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Century Radikal E640 - Swift 16 NX
› 3D-Pro Tail Explosion
03-28-2005 10:31 PM  13 years agoPost 1
HelicopterBoy

rrNovice

Morro Bay, Ca - USA

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I have heard from a few other people with the 3D-Pro, and I have also experienced the tail on the 3D-Pro coming apart.

I was running it up in my hand playing with the pitch curve and all of a sudden there was a POP and no more tail rotor. I am not sure what came apart first but when all was said and done the case was broke and the blade grips, well I found parts of the blade grips here and there.

How many have experienced this? I was really happy mine decided to do it on the ground or I would be much more bitter about the situation and I would be replacing many more parts. I’m also curious to see if I am the only one that this has happened to, if im not the only one hopefully century be fixing this problem.

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03-28-2005 10:43 PM  13 years agoPost 2
ozoneone

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NYC USA

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You're not the only one. My tail started rotating (not even off the ground yet) and as per advice on the forums, I drilled a small hole and inserted a tiny screw where the "nub" used to be on the inside of the tail gear box (TGB). (Look for a tiny bit of plastic inside the boom, that used to hold the TGB in place!) That worked for one test hover (<1 min). With trim-out not yet complete, I had it about a foot off the ground and heard a loud grinding noise and the other side of the TGB cracked open and around it went. It cost me a tail blade grip set and a new TGB. I asked for the boom bearing upgrade when I placed the order for the replacement parts, I hope that addresses this issue.

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03-28-2005 10:46 PM  13 years agoPost 3
Tmaster

rrKey Veteran

TX

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It probably has to do with the two gears that mesh inside the gearbox. If they are under a load and spinning very fast, IF the mesh isn't right I think the gears could slip on eachother and cause a quick force alowing them to become out of alignment, thus putting pressure on the gearbox. Remember also the shaft is CF and has a little bit of flex. Also on the other hand in a crash having the tail blade hit the ground so fast that it totally knocks the gear to a stop and the same thing happens.

A aluminum sold shaft and a CNC gear box would make all the difference, plus the right mesh.

This is what I think I could be wrong!!!
:

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03-28-2005 11:37 PM  13 years agoPost 4
wilsonj

rrApprentice

Waikerie, South Australia

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I think what Tmaster and Ozoneone are talking about is a differen issuet to what HelicopterBoy experienced.

If I am right I believe that the actual tail rotor grips came away from the hub?

This happened to me, lucky it was only in a hover 6 inches up. I found my grip and blade. The outer case of the bearing was still inside the grip. The inner was still on the hub. So it looks like the actual bearing itself failed. Maybe better quality bearings are required? Or better still it should have been a thrust bearing, not a radial.

Although I agree the gearbox case should be a little stronger. Thicker plastic walls would probably sufice.

Regards
Jamie Wilson

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03-29-2005 03:07 AM  13 years agoPost 5
ozoneone

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NYC USA

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Although I agree the gearbox case should be a little stronger. Thicker plastic walls would probably sufice.
I thought when I ordered from Century and they told me the TGB was out of stock, they must be re-tooling it. But what I received was the same. Thicker, fiber-filled plastic would work great.

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03-29-2005 03:35 AM  13 years agoPost 6
ozoneone

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NYC USA

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I think what Tmaster and Ozoneone are talking about is a differen issuet to what HelicopterBoy experienced.
when all was said and done the case was broke and the blade grips, well I found parts of the blade grips here and there.
Sure sounds like what happened to me... ???

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04-05-2005 10:39 AM  13 years agoPost 7
ozace

rrKey Veteran

melbourne, australia

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Mine has the same issues, but in my case it is the gears and the tail gb causing the probs not the blade grip bearings (yet)

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04-05-2005 08:29 PM  13 years agoPost 8
HelicopterBoy

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Morro Bay, Ca - USA

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To help save the gear box on the tail I mounted my tail fin just foward of it, and ran screws with nuts though were the tail fin was holding the gear box together. Now in a hard landing there is no load on the gear box hopefully it will last longer, so far so good.

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04-05-2005 10:06 PM  13 years agoPost 9
wilsonj

rrApprentice

Waikerie, South Australia

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Good idea Helicopterboy.

