Autorotation Hub, purpose

[jdracer]

I've been flying for about a year and a half now and my R50SE is now getting auto rotation hub lock ups. I remove it and re oil it almost every weekend. I probably need a new one but I still fly it even tho the auto rotation hub is locked up. Correct me if I'm wrong but I don't see much change when the hub is locked up. The only down side would be a dragging clutch bearing during autorotation which probably doesn’t affect it to much.

When the engine is idled the clutch is disengaged from the clutch bell. Now the clutch bell is directly connected to the main gear. So when the autorotation hub is locked up it turns the main gear and the clutch bell.

Dose having a locked up autorotation hub effect your flying? What is it's real purpose, and should I replace it before I fly.

Thanks,

[capebob]

If your autorotation hub locks up and your either practice or have a real autorotation the energy in your blades will be transfered to your engine and it will not decelerate enough to disengage the clutch. The good news is that when your autorotation hub locks up and your practice an auto the reverse force on the hub usually unlocks the hub and the loss of blade energy is minimal. The bad news is that if the hub locks up hard enough it will not unlock during an auto and the blade energy used to keep the motor turning over will greatly diminish the possibility of a successful auto. Some more good news is as your blades slow at some point they will slow below clutch engagement speed and you may have time to spool up your head enough to salvage your machine. Some more bad news, it's probably too late by then. :shock:

You can test if your hub is unlocking by flying aggressively for a time to make sure you have given your hub a chance to locked up. Then while hovering just above the ground hit hold. After your blades stop check to see if your hub is locked. Do this several times and if your hub unlocks every time your should be good to go. But I would get a new hub and shaft on the way. You're still taking a chance, but that's what we do in this hobby.

Bob

[jdracer]

Thanks, for the great info capebob. I tried what you said and when ever I do a pitch pump the hub locks up tight and never releases without help......help meaning physically jiggling the main gear until it unlocks.

I'm going to order a new one way bearing including a titan main shaft. Is there such thing as a heavy duty autorotation hub, I forgot where I saw that.

[capebob]

The Raptor 50 hub has never been a problem outside the few like yours that have failed early. The Raptor 90 has a much larger auto hub failure rate and there is an aftermarket hub by Quick UK that is reportedly better than the TT hub. I don't know of an aftermarket hub for the 30/50. I see from your post that you are getting the hub and the Titan main shaft and that's fine, but to be sure that you solve your problem you must also get PV0020 which is the shaft that the auto hub runs on and, if out of tolerance, could be the source of your problem. In the Raptor the auto hub does not ride on the main shaft but the one way clutch shaft PV0020.

Bob