On Wed, 22 Apr 2015 06:21:14 -0700, krasw wrote:

Yes it will indicate rate of turn even if switched on during
thermalling. There is always horizontal acceleration during turning, and
gyro indicates only this as rate of turn. However being used to
temperamental 50-something years old T&B's I might wan't to check gyro
action well before entering cu-nim (got to admit that I've flown into
smaller clouds switching gyro on "on the fly" just before entering
cloud). I think it takes 15-30 secs to achieve stable gyro rotation, or
little bit less with LiFePo4 battery as these old things seems to like
little extra voltage compared to lead acid batteries.

Thanks for that confirmation.

My T&B was already modified for glider use when I bought it. This meant
that its rate marks indicate a 30 second turn (nice for thermalling) and,
as it is a 28v instrument, it came with a solid state DC-DC converter so
it will run off a 12v battery. It comes up surprisingly fast: I haven't
timed it but would estimate 10-15 secs to come up to constant speed.

When first installed, it kicked up a nasty row on the radio that ferrite
cores didn't fix. What did work was installing a 500 uF electrolytic
capacitor across the 12v input to the DC converter. This is a special
capacitor designed to prevent electric motor noise from affecting other
kit on the same power rail. IIRC it is rated at 35v and 1.5 amps.


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martin@ | Martin Gregorie
gregorie. | Essex, UK
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