Re: sport rocket staging timer

D from BC <myrealaddress@xxxxxxxxx> wrote in
news:d5kf14p9alp1lvlkg9bc0bop7lm7vleqjn@xxxxxxx:

On Tue, 29 Apr 2008 22:19:56 GMT, Rich Grise <rich@xxxxxxxxxxx> wrote:

On Tue, 29 Apr 2008 08:20:12 +0000, Smaug Ichorfang wrote:

Some friends would like to build a down-sized model of a two-stage
sounding rocket. I'm trying to come up with a design for a timer to
ignite the second stage. The timer should be triggered by a "g"
switch which marks first stage ignition, and time out after (an
adjustable) 1.5-2 seconds, just after the first stage burns out.
Commercial designs are available for around $90. I only need to
build ONE of these andd don't have the programmer so a pic or BASIC
STAMP are out. Any ideas or schematics for an analog or simple
digital timer for this application?

When I was a kid, Estes rocket motors were available with an
"after-charge", which is basically a hole at the top of the motor
that shoots hot gas into the nozzle of the second stage right at
burn-out. So, no electronics, batteries, squibs, none of that schtuff
was needed.

called "ejection charge".
On today's AP-composite motors,such hot gasses will not ignite a second
stage,thus you need electronics and better igniters that use more current.
also,hybrid motors using Nitrous oxide as the oxidizer must use electronic-
actuated chute deployment.

"Model rocketry" has come a long way from the simple Estes motors of the
60's.


The idea of a 1.5-2 second timer with batteries and squib and all of
that just seems ludicrous on a rocket where the first stage only lasts
1.5-2 seconds.

Good Luck!
Rich


Long ago I made a 3 stage rocket with those types of motors.
Never found the rocket afterward. :(
There was a note inside..'If found please call......'
Never got a call :(

People now install loud beepers or RDF xmtrs in them to aid in finding a
lost rocket.

And that was the last of my rocketery...
Electronics looked better as a hobby.
Breadboards don't take off and disappear. :P


D from BC
British Columbia
Canada




--
Jim Yanik
jyanik
at
kua.net
.

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