I've thought on this for balancing rotor systems and components for RC
Heli use..
 Not really practical for that use, since a $20 high point does so well.
But, just for
 ideas:
    Use a bearing at one end, captured on 3 sides with the 4th against a
piezo disk.
Max voltage out will tell you where the heavy spot is, and Max VS average
will
tell how far out.  Remember that it's 90 deg behind due to precession, and
you'll
need a shaft encoder with index or an absolute encoder to relate data vs
object.
  Also make sure everything else is balanced, the encoder itself may not be
etc.
Simple on a rotor since there's only one main plane of weight.  Since
you're doing
a turbine I imagine you have one shaft with two fans.  So you'll need a
bearing/piezo
at each end and some trial and error, since adding weight on either fan
will affect both
ends some..  Minimum changes on each end should = balance, and should have
much
more sensitivity than you need..


Bill Blackburn wrote:

> Hi
>
> Has anyone ever seen the PIC used in a application for dynamic
> balancing.  I am interested to find some kind of application that could
> be used to balance the rotating parts of a small turbine jet engine.
> The complete shaft is 160 mm long and the wheels are 66 mm in diameter.
> Thanks in advance.
>
> Regards
> Bill