On Saturday, December 16, 2017 at 4:55:21 AM UTC-5, krasw wrote:
On Friday, 15 December 2017 19:00:02 UTC+2, Tango Eight wrote:
On Friday, December 15, 2017 at 10:12:52 AM UTC-5, krasw wrote:
I have yet to fly a glider which has electrical and mechanical variometer that display identical signal all the time. Until then i feel that both mechanical and electrical variometers give more information about the airmass than single one.

Mechanical plays hell with modern (pressure transducer type) electric on same TE circuit. In that event, the mechanical may well be giving the better information.

Results vary depending upon pneumatic impedance of your TE probe and other things...

best,
Evan Ludeman / T8

I had two TE probes in my previous glider, and made a some experiments how much mechanical variometer (Bohli and 0,35l bottle) affect electrical variometer. I flew both variometers with same TE tube or totally isolated TE systems. I could very easily tell different between two different TE probes, but could not see any meaningful difference in electrical vario behaviour if mechanical variometer was connected or not. After flying excellent electrically compensated system last summer I'm thinking that might be way to go in future.

Good for you for testing and paying attention. On my system (I have a 1980s vintage venturi style triple probe, the venturi being at the end of a very restrictive small tube) the capacity / flow of a std Winter vario turns any modern electronic vario into something useless. So my options are either use electronic compensation for the electronic and leave the TE probe for a mechanical, or (current setup) use a B400 as backup (with 4xAA).

"Electronic" compensation can work better than a TE probe. You can't ever get quite to 100% TE compensation with a probe but you can get anything you want with (probe sourced) pitot + static and a good vario. Compensation becomes more critical as TAS and wingspan go up. What works cruising at 80 kts & 6000' won't necessarily cope with 130 (true) and 16,000.

I've been using probe P & S with electronic comp in CNv for a couple of seasons. CNv has the interesting property that one can switch from TE probe to electronic, as well as trim the electronic compensation in flight. Works for me.

Evan Ludeman / T8