Gentlemen,

I am not a combat pilot.

In Stunt Design section of this site there is a topic named FLAPS AND ELEVATORS WORKING TOGETHER? PUZZLING.
There are many answers, but the answer is not clear to me.

When a combat aircraft is flying level (CCW) and the flap is rotated up, which direction does the aircraft travel?  Up or down.

Thanks for clearing up this lack of understanding.


T Michael Jennings     
Knoxville, TN.

The elevator is what pitches the nose up or down.  Elevator up, nose up etc.     The flaps are used to generate more lift to the wing, by increasing the camber of the airfoil.  So combat models do not need flaps, as they rely on very light wing loadings to achieve the tight turning ability.  A bigger, heavier stunter benefits from flaps in the hard corners.  This is a simple explanation, and the are more complicated aerodynamic issues at play here, but this will make it easier to understand.   Do not confuse the flaps with the elevator, they do completely different things.

 On the flying wing type of combat model, popular in Russia etc, the little flipper on the trailing edge is the elevator, not the flap.   Because these models have a very short tail moment.  This may have been another area of confusion.

Mark,
Rich,

Thanks for the Helping Info.

Can you or some one supply a Force Diagram of a combat aircraft.
Seems like there are two forces involved (gravity and lift) acting at different locations.
Those would make a stable aircraft.

Thanks again.

T Michael Jennings
Knoxville, TN.

You've gopt it exactly right, TMJ.  Gravity pulls the plane towards the ground, the center of gravity.  The plane is pretty much one solid object, so it will balance at the CG, if hung by a thread.  The air forces are also spread pretty much evenly over the whole plane and also effectively act at the aerodynamic center, which is slightly behind the CG.  In level flight the elevator pitches the nose slightly up so the symmetrical airfoil generates enough lift to fly the plane level.  I something such as a gust of wind bumps the plane up the elevator produces less lift and the nose drops.  If the nose gets pushed down the elevator generates more lift and the wing less, tipping the plane up and back to level flight.  The control handle also helps.  Most people generally fly with the up line on top.  If the plane happens to climb it automatically get less up elevator when it moves above the handle and tends to come back down.

The engineers call this static stability.  Many of the newer military planes either have no static stability, or even negative stability.  The computer controls figure out what the pilot wants the plane to do and adjusts the controls accordingly.

T Michael Jennings,

Just to make sure you understand, on Stunt Models when the elevator goes up, the flaps go down.  This helps them rotate for tight turns. 

Mike Stinson