circuit design help

Hey, I love rocketry! Got my first start with aerodynamics with it. Lots of years ago. Anyway, the first question: What kind of igniter current do you need? There are a couple different kinds, and it matters. Next...Why do you want to delay 5-10 seconds? Sounds a little scary to me. Easy to do, just I'd hate to have a hot rocket on a launch pad when someone comes over and says "gee, what's this???" So safety might be a concern.

While you are looking those things up, here is a link:

I was thinking i could set the box down and a bout 10ish feet and run away almost like a fuse but an electronic version. i'm not sure the voltage but i should be able to play with it cause its on a relay but

Fine.

You missed a step of basic rocket safety here. You need a keyed switch (either before, or as, this switch) so that you can take the key with you whenever you approach the launchpad, so that you are _certain_ that the launch circuit is dead, and cannot be accidentally turned on by someone else. You should use the type of keyed switch that can only have the key removed when it is off. Personally, I chose to put in both the keyed switch AND another switch, both of which have to be on to make the launch button live.

Seriously not fine. A lot can happen in 5-10 seconds. If you are trying to get further away (perhaps to take an angle measurement), use a longer wire, and/or some helpers to take measurements. The person pushing the launch button is responsible to be sure that it is safe to launch, and thus an automated launch delay is not an acceptable solution, as it could become unsafe to launch between the time the button is pushed and the time the rocket actually launches.

Well, mine is from parts found in an old Chevy and an old Saab, or was it a Volvo? Still gets used a couple of times a year. I keep thinking I'll come up with a new version, but I haven't actually needed to, so the first one I built (~30 years ago) stands. Made it to replace the unreliable plastic thing that came with the first rocketry kit I got.

A friend of ours has a site

For your application, I've used 100-200' telephone wire to trip for ignition. If you must have a timer, consider a 1 RPM motor that turns a hard wire to make switch contact on a flexible wire that is all visible. That way you can watch the wire turning prior to ignition.

Just to add, it's a lot easier to play a tape recording of all your steps going into launch, like a countdown. Things like wind, range safety, observers confirmed at the locations, the ignition procedure etc. oh yeah and play Major Tom between the instructions! Ken

Why not just use a match ?

cause i don't got any visco fuse or any fuse really plus its funner if you build/solder the circuit yourself