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HomeAircraftHelicopterCentury Radikal G20-30 N640 Hawk Predator › hawk sport tail drive wire/ or torque tube ???
03-08-2010 02:08 PM  8 years agoPost 1


eaglecreek,oregon - USA

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hello i am currently working on my older hawk sport been using it to pratice with currently has older gear but i just change the gyro to a gy240 from a helimax piezo when looking it over the other day i noticed that the tail drive has some play from the front drive gear to the tail box it seems to be in the slip porton of the assembly i have looked for parts and drawings on the century site which are not very informative i have a NIB hawk pro that i will be building very soon the pro looks to have a dogbone style torque tube and the sport just a slip together wire . can the sport be upgraded to the newer style torque tube setup and what all will be required to do this or should i just leave the sport the way it is .like i say i have some play in the wire slip area about 30 degrees or so by holding the gear at the front and turning the tail box input gear just looking for suggestions dont want to have a crash caused by loss of tail drive in flight thanks for you help motorhead540

wife says if i'm going to be an addict at least its to a heli

03-08-2010 02:16 PM  8 years agoPost 2


Sneads Ferry, NC USA

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I have the same bird and it is a steel drive wire. You will really see it at slow idle but it OK. The Torque tube upgrade can be doen but last time I checked, it was too rich for my blood.

Century Hawk Sport, OS .32, Futaba 7C, GY-601 9251
Predator Gasser SE G-23, Fut 3010 servos, JR gyro/servo

03-08-2010 02:32 PM  8 years agoPost 3

rrKey Veteran

Ottawa, ON - Canada

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I have no experience with the wire drive, but I thought I read a while back that HH gyros can put too much stress on the wire causing it to snap eventually. Just thought I'd throw it out there since you mentioned you upgraded from a piezo.

I'm sure somebody else who's had those wire drive systems can either confirm or tell me to put down the pipe.

Just some food for thought.

If it can't hover, it ain't worth flying.

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03-08-2010 03:09 PM  8 years agoPost 4
Frank Bostwick

rrElite Veteran

Cincinnati Ohio

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I flew wire for a year or so then went to a Raven size boom and Torque tube system. If you are learning the wire is better IMO. Yes it does "windup" but if you are just doing FF, hover, orientation basic stuff the wire is fine, yes keep your gain as low as possible. With the TT, every time you touch the tail, its gonna cost you $5 for tail gears. TTs are $30, not cheap to replace. (the Raven boom and TT system uses double dog bone and that saves alot of TT damage over the Hawk system since both ends can move in the coupling)
Last year when I wanted to concentrate on learning Autos I went back to the wire drive for a month or 2.


03-08-2010 06:21 PM  8 years agoPost 5


Vancouver, Canada

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Many of the first wire drives (e.g. Kyosho Concept series and Kalt Enforcer series) had a whipping issue as the support delrin bushings wore out.

But the later and much better wire drive designs, like you will find in the first generations of X-Cell 60's and in these Hawks & Falcons, used a system that had the wire riding inside a long brass tube that supported the wire through most of its length, thus preventing any whipping. So it worked more like a tube drive then a wire drive.

They did not suffer from whipping, which eventually would cause the wire to break. They did have a very minor amount of torque "wind-up", which could be detected when stopping from a hard pirouette. This would result in a bounce similar to that from some belt drive systems. This could easily be adjusted out, using the delay and gain adjustments in the HH gyros.

We did a lot of 3D back then, with HH gyros, on these wire-in-tube drive systems, including on the big 60 powered MinAir X-Cells. Though the 3D then was not as extreme as it is today.

These systems where also much easier on the drive gears and crown gears then are the torque tube systems, when the pilot would land a bit hard and have his tail rotor hit the ground momentarily. This bit of wind-up in the wire would absorb the force and save the gears.

Just insure that the allen screws that secure the shafts at the front, and at the rear, do not allow any slipping and all should be well.


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