On Feb 25, 2:13 am, "B4RT" wrote:
"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.

Definitely not true. Ever watch thet tv show 'Deadliest Catch' where
they embed a camera guys on crab boats in the Bering Sea? One of the
things they do to pass the time between getting cold and wet is to
jump up just as the boat plunges into a swell. They float like
astronauts for a moment. I've never done that but have certainly been
on the deck of a boat many times and felt very much unweighted as the
boat plunges into a trough. I assume it would be normal practice for a
vessel to steam into the wind when carrying out aircraft operations
and this gives the fastest drops into the swell.

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.

He sure did that beautifully. But even pros sometimes get sloppy for a
moment on rare occasions. It's not out of the question that he slipped
up, but then his training and experience snapped in to save the day.



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