On Fri, 08 Aug 2003 01:48:20 GMT, Roger Halstead
wrote:

If I'm in level flight and extend the flaps 10 or 15 degrees and
maintain the speed my plane *will* climb. To me that says the wing
has more lift when I extend the flaps 10 or 15 degrees than with no
flaps.

Ack. Pth. In equilibrium, lift == weight. This is a first-order
approximation, of course, but when you're climbing or descending, lift
is still weight. You climb because of excess energy, not because of
excess lift. If you lower the flaps, to maintain the same airspeed
without increasing the power, you will have to lower the nose. Flaps
increase drag, and if you don't add power the lost energy comes from
altitude.

There is a transient effect: if you maintain the same angle of attack
as you lower the flaps, the airplane will probably balloon initially,
until your airspeed bleeds off, then you will begin to descend at a
lower airspeed. Your airspeed at the same angle of attack needs to be
lower because lift is a function of the coeficient of lift (which you
increase by lowering the flaps) and airspeed (which you reduce to
maintain the constant lift).

HTH,

Morris