Lift. For a sailplane pilot it means the difference between a nice relaxing flight, or searching for an open area to land. Finding lift isn’t always easy though. This is especially true when the sailplane is hundreds of meters above a pilot whose feet are planted firmly on the ground. That’s why [Tharkun] created PropVario. PropVario is a combination variometer and altimeter for Radio Controlled sailplanes. We’ve seen a few variometers in the past, most often for full-scale sailplane or hang glider pilots. Almost every full-scale plane has a variometer as part of its suite of gauges – usually called a rate of climb or vertical speed indicator.
R/C pilots don’t have the luxury of looking at a gauge while flying though. At altitude even large 2 meter gliders can appear to the naked eye as no more than a dot. It would be somewhat embarrassing to lose sight of your glider because you were checking gauges. The solution is actually simple. A varying audio tone indicates the rate of climb of the plane. Higher pitched tones mean the plane is going up. Lower pitched tones mean the plane is descending. This system, coupled with a simple radio transmitter, has been in use by R/C sailplane pilots for years.
[Tharkun] decided to take things to the next level – adding voice output for altitude. He started with a Parallax Propeller and an MS5611 pressure sensor. The pressure sensor was a good choice for determining altitude. Even in today’s world of GPS, barometric pressure is still the gold standard for altitude measurement all the way up to commercial jetliners. A microSD card provides samples for voice output, making it easy to adapt the altimeter portion of the project to any language. Finally, a standard family radio service radio was hacked to create the down link. Using the PropVaro is as easy as listening to the tones and voice readout. Great job [Tharkun]! We hope all your flights are filled with plenty of thermals!