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  #13  
Old February 24th 07, 01:13 PM posted to rec.aviation.rotorcraft
B4RT
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Posts: 28
Default a VERY close call/ armchair pilots


"JohnO" wrote in message
s.com...

My armchair analysis is that the helicopter appeared to have a forward CG


Why would that be?

I dont know, maybe there were two fattys on board with the pilot. I've flown
an Enstrom and don't recall it being nose heavy, but each time the ship
pitched forward I thought I noticed it get light on the aft section of the
skids.

and the deck was pitching as much as 15 degrees and rolling about 7 or 8.
I
don't think the pilot really ever "wanted" to take off. It looked to me
like
the deck pitched forward a whole lot and he thought the helicopter would
nose over if he didn't take off. The deck angle was pitched very far


I don't think the problem was the angle of the deck - more that it's
acceleration down cancelled some gravity - a little POSITIVE
collective could have been enough to lift off. Seems like he had a lot
of forward cyclic as well though.


Nah... I don't think so. Boats dont go up and down in seas like that with
negative G's that significant. Enstrom pilots don't tend to spend a lot of
time getting light on the skids either because of the damn oleo struts and
ground resonance tendancy of that machine. That guy flying was no amateur,
he was locked and loaded when he chopped the throttle and did that auto.

There's several HUGE differences in the flight dynamics of RC heli's and
real ones. RC's tend to have very low CG's, this makes them more stable.
RC's have an assload more collective juice than the big things, you don't
come off the helipad in a real one without really intending to do it. The
static and dynamic relative rotor mass of a an RC is very small, you can
move the cyclic much more quickly in an RC and have it take effect without
lag. The big spinny gyrosope thingy on top doesnt wan't to change that
quickly on a big helicopter. These differences can make it hard to
extrapolate the operation of a big one from experiences with a small one.
Just imagine trying to drive a semi truck in the same manner you'd drive a
Porche.

Bart