RC India

Your help needed on-making a wing

1 bending a coro sheet without making it sloppy
2without loosing its tenacity and firmness
3 and get a nice firm wing without breaking it at the bend

There are no. Of posts around but non specifies how to bend it seamlessly.
Posting a snap- courtesy Sanjay rai55 Avispad build

I have explained this so many times before

Will post a thread on this shortly

 Useful for everyone in SPAD..
Waiting  :)

I used to cut corrugated sheet in empty spaces ( single line cutting on one side only)by blade to make it slightly bend . If more curvature is required , then used to cut whole empty space from one wall to another (one side ).

Yes sanjayrai55 pl post it, Tried doing on small part ,it lost its crispness

Aditya yes that is also a good method ,had no clue how to do it

The key is the direction of the flutes...
In the beginning, i used to make the smae mistake...
The flutes must be perpendicular to the span of the wing...

Hi,
Look at the thread.
http://www.rcindia.org/electric-planes/coro-wing-design-new-try/ (http://www.rcindia.org/electric-planes/coro-wing-design-new-try/)
(http://www.rcindia.org/electric-planes/coro-wing-design-new-try/?action=dlattach;attach=649221;image)
you have to take Sharp edged knife (1/2 inch or 1 inch width disposable type) and have to cut the flute slowly like 1"/1Sec speed. The edge of the blade should be kept at 45^O corner. The other flute corner will give you support and the edge of the blade should not touch the edge taking support of the flute so that the blade would not enter penetrating the corner and enter into other flute.

If you take support of the corner, for the knife blade and touch the face with flute, and holding the blade with thumb and index finger, and middle finger will give support so that the blade distance would be maintained and the blade would not cut the other side.

And, sand the surface (Actually scratch with 120 preferably for surface preparation) before cutting the flute if you are thinking to join with CA. As later sanding may fold the thin support(Cut out side) and sanding will not so good And bonding too. For constant curvature, you have to rest the piece in ant constant slope and then have to apply CA.
(http://www.rcindia.org/electric-planes/coro-wing-design-new-try/?action=dlattach;attach=649943;image)

And also
http://www.rcindia.org/electric-planes/single-coro-wing-corsair/ (http://www.rcindia.org/electric-planes/single-coro-wing-corsair/)
Hope you can get.

Very nice sir. It cleared my doubt as well. Good technique.

Also make leading edge folded to double at least initial half inch. It will improve the performance dramatically.

A friend of mine send me a few pics of building wings using coroplast. As soon as all pics are downloaded I'll post them. Want some expert comments on it.

Ok. All the pics are resized. I'm posting all these pics one by one. Kindly post your comments/suggestions/recommendations on this.

More pics.

One of the best way to make wings with coro.
from Spadtothebone.  link below
hope it helps.

http://www.spadtothebone.net/SPAD/Spadet/Page2/Page19/Page26/page26.html (http://www.spadtothebone.net/SPAD/Spadet/Page2/Page19/Page26/page26.html)

Yes Manoj. This is specific to a flat bottomed wing with top and bottom corro sheet in two pices and of different thickness. Unfortunately it is not the best technique IMHO for symmetrical & semi-symmetrical wings. Called the RNAF wing  ;)

The core knowledge on coro is shared ,Kalyanpradhan thanks for posting on a thread ,for you to come on beginners topic and help us also Sanjayrai55 really appreciated.

Utkarshag thanks too

Have I done it ok on spar ? Need to put servo on R and L side

1. I don't like what seems to be your aileron proposal. Should be separate pieces with the flutes length wise, of thicker corro or doubled up.
2. Glue small bits of ply inside the wing for the aileron servos to screw into

Will locate some pics and post

(http://www.rcindia.org/electric-planes/avispad-build-for-2014-sweepstakes/?action=dlattach;attach=690747;image)

(http://www.rcindia.org/electric-planes/avispad-build-for-2014-sweepstakes/?action=dlattach;attach=690723;image)


From my own build: http://www.rcindia.org/electric-planes/avispad-build-for-2014-sweepstakes/ (http://www.rcindia.org/electric-planes/avispad-build-for-2014-sweepstakes/)  :D

Practicing KALAYANPRADHAN tip : it's really easy and need bit of practice ,the angle of the blade is crucial.

Ok sanjayrai55 ,had a doubt about ailerons ,will follow you

If your spar is placed correctly, straight, and does not bend, and you've followed the art of scoring corro correctly, you should get smooth bends like shown in the picture.
I've never felt the need of scoring coro at multiple lines, one score at the leading edge and careful bending can give all kinds of shapes, symmetrical or otherwise, and a very fine leading edge. Scoring takes a little practice,  using a steel scale to guide and a screwdriver to score helps. The idea is to collapse the flutes where one scores...If collapsed adequately, the insides bend very easily, once the bend is formed, move the sheet back and forth a couple of times and then it folds neatly

For flat bottom wings and semi symmetrical wings, one can use doublers on one of the surfaces, to ensure that surfaces curves less than the other one.

Also posing a video of a still to close two part wing that might help...

http://www.youtube.com/watch?v=jVZLOnF01M4#ws (http://www.youtube.com/watch?v=jVZLOnF01M4#ws)

I agree fully. I have also never used cutting of one side flutes in a wing. In fact, the main advantage of Corro is it's rigidity when formed, and the cutting negates that very effect. Cutting is used for ailerons, and for cowlings/turtle decks where structural strength is not important. It is easy to bend the wing corro surfaces, and help will always be available if needed.

Girishsarwal:"using a steel scale to guide and a screwdriver to score helps. The idea is to collapse the flutes where one scores."   
1 So for wings -just puncturing them and not scoring is the key.
2 for ailerons-score them

Solves all the doubts thanks

Sir,
1. Scoring (Crushing) where you want a fold (wings)
2. Cutting (One side removal) where you want a hinge (ailerons, elevator, rudder, flaps etc)
3. No puncturing, hawa nikal jayegi  :giggle:

All the best