Discussions

35cc Engine vibration

Posted by hamadivo on February 23, 2011 at 10:27am

Hi all,

can some one help me to reduice and isolate vibations caused by the the engine (MLD35 engine).

I dont know if the propeller balancing can reduice them!

 

any ideas?

 

Thanks,

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Replies

  • RH1N0 February 27, 2011 at 1:51am

     

    Also check your ignition timing as this can be a source of extra vibration and poor running.

  • Marlan L. Kingsley February 25, 2011 at 12:40pm

    Any single cylinder engine has this problem, one of the best solutions is to find some isolastic (rubber) mounts.

    http://www.centralhobbies.com/engines/mounts/hydmnts.html

    when balancing a single cylinder engine you don't really "balance" them, rather the vibration is distributed evenly vertically and horizontally. 

     

    First check the prop and see if it is way out of balance,drilled off center or cracked. 

     

    Also, when running your engine do you have the wing(s) installed? I have a Great planes Giant Big Stik with a 40cc and the fuselage will vibrate like crazy without the wings.

  • Moderator
    Robert Krogh (hooks) February 25, 2011 at 4:07am

    The new version of the FY3ZT autopilot comes with a new Vibration damper and Alu case. This improved the vibration issue from Gas engines alot. 

     

    Some inspiration pictures

     

    Shock-mount-parts-of-flight-control.jpg

    Flight-control-shock-mount-assembly5.jpgFlight-control-shock-mount-assembly7.jpgFY3ZT autopilot

     

  • brakar February 25, 2011 at 2:15am
    As mentioned earlier in this thread, engines vibrates differently at different rpm's. (And resonance may occor). Finding a good speed for the engine and a prop to match that speed could reduce the problem.
  • Ritchie February 24, 2011 at 5:03am

    I cannot speak for RC engines but as I do build and repair my own car engine I can tell you the problem is universal. To reduce vibrations everything the spins must be balanced to reduce vibration. Reciprocating mass as described in engine tuning manuals is everything that can create a wobble (thanks to it being reciprocating :D) so the more you balance the less vibration you receive.

    Jools Holland famously stated on Top Gear that the only perfect standard engine was a Jaguar V12 as you can place a 6 pence piece (old UK money) and start the engine and let it idle without it falling over.

    Now I can only assume that an RC engine has just one piston making balancing like normal engine problematic. I assume that the largest difference is the prop so get that balanced after that isolation mounts would seem the only option except ripping the motor apart and balancing the little crank (assuming there is room to do so).

  • Ryan February 23, 2011 at 10:16pm

    1. Mount you engine on vibration isolation mounts

    2. Mount all you electronic on isolation mounts

    3. Try to use twin cylinder engine instead of single cylinder one. Twin engine significantly reduce the vibration

    4. Keep the electronic equipments as far away from the engine as possible, hence UAV has engine way in the back and everything else in the front

  • Brad Smith February 23, 2011 at 9:45pm
    you might try a variable pitch prop and a governor to keep the rpms at the best balance between efficiency and vibration ,,,
  • Chris Woodry February 23, 2011 at 5:48pm
    not sure how the small engines like this are done but some fo the larger aircraft that i fly have flywheel weights on them to help counteract the vibrations and smooth things out a bit. might be something worth looking into
  • Ramon Natal February 23, 2011 at 2:18pm
    Ok you wont be able to reduce the vibration too much with this engines, but yes you can on the part you wanna isolate, you could try this Shock Absorving Sorbothane or any ther ani-vibration foam.
  • Ramon Natal February 23, 2011 at 10:43am
    The prop MUST be balanced, otherwise your engine will suffer the effects and also your frame. With this engines, the vibration can not be totally isolated. There are several companies that sell vibration isolating mounts and standoffs , but my suggestion is to isolate the electric components to protect them from the vibration.

    BTW, where are you trying to mount it? what kind of frame? balsa & play? composite? let us know so we can suggest you better ideas ;) I have experience with giant scale planes and also with this engines
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