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HomeAircraftHelicopterCentury Radikal G20-30 N640 Hawk Predator › Hawk Sport Tail Drive, a little note of caution.
02-14-2003 11:01 PM  15 years agoPost 1
Phil_Mart

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Newcastle UK

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As I've mentioned in another thread, I had a problem with my tail drive today. Basically I landed the heli to reset the gyro gain and just as I was about to take off again the tail drive failed.

At first I thought is might be that the two grub screws on the tail coupling that had come loose. So tonight I stripped the tail down, no it wasn't the grub screws.

What has happened is that the drive wire had sheared off right on the point where it enters the tail coupler. Temporary fix has been to use the wire connector from the old Nexus tail pitch wire and some more wire to extend it and refit it into the coupling. I think the next acquisition will now be a torque drive.

This may just be one of those freakish things that can happen, or it maybe a repeatable problem. Just though it might be worth letting other Hawk owners know, just in case

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02-14-2003 11:17 PM  15 years agoPost 2
Indrid

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Hamburg, NY

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i had a wire drive fail on me because of grub screws coming loose....i upgraded to TT a day later, mostly because of problems with wind up. i now have an excellent holding tail with carbon struts, fins, pushrod, and torque tube.

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02-15-2003 01:45 AM  15 years agoPost 3
jimmyhua

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Guam

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Just like Raptor clutches, the wire-drive on the Hawk Sport do wear out (fatigue), and rather quickly too (100-200 flights).

Get extra wire-drive sets (real cheap), and change them out on a regular basis, or if you've stopped crashing, upgrade to the torque tube for $50.

Jimmy, yeah yeah I know some guys do get real lucky and 7 years go by without a single wire-drive incident. Unfortunately, I'm not one of those people.

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02-15-2003 02:02 AM  15 years agoPost 4
SteveH

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Texas

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Larger Drive Wire
Here's a mod I've been doing on Century drive wires for a while that's been working good. I take a piece of music wire from the hobby shop that just fits in the brass guide tube ( it's .092") and grind down flats on the front to fit in the Century output shaft and grind down flats for the set screws on the rear, and of course cut to the proper length. Then using a number drill the same size as the music wire, drill out the tail rotor input shaft to fit the music wire. Assemble the thing with the music wire for a drive wire using triflow lubricant in the tube as it's a close fit. This mod works almost as good as the torque tube and is CHEAP. Hope this helps.

SteveH

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

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02-15-2003 02:46 AM  15 years agoPost 5
heliman100

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CLOVIS CALIF

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torque tube
JIMMY SAID or if you've stopped crashing, upgrade to the torque tube for $50. That tube is alot tougher than you think ive crashed with a carbon boom and broke the boom in 4 pieces and the tube was ok,same tube in a aluminum boom bent at about 15 to 20 deg and was still ok,had to work at it to get it out of the boom but it was still alive no cracks. IM TESTING THE LIMITS, heliman 100

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02-15-2003 03:32 AM  15 years agoPost 6
Indrid

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Hamburg, NY

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yes i have heard the TT is quite durable. that is good, as they are $12 for replacement tubes. then you have to drill out the ends, re glue them, etc... heh.

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02-15-2003 05:10 AM  15 years agoPost 7
rcheliflyer

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calif., usa

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SteveH

upgraded wire drive,

That's a great idea Steve, the stock wire is pretty flimsy, and I don't
want to put a lot of money in the Hawk.
I think I'll do this the next time I have the tail off.

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02-15-2003 09:39 AM  15 years agoPost 8
Phil_Mart

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Newcastle UK

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Thats a very good idea about upgrading the wire drive. I'd like to put the TT in, but having just spent over £50 for upgrading the head spindle and bell mixers it'll have to wait.

