RC India

Hi everyone, especially free flighters.

Over 50 years ago, Frank Ehling, then the Technical Director of the Academy of Model Aeronautics, USA, designed this model.
It was initially considered too simple to interest anyone.
But the AMA used it to successfully introduce thousands of youngsters to the joys of aeromodelling.

You can find the plan and description if you go to:
Outerzone.co.uk
and search for Delta Dart.

To build it you need balsa strips, the prop and the prop hub, suitable rubber, tissue, glue stick and Feviquik.

Which I’ll try to provide.

I’m going to build it tomorrow and see if it flies!

Plans (from outerzone.co.uk) are attached.

Mr. Iyer picked another good model. I would have guessed you would pick Bobni, but this one is famous the world over.

Over some summer time, my RC club invites kids  to build this one. We give the full kit and help them build it at the field. Under me I have had about 30 plus students over the years. We take kids from grades 4th standard to 8th for the Delta bash.

We make jigs so they can move faster and use thin CA so everyone can be in the air after lunch. Hot air is quite abundant at 1 PM and a few kids have lost it in Thermals over in their second trim flights. So awesome to see the kids really enjoy the build and fly.

Late afternoon we have what is called "All Up , Last Down" and give special prizes for the first second and third longest flight but all get to take their model home.

Have fun! Very enjoyable.

Here is a good source on discussions :

http://customers.hbci.com/~bkuhl/building_tips.htm

Look up outerzone.co.uk
Type ‘Delta Dart’ in the search box.
You’ll get 3 plans.
Select the middle one (18” span)
Scroll down.
Download plan.
Print it at home on A4 paper.
It’s 4 pages. The full size plan is on pages 2&3.

All the wing and tail parts use 1/16” x1/8” (1.5x3mm) strips.
The longest pieces (wing leading edge) are just under 10” long.
I had a piece of 1.5mm sheet just over 10” long.
So I cut a few strips from it using a 3mm spacer.
Then made the angle cuts at the strip ends.
Notice that I added a base piece for the fin, though not shown in the plan.

Had some very old tissue paper,
But a warm iron took out most of the wrinkles.

A bit hard to see the plan throughthe red tissue.
Should be easier with plain white tissue.

Rubbed the tissue with a glue stick where the structure is.
A bit messy.
With the second wing, found it much better to rub the glue stick on the wood instead of on the tissue.

Then just tiny dots of Feviquik on the joints...

Poor workmanship!
Jagged edges due to using a dull blade for cutting the tissue  :banghead:

A bit surprised and disappointed that it’s possible to make a mess of the covering on such a simple model.
For the stab I used the traditional method. Built the structure first and covered thereafter.
Notice that I added a centre rib, not shown on the plan.
And used a NEW blade!

Sprayed with 80% alcohol, instead of water...

Completed.
Surprised at how well it flies (at least indoors)
Will try outdoors tomorrow.

Why is the wing covered at the top, and the stab at the bottom?

It actually says so on the plan!
To get a balsa to balsa joint without paper in between, I guess.
(This model was intended for kids. I built it now as I’m in my second childhood  ;D)

Incidentally, as per the plan, there’s no central rib in the stab, and no base rib in the fin, both of which I added.

I think because the stab is stuck to the bottom, wing on top. Long may you un-age Iyer sir!

Not to forget the DECALAGE, that I kept talking about in the Lunchbox Build and Contest threads...

For a beginner the best option is what the instructions suggest.
Print the plans, and build it directly on the plan, ie, stick the balsa strips with gum on the plan itself!
The plan paper becomes the covering.
No need to mess with tissue etc.
It won’t add more than 1gm or so to the weight.

Nice Home made prop. Lighter and probably more efficient.

What is your all up weight minus the rubber?

At about 36 square inch wing area an overall weight of 18 grams  puts you at the 0.5 grams per square inches. Looking at your pictures, you must be well under that, I think?

Get the motorcycle tuned up, it will be a long chase in the afternoon flight.

18gms?
This one is 6 gms with a 6” loop of 1/8” rubber.

Wow! at 6 grams with rubber is very nice light weight.

When we have a building session with the kids, it usually comes out at 9 to 10 grams using the plastic prop with bearing (about 3 grams) , packaging tissue, hardest wood for strength and resist warps. Then the weight of the rubber. The convention followed here is that we speak of the rubbered model weight always without the rubber.

Take a look at the Bobni video posted here. It does a nice ROG and model weight of 7 grams not including the rubber.

Vey much looking forward to your outdoor flight video at such a low weight. Should be great.

@Free Flight,
There are 2 short videos on the Whatsapp group.
At 150 and 250 turns.
Didn’t dare go beyond that!

