I built a new kind of glider called a DLG. These were invented a few years again. Essential you launch these from the wing tip. The pros can toss them up there as much as 66 meters (216 feet). 50 feet has been my best toss. My son tossed it for me the other day and we actually got it into some lift. I also have a tow hook on this 1.5 meter span glider and so I am also able use an 8 lb hi-start (10 meters of surgical rubber tubing) to launch this 15 oz glider, pretty spectacular. It comes off the line at something over 100 feet and climbs vertically another 50-70 feet. This glider has flaperons which make it easy to spot land.
I got to reading about some of the newer electronics that are available and when I saw an audio variometer I got interested. This is a device on board the aircraft that allow the RC pilot on the ground to know whether the sailplane is climbing or sinking. The sound is supposed to be like the same sound that a full scale sailplane pilot might hear. And this allows the pilot on the ground to center up a thermal (rising air) and climb. This is well outside my comfort zone as I consider electronics black magic.
It turns out that most of the production RC audio variometers are kinda expensive (3-500 bucks) and have way more features than the average pilot needs or wants. Many of them are made in Europe and so they run on frequencies that require a license here in the USA. I was hoping to find a simple inexpensive audio variometer that did not need a license to operate. Unfortunately nobody makes such a device. But that doesn't mean you can't put one together, which I did. Essentially what I did was put a Thermal Scout (audio generator) with a 72 MHz TX and RX. (It is a little more complicated than that.) I also built a special 2 meter glider to haul these electronics around.
Here is the body before the electronic installation. It is built of balsa and fiberglass, and it weighed 8 oz at this point.
This is what it looks like with the electronics installed:
You cans see the receiver in the upper left of the picture with the earphones attached.
This is what it looks like ready to fly:
The wing is a Tower Hobbies Vista with the decals removed.
I have flown it and the vario sounds like it is supposed to.