|
|
The touchdown is the
gentle settling of the airplane onto the landing surface.
The round out and touchdown are normally made with the
engine idling and the airplane at minimum controllable
airspeed so that the airplane touches down on the main
gear at approximately stalling speed. As the airplane
settles, the proper landing attitude is attained by
application of whatever back-elevator pressure is necessary.
Some pilots try to force or fly the airplane onto the
ground without establishing the proper landing attitude.
The airplane should never be flown on the runway with
excessive speed. A common technique to making a smooth
touchdown is to actually focus on holding the wheels
of the aircraft a few inches off the ground as long
as possible using the elevators while the power is smoothly
reduced to idle. In most cases, when the wheels are
within 2 or 3 feet off the ground, the airplane is still
settling too fast for a gentle touchdown; therefore,
this descent must be retarded by increasing back-elevator
pressure. Since the airplane is already close to its
stalling speed and is settling, this added back-elevator
pressure only slows the settling instead of stopping
it. At the same time, it results in the airplane touching
the ground in the proper landing attitude and the main
wheels touching down first so that little or no weight
is on the nose wheel.
After the main wheels make initial contact with the
ground, back-elevator pressure is held to maintain a
positive AOA for aerodynamic braking and to hold the
nose wheel off the ground until the airplane decelerates.
As the airplane’s momentum decreases, back-elevator
pressure is gradually relaxed to allow the nose wheel
to gently settle onto the runway. This permits steering
with the nose wheel. At the same time, it decreases
the AOA and reduces lift on the wings to prevent floating
or skipping and allows the full weight of the airplane
to rest on the wheels for better braking action.
It is extremely important that the touchdown occur with
the airplane’s longitudinal axis exactly parallel
to the direction in which the airplane is moving along
the runway. Failure to accomplish this imposes severe
side loads on the landing gear. To avoid these side
stresses, do not allow the airplane to touch down while
turned into the wind or drifting.
|
