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thinking of the airplane as a sort of "flying car.") A turn is actually the result of a
change in the direction of the lift vector produced by the wings.
A pilot turns an airplane by using the ailerons and coordinated rudder to roll to
a desired bank angle. As soon as there is bank, the force produced by the wings (lift)
is no longer straight up, opposing the weight. It is now "tilted" from vertical so that
part of it is pulling the airplane in the direction of the bank. It is this part of the lift
vector that causes the turn. Once the pilot has established the desired bank angle, the
rudder and the aileron are neutralized so that the bank remains constant.
When part of the lift vector is used for turning the airplane, there is less lift in
the vertical opposing weight. If the pilot were to establish a bank angle without in-
creasing the total amount of lift being produced, the lift opposing the weight would
decrease, and the resulting imbalance would cause in a descent. The pilot compen-
sates by pulling back on the stick (increasing the AOA and therefore lift) . By in-
creasing the total lift, the lift opposing the weight can balance out the weight and con-
trol level flight. This increase in total lift also increases lift in the turn direction and
results in a faster turn.
Turn Lift Requirements
As the bank angle increases, the amount of pull required to maintain level
flight increases rapidly. It is not possible to maintain level flight beyond a given bank
angle because the wings cannot produce enough lift. An attempt to fly beyond this
point will result in either a stall or a descent.
Physiologically speaking, the most important part of a turn is the necessity to
pull "Gs". As the back pressure is increased to maintain level flight, the increased
force is felt as an increase in "G" level. In a 30 degree bank, 1.2 G is required to
maintain level flight. The G level increases rapidly with an increase in bank; at 60
degrees, it goes to 2.0 G, and it takes 9.0 G to fly a level 84 degree bank turn. As long
as there is enough airspeed, the G level can be increased in any bank angle by pulling
back on the stick.
Finishing the turn, a simple matter of leveling the wings by using the ailerons
and coordinated rudder, takes time; the airplane continues turning until the wings are
level, so the roll-out must be started a little prior to reaching the desired heading.
Back-stick pressure must also be released as bank decreases or the aircraft will climb.
Maneuverability
Airplanes are not limited to being a relatively fast means of getting some-
where. Long ago thrill-seeking pilots discovered that aircraft have the potential for
providing loads of fun while getting nowhere fast. Aerobatics are an essential skill for
fighter pilots; and the training that it gives to pilots in position orientation and judg-
ment is considered so vital that a great deal of time is spent teaching these maneu-
vers. Maneuverability is defined as the ability to change the speed and flight direction
of an airplane. A highly maneuverable airplane, such as a fighter, has a capability to
accelerate or slow down very quickly, and also to turn sharply. Quick turns with short
turn radii place high loads on the wings as well as the pilot. These loads are referred
to as "g forces" and the ability to "pull g's" is considered one measure of maneuver-
ability. One g is the force acting on the airplane in level flight imposed by the gravita-
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