Techniques > Misc
HQ35/12 Airfoil
Fred:
Well, the symetric profiles generate no lift at 0 degrees and generate lift at incidence, but this thin type of profile stall rapidely, well, before starting to generate "lots" of lift.
That's why, on the "fun fly" type of plane, you do a really thick profile (stall later and can go to greater incidence) with a big LE (if that stall, that will stall "gently"). but those profiles are neutral, fly the same inverted and normal.
Happy Days:
Right...................... (I think :?: )
So now we come to the core of the matter, Fred.
A symmetric wing produces no lift at 0 degree of incidence, the same as a "flat" wing produces no lift at 0 degree of incidence. They both only produce lift by deflecting air downward. Neither wing produces any induced lift
A non-symmetric wing produces lift by both deflecting air downwards, via the underside of the wing, AND produces lift from the camber on the top of the wing. (What I call 'induced lift')
Assuming what I've just written to be true, Question; Why does any one bother producing a symmetricaly cambered wing when, according to the above, it flys no better than a plank of wood?
Why aren't all wings semi-symmetric or flat bottomed? They produce far more lift. (Induced and reactive lift)
I know there must be a reason for symmetric wings, but I just don't know what it is. :!:
So come on Fred, you aerodynamic guru,..........hit me with the answer!
Fred:
That's an easy one ! :D
As ymetric wing is far more efficient than a plank !
Less drag, and will stall later at far greater incidence !
--- Quote ---Why aren't all wings semi-symmetric or flat bottomed? They produce far more lift. (Induced and reactive lift)
--- End quote ---
Because they don't produce more lift ! :D A cambered profile like the Go535 will produce far more lift than a ClarkY or maybe any flat bottomed profile.
All that without taking account of the speed of the plane of course ! A flat bottomed or semi-symetric profile (well, not all of them.) will be much more efficient at a speed range, before the air layer stop sticking to the profile.
And all that without even talking about the Reynolds number ! :D :P
Happy Days:
Hmmmmmmmmmmmm :?:
Firstly Fred I have to say I'm very impressed with you being awake at such an early hour of the day.............very good :clap:
Now I'm starting to get confussed, which is very easy at my age!
Could you tell me please where I might be able to find a diagram of a Go535 and a Clark Y profile?
You see, I'm thinking if simply having a later stall and offering less drag is the only advantage of a symmetric wing over a plank, why not have a semi symmetric wing with slots in the LE. Surley they reduce the stall yet offer less form drag than a symmetric wing.
Happy Days:
I've found a Clark Y airfoil diagram, still can't find a Go535 though. :x
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