mattja, yes! AMOF I never stopped making them!
And it's [u]STILL[/u] fun to be a kid!
Didn't you poor ol' kids ever discover Estes C - 6 - 0, C - 7 - 0, or Ener-Ject F-13-0, H-15-0 engines (4, 6, 72, & 90 pounds of thrust respectively)?
The zero means it's a booster engine (for multiple stage rockets), instead of the warm "puff" to pop the chute the Enerjects shot a 4,000 degree 8" flame to ignite the next engine. The little Estes, & Century boosters shoot a 4" spark, that's still more than enough to ignite powdered magnesium reliably.
For delay use the cotton buffers, but then the [s]gunpowder[/s] I mean "payload" ignites after apogee.
To blow the big Enerject rockets take one or both of the internal safety buffers out -- that'll pop 'em on the way up under power (just over 800 MPH), with a little aluminum (for orange/white, magnesium dust is nice when you can find it) they'll leave a 300 foot long streak by the time the shockwave gets back to you.
I don't build any of the parts for quick changing the engine, just epoxy the engine, nose cone in solid (plain old aliphatic resin works fine too). You can double the noise by slipping one of the long engine standoffs (for full length main body tube lining), before dropping the charge in, & epoxying the nose cone permanently. You get a lot more bang for the buck by reinforcing the main tube too, it doesn't have to be anything fancy like fiberglass (although that IS LOUD!), just plain ol' gauze does just fine.
FWIW, if you ever DO find the big Enerjects (E,F,G, & H), or other military grade tubes, & metallic engines - blow the damned things when they reach apogee (even with Hi-ALM "flash powder"), or they [b]will[/b] break every picture window around (They'll set off the car alarms no matter what -- even at apex).
Really try it again, it's a great, safe way to make "serious" rockets sans mortar tubes, & the boosters can still found if you keep an eye out -- especially the military stuff.
It's a shame more people don't know that GREAT things can still be found at any well stocked hobby shop (Find one that's been around long enough, & you might just luck out, & find real Enerject engines).
It's STILL fun to be a kid!