Gear News

XC Tracer time lag-free vario

10 March, 2015

Swiss engineer Koni Schafroth has been developing the XC Tracer, a small lightweight variometer with real-time response, and has set up an Indiegogo campaign to crowdfund its production.

The tiny unit weighs just 55g and is a variometer and data-logger, which connects via Bluetooth to an iOS or Android tablet or smartphone.

Koni, who currently works for GIN, has been flying paragliders for 25 years and designed the XC Tracer primarily to eliminate the up-to-two-second time lag that is usually experienced with varios. With the XC Tracer, he says, what you hear perfectly matches what you feel, so it makes thermalling that much easier.

He has eliminated the time lag by the clever use of various sensors and GPS together. The GPS also outputs real-time speed and direction.

An attitude and heading reference system AHRS consist of microelectromechanical systems (MEMS) gyroscopes, accelerometers and magnetometers on all three axes. Using all the information from these sensors it is possible to calculate the orientation of the device in space, and therefore calculate the gravity compensated vertical acceleration. A Kalman filter then estimates the altitude and climb rate, using the vertical acceleration from the AHRS and the pressure from the pressure sensor.

The flight path is recorded on a micro SD card, currently as a Google Earth KML file, but he says eventually this will be replaced by an IGC file.

XC Tracer is Arduino compatible, and Koni says that once the campaign has been successfully funded, the code will be made open source so pilots can adapt it to their own needs.

Koni has set up an Indiegogo crowdfunding campaign, and is asking pilots to pre-order units (at €250 per unit, plus €10 postage) in order to put the vario into production.

It is planned to make XC Tracer compatible with the following apps:

iOS