But then I found this chart (see pic)

So can I really go to 600 turns on a 6” loop of 1/8” TAN?

That table is a good approximation. I would use 80 to 90 percent of the turn per inch suggested in the table. I would  do a sacrificial break on a 5 inch rubber and go 90 to 95% of that many turns in flight. My last batch of 1/8 rubber breaks at 97 turn per inch. So I go to 90 winds per inch. Of course as you know this is based on the rubber being well lubed and about 4 times the length of stretch winding for the first 50 percent of the turns. I find that home made torque meter is more reliable to get consistent torque for each flight and so usually  I no longer count my turns.

One more thing I found out is that the max turns varies within the batch of the rubber that I purchase. Hence 80 to 85 % of break torque is what works safe or me.

Would very much enjoy seeing your WhatsApp videos if you can mail it when you get a chance. Thanks.

Malav Sir’s gift  inspired me for more builds ... so I built this one - Initially built a “Hangar Rat” , but flight duration was not great , so replaced its wings with foam . And here’s the result - this is just a test flight - only very few turns (250-300) , I am sure it’ll fly forever :) if the winds are increased . Thank you @Freeflight and Glidiator (Anant sir) for the proper guidance .

https://youtu.be/duJrhOkb89U

https://m.youtube.com/watch?v=IJd5ro_2JAA&feature=youtu.be

Some pics...

More pics

https://m.youtube.com/watch?v=2rUJENFt6lc

I think Hangar Rat is more challenging(build, trimming and flight duration) -needs so much patience) . So if we are targeting beginners ( who are just into the hobby ) Delta dart would be a better choice .

But I would love to see all who accept that challenge for Hangar Rat ...

@SI74,

Can you share your experience with the different props on the Hangar Rat?

Sir , Different from the original plan , I thought , I would give it some spiral as  that would add more thrust . But after making it , I am not sure whether it helped my model , because the flight time was not great . So I tried a plastic prop from my old build , which worked fine and the model flew very well. Since the plastic one is heavier , I had to remove the landing gear to balance the increase in weight.

Thanks for posting the videos guys. Much more fun to watch it on a full screen via the YouTube.

S174, lets see you ROG. You and we will all enjoy

Sure sir . For those who wonder what ROG means , read this thread ... https://www.rcgroups.com/forums/showthread.php?47660-what-does-ROG-stand-for
And there they have an acronym for a plane landing on a tree :) ;)

Today I tried the propeller that I made . Flight time was more . It is a “mini” version of yday’s plane .

Video here

https://youtu.be/iC172msiz8o

Simply Marvelous. Almost 30 second flight in short circles (Yeah!) with the rubber still to be optimized. You did it ! Enjoy !
 :salute:

Thank you sir .Yes , did not stretch wind since it was a test flight . I made it today afternoon . So wanted to see how does it perform.

A photo would help those who are interested to build one .

It’s great fun to fly it everyday in your front yard :)

https://m.youtube.com/watch?v=9wIuBHnTJSY&feature=youtu.be&noapp=1

Seeing this post today, after more than three weeks  :o
I will have to come up to the speed !!!

How to calculate the turns of rubber band ?

Just count  ;D

I believe the traditional method is to wind it till it breaks.
Then wind one turn less  ;D

Remember to lube the rubber.
With whatever you have. Silicone spray, glycerine, castor oil, even soap and water if nothing else.

Regards

Yes, mine broke without lube and I bought glycerine. But don’t know which one in that list is better .

Take 50 % glycerin and 50 % of liquid soap (dishwashing liquid like Palmolive green color) by volume. Then mix well. Apply in such a way that the rubber has a shine not sloppy wet. The way I do it is put the lube in a plastic bag(Ziploc type bag). Then put the rubber in it and gently massage the lube all over the rubber. Note shiny appearance not wet like you use shaving cream on your face.

Then always stretch wind. Stretch the rubber about 2 to 3 times its length. Wind half the winds in a stretch situation, then walk toward the model to complete the other half of the winds.

Most important keep notes: This rubber, these many winds this high it flew and flight time. It is vital to keep these notes for your model to decide, do I need more length of the rubber, thicker rubber, thinner rubber, combination of thick and thin. In the flight the model should not go up like a rocket torque roll. A nice gentle climb , transition and glide.

Always count the number of winds left at the end of the flight. Too few or none left, then use a longer rubber, too many left, then you a smaller length rubber.

Okay , Thanks a lot sir .

Here is an easy way to make a foot stooge for stretch winding.

