HELP!! Vibration from HELL!!!!
 

Well after finally getting the motor to work (bought a Atomic Force) I tried to fly the Corona only to get discuraged again because of MASSIVE, MASSIVE Vibration. I'm not talking little swaying...its like TEETH CHATTERING and about the same frequency. This happened last night so I took the whole rotor head apart, took the main rotor shaft off and found that its not quite straight. I was happy that I found the problem so I went to the hobby shop with the intention of buying new rotor shaft. However when I got there the salesman told me that none of them are truly straight. I inspected the one I was going to buy and found that its not straight either (I wasnt sure if it was better than the one I had) in any event I didnt buy it. Put the whole thing back together with the straightest main rotor shaft I could muster (form the three that I had) and I'm back to square one....MASSIVE TEETH CHATTERING VIBRATION.

I dont think its the tracking because I get the vibration even with the two rotor blades removed. When I remove the tail and just spin the head with the stabilizer it vibrates. I still think that its the rotor shaft becaue it is by no means straight but where do I get a straight one and how do I solve this problem? Anyone else experience this same thing?

Please Please Someone Help a Newby!!!!

RE: HELP!! Vibration from HELL!!!!
 

Hi Talontsi96, welcome to the cursed world of heli vibration. Of all the things that I've dealt with in this hobby this is the one problem that drives me crazy.....ya know what I mean??? The main rotor shaft should be very straight.......some guys check it by rolling it on glass. The last vibration that I had was probably due to an "ever so slight" bend in the main shaft. I say probably because I also replaced the crown gear.....and upon reassembly the vibration was mostly gone. As far as the main shaft goes.....using a flat glass surface to see where and in which direction the bend is.......you can carefully apply pressure in the opposite direction to correct the bend. Also the m.r. hub can cause vibration. It's all so tedious! But once you get the problem corrected....... the other aspects of the r.c. helicopter hobby are great fun. Mark

RE: HELP!! Vibration from HELL!!!!
 

One more thing.....I had a hell of a vibration one time that I couldn't figure out. I took an eye loop (magnifier) and checked the gear teeth on all the gears. The main gear had a small stone wedged between two of the teeth making the gear jump momentarily. All was well when I removed the stone.........
Dick

RE: HELP!! Vibration from HELL!!!!
 

I would suggest getting either the one way upgrade (which helps a few different things) or at least the hardened main shaft upgrade from here: http://www.fxaeromodels.com/lite.htm

Some guys just buy stock lengths of hardened music wire and cut their own shafts.

RE: HELP!! Vibration from HELL!!!!
 

Thanks for all the suggestions guys. This is trully a great site. I would like to order the hardened steel main shaft but it looks like they are out of stock. I did attempt to straighten the main shaft and got it somehwat more straight and retracked the blades. Less vibration now but every now and then it would vibrate and the tail was all over the place (unconrollable tail). Upon closer inspection I found that the drive gear for the tail rotor was worn in such a way that there would be more resistance and even a tooth skip at one point of the main shaft revolution. I contacted my local hobby shops and one of them has the gear in stock. I will pick it up on my way home from work and try again. I'll keep you guys posted. Slowly I'm getting this thing more and more flight ready. I still want a straight main rotor shaft...though....

thanks again,

Paul

RE: HELP!! Vibration from HELL!!!!
 

OK guys here is an update. I hovered about two bateries worth in my yeard. I got the vibrations down to a level where it can be flown but I still need to work on it because if you look at the skids in flight they are still a blur (from vibration).

What surprised me as hell is during one of my hover flights my battery literally exploded (there was loud pop and ended up smoking). The heli went down like a sack of potates and the battery is toast (no charge what so ever). I've never seen that happen in flight. The good news is there was absolutely no damage to the heli which surprised me because it went down hard. I think I will love this heli once I work the bugs out. Time to work on the vibes and order some more battery packs.

Happy hovering!!!!!

Paul

RE: HELP!! Vibration from HELL!!!!
 

Paul,

I had to balance the feathering plate on mine. Here's a link to a post with some more information on this. I also have a picture in this post that should help. I don't know if this is a contributing factor to the vibration in your Corona, but it might be something worth looking into. You'll be able to test this out by removing the main blades and spinning it up with just the stabilizer. Mine had tremendous vibration with the blades removed. After I added the weight to the one side it smoothed out perfectly. Just something to consider.


http://www.rcgroups.com/forums/showthread.php?t=206441

RE: HELP!! Vibration from HELL!!!!
 

