On Sat, 5 Sep 1998, Bob Cousins wrote:

> Having done both a jump and electronics I don't think I'll be relying on
> a PIC, even if I programmed it ;-) The altimeter sky-divers use is
> calibrated against the plane's altimeter on each jump. Whatever it is
> has to be near-perfect, the chutes I used as a learner have *never*
> failed to open. Not once. Ever. We still carry a backup, and learn how
> to use it.

I guess 100 years of people jumping with various types of bedsheets and
strings has selected out those who choose the wrong type of bedsheets and
strings ;)

> The rockets you want to know the altitude of tend to be the bigger ones
> anyway.  I've often thought about getting telemetry, but the small size
> makes it a tough challenge. The real question I usually have though is
> not how high, but where the HELL is it? My brother launched a 3 stager

Eh. This one was solved presto a long time ago. A 432MHz ham transmitter
was built into the rocket or glider, powered by a watch battery (1
transistor + Al.  tuned cavity). It was built w/o PCB, 'in air'. The Tx
was activated by pulling a small paper flap from between the battery and
its clip before launch.

When lost, a 432 MHz fox hunting receiver and a car (open trailer) were
used for recovery. The Tx worked for more than 4 hours after turned on.

Peter

PS: This was not really for model rockets, but free-flight hang gliders in
high thermal environment + mountains + woods.