Fuel control for controlling helicopter rotor/turbine acceleration

An engine control for a free turbine gas engine, comprising:

• speed means for providing an actual speed signal indicative of the speed of the free turbine;
• fuel valve means responsive to a fuel command signal provided thereto for metering fuel to the engine;
• and
• fuel controlling signal processing means responsive to said speed means for providing a reference speed signal indicative of a desired speed of the turbine, for comparing said reference speed signal with said actual speed signal and providing a speed error signal indicative of the difference in said actual speed signal from said reference speed signal, and for providing a fuel command signal to said valve means in response to said speed error signal;
• characterized by:
• said signal processing means comprising means for providing a desired acceleration signal as a function of said speed error signal, for providing, in response to said actual speed signal, an actual acceleration signal indicative of actual acceleration of the turbine, for providing, in response to said desired acceleration signal and said actual acceleration signal, an acceleration error signal indicative of the difference in said actual acceleration signal from said desired acceleration signal, and for providing said fuel command signal in response to said acceleration error signal.