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Rotor Brake

Old 12-08-2009, 09:03 PM
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Default Rotor Brake

For those of you who like everything about helicopters as I do, here is a short clip on Rotor Brake Engagement.

With the volume cranked up a bit you can hear: At 1:06, the engines shut down. At 1:39, the Rotor Brake engage.

http://www.youtube.com/watch?v=305BT...F3047&index=23
Old 09-19-2010, 04:42 PM
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Default RE: Rotor Brake

Sweet ... Sure pulls the head speed down fast.

Thanks for posting.
Old 09-19-2010, 06:07 PM
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Default RE: Rotor Brake

You're welcome!

I wonder how much strain the airframe and / or other components have to absorb, in order to bring all that spinning mass to a halt!

One thing's for sure...all that energy, created by the rotating parts, has to go somewhere!
Old 09-19-2010, 10:26 PM
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Default RE: Rotor Brake

Rotor brakes (usually) operate off of the tail shaft and are not that different than the disk brakes in your car.
Old 09-20-2010, 11:24 PM
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Default RE: Rotor Brake

Thank you for that information!

One would think that using the taildrive to bring the main rotor assembly (greater mass) to a halt, is going about it backwards.
Old 09-22-2010, 11:12 AM
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Default RE: Rotor Brake

Some rotor brakes are for parking the rotors, but some are used to stop the blades but with the engines running. The bigger Sikorskys can stop the blades with the engines running to keep everything powered up and ready to go but stop the blade hazard. It is tough on the power turbine so most operators dont do it unless it is used in something like passenger carrier.
Old 09-22-2010, 07:55 PM
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Default RE: Rotor Brake

Thank's for that reply TFF!
Old 03-14-2013, 08:30 PM
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Default RE: Rotor Brake

The bigger Sikorsky's allow you to decouple the engines from the transmission when the rotor brake is applied. During the engine start sequence, the engines are decoupled to make the start easier. Once the engines are up and running the rotor is engaged.

The Huey uses a dedicated output quill off the transmission for the rotor brake. There is no way to decouple and the brake is simply used to reduce the spin down time from 10+ minutes to 3 or so. It's noting more than a hydraulic disk brake with the master cylinder mounted in the ceiling over the pilot's head. The pilot pulls the lever forward after the engines are shut down and the rotor speed has decayed to around 40%. If done as designed the brake would be applied around 50% rotor rpm and left applied until the blades had completely stopped. The heat from the friction between the pads and the disk causes the grip to fade and smoothly brings the blades to a stop. Our manual had us apply the brake below 40% and release it before the blades completely stopped. Reason being that the lower engagement speed kept the heat and the brake fade from really having an effect and if the brake is left on, it would grab at the very end and shock load the quill shaft and the transmission.

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