Perching Glider

[rds1g13]

Hey guys,

I am currently constructing a manoeuvrable glider capable of a fast pitch up (similar to how birds perch). For the design of my wings I was thinking just to use thin balsa wood sheets with an elliptical planform. I am aware that conventional aerofoils are designed to operate efficiently for AOAs below 15 degrees but I am interested in the manoeuvre, which will be at very high AOA (up to 90 degrees). My question is that will the aerofoil shape be really important for this case?

Thank you

 

[MikeHalloran]

When I hear "elliptical planform", I think "Spitfire".

When I hear "high AOA", I think "Helio Courier".

You might want to read up on both, and think about how they apply to your problem.



Mike Halloran
Pembroke Pines, FL, USA

 

[GregLocock]

No, the shape of the airfoil will not matter much at very high AoA, basically the low pressure side will be completely stalled. This does not mean your idea won't work, since quite obviously even a flat plate can produce lift in those conditions.

You may want explore multi element cascades of flaps, these can handle very high aoA without stalling.

I wouldn't get too excited about planform.

Cheers

Greg Locock


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[rds1g13]

Thank you Greg, that's what I wanted to know.

 

[rb1957]

do you want the wing to generate lift at high AoA ?
I'd look at the pitch up as turning the wings into a big brake, killing forward motion.
I somehow don't see the "perching" manoeuvre as being that simple ... are thinking of pitching the wing (only) or the whole glider ?

another day in paradise, or is paradise one day closer ?

 

[mohr]

Hi rds1g13 :
Entering recently this forum (long time absent) I found your question.
Read about airfoil POST STALL phenomenon...this occurs more frequently on HAWT (Horizontal Axis Wind Turbines).
But you will pay a price of a tremendous rises in airfoil CD beyond "normal" AoA...
Try with "Aerodynamics Coefficients at large angle of attack" by C.Lindemburg, December 4-5, 2000 NREL,IAE symposium, CO.
Cheers.