Back on the missing wing topic:
Loss of wing area on one side (e.g. right side) of the aircraft does the following:
1. It reduces the drag on the right side of the aircraft. This results in a nose-left yawing moment which creates a nose-left slip angle unless countered by use of right rudder (rudder deflected trailing edge left). If the aircraft has dihedral, the slip angle will create a left-wing-down rolling moment. The right rudder deflection will also create a left-wing-down rolling moment.
2. It reduces the lift on the right side of the aircraft. This creates a right-wing-down rolling moment, which can be countered by reducing the lift on the left wing. This lift reduction is accomplished by "left" aileron, i.e. the left aileron is deflected trailing edge up.
Note that the required amount of this aileron deflection is reduced slightly by the the aforementioned rolling moments due to the dihedral and rudder deflection. And the reduction of lift on the left wing (due to aileron deflection) reduces induced drag on that side and thus balances some of the yawing moment. So the rudder and the ailerons "help" each other.
There is also a side-force equilibrium to consider. A nose-left slip and right rudder deflection both result in a side force which pushes the aircraft to the left. This can be balanced by a small right-wing-down bank angle. The bank angle means that a slightly higher lift coefficient is required for level flight, which is obtained by deflection the elevator trailing-edge up.
If the aircraft is able to balance out all of these moments and forces by control deflections it is said to be trimmable.
The conditions described above favor an aircraft which has very effective ailerons. This aircraft will be able to most easily reduce lift and induced drag on the left wing.
Our conditions also favor an aircraft which generates small side forces for a given rudder deflection or slip angle, but has significant dihedral and a significant rolling moment due to rudder deflection.
It is the combination of all of these factors which determines whether the aircraft is trimmable or not. These factors all are very sensitive to the size and shape of each part of the airframe (the powerplant plays a role too), so every aircraft will require different balance of these factors to reach equilibrium
Remember that these factors all change with airspeed and altitude. In particular, aileron effectiveness is greatly decreased at very high indicated airspeeds for aircraft of the type in Aces High, and is usually decreased at very low IAS. So the trimmability problem can change greatly depending on your height or speed.
To sum it up, trimmability in this case depends on several factors which are very sensitive to the design of the aircraft and the airspeed/altitude condition for which one wishes to trim. If any one of these factors is not right, then the aircraft can become unflyable. Some aircraft may be trimmable for all conditions, some may be trimmable only for a limited part of the flight envelope, and some may not be trimmable under any conditions.
[This message has been edited by funked (edited 04-17-2001).]
