Brian, Au contraire! Please see below =>
> The turn-and-bank instrument is just that... ...it responds to bank
angle,
> while banking.
Negative. The ball indicates slip (or deviation from a
coordinated turn). The needle indicates RATE OF TURN - only
around the YAW axis.
> It is also a rate instrument, in that it indicates turn rate once the
turn
> is established.
It indicates instant deviation from straight ahead in the
YAW axis (and only the YAW axis) because it is a rate
instrument. As soon as there is any deviation, it is
indicated on the needle.
> The turn coordinator is a 'rate' instrument alone. That is, it responds
to
> the airplanes actual rate of turn, and only to rate of turn.
In both instruments, the needle indicates rate. In the Turn
Coordinator both rate of bank AND rate of turn are indicated
by the needle. In other words, as you bank, the needle
deviates - once a constant rate turn is established, the
rate of bank is zero but the rate of turn is indicated.
> For someone who has an AI from which to read bank angle, if he wants to,
the
> unambiguous pure rate information is invaluable.
The reason for preferring a Turn Coordinator is that it
gives a more immediate indication of a turn than a T&B. A
Coordinator shows that you have banked before a turn
begins. This is a short time, but if your vacuum system
gives out, an electric Turn Coordinator is a much better aid
to keeping the plane right-side up than a T&B (just as
stated in another email that it is better for smooth
autopilot operation).
> it would seem that the old 'turn and bank' might be a bit better for
saving
> your bacon, which, if you're in IMC without an AI and a load of IFR
> competance, is pretty well burnt anyhow.
Just the opposite - You want a Turn Coordinator. A standard
practice for us instrument pilots is flying with only the
compass and Turn Coordinator. A T&B is much tougher to use
because you have to wait until you are turning to see an
indication - rather than sensing a change in bank as the
Coordinator does.
David Smoler | __ | San Jose, CA
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Alon A-2 | \____/ | N6359V
s/n A35 () () () based at RHV
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