windsock9
9th Aug 2004, 15:51
Hi there, just wondering.... Can a helicopter equipped with one or more turbine engines have magnetos?
212man
9th Aug 2004, 15:58
Yes, if it also has one or more piston engines!
What has prompted you to ask this question? One of the odder ones I'd say.
Woolf
10th Aug 2004, 10:28
.... sounds like typical JAR-Exam question to me! :rolleyes:
Woolf
11th Aug 2004, 08:49
Magneto? Wasn't that the bad guy in X-Man? :E
sprocket
11th Aug 2004, 09:46
Here are the instructions for hand starting a magneto equipped turbine ......
According to the Perkins Mars manual, how to start the engine:-
1. Commence vigorous hand cranking, 2 operators.
2. At IGNITE speed, tachometer indicating 450 to 550 rpm and fuel pressure gauge reading 550 lb/sq. in. minimum, open fuel control valve to on position.
3. Continue vigorous cranking to STOP CRANKING speed, 1200 to 1300 rpm indicated on tachometer, from which point the engine will accelerate normally to rated speed.
With engine stabilised at rated speed, oil pressure should be 20 lb/sq. in. minimum and exhaust temperature normal operating range is 600 to 950 deg. F, (315 - 510 deg. C).
Normal running speed is 4430 rpm, speed must not be allowed to fall below 3600 rpm and avoid running at speeds in excess of 4500 rpm.
Shut down sequence to stop engine, allow 2 to 3 minutes running at no load in order that engine may cool down, turn engine fuel control valve to off position.
Note that all tachometer speeds quoted are output shaft speeds, the turbine is actually turning at over 40,000 rpm. The spiral bevel gear in the gearbox is rotated at 9.1 to 1 by the bevel pinion mounted on the end of the turbine rotor shaft. A reversal of this speed reduction by hand cranking, together with the speed increase in the chain and sprocket linkage, allows the operator to crank the engine with an approx. 70 to 1 speed increase. The magneto operates continuously to fire the spark plug whilst cranking and stops when hand cranking is discontinued, the sprag clutch disconnects when the turbine speed exceeds the cranking speed.
It isnt a helicopter engine but what did they use before the solid state exciter box was invented?
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