Nephew (just turned 9) is into model rockets. I built and launched a bunch when I was a kid. He's launched quite a few with his dad recently, so for Christmas we got him a few new rocket kits, another launch pad, and bunch of accessories, i.e. wadding, glue, motors, etc. Good gravy have rocket motors gotten expensive! Estes makes a fin alignment tool, got him one of those too, wish that was a thing when I was a kid. There are so many glue options now too. If CA accelerator existed when I was a kid I didn't know about it.
I'm well aware of the Estes hand held, AAA battery powered rocket launcher, but it's pretty boring.
I recall when I was a kid, i made my own "Mission Control" out of a little cardboard box I decorated, some switches I harvested from any number of random things I had a tendency to take apart, some lantern batteries, and some speaker wire.
I thought that Flight Director Nephew could use his own Mission Control, with count down timer, fighter pilot style arming switch, and big red launch button, so I got a little silly with it. All in a 30 cal, Plano, ammo can, and powered by one of his dad's Milwaukee 18V batteries.
Here's the layout on a sheet of 1/8" ABS plastic I cut to fit the box. Fighter pilot arming switch bottom left, programmable timed relay top left, quick disconnect for the lead to the igniter top center, big kitchen timer bottom center, programmable battery low voltage shutoff top right, and big red momentary switch bottom right.
Of course, if I had it all to do again, I'd do several things different. I wanted a timed relay so you didn't have to hold the button down to keep the igniter energized. I looked at a lot of relays on Amazon, and either misread the program options/features or just bought the wrong one. The one I got isn't designed to be used with an external switch, it's more for a set-and-forget repeatable on-off-on cycle. Of course I found this out way too late to get a viable replacement in time for Christmas. I thought about my options, considered a 555 timer since I actually have one, but after confirming the timed relay stays programed even after losing power, I decided I'd just use the big red momentary switch to signal a latching relay, since I had plenty of relays and diodes to choose from on hand, and I can trouble shoot that easier than a 555. Of course adding the relays further complicated things, and made the wiring a little messier.
The latching relay worked just like I intended. I set the delay relay to energize the igniter for 5 seconds when you press the big red button. Turn the arm switch off and back on to reset it.
The count down timer is literally a big kitchen timer, that you can turn the sound off. I recessed the timer into the center and glued some magnets in the bottom of the recess for the kitchen timers' magnets to stick to. I bottom mounted the battery low voltage safety with some standoffs, since that's how it was designed. I glued a piece of acrylic over the opening to make a window, and drilled a pair of holes over the buttons so you can still program it in situ. There's a 30 amp fuse there next to the arming switch too, that was part of the Milwaukee 18V adapter I used.
He's using one of his dad's larger capacity M18 batteries in the photo below, it eats up a lot of space, but with strategic placement you can still fit the 16.5' of dual strand, 14Ga, PVC insulated, wire I included. I of course attached the male end of the screw on quick disconnect on one end, and put about 6" of high temp silicone insulated wire with alligator clips on the other end. With a lower profile battery he shouldn't have any trouble keeping some extra motors, wadding, and other stuff in it too.
Gave it to him yesterday, according to his mom, he told EVERYONE at church about it today.
The kid is pretty low key, but he was about as excited about this as anything I've ever seen him emote about. I couldn't stop smiling to see him fiddling with it and asking me questions.
I'd do some things different, 1/8" ABS sheet was a little on the thin side. I doubled up everywhere there's a button, added reinforcement ribbing and yes even triangulation in strategic places. If I had put a little more thought into it instead of buying all the parts a month ago and waiting until 2 days before I've got to give it away to actually build it, I'd draw a panel up in CAD and have Send Cut Send make me one out of aluminum or steel.
The programmable timed relay as already mentioned, I think I found an appropriate replacement already. I had some surface mount relays but they're all 5V, lower profile relays instead of the Bosch/automotive style would save a lot of room, but really just getting the correct timed relay would save a lot of space and wiring complication. You could just teach the kid to hold the launch button down until the rocket takes off, too, I guess.
I originally planned to paint labels for all the switches, nephew's name, and NASA logo on the box. I bought a used, slightly older model Silhouette Cameo on eBay a couple months ago, bought the Silhouette stencil material, and messed around with Silhouette Studio a bit. I went to cut my stencils, and learned you need a self-healing mat backer to cut the stencil material. The used Cameo didn't come with that.
I'm going to at least paint up another ammo can to give to him when the mat and new blades show up.
I had a lot of fun building it, and was pleased as punch that he liked it so much.
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