Thread: Discussion New: Multiplex Acro Master
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Old Dec 09, 2012, 11:49 PM
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Arcee Moron
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The Netherlands
Joined Jun 2012
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Originally Posted by Watdazit View Post
By all means reinforcing the nose is a good idea but from my observations the problem of the vibrations stems from the fixing of the motor mount. The motor mount only has two bolts holding it in place and one needs to stop the mount vibrating on the axis of those two fixings. The four bolts which adjust the thrust angle are really the only thing stopping the vibration and unless they are hard down on the plastic face of the motor mount supports which are glued to either side of the fuselage the mount can twist on the two fixing bolts axis and vibrate. I found that I could not set the four bolts used to set the thrust angle of the motor in place on the motor mount and then fix the motor mount. You have no guarantee the bolts are contacting the face of the supports. After a while the bolts which adjust the thrust angle wear into the face of the plastic side mounts and the vibrations come back. Not only this but the motor mount plate needs to distort if the four bolts are to contact with the side supports. I find it hard to see how this can happen. Are well keep on keeping on. I am sure someone will have other ideas but I am about to build another AM....I know glutton for punishment.... and I intend to fit a ply firewall further back in the fuselage so that the motor is rear mounted as one would do on a "normal" firewall.
I'll keep a ply firewall in mind..

I just finished a FunCup with the normal (Alu) motor mount and see how that goes. I agree it's a problametic way of mounting with the 4 settings-scews. I do think it's better for airflow compared to a frewall behind the motor.

Maybe this is a idea and simple solution: just try to add some glue that stays soft (like silicone or something better) between the 2 plastic mounts and the Alu plate / setting screws. This could stop the vibration.

This should be done after the first flights to check if the motor ofset is ok. And you should be able to get if off if needed, so it has to be a glue that stay's a bit soft.

Maybe adding some good quality rubber washers between it could do the trick as well.
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