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HomeAircraftHelicopterThunder TigerOther › Raptor 30 clanking tail
11-25-2006 05:10 PM  11 years agoPost 21
kcass518

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Manhasset, NY - USA

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Haven't had the opportunity to check my Raptor lately, but if this weather holds, maybe between tomorrow and Monday I can spend some time on it. I'll put it on my test stand and run it up while trying to isolate the problem. I should take the belt off and give it a good look, but we'll see how much time I have.

More on Tuesday!

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11-29-2006 06:58 PM  11 years agoPost 22
kcass518

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Manhasset, NY - USA

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Still can't figure it out, but in all fairness, I haven't had time to really get into it. One thought. Could a single missing tooth on the belt be the cause? I realize anything is possible, but really, one tooth shouldn't make a big difference, should it?

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11-29-2006 07:17 PM  11 years agoPost 23
vavavoom

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London, England

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Probably not, but a couple might. Realy you need to take the whole belt off and inspect the whole length of it. This can't be done properly while on the heli

## Inteligence is knowing a tomato is a fruit...Common sense is not putting it in a fruit salad

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11-29-2006 07:53 PM  11 years agoPost 24
Yug

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UK. Herts

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This can't be done properly while on the heli
you can inspect the teeth without removing it, but you're gonna have to take it off to check how stretchy it is. Only takes a couple of minutes

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11-30-2006 05:30 PM  11 years agoPost 25
kcass518

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Manhasset, NY - USA

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It ain't the belt. It's got all its original teeth and doesn't stretch at all. It's my Trex belt that's missing a tooth.

I'll try lubing the one-way bearing and see if that does anything.

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12-03-2006 07:20 PM  11 years agoPost 26
sgtmike74

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I think I got it.
When I originally posted this I was sure that the source of my clanking noise was coming from the damaged pulley. After replacing the part imagine my surprise when I still heard the clanking noise emanating from my tail section accompanied by the momentary stop of my tail blades. Don't get me wrong, I am glad I found this part before it failed completely I just felt lost as to what to do next concerning the noise. I started looking at different forums, namely raptortechnique.com and the raptor own manual, when I made a discovery. If you look at the pic of my original post (#1) you might see it. My blade grips where on backwards!! According to raptortechnique.com the lead edge of the top blade should be facing backwards AS WELL as the pitch arm of that corresponding blade grip. In the manual I had to zoom in very closely to make it out but sure enough it was true. So I had to flip my grips as well as switch out the grips to make sure they were facing the right way. They are now set up like the following picture. Once I did this tho, I had to manually flip the reverse switch on my GY401 to keep the heading hold holding in the correct direction. (failure to do this will lead to a really bad day). After all said and done I tested my heli out and the noise was gone!! Not only that, but the heli holds much better in the None Heading Hold mode as well. So if you are experiencing clanking noise looked to see what your blade grip orientation is.

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12-04-2006 04:19 AM  11 years agoPost 27
kcass518

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Manhasset, NY - USA

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Glad you found the source of your noise. I'm not sure that I have the same problem, but your symptoms are the same as mine. Looking at your photos, I'm not sure I'm seeing what you're saying. Is it possible that my blade grips are mirror images of yours? I checked my Raptor manual and it looks to me like mine are on correctly, but yours, which look like they operate like mine, have the bolt and screws going from left to right while mine have the bold and screws going from right to left. My high rotor blade has its leading edge facing aft, and its pitch arm leads it as it rotates around the shaft, just like yours. I think I'm not getting it. If I can, I'll post a photo of mine tomorrow to see if you can show me the difference. I would love to get to the bottom of this question.

Ken

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12-04-2006 06:06 AM  11 years agoPost 28
sgtmike74

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I might have spoke too soon on this one. Though my tail blades are now set up in accordance with the manual as well as raptortechnique.com that noise started up again after my third flight. I tighten up my boom with the help of a buddy and the noise disappeared, but came back later that day.

This is what I THINK is happening inside the boom.

The belt itself forms a loop that goes from the main gear assembly through the boom around the tail pulley and back again.

Half of the belt is pulled, while the other half is pushed.

When the engine spools up it increases the load on the belt and spins it faster which causes it to stabilize and not bind. (no noise)

As soon as the load is gone (you drop your throttle) you still have excessive rpm of the belt.

