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. 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 mini- mum 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. 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 suc- cessful outcome of the maneuver in doubt, it should not be attempted. The prudent predicting performance before attempting a jump take- off. As an example, suppose that a particular gyroplane is known to be able to make a jump takeoff and remain airborne to accelerate to V$_{X}$ 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 den- sity altitude. The “rule 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 deter- mine 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 pres- sure 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 Gyroplanes with collective pitch change, and the  ability to prerotate the rotor system to speeds approxi- mately 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. A jump 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 Density Altitude—Pressure altitude corrected for nonstandard temper- ature. This is a theoretical value that is used in determining aircraft performance. 20-5 JUMP TAKEOFF COMMON ERRORS SOFT-FIELD TAKEOFF 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. 9. Drifting from the desired ground track during the climb. 8. Failure to establish and maintain proper climb attitude and airspeed. 7. Settling back to takeoff surface after becoming airborne. 6. Improper pitch attitude during lift-off. 5. Poor directional control. 4. Allowing gyroplane to lose momentum by  slowing or stopping on takeoff surface prior to initiating takeoff. 3. Improper application of power. 2. Improper initial positioning of flight controls. 1. Failure to check rotor for proper operation, track, and r.p.m. prior to takeoff.