Shell Wing Structure (without spars)

[Anemoi]

Hi there. I am investigating designing a wing with a shell structure, without spars, for a telescopic wing. It will most likely require thin stiffeners to handle a post buckling condition.

I have been using the NACA/NASA Handbook of Structural Stability Part I-VIII and Bruhn (A&D of FVS Chapter C9) focusing mostly on curved plates and shells.

Does anyone know:
-Examples of such wing structures?
-References that could be of assistance to me?
-The application of the above references to composites?

I would appreciate any advice given.

 

[berkshire]

Anemoi
The Akaflieg at Stuttgart university built a Sailplane with a variable wing span. The FS29.
I am attaching a link to a PDF of a lecture on sailplane construction that contains a copy of the patent description of this wing, it is pretty much buried in the middle of the lecture.

http://www.roastedseaweed.com/content/A0346584[1].pdf

The other aircraft that used a shell construction wing, was the Schleicher ASW 17, designed by Gerhardt Waibel.
The wing has no spars, and uses increasing layers of glass in the skin, starting with 4 layers at the tip, and 20 something layers at the root.
B.E.

 

[Sparweb]

Composite wings can have honey-comb or nomex core skins. The skins, on their own, may be made stiff enough for what you want. Of course it depends on a lot of factors, like how much you want to change the span. Is this for a sailplane?

I am somewhat familiar with the Diamond DA40/42 wings. Their wings have dual spars, so it's not directly applicable experience.

A thick skin could have segments of space-filling core in some areas, and structural laminate in other areas, to simulate a spar, like dis-connected spar caps. Shear from upper and lower spar caps must be carried around the LE and TE skin joints.

Connecting ailerons to this will be difficult, because the deflection of this kind of wing would be large.


Steven Fahey, CET

 

[berkshire]

Sparweb

On the FS29 The shear connection was made by wrapping the wing root with continuous strands of carbon fiber as though filament winding, in a bobbin like structure at the open end of the sliding part of the wing.
B.E.