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## ELECTRIC PREROTATOR 

The electric prerotator found on gyroplanes uses an automotive type starter with a bendix and ring gear mounted at the rotor head to impart torque to the rotor system. [Figure 18-5] This system has the advantage of simplicity and ease of operation, but is dependent on having electrical device can alleviate the problems associated with the high starting torque initially required to get the rotor system turning. This device delivers electrical pulses to the starter for approximately 10 seconds before con- necting uninterrupted voltage. 

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## TIP JETS 

Jets located at the rotor blade tips have been used in sev- eral applications for prerotation, as well as for hover flight. This system has no requirement for a transmission or clutches. It also has the advantage of not imparting torque to the airframe, allowing the rotor to be powered in flight to give increased climb rates and even the ability to hover. The major disadvantage is the noise generated by the jets. Fortunately, tip jets may be shut down while operating in the autorotative gyroplane mode. 

## INSTRUMENTATION 

The instrumentation required for flight is generally related to the complexity of the gyroplane. Some gyro- planes using air-cooled and fuel/oil-lubricated engines may have limited instrumentation. 

## ENGINE INSTRUMENTS 

All but the most basic engines require monitoring instrumentation for safe operation. Coolant tempera- ture, cylinder head temperatures, oil temperature, oil pressure, carburetor air temperature, and exhaust gas temperature are all direct indications of engine opera- tion and may be displayed. Engine power is normally indicated by engine r.p.m., or by manifold pressure on gyroplanes with a constant speed propeller. 

## ROTOR TACHOMETER 

Most gyroplanes are equipped with a rotor r.p.m. indica- tor. Because the pilot does not normally have direct control of rotor r.p.m. in flight, this instrument is most useful on the takeoff roll to determine when there is suf- ficient rotor speed for liftoff. On gyroplanes not equipped with a rotor tachometer, additional piloting skills are required to sense rotor r.p.m. prior to takeoff. 

