yarray2000

Hello all,

I want to build a new wing for a SIG Kadet LT-40, from scratch.

I want to keep my standard wing, and build another one, so I can swap anytime.

I'd like it a few inches shorter (to fit better in the car), with less dihedral, and I'd like the airfoil to be either symmetrical or semi-symmetrical.

I'd like to keep the plane as it is because I want to be able to change the wing, or even bring the two wings at the field. I don't want to touch the wing cradles on the fuselage, or alter any other thing than the wing.

I think I'll start with the original wing design (the center ribs and center block of the wing).

Also, you know of the tip of the wing on the LT-40 is made !? Like a 30 deg angle... How do you call that, and what's the purpose ? Anyway... I'd like to finish my wing tip in a straight edge, like on a SIG 4 *.

For the dihedral... I don'think I want any.

Any of you have a favorite airfoil design you would recommend for an LT-40 ? Any of you familiar with the [link=http://www.aae.uiuc.edu/m-selig/ads/afplots/s8036.gif]Selig 8036[/link] (semi-symmetrical) and [link=http://www.aae.uiuc.edu/m-selig/ads/afplots/s8035.gif]Selig 8035[/link] (symmetrical) ?
Is it possible that the [link=http://www.aae.uiuc.edu/m-selig/ads/afplots/s8036.gif]Selig 8036[/link] (wing root airfoil) should be used with [link=http://www.aae.uiuc.edu/m-selig/ads/afplots/s8037.gif]S8037[/link] (wing tip airfoil) ?

Any of you have plans to get me started ? I don't know where to start...

Thanks all.

canadagoose

My Feedback: (2)

When you change a wing for a plane that have different airfoils which probably have different pitching forces as well, the stab insidence may need to be changed as well. You might be able to compensate by adjusting the incidence of the new wing instead of the stab.

Balsa Master

the wings gonna rock under flight on a flat cradel...make inside of wing (over fuse) flat like your first then make the rest semetrical and make a doubler that is against either side of the fuse, use the existing ribs and add a little to the bottom to make it "rounder" although this will certainly solve the lt40's glide slop problem so many ppl talk about...

-edit-
oh bty why do u want to do this????

Murphey

My Feedback: (11)

I made a symmetrical wing for a Kadet LT-40. It flew like a Kadet LT-40 with a symmetrical wing! No bad habits, no problems at all. The advantage was that it didn't climb with more airspeed. I did it the non scientific way...from the stock wing I made a template of the top of the rib and added that to the flat bottom then added a balsa spar to the bottom for rigidity. Balsa Master is correct in that you should leave the inner ribs flat to sit on the wing saddle properly. I no longer use that wing and you are welcome to it. Just a little tip damage that can be easily repaired. Send a PM if interested.

Murphey

Tall Paul

Kadet airfoils ARE semi-symmetrical.
As for a symmetrical airfoil, look at any of them, and choose the cutest. It won't make much difference.
To fit the new wing. I would cut into the top of the fuselage for the bottom curve. And then make a filler piece to use when
the kit wing is used.
Building a flat-to-symmetrical center section is more trouble than it's worth, and creates a stress riser on the side of the wing where most stress
will be concentrated. If you do it , double the bottom spars out a couple rib bays.
The plane should fly faster with the symmetrical wing, if it's mounted with no incidence.
The tip shape can be anything pleasing to the eye.

cappio777

My Feedback: (2)

I agree with Tallpaul, any alterations to the skin structure of the wing at that point is going to accentuate the stresses which could lead to failure. Better to make the craddle for the original wing out of the pieces cut out from the fuselage. Its the same piece so HAS TO FIT! If a the other wing has a full symmetrical airfoil then add 1 to 2 degrees of incidence to it.

dega500

Hey Murphy

How thick did the symmetrical part of your wing end up being? I've been playing around with your idea and mine all look too thick.

Also did you shorten the wingspan any or take out any of the dihedral?

Thanks

Mike