Multiple varios

You don't need to disable the sink tone - simply fly in lift!

On 12/15/2017 7:38 PM, Darryl Ramm wrote:
And thank God you can disable it :-)

On Friday, December 15, 2017 at 5:10:00 PM UTC-8, Dan Marotta wrote:
The ClearNav XC Vario emits a sink tone.

On 12/15/2017 1:24 PM, john firth wrote:
On Thursday, December 14, 2017 at 5:00:23 PM UTC-5, John Foster wrote:
Why do so many gliders seem to have multiple varios? Is it that critical to have a back-up for this instrument? Do they often fail and leave you in "
the lurch"?
There is only one essential instrument for VFR and it lies between you ears.
a vario is next, with a vent to cockpit static if the TE gets plugged.

BTW, which Elec varios have an audible sink alarm; the old Cambridge audio was useless in sink as airspeed noise over 60-70 kts covered the LF tone.

In 1970, I built an analogue vario-computer with audio, head up speed to fly reader, TE comp etc..and audio rising tone in lift, and broken tone louder and rising in sink. Just what I needed , but the transducers gave trouble.

John F
--
Dan, 5J

--
Dan, 5J

Several manufacturers make excellent electrical backup vario's LXNav V3 has a built in speaker is small and and one can purchase the associated UPS battery pack to give you 8 hours of electronic vario with audio, if the electrical bus fails. Nice little unit. I have not had a mechanical vario in a sailplane since 1999 when I purchased a Borgelt vario that would run on a 9 volt battery as a backup. If it truly is a backup, nice to have the audio.

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

On Friday, December 15, 2017 at 4:17:35 PM UTC-7, wrote:
Many years ago Mario Crosina and I launched in the Central Valley for our first flight of the season. My airspeed failed immediately and Mario's vario died. We developed a new form of team flying on the spot and did a nice x-country.

I had a problem this year with my Cnav audio and discovered it was almost impossible to thermal by looking
Inside after over 30 years of listening to an audio nag. Try turning off your audio some time, hopefully you will find it has become an essential item when flying.

Bruce Patton

I tried getting home once on just the Mechanical Vario, while doable, it was very shortly afterwards I bought the B40 with the battery backup and replaced my Mechanical Vario with it so if it happened again I would have an audio.
I don't recall every having to use the B40 as my primary, but maybe that just means it was such a no-event I don't remember it.

I also had the B40 running of the TE prove and the Cambridge running off the pitot and Static (electronically compensated) they indicated pretty close, but was nice know they were working off 2 completely independent systems.

Brian

I did a flight many years ago in a ASW-20 in the spring. The "normal" checks said everything was fine.
Crossing 200' on tow, nothing added up.
Result was a mouse chewed hole in a TE probe tubing.
It was a 3hr flight, mostly seat of the pants and sound.
No ASI, no vario.......

While I have not had an electrical failure, it's nice to have a mechanical vario.
Yes, I really miss the audio, but for fun flying, butt vario and a mechanical gauge is good enough.
Yes, this is in eastern US, so not major issues with wave or ridge.

BTW, my first audio vario was a Development vario from Cambridge ( yes, Raouf Ismail) from when I crewed for him in Elmira. It was in SGS-1-26 SN 002 for many years. I still have the paperwork for it, we still have it.
Gosh, I have loved an audio vario since then.

And as others have stated, a paper map and mechanical instruments may get you home.......at least....in the eastern US. Not sure about the mountains in the west.

These are popular in the paragliding community. Tiny audio only vario.
Obviously not TE though.

https://skybean.eu/skybean-vario

Would this be a reasonable backup in conjunction with a non-audio
mech vario?

I have three various in my panel. All are electronic and two have their own TE systems and separate bottles. The third is the averager on the flight computer. One of the various is a dedicated netto. The borgelt is battery backed up. If one fails the others are not perfect and will allow the flight to continue.

On Thursday, December 14, 2017 at 4:00:23 PM UTC-6, John Foster wrote:
Why do so many gliders seem to have multiple varios? Is it that critical to have a back-up for this instrument? Do they often fail and leave you in "
the lurch"?

Maybe I'm missing something, but it looks like nobody in this thread has mentioned the advantage - once you have more than one vario - of different scale ranges. I can remember most of our club gliders had two varios: one up to 5m/s and the other one up to 10 or 30 m/s.

Pretty sure Ray Lynskey had a 30kt vario in his glider. Not to know how fast he was going up, but how fast he was coming down in the wave

On Sunday, December 17, 2017 at 12:21:37 PM UTC-7, Tom BravoMike wrote:
On Thursday, December 14, 2017 at 4:00:23 PM UTC-6, John Foster wrote:
Why do so many gliders seem to have multiple varios? Is it that critical to have a back-up for this instrument? Do they often fail and leave you in "
the lurch"?

Maybe I'm missing something, but it looks like nobody in this thread has mentioned the advantage - once you have more than one vario - of different scale ranges. I can remember most of our club gliders had two varios: one up to 5m/s and the other one up to 10 or 30 m/s.

I had set a different range and response time on my Westerboer 1020 than the scale on the Sage but did not find any real advantage and changed the range back.

Mike