Just a thought for the pitch up & down people:
(1) In a low wing aircraft, application of flap will tend to cause a pitch down.
(2) In a high wing aircraft, application of flap will tend to cause a pitch up.
This is because the increase of drag at a low point (high point) on the airframe will give a pitch down (pitch up) tendency.
(3) In an aircraft where the tailplane is in the downwash of the wing, application of flap will tend to cause pitch up. This is because downwash increases with flap application.
(For those thinking "why?" consider this: Relative airflow from the wing will be approaching the tailplane from ahead & above it. The tailplane will be operating with negative angle of incidence, and generate a downwards lift force which will increase with increased downwash.)
- T-tail aircraft such as the Arrow and Tomahawk have tailplanes well clear of downwash, so might be expected to pitch down with flap application.
- High-wing Cessnas and similar aircraft, where the tailplane is squarely in the wing's downwash, experience (3) quite strongly, so might be expected to pitch up with flap application.
- Warriors and similar have middling effects, because the stabilator is affected by the wing's downwash but is not in the strongest part of it. You might have to go and fly them to figure out whether point (1) or point (3) wins out when the pilot extends flap!
- Designers use lots of subtle tricks to minimise trim changes with flap, so all of the above is only a crude explanation...