Im thinking that the half of the belt being pushed is bending and warping
with this high rpms/no load, instead of staying tight. Just like a tank tread when turning. When the belt warps the teeth on the belts are catching each other and snagging. Every time the belt snags on it's self it causes the tail blades to stop here and there.

My next step to tighten up the boom. place a mark on the boom exactly where it enters the main frame. If the boom slides inwards over a period of flights then my mark will disappear and let me know my problem lies with the securing of the tail boom.

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12-04-2006 01:21 PM  11 years agoPost 29
kcass518

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Manhasset, NY - USA

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I think you're right. Since it only happens on spool up, it would make sense that the slack on one side of the belt and tightness on the other side would make the teeth touch each other for that moment. Fixing this problem by excessively tightening the belt might cause other problems. I think I'll leave mine alone and just keep an eye on it.

Ken

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12-04-2006 07:06 PM  11 years agoPost 30
Pickle

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Shorewood, Illinois - USA

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On my machine, it works this way:
If you spool up the rotor system with the engine off, the belt won't catch. Even if you try very hard and spin up the system even faster than you would with the engine - no catching. Therefore it seems like the engine unsteadyness or vibration on spool up is also required to create enough slack (or slap) in the belt to catch itself. I plan on opening up the clutch liner a little - it's way too tight.

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12-05-2006 01:04 AM  11 years agoPost 31
sgtmike74

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I just got a suggestion that would help if in fact it was the boom sliding back into the main frame. That was to put some tape around the boom right at the point where it enters the main frame. I guess I can give it a shot.

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12-05-2006 01:44 AM  11 years agoPost 32
Yug

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UK. Herts

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Tape around the boom or whatever will hold it firm, but will only discuise the problem. I had a situation earlier this year where when I went to idle up, there would be this ZZZZ sound so I'd land immediately only to find the belt had gone slack. I checked everything, shafts, belt, bearings, blade balance (both static and dynamic) etc etc and all was well; even tried aluminium and carbon booms as well as making my own sleeves to minimise play in the tail slider pitch fork. The problem persisted and I became very frustrated. I ended up putting a bolt through the boom and frames to prevent it from slipping. This resulted in the tail hub fracturing as well as the tailbox.
Eventually I tried some round tipped SAB tail blades and the problem was solved. Upto this point, I'd been using NHP blades which were balanced to within 0.01g and CGs were within 0.2mm. I also dynamically balanced them in my dremmel. My reckoning was that there was aerodynamic inbalance between the blades. This would have the effect of one blade providing more thrust than the other resulting in axial vibes on the boom; this in conjunction with the belt tension would overcome the friction in the boom mount, allowing the boom to travel into the heli by 1mm or so. Note that the problem was worse with a crabon boom then ana aluminium boom; a carbon boom is more transmissive of vibes.
I've since tried V tail blades as well as Radix and both work well.

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12-05-2006 03:10 AM  11 years agoPost 33
Wally_Gator

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Diamond Bar, CA

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I was told...
By a reputable pilot who competes...
That the "kicking" of the tail can be caused by a lean condition.
This can also present itself in flight.

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12-05-2006 03:18 AM  11 years agoPost 34
Pickle

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Shorewood, Illinois - USA

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I agree - if the boom "wants" to go in, it will go in. Had the same issues as Yug when I tried an 8 tooth pulley to speed up the tail. Pulled the boom in every time, and efforts to stop it only broke parts. I think the tail resonated at the higher rpm and the belt came together. Makes me wonder how well the new Titan, longer boom and belt works. It should be even more prone to coming together.
Rather than trying to see a mark, try measuring the distance between frame and a guide hoop with calipers.

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12-05-2006 07:50 AM  11 years agoPost 35
Yug

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UK. Herts

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I run both my 50s with Titan aluminium booms. Absolutely no problems what so ever with HS of 2k. Currently have Radix 92s on one and Radix 95s on the other.

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12-06-2006 04:26 AM  11 years agoPost 36
sgtmike74

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On my way to Iraq.........AGAIN!! !

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Guess I will hold off on the tape. I would rather deal with a sliding tail every 3rd or 4th flight as opposed to a cracked tail case. My only problem now is getting free time in conjunction with fair weather to fly in.

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12-06-2006 09:49 AM  11 years agoPost 37
Yug

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UK. Herts

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sgtmike74 - you'd be better off fixing the problem otherwise things will eventually break. Try different tail blades

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