Vibration!!

[mctrev]

Hi Guys,
Need your advice please. Have just finished a model with a Roto 25 petrol engine installed. When it's running the whole plane is shaking and the control surfaces are moving badly.

It's my first petrol engine plane and I am worried about flying it bacause of this,

Is this normal?

Any help/advice gratefully received.

Regards

Trevor

[gapple12]

Its possible your to rich on low end. Once engine gets tuned correctly, SOME vibration will go away. Single cylinder engines usually will shake a little. Is this only when at idle?

Drew

[Mithrandir]

Vibration is one of the reasons we use larger capacity batteries and higher quality servos.

Is this a wooden plane or composite... chances are you can hear a "Drumming" sound as well from the covering...

Answer: Some vibration is unavoidable.. hard to say if what you are experiancing is "Too Much".

[mctrev]

Hi Drew,
I guess it could be rich at the low end. Didn't touch it as I am new to petrol's and don't want to mess it up completely.

But it does not seem to go away when throttled up, Using a Menz 18 x 8 prop which I have now balanced ( it was out a bit)

Thanks for your reply

Regards

Trevor

[mctrev]

Mithrandir,
It is a traditional wooden construction built from a kit.

I understand your comment re the servos, but forgive me , not sure what you mean re the larger capcity batteries.

Sorry, but learning all the time!!

Regards

Trevor

[Tired Old Man]

Idle too low? Propeller well balanced? Loose engine mount bolts? Loose firewall? Running the engine without the wings being attached to the fuselage?

All of those either provide the appearance of excess vibration or generate excessive vibration.

[Mithrandir]

	Quote: Originally Posted by mctrev
	.......... , not sure what you mean re the larger capcity batteries............ Trevor

On my 150CC SX, I have two 4400 mah batteries... a lot of capacity... the servos are drawing more then "Idle Current" as long as the engine is running because they are working against the constant vibration... prolly 5 to 10 times the idle current.

[mctrev]

All,
Thanks for your responses and plenty for me to go back and check.
"Tired old man"...Have checked all that you mentioned but.......I was doing the test run with no wings on the fuselage. Didn't realise that would have an effect. You learn something everyday!!!

Will have another go with the wings on.

Thanks Again

Trevor

[mctrev]

All,
Update on the vibration problem I was experiencing. Installed a freshly balanced prop, and put the wings on during the test.

A completely different model, vibration now at a minimum. Though I think it is still very rich as after the run there was a lot of black stuff on the fuselage/wings. Will tweak it on the next run.

Thanks again to all for your comments/help, it is appreciated.



Regards

Trevor