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HomeAircraftHelicopterCentury Radikal G20-30 N640 Hawk Predator › Century Predator Gasser tail rotor issue
03-11-2010 05:06 AM  8 years agoPost 1
Scorpion

rrApprentice

Socal USA

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I'm having problems with the tail rotor hub spliting in half when hovering,right by the end of the blade grips.
I called Century Helis to get some feet back but they told me they never heard this issue before, any ryder's out there with some feet back on this issue?

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03-11-2010 06:23 AM  8 years agoPost 2
Furious Predator

rrProfessor

Kitchener, Ontario, Canada

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The metal hub itself? or the grip?

Either way, i have never had any trouble on my predator.

Got a picture?

Shawn
Team Leisure-Tech
Team HelixRC

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03-11-2010 06:40 AM  8 years agoPost 3
Scorpion

rrApprentice

Socal USA

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Here is the picture of the tail rotor

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03-11-2010 03:41 PM  8 years agoPost 4
Billme

rrElite Veteran

MS

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There has never been tail problems on the Predator that I know of..

I notice that you have different tail blades in some of the pictures.. You may have got a set of blades that went into a buz, this will do that kind of damage...

What tail blades are the orange ones?

Nice Condor, you have it setup like mine with the tall gear

Bill

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03-11-2010 05:14 PM  8 years agoPost 5
oldfart

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Vancouver, Canada

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From the pictures I think the key is that one blade & blade grip is off due to a break at the base of the spindle area on the hub, and the other blade is off because the blade itself broke at its' root where it enters the blade grip.

That clearly indicates a flutter (buzz) situation occured in both blades.

This is usually caused in tail rotors by badly molded or designed (chordwise CG is too far back from the pivot point and/or center of lift) tail blades. This will even be made more critical to flutter/buzz if they are too flexible or poorly molded, so that they do not have the same relative pitch. This will cause tail blade mistracking that has the same effect as mainblade mistracking. But because the tail rotor is turning up at close to 10,000 rpm this becomes very critical.

All of the above is less of a consequence in tail rotors with smaller disc loading (e.g tail rotors that use 85mm blades or smaller), but become exponentially more critical as the tail rotor gets bigger and tail rotor speeds increase. Both of these factors increase the critical tip speeds of the tail blades.

Looking at your pictures, I would suspect your tail blades caused a catastrophic failure because they induced some very high frequency flutter.

There are other possibilities (e.g. a worn tail blade bearing) that can also result in flutter/buzz. But in my experience I have found it usually is blade oriented (be it main blades or tail blades).

Our main rotor heads have built in damping (dampers and GRP grips) that will look after minor flutter causes, but your tail rotor (specially with the metal tail grips, have absolutely no area that has any damping (e.g. GRP gips would have some) so good tail blades become a must have.

That is why I prefer the RT tail blades, they are very stiff, yet the only tail blade I have found that is dynamically neutral. With them, I bet that even if your heli lost a tail slider link, it would not be critiacl as the blade would just feather and the other would continue to give you yaw control.

Most do not realize that there is a lot more to a blades (main or tail) performance then just looks...much like good wimin'

Phil

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03-11-2010 05:48 PM  8 years agoPost 6
Frank Bostwick

rrElite Veteran

Cincinnati Ohio

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Ole'Fart, you da man, heck hes even a yank!
Hard to break old habits eh?

RIP ROMAN

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03-11-2010 07:22 PM  8 years agoPost 7
FloridaHeli

rrVeteran

jacksonville, florida

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Exact same failure
This exact same failure occurred to me with my aluminum framed Predator 2 years ago. I believe what caused it was overspeed. I think the GV-1 and Stator Gator were not working together and the throttle curve was too high; I was using nitro engine curves not gasser. The heli was 4 feet off the ground in a hover but the engine sounded like it was way over a hover speed. All of a sudden the tail exploded with parts flying everywhere. The shaft had broken exactly like yours in the photos. I hit negative pitch to lower the speed but slammed the heli into the pavement; broke the landing gear, destroyed the starter (yeah I'd left it on too) and bent the crankshaft on the Zenoah. I've now trained myself that tail rotor failures can be saved by just flipping the Throttle hold switch. Wish I had trained my mind and hands to do it automatically back then.

The heli was running pretty good up until then. Took quite awhile to get it back running nice again.

This hobby is WAY too expensive!!

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03-12-2010 04:56 PM  8 years agoPost 8
oldfart

rrProfessor

Vancouver, Canada

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Ole'Fart, you da man, heck hes even a yank!
Hard to break old habits eh?
LOL - yep as I don't want my Canadian Centurians to not understand their helis.

Phil

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03-13-2010 12:38 AM  8 years agoPost 9
Furious Predator

rrProfessor

Kitchener, Ontario, Canada

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I didnt study last night. Whats a heli?

Shawn
Team Leisure-Tech
Team HelixRC

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03-13-2010 01:15 AM  8 years agoPost 10
Scorpion

rrApprentice

Socal USA

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Whats a heli?
it means Helicopter

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03-13-2010 01:42 AM  8 years agoPost 11
oldfart

rrProfessor

Vancouver, Canada

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ROFL!!!

Shawn & Scorpion - that had me chuckling for a few minutes.

Phil

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03-13-2010 01:58 AM  8 years agoPost 12
Furious Predator

rrProfessor

Kitchener, Ontario, Canada

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Why are you laughing at me? Im being serious!

Shawn
Team Leisure-Tech
Team HelixRC

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03-13-2010 07:29 AM  8 years agoPost 13
Scorpion

rrApprentice

Socal USA

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Thanks oldfart
this is great feedback on the subject above

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03-13-2010 06:10 PM  8 years agoPost 14
oldfart

rrProfessor

Vancouver, Canada

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Scorpion,

You are very welcome. I hope it helps solve your problem.

Phil

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03-13-2010 10:47 PM  8 years agoPost 15
Scorpion

rrApprentice

Socal USA

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how to reply to a post
how do I reply to a post, I'm sure I'm doing it right!!!!

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