"Paul Mennen" wrote in message
m...
I'll tell you why. The needle only shows a real turn of the nose.
The turn coordinator will bank on you if you rock the wings and the
nose stays pointed straight ahead. So, the turn coordinator gives you
fales information. If you hit a bump and your left wing lifts
momentarily, the turn coordinator will bank right on you when you
aren't turning at all. Hell, in turbulence the son of a bitch is all
over the place and is unusable. The needle works on a gyro that ONLY
makes the needle move if your nose is changing heading just like the
DG.

You can see the problem. The turn coordinator gives you too much
information but it gives the same indication if you bank or if you
stomp a peddle. That's no good. You don't know what really is
happening...it could be either.

Badwater, "you can stuff them damn turn coordinators" Bill

I think you are wrong. The turn coordinator doesn't give you bad
information, just different information.

Consider for a moment what your best response should be if during
straight and level flight you suddenly find yourself in a 30 degree
right bank because of turbulence or any other reason for that matter.
I think you would agree that you should apply left aileron (as well as
left rudder to remain as coordinated as possible) until any turning
and/or banking indications are removed and you are on your proper heading.
This is not that much different from your response if you suddenly find
yourself in a right turn.

Consider also the situation where you are flying partial panel
(i.e. your AI is not working). In response to the 30 degree bank
above, your response with a turn indicator will be nothing since
you won't even know that anything is wrong. Eventually the 30 degree
bank will cause turn and only then will you be able to correct for
it. Assuming you don't over-react to the turn coordinator's indication
you should be able to fly smoother than when using the turn needle
because you can respond sooner. In fact the turn coordinator was invented
because the engineers noticed that their autopilots (connected only to
the rate gyro) flew smoother when the gyro axis was tilted slightly
(and thus causing it to respond somewhat to roll rate in addition to yaw).

While it's true that some pilots fly better with one type of turn
indicator
or the other, the difference usually depends on which instrument the
pilot started with or has become most accustomed to. And many pilots
fly just as well using either turn instrument even in turbulence. It often
helps to understand exactly what the needles indicate for the two
different
instruments (although surprisingly even that is not always needed).

~Paul

I have always though of a turn coordinator as a magnificent solution..... to
a non-existent problem.

The purpose of a needle is not only to keep the aircraft upright, it's to
facilitate accurate timed turns to an exact heading. If turbulence bumps
the aircraft to a 30 degree bank but the aircraft does not turn, the ball
will instantly show this by moving toward the low wing. Since the ball does
not over-react, the pilot won't either.

The thing I like most about a needle is that if held exactly on the standard
rate turn "doghouse" timed turns are very accurate - the kind of accuracy
that makes partial panel approaches practical. I've never seen anybody get
that kind of accuracy out of a turn coordinator.

Bill Daniels