Very interested to hear of any budget solution to prop balancing using
acclerators and lap tops. For standard propellers of three blades or more I
beleive static balancing is perfectly adequate. That does not take account
of any out of balance of the spinner etc.. Balancing a in-flight variable is
usually more difficult as its difficult to mount them on a balancer with
sufficient accuracy. Skydrive in the UK have produced a balancer based on a
Rotax gearbox fitted with low friction bearings. The propeller mounted to
the gearbox tends to rotate until the heavy part is lowest? haven't tried it
myself?
In my opinion 100% carbon reinforced blades produce a harsh installation and
some people may mistake the natural feel or resonance of the prop for out of
balance.
I understand Noel Trigg in the UK uses a lap top and his own software to
balance props. I have not heard anything other than good about the results
he achieves but he is not cheap at around 300 pounds a pop. Anybody with
good/bad results from other balancers in the UK would be useful infromation.
Jerry
lts@avnet.co.uk
http://www.avnet.co.uk/touchdown
----- Original Message -----
From: <BRYNALL@aol.com>
Subject: Re: Europa_Mail:Prop balancing
> Dear Kim,
>
> Many thanks for your interesting response to my prop balancing problem.
>
> Graham Singleton is working with me on this one. He is down with the Flue
as
> I write, but he asks me to send his regards to you and your family.
>
> We both entirely agree with you about the undesirability of OOB, and we
are
> very interested in your apparent insider knowledge.
>
> Is there a reference on the use of accelerometers with a computer,
together
> with an IR. timing source? Could you be more specific about the a suitable
> accelerometer spec?
> Could we use a scope and a radially adjustable timing source to do the
same
> thing? Is there any software available for the computer solution?
>
> Despite careful static balancing we do have some vibration at about 2800
RPM.
> This changes as the prop assembly is repositioned radially around the
> mounting flange. (Thanks Dale Hetrick, you are correct on that one)
> Graham says that balancing is a very common problem. I can understand why.
> Indeed it is noticeable that the characteristic is different going up in
RPM
> to going down. Could it be that the gear box backlash has some role to
play
> in this?
>
> Please forgive me responding to your advice through the group address, but
> perhaps others may be able to help. Remember I am hoping that there is an
> inexpensive solution.
>
> Happy Flying .........Bryan Allsop
>
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