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in atmospheric pressure through turbocharging or other means.
20-5
adjust the fuel/air mixture to achieve the best possible
power output. This process is referred to as “leaning
the mixture.” If you are considering a high-altitude
takeoff, and it appears that the climb performance limit
of the gyroplane is being approached, do not attempt a
takeoff until more favorable conditions exist.
SOFT-FIELD TAKEOFF
A soft field may be defined as any takeoff surface that
measurably retards acceleration during the takeoff roll.
The objective of the soft-field takeoff is to transfer the
weight of the aircraft from the landing gear to the rotor
as quickly and smoothly as possible to eliminate the
drag caused by surfaces, such as tall grass, soft dirt, or
snow. This takeoff requires liftoff at a speed just above
the minimum level flight speed for the aircraft. Due to
design, many of the smaller gyroplanes have a limited
pitch attitude available, as tail contact with the ground
prevents high pitch attitudes until in flight. At minimum
level flight speed, the pitch attitude is often such
that the tail wheel is lower than the main wheels. When
performing a soft-field takeoff, these aircraft require
slightly higher liftoff airspeeds to allow for proper tail
clearance.
COMMON ERRORS
1. Failure to check rotor for proper operation, track,
and r.p.m. prior to takeoff.
2. Improper initial positioning of flight controls.
3. Improper application of power.
4. Allowing gyroplane to lose momentum by
slowing or stopping on takeoff surface prior to
initiating takeoff.
5. Poor directional control.
6. Improper pitch attitude during lift-off.
7. Settling back to takeoff surface after becoming
airborne.
8. Failure to establish and maintain proper climb
attitude and airspeed.
9. Drifting from the desired ground track during the
climb.
JUMP TAKEOFF
Gyroplanes with collective pitch change, and the
ability to prerotate the rotor system to speeds approximately
50 percent higher than those required for
normal flight, are capable of achieving extremely short
takeoff rolls. Actual jump takeoffs can be performed
under the proper conditions. Ajump takeoff requires no
ground roll, making it the most effective soft-field and
crosswind takeoff procedure. [Figure 20-5] A jump
takeoff is possible because the energy stored in the
blades, as a result of the higher rotor r.p.m., is used to
keep the gyroplane airborne as it accelerates through
minimum level flight speed. Failure to have sufficient
rotor r.p.m. for a jump takeoff results in the gyroplane
settling back to the ground. Before attempting a jump
takeoff, it is essential that you first determine if it is
possible given the existing conditions by consulting the
relevant performance chart. Should conditions of
weight, altitude, temperature, or wind leave the successful
outcome of the maneuver in doubt, it should not
be attempted.
The prudent pilot may also use a “rule of thumb” for
predicting performance before attempting a jump takeoff.
As an example, suppose that a particular gyroplane
is known to be able to make a jump takeoff and remain
airborne to accelerate to VX at a weight of 1,800 pounds
and a density altitude of 2,000 feet. Since few takeoffs
are made under these exact conditions, compensation
must be made for variations in weight, wind, and density
altitude. The “rule of thumb” being used for this
particular aircraft stipulates that 1,000 feet of density
altitude equates with 10 m.p.h. wind or 100 pounds of
gross weight. To use this equation, you must first determine
the density altitude. This is accomplished by
setting your altimeter to the standard sea level pressure
setting of 29.92 inches of mercury and reading the pressure
altitude. Next, you must correct for nonstandard
temperature. Standard temperature at sea level is 59°F
(15°C) and decreases 3.5°F (2°C) for every additional
Figure 20-5. During a jump takeoff, excess rotor inertia is
used to lift the gyroplane nearly vertical, where it is then
accelerated through minimum level flight speed.
Density Altitude—Pressure altitude corrected for nonstandard temperature.
This is a theoretical value that is used in determining aircraft
performance.
20-6
one thousand feet of pressure altitude. [Figure 20-6]
Once you have determined the standard temperature
for your pressure altitude, compare it with the actual
existing conditions. For every 10°F (5.5°C) the actual
temperature is above standard, add 750 feet to the
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