I'm sorry I didn't really answer your question completely. My error :-(
"I don't understand.. "It is a fixed shaft engine with a centrifugal clutch mounted on the drive shaft connecting the engine and transmission. " So when you start the engine the rotor starts moving or not?"
The rotor system does not start moving with the engine starting. The rotor system is isolated by the clutch. The rotor brake may or may not be applied during the start. I usually did not have the brake on unless there was a high wind condition or there was creep because the clutch was dragging. A dragging clutch was not common and was a condition for removal if the idle rpm was set properly. The reason for all this was to insure that a rotor blade was not parked over the engine exhaust resulting in damaged blade. Allouette and Lama pilots always stop the rotor system with a blade in front. For me it carries over into the Astar. By the way the rotor brake system was excellent. The French make great rotor brakes.
"The major difference to the pilot was the engagement rpm.
The clutch system worked well IF the pilot used proper technique. Both clutches had a 10 second window for proper engagement. Faster than 35 seconds and you were using too much of the clutch shortening it's life. Longer than 45 seconds glazed the clutch."
centrifugal, manual or what?
The clutch is centrifugal, controlled by engine RPM. As the engine RPM comes up mechanical fly weights inside the clutch make contact with the inside rim of the clutch, very similar to Bell 47 system. The pilot controls the engagement in the manner that he/she increases the fuel flow to the engine from idle. As the fuel is increased and the blades start to move a stop clock on the panel was pushed. This started the 35-45 second window for engagement. There was also a maximum T4 (EGT, TOT) increase during an engagement. If this was exceeded it was an indication that you had a severely worn clutch and it needed new shoes.
What's the rpm for rotor engagement?
I'm sorry but the exact numbers have faded with time. I am in Mexico and my books are in the US. I would be happy to get some real numbers to you as I go on break next week. Don't quote me but I THINK the Standard clutch was 17,000 to 19,000 rpm and the Unified was 19,000 to 23,000. And remember the whole engine is turning at these rpm's. The unified clutch was also used on the Gazelle. It was interesting to become accustomed to the Standard clutch and then get in a ship with the Unified, seemed like it was never going to start turning.
These are grand old ships. If you ever get a chance to fly one don't turn it down. I will say they are probably harder to get comfortable with than any other I have transistioned into. It usually took pilots several hundren hours to get used to all their noises and vibrations, let alone be able to work one anywhere near thier maximum capability.
I'm sorry but I'm lost.
Thanks anyway
And you have me for a guide???? You are truely lost! :-[