Hi Jim and newsgroup,
I concur with your approach.
My 'classic' spinner has been a constant irritation over the years. I've
never tried to have it dynamically
balanced, due cost.
It is now within acceptable limits throughout the entire rev. range. (though
there are rev. ranges where it
can be detected)
I achieved this by following the approach that you have described.
Basically, there are three potential
sites for washers, and with each flight I repositioned them. When I achieved
a result with lower vibration,
I varied the weight of the load. (NB. take care the screw threads are long
enough as the prop is vulnerable
in this area).
The other thing to bear in mind is that not all classic spinners are the
same. One of mine was too out
of balance to correct. This can be because it is mis-shapen, or because of
variable weight distribution
as a result of the manufacturing process.
My cone was carefully rubbed down and balanced as much as possible before
attempting final adjustment
on the aircraft.
I often wonder if the result would have been better, if I had spent the
money and had it done professionally.
alan
----- Original Message -----
From: Jim Naylor <jnaylor@avnet.co.uk>
Subject: Re: Europa_Mail:Prop balancing
>
> I balanced both my fixed pitch and variable pitch props by trial and
error.
> I just added a washer to one of the screws that hold the spinner on, and
> then ran the engine up through the range. You can feel if the vibration is
> better or worse, and by trying the washer in different locations determine
> the best position.
> Once the best position is found you can then experiment with the
> size/quantity of washers to obtain the best results.
> I managed to get mine near perfect quite easy, but I still had a small
> vibration in the 2 - 3000 rpm band, so I decided to have it dynamically
> balanced thinking that would cure it. After spending 120 plus half a day
I
> came away with a couple of washers fitted in exactly the same place
weighing
> almost the same as my originals and no significant difference.
>
> Apparently the prop can only be balanced perfectly at one rpm setting,
which
> would sensibly be the cruise and I had found this by my trial and error
> method. The rest of the range is a compromise, but is usually within
> acceptable limits. Even the slight vibration I get between 2 - 3000 rpm is
> acceptable as it is within a band that is little used.
>
> So its worth having a go at it yourself, it only costs a bit of fuel.
>
> Jim
>
>
> > Very interested to hear of any budget solution to prop balancing
> > Balancing a in-flight variable is
> > usually more difficult as its difficult to mount them on a balancer with
> > sufficient accuracy.
> > 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.
>
>
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