shake/vibrations please help! (video)

[mikebilyk]

im getting a weird shake/vibration at certain head speeds. i dont think its a glitch in the radio and the clutch is pretty much band new(5 flights of mild 3d)i have no clue what this could be:arggg:

please let me know what you guys think it could be. you can really hear it in the vid and also see it a little when it goes nose in for a second. heres the video...

http://youtube.com/watch?v=5GYg681E2KY

[derrill84]

The first thing that I noticed is your motor is way to lean and could be causing an in consistent head speed that is messing up your gyro causing it to twitch.

[archiebald]

The most important thing wrong in that video is the location.

Do you have a grudge against your neighbours?

Get to a proper flying field before someone gets killed.

[JimLerch]

While the safety freaks have their way with you (and they should!) I'd suggest it is either one of the following:

Tail belt drive loose
Forward belt drive pulley lost its teeth
Harmonic of the tail push rod vibrating (strongest suspicion).
As engine RPM changes, the tail push rod will vibrate around its harmonics.
As it vibrates it gets shorter, then longer
The change in push rod length changes tail pitch
Tail pitch moves air frame,
Gyro corrects for it
Oscilation is re-inforced For instance, it is similar to the idea shown in this video (one of the coolest things I've seen, Salt finding the lowest point on a steel table.)

sOMiowrff0Y

[Lota Fun R]

If it were mine, first thing I would think is fuel problem, very lean condition and when it ran for a bit it improved but only slightly.

It could be anything related to fuel.

size of the fuel line
hole in fuel line
hole in fuel line to clunk or broken

What I would do: Replace all fuel lines "all". Use a short piece of fuel tubing over any connections, ie. double it up, short piece at connection to secure the line and prevent leaks. the extra piece is "instead of using a clamp or zip tie". Hope that makes sense.
Check carb to make sure it is on properly.
Go thru tuning set up to make sure it is correct, ie. high and low adjustments.

Check engine temps, I'll bet you'll find it's running hot. It looked like it was pulsating and just about dieing.

I could be way off? But from the vid, that's what I see.

I guess vibration can cause the lean condition too. Hmmm?

[mikebilyk]

i will check out the tr push rod thing, would you suggest a one piece carbon tail pushrod, the type that go from servo to the tr control horn?

the engine is not running lean, there is plenty of smoke and if i hover for a bit and set it back down, the back of the engine is warm to the touch:confused:

[BCass]

If your fule lines are ok then check the head bolts, back plate, carb, glow plug. make sure they are tight. If so, inspect the front bearing, however you will most likely need to pull the motor to do this. after the motor and the glow plug have been removed, hold it up right and squirt some fuel in to the carb. turn the the motor over. If fuel runs out the front then there is an air leak and the bearing may need replacing. Also check the block for hairline cracks. Good luck and keep us posted

[mikebilyk]

If your fule lines are ok then check the head bolts, back plate, carb, glow plug. make sure they are tight. If so, inspect the front bearing, however you will most likely need to pull the motor to do this. after the motor and the glow plug have been removed, hold it up right and squirt some fuel in to the carb. turn the the motor over. If fuel runs out the front then there is an air leak and the bearing may need replacing. Also check the block for hairline cracks. Good luck and keep us posted

will def have to check out the engine:thumbup:

i redid my tailrotor pushrod setup and it still doing it, so i dont think its harmonics or something of that nature.

[Brad Collins]

Your engine is lean. It doesnt have enough fuel to keep a steady rpm.
Brad

[matador_24]

when you figure it out, please, post the answer to know what it was.

[thorpdrvr]

Hi,

Way too lean. It's not putting out hardly any smoke.


Good luck,
Bernie

[LITHIUMSTATIC]

I call it lean. Check your fuel system.

[mikebilyk]

i did the fuel in the carb and it doesnt seem to be leaking.

i disassembled the carb and found that the main gasket, needle gasket and the idle gasket were all very brittle and had some small cracks.

noone has the gaskets local so i have to order them:thumbdown:

[BCass]

Certainly sounds plausible, i hope the new gaskets work out. Dealing with the down time is tough, however it gives us opportunity for preventative maintenance for the rest of the bird :thumbup:. Good luck and keep us posted.

[bkervaski]

It could be gunk in the carb... but definitely leaning out

[matador_24]

Hey Mike, please update to know what happens when you replace the gaskets... can you please give the link of the website where you got the parts? I'll order some to have on hand just in case... thanks

[mikebilyk]

Hey Mike, please update to know what happens when you replace the gaskets... can you please give the link of the website where you got the parts? I'll order some to have on hand just in case... thanks


soon as i get them ill tell you guys if that was the problem.

the site i ordered from was Towerhobby.com

heres the part numbers;
22615000 - main carb gasket
24881824 - O ring (2 pc)
24981837 - O ring (2pc)

i also went ahead and ordered the rear backplate gasket
23414000 - gasket kit

[EatMorePizza]

While the safety freaks have their way with you (and they should!) I'd suggest it is either one of the following:
Tail belt drive loose
Forward belt drive pulley lost its teeth
Harmonic of the tail push rod vibrating (strongest suspicion).
As engine RPM changes, the tail push rod will vibrate around its harmonics.
As it vibrates it gets shorter, then longer
The change in push rod length changes tail pitch
Tail pitch moves air frame,
Gyro corrects for it
Oscilation is re-inforcedFor instance, it is similar to the idea shown in this video (one of the coolest things I've seen, Salt finding the lowest point on a steel table.)

sOMiowrff0Y


Choice 3 was my bet. BTW the salt isn't finding the low spots its matching the frequency sine wave of the tone generator.

Just to be safe pull out the tail pully axle and inspect it. I had this issue in my 400d, and found it to be the tail axle was very very slightly bent and caused a crazy vibration in the tail.

Well I just saw the video again of your heli and I noticed it loss power and dipped when it wagged. Not the tail issue like I expected. These guys are right about the mixture.

Good Luck

[archiebald]

Content of PM sent to me a while back
thanks for not contributing anything to my thread:thumbdown:

unless you have any suggestion or help for my problem please stay out of my thread.

thanks,

-Mike

Err, actually my contribution is to safety. If you are going to fly your helicopter in the street, you are going to kill someone, especially since it is obvious you aren't capable to set it up correctly.

[collegeboye]

Last week I was flying my raptor 30 and had the same issue as you. It seemed to only vibrate at certain rpm's especially when decelerating. Mine actually cut off before I had a chance to land it safely; need more auto practice. But when repairing everything i foind that i did not have the glow plug metal gasket installed. (fix was a new plug with gasket) Im assuming I lost it when trying to clear my flooded engine that day. My engine did have lots of oil on it that day but I thought that an exhaut leak was the culprit. I just tested everything out and it flys like a champ now. May not be your problem but its worth checking out.
Hope you figure it out
:dontknow