New to making delta type wing questions - RC Groups
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Sep 01, 2016, 07:20 PM
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ninjasword71's Avatar
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New to making delta type wing questions


Seeing some designs and using DT foam board, I decided to attempt my own variation. However, after cutting out my design, I noticed it may not be so simple. My wingspan is 36", 16" and 40 deg tapering at 16" to 20 deg. If that makes sense. The overall length without fuse is 30". I don't understand the centre of gravity or the crazy formulas as well as wing foil type to use. I am working with a 2627-1950kv and a 3s 2200 lipo. Is there an easy formula and wing design that would make my project work like the shuttle design? This is a bad pic
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Sep 01, 2016, 08:02 PM
Kimbers Keeper.
BHOFM's Avatar
Can't tell any thing in the picture, but with the numbers you have, i think you have about twice
the motor and battery you need for a plane that size.

This is similar size and flies on a CL2822, 1300kv, on a 2s 1300 battery. The CoG is about 30%
behind the wing where it tapers to the nose.

Sep 01, 2016, 09:12 PM
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ninjasword71's Avatar
If I do extra reinforcing to add weight, would that counter having too powerful of a motor? Here's a better pic just with less light.
Sep 02, 2016, 01:51 AM
If it flies - I want one!
Petem's Avatar
A good way to determine the required CG is to cut out a small scale version from thin foam, jack the elevons up a smidgen and add weight to the nose till it glides nicely. You can even do this with the bare airframe before you add all the gear.
That will give you a good first guess, so go a tad further forward for your first test flights.
(conversions: 10 smidgens to the tad, 10 poofteenths to the smidgen, and one poofteenth is near enough to a beesdik)
Cheers, build and go fly,
PeteM
Sep 02, 2016, 10:34 AM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by Petem
A good way to determine the required CG is to cut out a small scale version from thin foam, jack the elevons up a smidgen and add weight to the nose till it glides nicely. You can even do this with the bare airframe before you add all the gear.
That will give you a good first guess, so go a tad further forward for your first test flights.
(conversions: 10 smidgens to the tad, 10 poofteenths to the smidgen, and one poofteenth is near enough to a beesdik)
Cheers, build and go fly,
PeteM
How much is "just a hair" ?

Sep 02, 2016, 11:18 AM
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rajazo's Avatar
+1... try with the clean airframe, fixed elevons and make it glide .. I use a carbon tube fixed with tape to the fusselage (nose) with a nut (1/2") or AAA battery atached at the from of the tube, then if the nose goes too step to the ground the tube detach and nothing breaks...

Where to start? Try with this diagram. Use the simplified geometry, the big delta.

Sep 02, 2016, 11:22 AM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by ninjasword71
If I do extra reinforcing to add weight, would that counter having too powerful of a motor? Here's a better pic just with less light.
There's nothing wrong with having too powerful a motor , the power is managed by the throttle .

But IMHO , adding weight is not a good idea - more weight ( high wing loading ) will just force the plane to HAVE to go fast in order for the wings to generate enough lift to become/remain airborne .

Have you scratch built a foamy before ? And do you have experience flying a faster NON self-righting bank'n'yank plane ? If no , then I recommend starting with something simpler and with LIGHT wing loading for building/flying practice .

Here are two planes good for building practice and bank'n'yank flying practice , both use 2200mah batteries :


Simple Delta


Giant simple delta (2 min 0 sec)




Flying Sheet of Dollar Tree Foam Board


"Literally" just a Flying Sheet of Dollar Tree Foam Board (1 min 13 sec)
Sep 02, 2016, 06:08 PM
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ninjasword71's Avatar
I have flown the corsair before with great success. I tried to build the sea plane but did not fly. Just went up, turned onto it's back and nose dived. I loved the shuttle design but decided to experiment on my own. My delta is almost ready to try out in a couple days. It's at 650 grams now. Mostly from reinforcing the bottom. If it's too heavy, I'll buy another couple sheets and try again.
Sep 02, 2016, 09:08 PM
Sokol
JureZ's Avatar
use this calculator, enter your geometry data

http://winglib.com/wings/create
Sep 03, 2016, 12:04 AM
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ninjasword71's Avatar
Quote:
Originally Posted by JureZ
use this calculator, enter your geometry data

http://winglib.com/wings/create
That looks like the right calculator. Tomorrow I hope I can get pretty close to the cg. There is plenty of room to adjust my 2200 lipo. Just from the feel, feels pretty close already.
Now if I just want subtle turning and rolls, would I make the control surfaces smaller or use the TX for smaller throws? I don't have the eyes or coordination for wild manoeuvres.
Sep 03, 2016, 06:13 PM
If it flies - I want one!
Petem's Avatar

Small control throws


If you want smaller control throws the best way is to use an inner hole on the servo arm, and outer holes on the control horns (or longer horns) - this retains the full accuracy of your radio system.
You can then use the rates function on a switch if you want even lower throws available.
Sep 03, 2016, 07:11 PM
Registered User
ninjasword71's Avatar
Petem thanks that makes sense. Never had to adjust them that way yet. Here is a picture from earlier today. Elevons, vertical stab, wing stabs cut and ready to put on. Everything so far are from my own measurements with the guardian as a rough guide.
Numbers don't enter properly no matter what cg site I try. I tossed it with motor and battery and glided perfectly flat to the ground.
Hopefully the motor can fly a 700 gram delta.
Sep 03, 2016, 09:35 PM
Sokol
JureZ's Avatar
would you consider adding a vertical stabilizer, there are no vertical surfaces behind the CG.
Sep 03, 2016, 10:49 PM
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ninjasword71's Avatar
Yes a single vertical stab right on top of the motor cover. Would two, one on each wing be better? I have small ones on the wing tips already.
Last edited by ninjasword71; Sep 04, 2016 at 01:25 AM.
Sep 04, 2016, 01:38 AM
If it flies - I want one!
Petem's Avatar

Looking good!


That is looking a mean machine! Might be worth sneaking the CG a bit further forward than you think necessary - those long leading edge extensions/ narrower forward delta will have a higher stalling angle than the main part of the wing, and may give you some grief pitching up into the stall.


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