Grob 103 question

Darryl Ramm wrote:
Lets make it a concise short thread then. You got me - I'm not sure
how this would hurt a vane style (winter) vario or even a Sage vario
since all ports of the triple probe mechanism will be at the same
pressure and may all be increasing or decreasing in pressure (but at
the same pressure) due to temperature changes or altitude (towing
glider in the trailer). So what exactly causes the failure?

The relative static and pitot pressures are irrelevant, as only the TE
port is connected to a pneumatic vario, with the capacity on the other
side. Best theory I've heard (from the current owner of Sage ;^) is
that the capacity contains relatively warm air when one puts the glider
away in the early evening, which then cools at night lowering the
pressure (and tightening up the tape seal). Removing the tape in the
morning can cause a sudden influx of high pressure air, which results in
a high enough "sink" rate to bend/break delicate parts inside the vario...

Marc

On May 23, 10:29*pm, Marc Ramsey wrote:
Darryl Ramm wrote:
Lets make it a concise short thread then. You got me - I'm not sure
how this would hurt a vane style (winter) vario or even a Sage vario
since all ports of the triple probe mechanism will be at the same
pressure and may all be increasing or decreasing in pressure (but at
the same pressure) due to temperature changes or altitude (towing
glider in the trailer). So what exactly causes the failure?

The relative static and pitot pressures are irrelevant, as only the TE
port is connected to a pneumatic vario, with the capacity on the other
side. *Best theory I've heard (from the current owner of Sage ;^) is
that the capacity contains relatively warm air when one puts the glider
away in the early evening, which then cools at night lowering the
pressure (and tightening up the tape seal). *Removing the tape in the
morning can cause a sudden influx of high pressure air, which results in
a high enough "sink" rate to bend/break delicate parts inside the vario...

Marc

Oh doh, sounds good to me. I guess I'm lucky and/or just have the
elcheapo type mechanical varios. So good point.

Darryl