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the wing simply do not want to inflate. It is imperative
that the pilot visually sees end cells inflate before
taking off. Sometimes all you have to do is wait for
the end cells to open. On some wing configurations it
is recommended that the steering tubes be “pumped”
lightly to help open the end cell openings.
Pressure knots are harder to determine during a rolling
preflight. It may be very hard to see what is going on
with the lines themselves, so the pilot may find it better
to look for deformations on the bottom surface of
the wing caused by one line being pulled more than it
should be. Trying to take off with a pressure knot will
result in the powered parachute turning very sharply
to the side of the pressure knot. It will be nearly impossible
to correct for that turn without nearly stalling
the wing with the input on the other side. The engine
will have to be kept at a very high setting just to maintain
what little altitude is gained.
Wing oscillations occur for several reasons. There
may not have been enough power added initially to
kite the wing, or the pilot may have waited too long
to correct for a wing that was flying to one side. Some
light oscillation is okay, and will merely lift one side
of the powered parachute into the air before the other.
On the other hand large oscillations will actually
change the lift from a straight upward vector to an
upward and side-pulling force. An oscillating wing
forced into takeoff will most likely roll the airframe,
which is an undesirable cause and effect.
Oscillations are easier to prevent with good inflation
techniques than they are to correct. However, if a
wing is oscillating, it is possible to correct by steering
the wing opposite to the side that the wing is drifting
towards. In other words, manage the wing, steer
it straight. The wrong inputs can make the problem
worse. If the oscillations become too severe, it is best
to abort the takeoff and set up again.
It is critical for the wing and lines to become verified,
or fully inflated, directly overhead and centered, with
the lines free of tangles. An acronym of LOC is often
used to verify the wing is ready for takeoff: L – Lines
Free, O – Cells Open, C – Wing Centered. Once the
wing is fully pressurized, centered above the cart and
the suspension and steering lines are free of tangles,
slowly increase the throttle to takeoff thrust. The increased
thrust accelerates the powered parachute forward
until the airflow over the wing generates enough
lift to get the PPC airborne. Continue to increase
throttle gradually to the desired pitch attitude. Your
feet have been resting on the steering bars throughout
all the ground operations, and can be used to steer.
7-5
Normal Takeoff
A normal takeoff is one in which the powered parachute
is headed into the wind and the wind is light
to moderate. [Figure 7-4] The takeoff surface should
be firm, free of debris, and not have any obstructions
along the takeoff path. The takeoff surface should
have sufficient length to permit the powered parachute
to quickly accelerate to normal flight speed.
There are three reasons for making a takeoff as directly
into the wind as possible:
1. A slower ground speed reduces wear and stress
on the landing gear;
2. The headwind helps inflate the wing and get it
overhead more quickly;
3. A shorter ground roll, and therefore less runway
length, is required to lift off.
Rotation
When the wing has enough lift to rotate the cart nose
off of the ground, nosewheel steering becomes ineffective.
This means that even though the back wheels
of the machine are still on the ground, the cart will be
steered by the wing. You should not attempt any kind
of tight radius turn during this process.
Lift-Off
Once the wing is overhead and enough power is added,
the powered parachute will lift off the ground.
Initial Climb
Once the cart is off the ground, it is important to maintain
at least the same throttle setting that got it off the
ground in the first place. When the cart is free from
ground friction on the landing gear, it will begin to
climb.
Once the powered parachute is off the ground, prop
torque may become noticeable. It will typically steer
the aircraft to the left (with a clockwise spinning propeller).
Wind can also affect the direction of the PPC
after liftoff. During initial climb, it is important that
the initial climb path remain aligned with the runway
to avoid drifting into obstructions, or the path of another
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Powered Parachute Flying Handbook动力伞飞行手册(60)
