I recommend reading this:
http://www.faa.gov/library/manuals/a...apter%2002.pdf
Remember aerodynamics and the four forces:
Code:
lift
!
!
!
thrust <----+----> drag
!
!
!
weight
When the elevator control is pushed or pulled, the angle of attack is changed.
The angle of attack has a direct influence on lift, the aircraft starts decending or climbing.
When thrust is changed, thrust becomes greater or smaller than current drag, the aircraft accelerates or decelerates.
Lift is a function of airspeed as well, in result a change in speed is followed by a change of lift, creating a requirement to correct the angle of attack by using an elevator input in order to maintain level flight.
To maintain lift the same when accelerating, a decrease in angle of attack is required. The opposite applies to decreasing speeds, an increase of angle of attack is required.
The same applies to climb or decent, the difference is that in climb excessive thrust is used to add potential energy (altitude), while in decent potential energy (altitude) is used to overcome drag.