Deano
Member
Posts: 52
Loc: Indiana
Reg: 04-06-05
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 08-08-05 01:29 AM - Post#64409
I have a raptor 30 and lately after I lift off and hover for a couple seconds, I will get a very bad vibration or shake, bad enough that I need to set it down quickly. Everything is balanced and adjusted porperly. It has flown great with the adjustments the way they are so my thought is it is something mechanical that is failing. I have noticed that the main rotor grips seem to be slightly loose. When I lift on one of the blades, it has some play in it. Is that normal? Can bearings that are going bad cause this and which ones?? Would a metal head assembly work alot better than the factory plastic that I have?
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Deano
Member
Posts: 52
Loc: Indiana
Reg: 04-06-05
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08-08-05 01:45 AM - Post#64415
In response to Deano
One more note. I have checked the tracking of the main blades and have even swapped out blades to make sure but the vibration is still there. I need to mention that I have also recently been using some homemade training gear for landing as the ones I bought from the hobby store broke in my garage. The homemade pair is made of 1/2" pvc. I had heard that the training gear will calm a vibration but I read in this forum that it will intensify.
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chase
Senior Member
Posts: 1643
Loc: Oklahoma city
Reg: 03-20-05
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08-09-05 03:29 AM - Post#64462
In response to Deano
Alot of times training gear does cause vibration just after take off. I have never used them but I am pretty sure it should go away after you get off the ground. What kind of surface are you taking off from?
Justin
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RC Man1
Full Time Senior Member
Posts: 2271
Loc: Central Illinois
Reg: 12-05-00
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08-09-05 10:27 AM - Post#64467
In response to Deano
Home made training gear frequently causes problems. Just keep cutting it down until the vibration stops.
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Deano
Member
Posts: 52
Loc: Indiana
Reg: 04-06-05
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08-09-05 10:24 PM - Post#64485
In response to RC Man1
I am lifting off from grass. I don't have the vibration until I am in the air so I am thinking that when on the ground, the training gear is stable but once in the air it begins to vibtate. But wouldn't something have to cause it to start vibrating in the first place??
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RC Man1
Full Time Senior Member
Posts: 2271
Loc: Central Illinois
Reg: 12-05-00
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08-09-05 11:16 PM - Post#64489
In response to Deano
Quote:
I am lifting off from grass. I don't have the vibration until I am in the air so I am thinking that when on the ground, the training gear is stable but once in the air it begins to vibtate. But wouldn't something have to cause it to start vibrating in the first place??
The rotating blades are what provide the energy to cause the vibration. It is an in flight structural dynamics problem when the resonant frequency of the flexible training gear are close to the frequency on the rotation blades. You MUST change the resonant frequency on the training gear. To do this you can by changing the mass or stiffness of the training.
Shorter pipes will help. Lighter weight and stiffer material such as carbon fiber tubes are the best but cost a lot. You really don’t need them very long to do the job. You just don’t want anything that is heavy and flexible like PVC unless it is very short.
Just shorten the darn things and get on with flying and having run.
RC
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Deano
Member
Posts: 52
Loc: Indiana
Reg: 04-06-05
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08-10-05 01:10 AM - Post#64502
In response to RC Man1
I switched to another set of training gear made from 3/8" dowel and got the same problem. I would like to try without any training gear at all but I'm afraid as hard as it shakes it would be a mistake. I did have the engine out prior to this problem, could I have done something to cause this while putting the engine back in? I did run it for about a half hour after installing the engine before this problem occured.
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chase
Senior Member
Posts: 1643
Loc: Oklahoma city
Reg: 03-20-05
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08-10-05 11:15 PM - Post#64543
In response to Deano
Ok your gonna have to face your fears. If you are scared of flying a heli you must get over that. Dont get me wrong you have to repsect these things. But if your afraid then that is goona couse something to go wrong. Kinda like riding a horse, if ya get on a horse and your afraid the darn horse knows it and dont want ya on it. Take your gear off and take it up a foot or so. if the vibration is gone then its your gear. I tought myself with a nexas 30 and no gear. never used them. most people only need them for a few hours anyways. I bought a few sets of landing gear but that was becouse i was setting it down to hard. 3/8 dowel is probaly to stiff. You dont need any heavy heavy duty stuff just something to keep ya from tipping over and to take some impact. Thats why most training gears come with the balls to help take some impact. Its all about faith and dont be scared of crashing becouse everone does. Its gonna happen. But have faith in yourself and take the gear off and take it up about a foot or so. Good luck
Justin 
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RichWilabee
Senior Member
Posts: 256
Loc: Cerritos, CA about 16 mi...
Reg: 11-20-04
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08-10-05 11:52 PM - Post#64548
In response to chase
Do you have an experienced heli flyer in the area that could check out your heli without the training gear?
