Altimeter questions

[ben levitt]

Hi gang,

I hope you're all doing well these days.  I have some questions for any of you who fly gliders or have experience with OpenTX and telemetry.  I'm learning to fly Discus Launch Gliders, and am starting off without a UDB on board, to make sure I still remember how to pilot solo.  :)

I'm flying now with the Crossfire radio system, using a TBS Tango 2 transmitter, and had trouble finding an altimeter that worked with that system, so I built my own, so that I could keep track of my launch heights, and try out flying with a vario.  While I was at it, I built some extras, which I'm now interested in selling off, so my project can help more people than just myself.

But since I'm new to flying with altimeters, I wanted to sanity-check my altimeter's performance with people who actually know what they're doing!  Any answers below will help me out!

1. For live altitude data, do you expect to see whole-numbers of meters?  Or tenths also?  (12m vs 12.3m)

2. For vertical speed / vario data, do you expect accuracy of ~0.1m/s?  ~0.2m/s?

3. I know that barometer-based altimeters can drift by non-trivial amounts along with the weather.  But over the course of a few minutes on a gusty day, how much drift in altitude would you find normal?  A few meters?

4. I've only used OpenTX on my current transmitter.  Does telemetry over other long-range systems, or using other radios get picked up as OpenTX sensors?  Through MavLink?  CRSF?  Other protocols?

If you're interested to see what I have now, they are available here:

- The first is just an altimeter, with approximately 1m accuracy for relative altitude, and no variometer/vertical speed data.

  https://octopilot.com/index.php?main_page=product_info&products_id=3
- The 2nd variant uses an even higher precision altimeter, which is getting me approximately 0.1m accuracy for relative altitude, and 0.1-0.2m/s accuracy for vertical speed.

  https://octopilot.com/index.php?main_page=product_info&products_id=4

Thanks for any insights you have!

Ben