Hi Paul,
Good point about the effect of switching pressure source on the
mechanical vario. Cp on static is zero though not +1 That is the Cp
on the pitot.
I'd use a little solenoid valve, switch electrically and put a second
electronic valve in across a restrictor in the line from the first
switch to the vario. After some seconds of the vario moving slowly as
a result of the restrictor it will reach equilibrium and the second
vale can open. A little electronic timing/logic will sequence the
switches correctly.
OTOH I'd just put an electronic vario with backup power supply in
instead of the Winter . It doesn't care about rate of pressure change.
Regards
Mike
At 05:21 PM 30/07/2013, you wrote:
Without studying the circuit in great detail, I can say that I
installed an "air switch" into GOA so that whilst the engine is
running the vario can be driven from static pressure inside the
cockpit. No compensation but it avoids the chaotic movement of the
needle that arises from having the jet efflux (prop wash) impinging
on the tail mounted TE probe and since one is flying at a constant
speed it is useful in establishing oneself in lift.
The biggy is that one is taking one's signal from CP of +1, and when
one switches back to the normal TE, one is switching to a CP of -1.
A violent thing to do to one's vario, particularly the good ole
Winter. So violent that I have stopped doing it until I can find a
way to damp things down.
I cannot think of a way to damp out the event without putting an
unwanted restriction in the TE line. Ideas?
All the best, Paul
On Tue, Jul 30, 2013 at 10:43 AM, Mike Borgelt
<<mailto:[email protected]>[email protected]>
wrote:
Please treat this an opportunity to learn.
I got the attached diagram from someone in another country who
traced the instrument plumbing installed in his motorglider.
The air switch is so the varios can be run uncompensated when the
motor is extended and running.
Variometer performance is described as "not optimal".
What is wrong?
If anyone cares to comment on this with private replies I'll put
together a de-identified digest of the replies in a couple of days.
Mike
Borgelt Instruments - design & manufacture of quality soaring
instrumentation since 1978
<http://www.borgeltinstruments.com/>www.borgeltinstruments.com
tel: 07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784 : int<tel:%2B61-42835%205784>+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia
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Borgelt Instruments - design & manufacture of quality soaring
instrumentation since 1978
www.borgeltinstruments.com
tel: 07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784 : int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia
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