Jim
Thanks, I’ll look it up. There’s no point in wasting all your knowledge and
experience, surely?
I didn’t know the name, “variometer”, but that device sounds like a VSI’s
function, effectively. It compares, mechanically, the ambient pressure now and
that some seconds ago; it’s a lag instrument. I teach my students not to use
it when trying to assess whether or not they are flying level. The altimeter
(or even air speed) gives a more immediate indication of climb or descent.
I use the VSI only when established on an instrument approach.
Chris
> On 31 May 2015, at 14:53, Jim Nichols <jhnichols@xxxxxxxxxxxxx> wrote:
>
> You can learn about the Winter Variometer via a Google Search. They are made
> in Germany, in several forms. If I understand correctly, one side of the
> internal aneroid is vented to static pressure directly and the other is
> vented through a bottle of a specified size. This means that one side is
> damped, while the other reacts quickly, providing a needle indication of the
> change in pressure.
>
> I used the same principle to locate the shock wave position in the diffuser
> of a large supersonic wind tunnel. We designed and installed a small "tank"
> that contained a sensitive pressure transducer, with one side of the
> transducer connected directly to a static orifice in the diffuser wall, and
> the other side vented to the tank, which was itself vented to a diffuser wall
> orifice. We placed a row of these devices down one side of the diffuser, and
> connected them to a display that reacted to the pressure difference measured
> by each device. Once flow was established, the signals ahead of the shock
> were steady, while those downstream were very active. We could actually
> observe the shock movement during the process of establishing supersonic flow
> in the test section.
>
> Too much said about another life...........................
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