To avoid the onset of blade flap, always taxi the gyroplane at slow speeds when the rotor system is at low
r.p.m. Consideration must also be given to wind speed and direction. If taxiing into a 10-knot headwind, for example, the airflow through the rotor will be 10 knots faster than the forward speed of the gyroplane, so the taxi speed should be adjusted accordingly. When pre-rotating the rotor by taxiing with the rotor disc tilted aft, allow the rotor to accelerate slowly and smoothly. In the event blade flap is encountered, apply forward cyclic to reduce the rotor disc angle and slow the gyroplane by reducing throttle and applying the brakes, if needed. [Figure 20-3]
BEFORE TAKEOFF
For the amateur-built gyroplane using single ignition and a fixed trim system, the before takeoff check is quite simple. The engine should be at normal operating temperature, and the area must be clear for prerotation. Certificated gyroplanes using conventional aircraft engines have a checklist that includes items specific to the powerplant. These normally include, but are not limited to, checks for magneto drop, carburetor heat, and, if a constant speed propeller is installed, that it be cycled for proper operation.
Following the engine run-up is the procedure for accomplishing prerotation. This should be reviewed and committed to memory, as it typically requires both hands to perform.
PREROTATION
Prerotation of the rotor can take many forms in a gyroplane. The most basic method is to turn the rotor blades by hand. On a typical gyroplane with a counterclockwise rotating rotor, prerotation by hand is done on the right side of the rotor disk. This allows body movement to be directed away from the propeller to minimize the risk of injury. Other methods of prerotation include using mechanical, electrical, or hydraulic means for the initial blade spin-up. Many of these systems can achieve only a portion of the rotor speed that is necessary for takeoff. After the prerotator is disengaged, taxi the gyroplane with the rotor disk tilted aft to allow airflow through the rotor. This increases rotor speed to flight r.p.m. In windy conditions, facing the gyroplane into the wind during prerotation assists in achieving the highest possible rotor speed from the prerotator. A factor often overlooked that can negatively affect the prerotation speed is the cleanliness of the rotor blades. For maximum efficiency, it is recommended that the rotor blades be cleaned periodically. By obtaining the maximum possible rotor speed through the use of proper prerotation techniques, you minimize the length of the ground roll that is required to get the gyroplane airborne.
 

The prerotators on certificated gyroplanes remove the possibility of blade flap during prerotation. Before the clutch can be engaged, the pitch must be removed from the blades. The rotor is then prerotated with a 0° angle of attack on the blades, which prevents lift from being produced and precludes the possibility of flapping. When the desired rotor speed is achieved, blade pitch is increased for takeoff.