RunRyder - os vibration

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Engines Plugs Mufflers Fuel > os vibration

Bdmcobra
Senior Heliman
Location: Manassas, Virginia

I have a nice .60 MA heli with a 91sz pumped in it. I have a vibration that you can hear more than see in this heli. I have replaced every single shaft in the heli, but still this slight vibration that you can hear (like a droning sound like that of a lawn mower).
I have read on other posts that the os is not the smoothest thing around and that adding head shims could help. Is this true?
The other thing is that I have only one weight on my fan for the govenor. Could this tiny little weight cause a substantial but slight vibration?

fly once a day to keep the insanity away

09-14-2008 02:56 PM

Eagle2bravo
Senior Heliman
Location: Working or flying helis

Don't know much about that engine, but could be the rear bearing or it's not tuned right..ie: too rich

T-rex 600n, Trex 450 se, Gaui 200, Trex 500, Blade cx, . "If ya plant corn, ya get corn."

09-14-2008 03:25 PM

Bdmcobra
Senior Heliman
Location: Manassas, Virginia

Yes about the rich. It was too rich and worse vibs, but now I have it leaned out and running between 200degrees f and 230f. I bought the engine second hand with only break in on the engine (so I heard). I have considered bent crankshaft, but it runs very well, just vibrating bolts loose.

REcently bought a trex and looking at instructions saying to install two magnets has me wondering if one magnet can cause this vib. Then the top of this engine list talking about diff. between ys and os; talks about how rough some os engines run has me wondering if it is something I might need to live with or increase head clearance.

fly once a day to keep the insanity away

09-14-2008 03:56 PM

nivlek
rrProfessor
Location: Norfolk England

What gear ratio are you using? If you are reving the engine at the same speed that a 60 engine runs at , that could well be the problem .

At the end of the day , it gets dark .

09-14-2008 04:17 PM

Eagle2bravo
Senior Heliman
Location: Working or flying helis

Yep, good point.

T-rex 600n, Trex 450 se, Gaui 200, Trex 500, Blade cx, . "If ya plant corn, ya get corn."

09-14-2008 04:58 PM

Bdmcobra
Senior Heliman
Location: Manassas, Virginia

no gearing has changed to 7.92:1

fly once a day to keep the insanity away

09-14-2008 06:24 PM

Jeff polisena
Veteran
Location: westpalmbeachflorida usa

When you get into the 90 class every little thing matters when it comes to balancing and vibrations.

I dont know how to fly just how to not crash !!!!!

09-14-2008 09:44 PM

Dr.Ben
Elite Veteran
Location: Richmond, VA, USA

If the sound you're hearing is a drone pattern of about 1 every 2 seconds or so and is otherwise undetectable in the way the model looks in flight, it's not uncommon on either the ProIIK's or SE's that are built correctly.

Balance the fan, dial it to under 0.001", and set the fan to clutch gap at about 0.020" with no more than 0.001" variance when measured from all four sides.

Ben Minor

09-15-2008 01:42 AM

Bdmcobra
Senior Heliman
Location: Manassas, Virginia

Dr. Ben you have helped me a lot in the past with MA! The heli I have is the #1004 60 pro...fantastic looking and easy to work on machine! Yes in flight, it is graceful to watch until you hover 10 feet away when you can see the tail fin vibrating. Also my 401 gyro is up to 75-85 % gain which is a little high, I think. I am looking at getting a different fan and two magnets, but I am unsure of the .02 clearance you are talking about. Are you talking about the spacer between the clutch and fan? Could you discuss the fan to clutch clearance? I am using a new Gasser clutch and bell for the 90 to work properly with ratio and clutch grip.

fly once a day to keep the insanity away

09-15-2008 03:51 PM

Dr.Ben
Elite Veteran
Location: Richmond, VA, USA

Correct. The 0.020 gap is between the clutch and fan.

With the SZ, it's going to be tough to get the model dead smooth with those mechanics, but before we attribute the vibration to the engine itself, recheck/redial everything, balance the fan, and make sure the engine is square to the clutch base.

Ben

09-15-2008 06:37 PM

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Engines Plugs Mufflers Fuel > os vibration

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