Thermal Detector?

[RMoore]

A free-flight friend of mine has found a pretty old circuit design for using a thermistor mounted on an 8-foot pole to detect temperature variations to be used for detecting thermals passing over the field. The "user interface" to this thermal detector is a Triplett microammeter (+/- 50 microamps). As far as I can discover, these meters are not available any longer. Besides, it doesn't seem very effective to stand around watching a meter to determine when to launch. It would seem much better to have an audio interface, perhaps like full-scale sailplanes use on their variometers - high pitch beeps for up (rising temp), low pitch beeps for down (lower temps), with pulse rate on the beeps increasing with the absolute value of the temp.

Anyway, I am wondering if anyone has seen a design that works anything like this that might be reproduceable with modern parts? Or anybody who might be up to designing such a thing???

Thanks!

Randy

[vario]

i can tell you that i few years back in the hanggliding mags there was a little thermal snooper it was controled buy temperature and had an audio tone,stuck on your helmet,very small

i have also heard of thermisters being used on each wing tip of full size craft to tell which direction to turn when finding lift


non of these ever catch on and i found them more confusing than help full but they where cheap!100 buck ,i think look in a hanggliding mag [thermal snooper,with a picture of a hound dog]

[John Gallagher]

There are in fact commercially available thermal detectors for RC gliders. At least they were available up to several years ago. The vario unit mounted in the glider and transmitted a signal to a receiver with an earpiece that the pilot carried. It worked on it's own frequency and gave a tone to indicate when the glider flew into or out of lift. They were expensive and I believe outlawed in national competition. They may still be popular in europe.
Hobby Lobby's mother company in Europe probably sells them.

John

[rrowley]

They are still available, a couple of guys at our club have them. They are popular among the cross country soaring folks. I don't own one but I would think that they would help as a training tool. It would allow you to see what your plane does in lift, while you hear that you are in lift in the earphone. Here is the link to one of the companies that sell them.

http://www.picolario-usa.com/

Rod

[Miami Mike]

Originally posted by rrowley
http://www.picolario-usa.com/Here are some other sites that I bookmarked a few months ago while I was researching this:

http://www.riverland.net.au/~awallace/variointro.htm

http://www.soaringissa.org/forum2/forum2/00000176.htm

http://www.sailplanes.com/_messages/00000569.htm

http://www.tek-variometer.de/englisch/