Sending TAS to the ground for winch operation
Sébastien Chauvin
Our club operates a winch, and while we currently manage fine with radio communication to request speed adjustments from the driver, we’ve been looking at ways to improve safety and precision. To do that, we have considered buying a remote TAS indicator : the WLA-DR-KPH / WLA-T from Skylaunch ( http://www.skylaunch.de/components.html ). This system shows the airspeed of the glider to the winch driver.
Unfortunately, they don’t seem to be able to produce them anymore (supply chain problem).
Most of our club gliders already have XCVario and I am considering putting together a sender / receiver pair with two SoftRF boards:
The emitter (in the glider) will be a SoftRF board with its own antenna. It will emit towards the ground and aim to have a 1km range. The board will get the TAS, static pressure (and possibly accelerometer, coordinates) from the NMEA output of the XCVario. It will then send all of the data with a custom radio protocol (based on OGNTP) to the receiver. Once we detect the end of the winch launch, we can turn off the emission to reduce radio interference.
The receiver (in the winch) will receive the radio message and show the glider TAS with minimum latency to the winch driver.
Some nice to haves:
Modify the local OGN ground station to receive this new protocol as well. So that we can store and later display some interesting stats on each winch launch with some indicators (rotation speed, pitch and slope of the aircraft)
Have a bigger display in the winch to show the apparent wind and drift of the last launch to the winch driver so that she can adjust the piloting and pre-warn the pilot.
The emitter could act as a backup FLARM using a toggle (we have had a fair share of FLARM malfunctions)
About me:
I am a software engineer, I have toyed with ESP32 and C dev back in the days. I also use a couple of SoftRF boards as paragliding standalone beacons. I volunteer in the club for other tasks and might find some time this winter to work on this. My main goal is simply to get this working locally. I’ll be happy to share all code and findings as the project evolves.
What needs to be done:
In terms of hardware, there is no need for anything new : XCVario has all the required sensors. The appropriate SoftRF board with NMEA input already exists. The connection could also be wireless but I believe I’d like to set this up permanently with a wired connection and leave the XCVario BT free for other usages.
In terms of software, the complicated part is already done and available (thanks!). We have a clear definition of the NMEA protocol on XCVario side, and a very good base code for SoftRF. What’s left is to write this new protocol and test the setup with the gliders.
My questions:
Does anyone know of a similar project, or another commercial product ?
Any suggestion for a simple SoftRF board powered with 12v, connected to XCVario
Any advice or feedback ? (from those who took the time to read that far)
And many thanks to all the contributors for making such great open software available,
Sebastien
XCVario : https://github.com/iltis42/XCVario/blob/master/main/Protocols.cpp
XCVario to SoftRF : https://github.com/iltis42/XCVario/discussions/178
Send TAS to NMEA in cambridge (or other format) but not in XCVario
TODO: Test NMEA
Radio Protocols:
https://github.com/moshe-braner/SoftRF/tree/master/software/firmware/source/SoftRF/src/protocol/radio
-> single speed in protocols : only GPS speed
Steps :
Connect board to NMEA output of xcvario, read Serial output
Extract TAS speed from vario, show on screen
Create new protocol in SoftRF for Winchlaunch
Encode + decode protocol in SoftRF, Add to display
