Post by thread:(OT) Altitude or lack of it

Peter L. Peres wrote: >> 2. For free-fall parachuting - you just passed 3,000' (2,000', whatever) >> going too fast - BEEP! pull now! > >Same answer as above, imho, but I was under the impression that free >jumping has a limit on the speed at which you can pull with certain >umbrellas. So this is better answered by a speedometer (heated thermistor >probably). The height problem is solved by a VERY special barometric >device that is a SAFETY device and is mounted on the harness proper. 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. >> 3. I have a friend into model rockets - how high do they get? > >Almost everything that you can build @ home, including SMT, is too heavy >to ride on all but the heaviest model rockets. 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 with D engine booster in less than ideal conditions, and well, we found the second stage over half a mile away, and the third stage could be still up there. -- Bob Cousins, Software Engineer. Home page at http://www.lintilla.demon.co.uk/

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.

Peter L. Peres wrote: > 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. We did a tiny TX for use inside the darts the rangers use to tranquilise the animals before transport. Those darts are expensive and hard to find if you miss. This was also built w/o a PCB and was a few millimetres square. I later hooked up a PIC to try some data TX, but the modulation didn't work all that well. -- Friendly Regards Tjaart van der Walt spam_OUTtjaartTakeThisOuTwasp.co.za |--------------------------------------------------| | WASP International | |R&D Engineer : GSM peripheral services development| |--------------------------------------------------| |SMS .....tjaartKILLspam@spam@sms.wasp.co.za (160 chars max)| | http://www.wasp.co.za/~tjaart/index.html | |Voice: +27-(0)11-622-8686 Fax: +27-(0)11-622-8973| | WGS-84 : 26¡10.52'S 28¡06.19'E | |--------------------------------------------------|