Next MUST build a home made torque meter. I usually do not count my winds, but go to a torque setting that I have marked for MY meter for that model. It is not calibrated by a standard, just marking points where I need to torque to for that airplane.

https://www.endlesslift.com/make-a-simple-foot-stooge/

Bookmark this site. Great information when one is starting out with good explanations and photos .

https://www.endlesslift.com/

Other than just lubing and stretch wind with torque meter, a couple other things also help. For example, make sure the propeller is BALANCED. Then put a small drop of oil (regular cooking oil, not Dalda vanaspati) at the bearing for a smoother prop run. Just a drop with a fat needle.

When you come home, wash your flight rubber band with very luke warm water and dishwashing liquid soap thoroughly. Let it dry in towel, but do NOT dry in the sun. Next outing, lube the rubber, stretch wind and to the torque.

You did take your notes with you to the field so you do not start reinventing from scratch?

Now let us see some more videos please.

Hello Friends,

My Delta Dart - Ready for assembly  :giggle:

 :help: Would like to know, whether I can do some color work on it, to make it decorative ?  :)

Really Neat. Very good angle cuts, your structure will be rigid and strong glue bonds.  :goodjob:

Yes you can color. In your next plane use colored tissue to begin with. But use something like Sharpie pen. You can use a black ball point pen to make panel lines like ailerons etc. Good idea to get innovative and decorate.

Just be mindful of your wing loading, grams of model weight (with rubber) divided by wing area in square inches. Definitely want to be below 0.5 gms /Square inch. A value of 0. 43 would be desirable.

Looking forward to your video.

Regarding planes like Delta Dart , Bobni etc. with a wing span of less then 14 inch, there is no need to shrink the tissue after attaching it to balsa. Also there is no need to dope the balsa.

For Bobni, I crumpled the tissue into a ball. Then straighten it out with your hand. Use 90 percent isopropyl alcohol and spray it well . Let it dry overnight by hanging it with a clothes peg. I then ironed out all the wrinkles. Apply straight with a glue stick on balsa and pull tissue firmly, avoid warping it. You are done and the tissue is taught.

One more thing: I do not waste a sharp blade to trim the tissue. Use a nail file and gently go over the edges. The tissue will fall off and you will trim it very neatly.

@Free Flight
Thank you for the suggestions on the covering.
Can we have something on making props and the size of props to be used for good thrust for the delta dart ?

Delta Dart was designed to be a simple and fun flyer to attract kids for model airplane building. That is why it uses a 5 and half inch commercially available prop. No need to make one from balsa for such entry level planes. You could use one from a foamy flyer, just transfer it here assuming it is at or just just around 5 and half inch in diameter. 

I would also suggest you contact Mr. Madhav and get it from him. His Spinboy kit is very nice and has the prop plus contest rubber (extra) that you need for this model.

Try putting a capacitor instead of a rubber power. People claim it flies very well on a capacitor motor. I have no experience with capacitor type flying but Mr Glidiator can advise.

@Weekendflyer,

Long queue at Post Office today.
Will try early morning tomorrow.
(Prop, hub and motor stick)

Regards

Here is one beginners rubber powered airplane. So easy to build in couple of hours and flies very well. The video is very nice. Book mark this page and build one simple but enjoyable model. Very popular here among very young teenager's.

http://www.rubber-power.com/make-it.htm

@KK Iyer
Sir,  it is to inform you that I have received the parcel (Prop hub and motor stick) posted by you.  Parcel was nicely packed and everything is in order.   

:salute: Thanks for extending the support in building models and maintaining our motivation.

Looking forward to your support in future as well.

For those who need more information on rubber powered model airplanes, here is a fantastic video on how to build a simple one. Bookmark it!

https://www.youtube.com/watch?v=XD3rFRntAxk

Late but fun . Here is the video of my Sig Cub flights. Trials were done in my front yard, then off to the field. Was very enjoyable with a cost effective kit. If you make one, I recommend, then, do ROG and assure that the prop free wheels and that the rubber is braided.

Enjoy,

https://www.youtube.com/watch?v=VhuQlJcI8aI

Lovely. That seems a perfectly trimmed model

Thanks Sanjay.

These Simple Rubber Powered Stick Models (SRPSM) are easy to trim. No washin, no washout, no down or side thrust. Adjust glide test for best L/D and Not a floaty glide. Then just adjust the wing position on the fuse and rudder deflection only for best power flights. That is all I did, making sure the AUW is low enough to give a wing loading of just around 0.4 grams per square inch of wing area. Pick the rubber as recommended by the kit.

To get a max (2+minute flight) need to hunt for thermals. These flights were done on a very cloudy sky, cold at 16 degrees, but I came home with the plane. Not another lost one.