The other thing that could help is a slightly longer vert fin. help keep the tail blades further away from the ground.

Regards
Jamie Wilson

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04-06-2005 12:01 AM  13 years agoPost 10
HelicopterBoy

rrNovice

Morro Bay, Ca - USA

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I ran a piece of an old broke carbon fiber flybar down the frount of the fin, this gives me another 1" or so below the tail fin. I would say something is a must if you fly off even the slightest of an uneven surface.

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04-06-2005 02:15 AM  13 years agoPost 11
cgroves

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Ottawa, Canada

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Just had mine explode this evening. Only the second flying session and I inspected it carefully. One tail blade is missing and the tail box was spun around on the boom with the TR pushrod candycaned on the boom. Pretty much totaled the chopper since the tailshaft stopped which dragged the main rotor to a stop, no auto onto pavement. I am very unhappy right now. High point is the new version of the landing gear survived just fine .

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04-06-2005 02:27 AM  13 years agoPost 12
rscamp

rrVeteran

Ontario, Canada

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Yikes.

I wonder if balancing the tail rotor helps. Another thing that seems common is a lack of a hardware retainer (i.e. LocTite) on the tail rotor blade retention screws. I wonder if in some cases the screws are backing out and the resulting unbalance eventually breaks the gearbox.

I've looked mine over and found no threadlock on the tail rotor blades. I just ran it up and smoothed out the tail a bit with trial and error application of tape to one of the blades. I hope this helps!

Rob

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04-06-2005 02:42 AM  13 years agoPost 13
HelicopterBoy

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Morro Bay, Ca - USA

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Sorry to hear that cgroves I lucked out and mine was on the gound, I did have another problem tonght. My tail has been acting funny and I found out why. There isnt a setscrew in the metal crown gear . I had just been holding on the shaft spinning every now and then. Tonight it pretty well turned loose and I barly got it back down in one piece. No damage I probably would have broke the case again if the the tail fin was attached to it as hard as I landed. Now the task of trying to find a new setscrew . mabey the hardware store if im lucky.

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04-06-2005 03:39 AM  13 years agoPost 14
ozoneone

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NYC USA

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mabey the hardware store if im lucky.
that must be one great hardware store! my LHS doesn't even have this stuff!

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04-06-2005 04:25 AM  13 years agoPost 15
HelicopterBoy

rrNovice

Morro Bay, Ca - USA

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My neighbor had a screw that the right size so I put a grove it for a flat head screwdriver and \shortened it up. Should work, its not a allen set screw but it will get me back in the air. By the way, I dont think my local hobby store would have it either.

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04-06-2005 05:39 AM  13 years agoPost 16
albatross

rrApprentice

Texas, Houston area

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Here is what mine did.

http://rotorworks.net/viewtopic.php?t=1088

Thread was reposted here as well. Ross

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04-06-2005 05:41 AM  13 years agoPost 17
albatross

rrApprentice

Texas, Houston area

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I also had problems with the gearbox turning on the boom...waiting on parts Ross

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04-06-2005 07:51 AM  13 years agoPost 18
mdttb

rrApprentice

Anaheim, Calif USA

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Tmaster

It probably has to do with the two gears that mesh inside the gearbox. If they are under a load and spinning very fast, IF the mesh isn't right I think the gears could slip on eachother and cause a quick force alowing them to become out of alignment, thus putting pressure on the gearbox. Remember also the shaft is CF and has a little bit of flex. Also on the other hand in a crash having the tail blade hit the ground so fast that it totally knocks the gear to a stop and the same thing happens.

A aluminum sold shaft and a CNC gear box would make all the difference, plus the right mesh.
.
I havent had the time to try a solid aluminum tail drive shaft but it's going in the next couple of days, I'll let you know how it goes.

I made a few upgrades to my 3D Pro. Got the CNC Blade grips and CNC swashplate Cenutry makes for the heli. Glad I did as the stock swash was bidding up on the main shaft something terrible it made all the linkage on the head feel like sheet . Made a CF vertical tail fin, CF gyro tray and replaced the POS LG with some Tuff Struts. With the new LG my 3D Pro looks more to scale. The Stock OEM LG my heli was getting nose bleeds

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