Słomkowski's technical musings

Playing with software, hardware and touching the sky with a paraglider.

Cheap flight computer combining Kobo Mini and BlueFly Vario module

Using e-book reader Kobo Mini with BlueFly Vario is a really cheap alternative to of-the-shelf paragliding variometers. I have built one with custom 3D-printed case.

Vario- and altimeter is a must if you do free-flying, even when paramotoring it’s nice to have one. These devices are not cheap so I decided to build one by following this tutorial. My device has to meet following requirements:

Apart from combining XCSoar, Kobo Mini and Blue Fly Vario, I designed in FreeCad a custom 3D-printed case for the module so everything sits together nice and tight. The project repository is on GitHub. The case has holes, so Blue Fly’s speaker is clearly audible even when wearing noise-muffling headset. Despite this, I added mini jack socket for the headset. Speaker’s volume is adjustable by Blue Fly’s commands. To the back of the Kobo I glued stripes of velcro tape, so I can easily attach it to the reserve compartment as shown in the photo:

The module’s pressure sensor is secured with a piece of foam as described in the manual. The case has holes for the speaker; they are covered with a piece of dark cloth. There is also a piece of rope attached to the case which prevents the device from flying away in an unlikely scenario of velcro failure.

The case is attached to Kobo by two M3 (3 mm) screws with nuts. First you have to put the case on the Kobo and mark the holes’ positions. The holes are positioned in such way that they don’t collide with electronics but be careful when drilling anyway.