A long time ago .... before the time of drones, in a desert area, with nothing around for miles, and using cheap high wing 3 channel trainers, and 4 channel radios, with the fail safe set to full down elev. and reliable transceiver ranges of much less than 'miles' .... we would use 4 coat hangers bent into a U shape and fastened them under the wings, with two to each wing using duct tape so one side of the U was a weapons rail of sorts, and then we'd slide the smallest Estes, electrically fired rockets onto them.
We used a tab of plastic cut from a milk bottle, tacked to the leading edge of the wing above each rail, as a flap that was stiff enough to hold the nose of the Estes rockets so they wouldn't slide off in a dive, but still allow them to slide off when launched.
Then by using a servo that activated 4 micro switches by staggering them so the 4'th channel control (with trim centered) would move in one direction to close one switch and fire the inboard rocket on one wing, then in the other direction for the inboard rocket on the other wing, then back in the original direction but with the full trim to fire the outboard rocket, and then the other direction with full trim that way, to fire the last rocket.
The fuse of the trainers held some Tannerite, and we'd fly combat.
99% of the time the rockets missed, and after flying a number of sorties and shooting all of our rocket we'd use up the rest of our fuel jug trying to fly into each other to get the Tannerite to go off.
Most times we came back home with the trainers intact, but every once in a while the rocket would hit and Tannerite would go off.
Making a fun camping trip to the dessert a bit more fun.
But IMHO, with Phantoms this type of 'sport' is just too dangerous.
They have no way (that I know of) to set a fail safe that would put them in the dirt under all malfunction circumstances, and can end up flying off for way too much of an undetermined distance for it to be safe .. let alone legal.
If you do try the roman candle thing (and I really advise against it) only do it inside an all metal building, or well beyond international waters ... etc.