weaker rubber."
Unfortunately the new rubber (10m, 6/4mm od/id) is shorter and stronger than the existing one that is getting tired (15m, 5/3mm od/id)

Iyer sir, try and see if you can get surgical rubber tubing; as used in BP Cuffs, tourniquets etc.

Iyer sir if you do get a hold of surgical tubing source do share with me also, i am also on the hunt.

Sanjay sir i heard that surgical tubing gets cracked when used in sunny days. What other alternative for surgical tubing? is butyl rubber tubing that is in cycle tubing ok, though a long tube of small dia will be hard to find

Also sir if i find tubing suitable for hi start will tell you. Had gone to bafna surgicals thinking they might have some but they are only distributors of medical devices :(

Currently using 15x1m pieces of the yellow surgical tubing.
Will try red HK tubing 10m tomorrow.

Nose weight needed last Sunday was stone(white)+plasticine(blue) 13gms.
The keychain camera weighs 14 gms.

Wondering which to use as nose weight tomorrow...

Found that the Hobbyking rubber 6mm x 10m was not suitable for this 200gm glider.
Low pull gave less height.
More pull gave gave a loop.
Leading to a hit on HT lines.
The CF tube led to a short circuit.
That set the tail on fire.
Fin burnt away before rescue.
Towhook vanished in the spark.
Fibreglassed wing shows only a small dent.
Hope Rx and servos are not fried.
Though the video from the onboard camera has vanished...

Sorry to hear of this Iyer sir

The spring constant " k " was indeed too high. Too much force at start.  :(

Go back to surgical I think.

Neil, a little Glycerin rubbed into the rubber keeps it soft and pliant, no cracking

Similarly, store rubber bands in Talcum Powder to prevent them getting sticky ;) 

Hope the MP grid survived the hit Iyer sir.  >:D

 :rofl: :rofl:

@sanjayrai55 sir,
Meri poonch jal gayi
Was expecting sahaanubhuti!

Wonder if anyone will buy that HK rubber from me at a discount...

@sundaram sir,
Haven't moved out of home for fear of getting caught!

Henceforth will fly only DRONES...

Sad to know the end to a beautiful model.

Needs a wrap of glass cloth near the tail, and a new fin.
New pull strings for elevons.
New towhook.
If the Rx and servos are not fried, should be back next weekend.
On 20m of slightly rotting surgical tubing and 50m thread...
With the keychain cam instead of nose weight

Flight of the Phoenix inspiration...

 Iyer Sir....that's a fantastic project. Getting 50-60 sec flights is a great deal - Congratulations !

 I have tried my hand at HLG and got about 30-35 sec flights with javelin launch for a 200g, 48in span plane.

 All three pics are of different wings - the orange one performed the best. KF2 does not work very well for HLG/DLG. and the sanded depron wing is yet to be tried.

 Nvertheless, an awesome project

Oops....here are the other pics

Here's the one with KFm2 wing. Somehow not sufficient lift in a HLG but flies well in a powered plane. The orange one is made out of EPS, reinforced with Balsa spars.

@bmblb,
Thanks.
How did you manage to sand the depron so accurately?
CF for LE is a good idea. But may need a 3-5mm spar too.
You could also try glass fibre covering (detailed somewhere earlier in this thread)
Best of luck.
Regards

For Free Flight Tip Launch Glider, you may like to see this:
www.rcindia.org/kites-trains-free-flight-and-all-others/for-the-5th-sweepstakes-first-model-k-k-iyer/msg181492/#msg181492 (http://)

Thank you Iyer Sir.......making a wing is almost therapeutic for me. It gives me great joy ! Here's another pic of the wing.

It felt like Hattori Hanzo making The Sword for Beatrix

 just kidding  ;D

 Sir....what do you think about just taping it? Would the weight penalty be significant?
 Also, the sanded wing has a bit of an undercambre - depending on how I tape it, I can TRY to either increase or decrease the cambre.

 Which would be a better option? Span is 1m. Chord about 6.5in

Haha.
My wing needed eight hours of sanding.
But recently got a razor plane and some 10mm balsa...

Weight will not be a problem with tape, but strength will be inadequate without CF spar.
Try not to increase camber.

Just curious about the razor plane - is it the Master Airscrew one available on HK or is it the type which uses a regular razor blade(7 o'clock, topaz type)?

Apologies for digressing from the RCTLG.