sport rocket staging timer

That is unnecessarily complicated and RS has dropped their logic line. How come you can't use the g-switch alone to trigger the circuit and skip the timing from liftoff? The amateurs can't figure out how to do it? And why do you need a delay from 1st stage burnout to 2nd stage ignite, why can't you just use the g-switch dropout to trigger the 2nd stage igniter immediately?

Picas are overkill for this simple app.

You don't want an SCR for a few reasons such as too much terminal voltage drop in a low voltage app and they capture transients, something you want to avoid. An ideal switch would be something like the FDC637BNC N_channel MOSFET in miniature package, low voltage threshold, very small resistance, cheap and in stock at Mouser:

*FDC637BNZ*&N=1323038&Ntx=mode%2bmatchall&Ns=P_SField&OriginalKeyword=FDC637BNZ&Ntk=Mouser_Wildcards

Pica Definition Pica is the persistent craving and compulsive eating of nonfood substances. The Diagnostic and Statistical Manual of Mental Disorders, fourth edition, classifies it as a feeding and eating disorder of childhood.

Such as a "nose pica" - common among the JTFC crowd...

Fred Bloggs wrote in news: snipped-for-privacy@nospam.com:

Mignt not want to ignite the second stage at )g. This might not be moment of burnout as solid fuel engines taper thrust and not "turn off". Might want to coast a bit before staging - these are very powerful engines. Amateures *did*/do figure out how to do it (obviously).

Smaug Ichorfang wrote in news:Xns9A92B01EBAEF4goblinbiter@207.115.17.102:

the APCP thrust curve is either a huge spike for about a second max,with a

duration(slot core),or a medium ramp up to max and then a ramp down.(center core)

Some 2nd state initiator circuits use an accelerometer to determine the coast period. Mainly HP rockets,Level 1 and up.

you want a firing circuit that has some fault protection if the rocket is disturbed or has to be removed from the launcher,so the 2nd stage doesn't fire unexpectedly on you,a safety hazard. you need a disable switch where you can insert a flagged safety pin to inert the system.

some clubs have a range safety officer that inspects the rockets before allowing them on a launch pad,and will refuse an unsafe rocket.

--
Jim Yanik
jyanik
at
kua.net

Okay- I thought it might be something like that, some kind of sputtering near the end. Bit the timing from liftoff is still unnecessary.

So these rockets reach some kind of terminal velocity during boost, then how come you can't use a negative g-switch to activate a delay + ignite for the second stage?