A trip to my LHS is called for this morning

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02-15-2003 12:49 PM  15 years agoPost 9
SteveH

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Texas

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Larger Drive Wire
I've used the larger drive wire on three different helis now and the torque tube on one, and honestly I can't tell the difference in flight. The original wire is flattened on the mainframe end, but the larger .092" wire is large enough that all you have to do is carefully grind flats on it and it will fit just fine. Just be carefull not to grind the flats too much or you will have excessive play in the drive. I just grind a little at a time and keep testing as I go to get a good snug fit. I grease the flattened end and oil the wire in the tube. It will seem as too snug a fit at first in the tube, but with light lubrication, quickly works into a perfect fit with absolutely no chance for wind up. Hope this has been of some help.

SteveH

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

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02-16-2003 08:09 PM  15 years agoPost 10
Phil_Mart

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Newcastle UK

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Oops!
Nearly spoke too soon, was going to post this morning to say that I'd been successful in fitting the upgraded wire drive to me Hawk. But then I got busy doing other things and left for the club field early today.

I'd had several flights with the Hawk already when I decided to take it out again. What I achieved, in front of all the other fliers, was to demonstrate how to land a spinning top from 30 feet up. Yep it went again, only NOT on the ground. As it hit the deck a couple of members came rushing over to see what the damage was.

Boy was I lucky, I had managed to keep it level and pulled the power of gently. All I got was a broken tail fin, oh and a broken drive wire. Stripping it down it had broken in exactly the same place again.

On stripping the tail down tonight, including the boom, I noticed that Century use a long length of brass tubing with 3 supports on it. This as opposed to Kyosho who use individual supports. Anyhow, the whole unit had moved forward, right up to the frame end of the tube. This may well explain the failure of the wires, leaving them with too much slop at the far end of the boom. Also I figure the metal blade grips might have some impact on the situation, the drive having to slow down and speed up this slightly heavier mass?

Mod number two, tomorrow, is going to be replacing the wire with a length of 4mm stainless wire and a new guide tube. This will then be GLUED in place.

We shall see

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02-17-2003 12:30 AM  15 years agoPost 11
Isaac F

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Panama Republic of Panama

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On stripping the tail down tonight, including the boom, I noticed that Century use a long length of brass tubing with 3 supports on it. This as opposed to Kyosho who use individual supports.
Just for your info: The inexpensive US$10,00 Kyosho boom use only 3 supports inside but Kyosho use to sell a upgraded boom that comes in blue or red anodized at US$22.00 and this one comes with a brass tubing inside the tail boom hangin by the 3 plastic supports.

Speed of light is greater than speed of sound. Some people seem very bright until U hear them speak

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02-17-2003 01:00 AM  15 years agoPost 12
gwallace1

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Susanville, CA

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Hope this does not come out wrong, but did you drip some CA down the boom after you put the brass tube and guides in the appropriate spot? Or if you did do it, did the CA come loose and allow the guide assy to slide forward? The instructions say to do this and so far I have had no problems with the wire drive. Anyways, hope you solve the problem.

Greg

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02-17-2003 04:59 AM  15 years agoPost 13
ThBrtmn

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Savannah, Georgia

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I got my sport in the middle of January..Christmas Backorder...when putting it together it seemed like the guides w/tubing were pre-glued so I didn't add any extra CA to it....Should I double check and add some more?

~BART~

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02-17-2003 05:18 AM  15 years agoPost 14
gwallace1

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Susanville, CA

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You can double check it if you have the boom off. With the drive wire out of the guides lightly push on the guide assembly with a dowel. If the assembly moves reposition it centered in the boom and CA it in place. Be sure not to get any CA inside the brass tube. Let it cure before reassembling I have heard the CA can build unwanted crystals in the boom. Hope this helps.

Greg

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02-17-2003 05:37 AM  15 years agoPost 15
ThBrtmn

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Savannah, Georgia

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Sounds Good,
Better safe than sorry

~BART~

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02-17-2003 08:10 AM  15 years agoPost 16
Phil_Mart

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Newcastle UK

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Better safe than sorry
Yes,

Or learn how to land a spinning top real quick

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02-17-2003 03:26 PM  15 years agoPost 17
Indrid

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Hamburg, NY

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i did that phil, have one thing to say...


THANK GOD for soft, fluffy snow!

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