airxliban
Posts: 4285
Joined: Wed Oct 01, 2003 12:14 pm

Airspeed Vs Angle Of Attack

Sat Nov 27, 2004 5:16 am

is there a equation or something that can give you airspeed as a function of the angle of attack....

perhaps something like V(theta,W,D,L)= something?
PARIS, FRANCE...THE BEIRUT OF EUROPE.
 
QantasA332
Posts: 1473
Joined: Sat Dec 13, 2003 5:47 pm

RE: Airspeed Vs Angle Of Attack

Sat Nov 27, 2004 6:39 am

Airspeed isn't directly related to AoA - rather, it is related to total drag, which in turn is related to AoA. So yes, AoA does affect airspeed but not in a very direct sense. So, an equation? The best relationship I can think of at the moment is the very obvious restatement of what I just said - 'airspeed is inversely proportional to AoA' (as AoA increases, drag increases and as a result airspeed decreases).

To conjure up a 'raw' equation, one would most likely need a graph of AoA versus CL for the particular airfoil involved, to obtain a value for CL which could then be plugged into the equation for induced drag, the main contributor to changes in drag from changes in AoA. You would then need to set up a thrust-required graph and somehow derive a workable equation from all of that. This is beyond me, but someone else may be able to find a feasible equation for you. Or, better yet, there may be a pilot out there who has a handy rule of thumb regarding airspeed versus AoA.

Sorry I couldn't be of more help!
Cheers,
QantasA332
 
airxliban
Posts: 4285
Joined: Wed Oct 01, 2003 12:14 pm

RE: Airspeed Vs Angle Of Attack

Sat Nov 27, 2004 5:34 pm

thanks for that Qantas! All I need to do now is figure out the constant of proportionality...

anyway, you also conjured up old memories of me in my freshman Introduction to Aerospace Engineering class and looking up Cl and calculating T(r) etc!
PARIS, FRANCE...THE BEIRUT OF EUROPE.

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