Vario pneumatics

the M/Nav and even L/Nav and S/Nav were the last of even Cambridges use of
old thermister technology....they also switched to pressure transducers with
all later products
tim

"Andy" wrote in message
...
On Dec 19, 9:03 am, "Tim Mara" wrote:
you will likely get some error in the instruments, most variometers with
capacity flasks are "calibrated leak" or thermister type variometers
(heated
wire/air flow). Having more leaks in the system will have some effect on
the
actual readings but this leak is rather small for most
instruments..actually
pretty amazing that an instrument can read such small airflows and
temperatures to begin with and translate these to instrument indications
when you really think about it! Most sailplane instrument installations do
have small errors (some have large errors!) and the pilots don't even
recognize the errors.....many sailplane variometers are from the start
highly inaccurate..you can't always believe simply because the seller has
a
great looking ad and touts all the fine features that the actual
instrument
is producing the fine accuracy they might claim...pretty easy today with
all
the electronics components for someone to take a collection of easily
available components and toss them in a box and produce something the
appears to be an aircraft instrument! Pilots may tend to see a needle go
up
or down and either slow down and circle or speed up and run away...and the
indications are pretty much telling you that you've encountered a higher
or
lower pressure and hence all works out....sort of ..
But that said, you can live with some small errors that cannot be
completely
corrected.....or use different pneumatic systems to avoid connecting
calibrated leak systems..most newer variometers have adjustments to
compensate for minor errors and electronic TE variometers don't require
connection to TE but may be connected to pitot and static alone and
adjusted
for higher accuracy.
If in fact you have one of the older electric variometers with a capacity
flask and a pneumatic variometer like a Winter or PZL then likely your
eclectic variometer is a very old and likely highly inaccurate instrument
now anyway. It's older for sure, no new electric variometers rely on this
technology anymore and so it may be due or overdue to replacement or at
least testing for it's own leaks and errors and even without the errors
from
connection with another capacity instrument may never give you totally
accurate indications.
tim
Please visit the Wings & Wheels website atwww.wingsandwheels.com

"Colin Roney" wrote in
. ..



Does anyone have a solution to the problem of having two `flask` varios
fitted with one total energy tube.
I understand, although I may be wrong, that having a tee piece split
near
to the panel to provide the two t/e requirements is a `no no`.

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Don't give the electronic flow type varios too bad a rap. In my
opinion the Cambridge MNAV vario was very good. Of course the glide
computer became obsolete when GPS arrived on the scene.

Andy

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