Tony Peden wrote: > Induced drag is a function of the vortices surrounding the wing. > Those vortices vary in strength with lift, not angle of attack.
Not so. The induced drag of an aircraft in high-speed cruise is much lower than an aircraft in level flight at stall speed. The lift in these situations is the same (and equal to weight, of course). Think about it: if induced drag depended solely on lift, there would be no such thing as the "back side" of the power curve. Drag would go asymptotically to some constant as airspeed dropped to zero -- that clearly isn't right. For real aircraft, drag always increases with AoA. In reality, induced drag looks much more like a function of AoA than it does a function of lift. Well, in "real" reality induced drag is just a metaphor; so it isn't "really" a function of anything. Maybe you mean to say that induced drag is a function of lift *coefficient* -- as on a drag polar plot? This is true, but unhelpful to me. I don't know what the lift coefficient is until I calculate the AoA. And we're back to where we started. Andy -- Andrew J. Ross NextBus Information Systems Senior Software Engineer Emeryville, CA [EMAIL PROTECTED] http://www.nextbus.com "Men go crazy in conflagrations. They only get better one by one." - Sting (misquoted) _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
