OT: Rattling helicopter

ISTR that the military version has something to prevent that. Even so, I really didn't like a time when a Chinook would fly along a local road at very low altitude. Several times it was above me - I was doing about 15 -

20mph and the Chinook was about twice that, so rather a long time when it was a danger. I guess that crashing at a shallow angle isn't the shortest stopping it can do.
Reply to
PeterC
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If the shaft or gearbox driving the tail rotor fails (even if both engines of a twin-engine carry on working) it is usually non-survivable.

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is a talk by air-sea rescue pilot Jerry Grayson (who also flew the comms helicopter in some episodes of Treasure Hunt) in which he describes how he lost the tail rotor while flying a TV film crew back after a day's filming. He makes it sound very laid-back, but when you think of the reality, it hits home - the helicopter flying sideways-on, slightly rolled over - and he has to land it without rolling it and while keeping the rotor tips off the runway, knowing that the only thing which stops the aircraft spinning is the forward motion of air over the "shark's fin" (his description) on the tail.

Reply to
NY

I am willing to accept that Rotor Slap was the cause, although the noise was really more of a rattle, as though the chain/belt or whatever that drove the tail rotor was flailing around inside the bodywork. And it didn't change as the machine past me, which does seem to be a general effect. But it seems that it landed ok, so all's well.

Reply to
Davey

A little more explanation would have helped. I thought you were insulting me.

Reply to
Davey

But if the Pilot-in-command ignores all gauges etc telling him there is a fuel problem, seems it doesn't matter what duality there is.

Normally there is a 'pilot erro'r finding in a lot of these cases where it seems the pilot was not really to blame at all, but in this case (IMHO) the finding of 'pilot error' was apt.

Reply to
soup

You have heard rotor slap before (every Vietnam film ever) that's more of a whump-whump than a rattle.

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Could you possibly have misdescribed this noise?

Rotor slap is generally heard on fewer blade 'copters. (two for Hueys [Vietnam again]) But can be heard on any, usually if a novice pilot or the necessity to pull lots of pitch on the rotors

Reply to
soup

You have to autorotate damned quickly. Then it just comes down stably. Or go to a very low power level.

Reply to
The Natural Philosopher

you can get a hell of a noise from a twin rotor when one blade passes through the wake of another. Easy to go locally supersonic. And that gives a crack rather than a 'thwap'

Reply to
The Natural Philosopher

Whilst it was pilot error, I?m astonished by the stupidity of a design that requires pilots to faff around with transfer pump settings whilst in flight to prevent the aircraft falling out of the sky.

You would never buy a car that required similar attention to stop it conking out on the motorway say and that?s a vastly less hazardous situation than hovering over a city.

I followed the PPRUNE forum for a while and it seems quite a few pilots ignore the instructions to only turn the transfer pumps on when needed but just leave them on all the time removing the risk of what happened in Glasgow.

Tim

Reply to
Tim+

If you could hear it then so could the pilot. If there was a problem, he would have landed right away.

Reply to
harry

This was a single rotor craft, though. It sounded a lot sharper than the noise in that Youtube video.

But it's gone now, and unlikely to return. We get more Apaches than any other type of helicopter here, and we can usually hear them from miles away.

Reply to
Davey

Or even more likely felt it. I guess TNP's suggestion is the best I've seen.

Reply to
newshound

Its quite alarming how close propellor and rotor tips get to the speed of sound

Optimal is the sort of 200-300mph of a wind turbine tip, but late WWII fighters had to use enormous propellors with all the issues that that entails to stay below transonic, especially with the aircraft themselves approaching transonic speeds in a dive. And helipoppers are close on as well. Larger rotors could move slower, but then the whole machine gets unwieldy.

Of course jet turbines are well into supersonic airflows post combustion.

Reply to
The Natural Philosopher

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