Undersling and 2/rev

"Steve R." wrote in message
...
"Stu Fields" wrote in message
...
If an over weight pilot exceeds the recommended seat weight of his
helicopter, will this affect undersling enough to cause an increase in
the 2/rev vibration??? Does increasing G forces cause an increase in
2/rev??
Stu



On the first question, if you're talking about flying the bird outside the
recommended CG range, I'd think it's a possibility, especially the farther
out you go. Taken to extremes, wouldn't flying an under slung system far
enough out of the CG range risk mast bumping during certain maneuvers?

Don't know about the second question. Is the 2/rev vibration really
increasing or are the pilot and passengers just feeling it more because of
the G loading? Either way, I'd think it would "encourage" those involved
to try to improve the situation!

Fly Safe,
Steve R.

What I was thinking of was just a heavy pilot within the c.g range. Since
the coning angle and subsequently the proper undersling depend on the gross
weight. Since an extra heavy pilot would exceed the design maximum gross
weight, the existing coning angle and undersling would not be optimum.
Could we expect an increase in 2/rev and if so why? I have found a case of
a Mosquito pilot who stands closer to the lunch line than he should,
complaining of 2/rev after he had taken pains to track and balance thinking
that the vibration might be 1/rev.
It seems that if the heavy pilot could cause increase 2/rev, you should feel
it also in an accelerated turn. I'm not just talking about pilot
sensations, we can measure the amplitude of the 2/rev vibrations both
vertical and lateral by fooling the electronic balancer with two reflective
tapes on the blade position sensor. I have not done a measurement in an
accelerated maneuver and my ship is down now so I ain't got a vehicle for
the test. I am hoping to stumbel accross some individual that has already
experienced and measured the 2/rev vibration in say a 2G turn and straight
and level...
As an engineer, I have to have a problem to look at or my mind goes numb. I
love helicopters. There is no end of problems to look at. Especially
vibrations.