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HomeAircraftHelicopterCentury Radikal G20-30 N640 Hawk Predator › Used Hawk III won't lift off
05-09-2005 02:16 AM  13 years agoPost 1
RadioRob

rrVeteran

Schaumburg Illinois USA

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I got a good deal on a used Hawk III.... Maybe!!!
I own a Raptor V2 so I know some stuff about Helli's
I only had a TT pitch gage but I am sure I am getting a least +9 at the top end.
The only way I can get it off the ground is to bring it to full throttle to almost 50 % full and the pitch at 100% 3/4 stick then it will lift off about a foot off the ground.
I am stumped. I made some of the push rods longer to get more pitch than I should and still barely gets off the ground and almost no neg pitch to get down?????I think the blades are flattening out in flight.
Is something worn? I think I am getting allot of play when I twist the blades not slop but play. I am not familiar with the Hawk mechanics, its not like the Raptor more like a Hornet II.
Any thoughts?


Rob...

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05-09-2005 02:50 AM  13 years agoPost 2
SteveH

rrProfessor

Texas

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Rob,

Check the condition of the rubber dampers in the head. If they are worn too bad, when load is applied to the head, they can flatten causing the feathering shaft to move up effectively reducing the positive pitch.

The government cannot give you anything without first taking it from someone else.

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05-09-2005 02:57 AM  13 years agoPost 3
RadioRob

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Schaumburg Illinois USA

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are they in the blade grips?

Rob...
Nevermind I found where they go now
I will take a look at them.
Thanks...


Rob...

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05-09-2005 03:52 AM  13 years agoPost 4
RadioRob

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Schaumburg Illinois USA

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I removed the rubber dampers and they were a little worn but not that bad. Is there something else I should look for?

Rob..

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05-09-2005 05:24 AM  13 years agoPost 5
wedge

rrElite Veteran

Victoria BC, Canada

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What about if someone put the fearthing shaft together wrong, and put the washers on in the wrong order, it could bind when it gets load on it, and cause what your experencing.

Take a look and see. You will have to pull the blade grips off, and check the order of the two washers behind the bearings, the larger one goes in first.

Victoria BC, Canada, Century Swift,Trex SA 450, Hummingbird V3.

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05-09-2005 10:49 AM  13 years agoPost 6
RadioRob

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Schaumburg Illinois USA

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Yes the washers where in backwards.
I ordered new rubber dampers and will try that.

Thanks alot
Rob...

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05-09-2005 12:46 PM  13 years agoPost 7
SteveH

rrProfessor

Texas

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Rob,

Wedge has hit on the other possibility. The washers under the lock nuts that hold the blade grips on the feathering shaft can be installed backwards locking the blade grips when at speed.

The washers under the outside lock nuts MUST be installed small washer first followed by the large washer and then the nut.

If the large washer is installed first, it will contact the outside race of the outside radial blade grip bearing effectively locking it from turning when the cyntrifical force from the rotor speed is applied, which will not allow the blade grips to change pitch.

The government cannot give you anything without first taking it from someone else.

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