Gyroplane rotors generate lift via autorotation, if the rotor blades slow down, the lift is reduced. Some gyroplanes have a lack of responsiveness to nose-down inputs at specific rotor speeds. A finite gross inflow angle to the propeller produces an AOA that varies around the propeller disk, leading to a force imbalance. An unstable phugoid in a gyroplane can cause unstable rotor speed responses to control inputs, therefore affecting the safety of flight. Any flutter phenomenon arising from an Aft CG will manifest as a 1 revolution varying disc tilt. Blade elasticity doesn’t seem to have a large effect on the fidelity of the models, therefore, it is typically left out. The mass of the rotor blade affects the pitch-damping aerodynamic derivative. A rotor with more inertia reduces the gyroscopic precession moment generated by the flapping hinge. This moment is generated around the roll axis, but the flapping hinge causes a 90-degree phase lag, which means that the effects occur in the pitch axis. The gyroplane rotor head uses ball bearings. Sometimes inertial is built up in the rotor system to achieve a jump takeoff. Gyroplane rotor systems are simpler than helicopter rotor systems. Jump takeoffs can be performed if there is a variable 2-position collective control.[^6]
To increase lift, the rearward shaft angle is increased.[^6] This increases the area of the rotor that accelerates the autorotation, which give an increased rotor speed.[^6]
To decrease lift, the shaft is tilted forward, which decrease the autorotative speed, thus decreasing lift.[^6]
To start an unpowered gyroplane rotor, the pilot would manually spin the rotor until it was moving as fast as possible. [^6] Then he would accelerate with 9 deg rearward collective to accelerate the rotor from 100rpm to 200-250 rpm.[^6] Then the collective was increased to full back 18 degrees and the gyroplane accelerated until takeoff at around 300 rpm.[^6] Upper limits of the RPM range are due to centrifugal forces, and lower limits are due to excessive blade flapping.[^6]
[[Gyroplane Rotor Aeroelasticity]]
[[Montgomerie-Parsons Two-Place]] – first ever gyroplane teeter angle was measured using this type of aircraft.
[[Gyroplane Phugoid Mode]] – an unstable phugoid mode creates a dangerous aircraft.
[[Wallace Wa116]]
[[MagniGyro]] – developed fiberglass composite rotor blades
[[Autorotation]]
[[Helicopter Rotor]] – powered rotor
[[Advance Ratio]] – gyroplane rotors can have advance ratios of 0.5-1
[[Mast Bumping]] – can occur if accelerated too quickly, or too much aft cyclic early in the run[^6]
[[Glauert’s R&M 111]] – older inflow model
[[Pitt Peters Inflow Model]] – used for gyroplane models
- CAAPaper2009
- gyrocopterflyingclubGyrocopterRotorBlades2020
- adminbagBuildItYourselfGyrocopter2018
- florosPerformanceAnalysisSlowedRotor2009
- AutogyroHistoryTheory
- GyroplaneRotorAerodynamics[^6]
Backlinks:
[[Flapping Hinge]]
[[Gyroplane Phugoid Mode]]
[[Gyroplane Stability]]
[[Gyroplanes]]
Phase Lag
[[Rotor Modelling]]