Rich
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Deano
Member
Posts: 52
Loc: Indiana
Reg: 04-06-05
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08-11-05 02:40 AM - Post#64566
In response to RichWilabee
I'll take it up with no gear but I wanted to try another set first. There is no one experienced near that I know of but this Sunday I am going to the AMA deal in Muncie Indiana and I plan on taking it and asking someone for some help.
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chase
Senior Member
Posts: 1643
Loc: Oklahoma city
Reg: 03-20-05
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08-11-05 02:50 AM - Post#64567
In response to Deano
good idea 
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airbrush dude
Senior Member
Posts: 746
Loc: Howell nj
Reg: 09-12-03
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08-11-05 03:21 AM - Post#64571
In response to chase
are your blades too tight maybe? some times if you crank down on the blade bolts it will vibrate.
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Deano
Member
Posts: 52
Loc: Indiana
Reg: 04-06-05
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08-11-05 03:43 AM - Post#64572
In response to airbrush dude
I don't believe the blades are to tight. I have not changed how much I tighted them. If I hold onto the flybar rod and pull a main blade toward me, the flybar rod will flex about 1/4".
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Deano
Member
Posts: 52
Loc: Indiana
Reg: 04-06-05
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08-11-05 06:56 PM - Post#64587
In response to Deano
I flew it without training gear, that is about 6 inches off the ground and the thing shook like crazy. NOT the training gear  As I said before, I had the engine out, could something be out of whack after installing it,cooling fan, allignment, ect?? I'm at a loss here, I've looked the thing over and nothing is standing out. I don't have a lot of experience here so I am not sure what all to look for. 
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RC Man1
Full Time Senior Member
Posts: 2271
Loc: Central Illinois
Reg: 12-05-00
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08-11-05 11:27 PM - Post#64592
In response to Deano
Has this thing ever had a crash, tipover, boom strike, or the tail rotor contact the ground?
If it shakes that badly then there may be some problem with the rotor system. Parts that rotate very fast like the fan and tail rotor cause vibration but not the kind of shaking that you describe. Blade balance, paddle alignment or balance, or something is bent or not aligned properly.
Do a static tracking test. Extend your transmitter antenna to touch the end of one blade then rotate the head until the other blade comes around next to the antenna. If it’s more than 1/16” off you have a problem that needs to be solved before you try again.
It could also be some problem with the frame causing the head to tail boom to vibrate. Hold the landing gear and apply some force to the head and tail boom to see if anything is wrong. There could be a crack in something that is hard to see but allows it to flex. Just give it a real good inspection for anything loose. Check all the screws to make sure they are tight and there are no stripped threads.
Another thing that I just thought of is the blade grip thrust bearings. If one or both are not installed properly it could cause unequal pitch in the blades as you apply cyclic and throttle.
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Deano
Member
Posts: 52
Loc: Indiana
Reg: 04-06-05
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08-12-05 01:19 AM - Post#64597
In response to RC Man1
I'm glad you mentioned the blade grips. When I was checking it over I noticed that one of the blade grips has no slop and another moves very slightly, maybe around a 1/16". Can there be any play in this? I had already ordered new thrust bearings and a few other bearings to replace but the movement was so small I was not sure if it would effect it the way it does.
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RC Man1
Full Time Senior Member
Posts: 2271
Loc: Central Illinois
Reg: 12-05-00
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08-12-05 05:31 PM - Post#64616
In response to Deano
How did the static tracking test come out?
If you replace the bearings be sure and replace the spindle and rubber dampers. The head spindly can have a slight bend that is hard to see and cause serious vibration problems.
A good upgrade is the hardened main shaft. It is much more durable than the stock shaft and the cost is reasonable. http://www.onlyraptors.com/new_search.php?PHPSESSID=c65203a981ebf6ba053794f56ee60bd2&T=350
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n5ofc
Member
Posts: 25
Loc: Dallas, Tx.
Reg: 02-01-05
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08-13-05 05:40 AM - Post#64640
In response to RC Man1
Make sure the spindle is centered in the hub or it will be forced to one side as the head spools up due to the disk as a unit being shifted to one side of center. Even with balanced blades if the spindle is being held just a bit off center as the head spools up this offset will only get worse as forces pull the blade/spindle assembly to one side.
I found this to be the case on one of my hyper 50's, I had a blade slightly out of balance and it pulled the spindle to one side compressing one of the dampers and it stayed off center just slightly even after balancing the blades better.
The dry (blue) dampers had gripped the spindle and did not let it rebound I had to disassemble the head and lightly grease the dampers and spindle. I could see the differance in the distance between the grips and hub.
To keep grease out of the spindle end threads so thread locker would hold, I slid the damper on the spindle dry then put a little tri-flow grease on the spindle behind the damper and slid it over the grease into place in the hub.
Good luck tracking it down.
| Bob
Member DRCC
Twin HyperRaptor 50's
X-Cell 60 Sport Trainer (Vintage Bent Frame)
Futaba 9CHP-S / 9252's
Futaba GY-401 / 9254's
TJ-Pro's
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