Thanks for all the help guys. I think I found what my Vibration was caused by. It was something so simple I feel stupid but I figure I'd let everyone know so if it happens to them they can consider that first. What it ended up being was my main rotor shaft was positioned too low on the cruch such that a short portion of the shaft was sticking out under the main drive gear. Anyway, because the shaft woas too low the follower arm on the head was well NOT LEVEL (at least not horizontal). The subrotor and follower arm were both parrallel but they were not horizontal. This caused massive vibraton of the rotating assembly. After I repositioned the main rotor shaft to the proper location and the follower arm and subrotor were both facing horizontallu the vibration basically dissapeared. I havent had a chance to fly it yet bacause my batteries were discharged but when spinning the rotor up to speed the heli felt pretty solid (not like chattering teeth). Anyway thats the update to my Vibration Woes. We'll see what happens next...

Cheers,

Paul

RE: HELP!! Vibration from HELL!!!!
 

Ooops I spoke a little too soon. Although its better now, the vibration problem is still active. I will still fight it untill I fix the damn thing, I hate the vibes, its just not funt to fly that way.

Paul

RE: HELP!! Vibration from HELL!!!!
 

How about posting some closeup photos of parts of the heli. Sometimes we can see things that you are overlooking.
Dick

RE: HELP!! Vibration from HELL!!!!
 

Thats a great suggestion, I will post some pictures of it if I cant figure out the vibes, however at the moment I cant even get it off the ground as per ATOMIC FORCE motor sucks thread. So I gotta work that out first.

great suggestion though,

Paul

RE: HELP!! Vibration from HELL!!!!
 

What batteries are you using and how many cells?

RE: HELP!! Vibration from HELL!!!!
 

I have 3 packs total. 2 packs are 7 cell Sanyo 2400 Nicd and one (brand new) is a 7 cell Sanyo 3300mah NiMh.

RE: HELP!! Vibration from HELL!!!!
 

Here is another update. After I got the new motor in the heil I hovered it for 3 batteries worth. The vibration is till there. Not too too bad bust still there. I find that it starts to vibrate more when throttle is appled as the RPM's settle down the vibration get minor as a suddent throttle is applied again the Heli vibrates ( goes up like stink with this new Hacker). Did anyone else experience these vibrations at throttle up? If so what was the problem/ fix?

RE: HELP!! Vibration from HELL!!!!
 

Some vibration at start up is normal. This is due to the blades being slightly out of alignment as they begin to spin up to speed. Once the rotor head gets up to speed, the blades line up and it smooths out.

RE: HELP!! Vibration from HELL!!!!
 

As Nitrocrushr say's there is alittle wobble on start up. Did you balance your blades and subrotor~? Are the blades tracking correctly~? I found that taking the time to do all these correctly really smooths out the heli. Also how tight or loose your main blades contributes to some wobble. Good luck.

RE: HELP!! Vibration from HELL!!!!
 

Thanks for the tips. I know that at startup before the blades set themselves up properly some wobble is normal. This is happening while in flight (slight vibration throttle up more vibration, throttle settled less vibration...etc...) I will pickup some new main blades today and see if that helps. Its possible that the main blades got warped or something.

RE: HELP!! Vibration from HELL!!!!
 

Make sure you balance the blades individually. Both should weigh the same overall and have the same c of g

RE: HELP!! Vibration from HELL!!!!
 

Have you gotten rid of the vibration~? I have to believe it's balancing or tracking. I just finished building a second corona, and spun it up today. I balanced the blades and sub rotor and got lucky with the tracking but it was solid as a rock. Good luck.

RE: HELP!! Vibration from HELL!!!!
 

I've occasionally noted a violent low RPM vibration with my C40-12T Corona 120. After trying to rebalance everything the intermittant vibration continued. I have ultimately decided the problem is an intermittant glitch. I was able to slowly spool up until I saw the glitch and remain at that RPM setting. I could see what appeared to be a throttle glitch, which would cause some funky movement. It stopped as mysteriously as it started with no help from me.

RE: HELP!! Vibration from HELL!!!!
 

Talontsi96,

You may also try to snug up the bolts in your blade grips a little bit. You may have your blades too loose? Just a thought. I had to tighten mine a little bit in the beginning to help smooth things out.