Get Real, Kay?
One of the first things that got me interested in model airplanes, other than being conceived in the flight path of Forbes Air-force Base and loving airplanes ever since, was a movie on Kookla, Fran and Ollie's show that was about how a group of children friends and one of their grandpa's foiled a diamond smuggling plot where diamonds were sent over the English channel in an RC airplane. These rocket scientists, patriots of course, knocked down the RC airplane by shooting it down with darts from their modified RC scale Spitfires.
Hey!!! I was a kid, I ate it up!
Now to reality for some grownups and hopefully soon to be grownups.
The top RC combat pilots in the nation find it hard enough to put the prop of their airplane in the streamer of their intended victims so that they rather rely on long wings with sticky stuff on them. I'm not one of the top pilots by the way, but at the height of my combat career (so far I hope, just a wee break) I could regularly chase down my victims and remove their streamer with prop or wing. But back away and pull a trigger? It's hard enough for gunners on aircraft with manual guns that swivel for them to calculate lead on an aircraft, let alone hit them with fixed guns without being in the cockpit. Even then, not everyone is a combat pilot. Now you want to try and do it from the ground with aircraft that are at a distance and traveling at a pretty good clip?
The sonic systems used by the new electric war-birds distribute a dispersed sonic stream in a cone that I can't remember the specifics on, but it is fairly limited and the only way it works is because the cone extends out AND is on all the time AND more importantly doesn't hurt anything else it hits that gets in the path, like cars, windows, PEOPLE!!!
Would it be cool? Yeah. Is it possible? Yeah. Does the wow factor make it a reasonable thing to attempt. Hell NO! Is it illegal? I do believe there are laws against arming aircraft with guns and in the modern times, this could probably be applied to model aircraft too. Oh, they know you;re just playing around with model airplanes, but it would take you some pretty nice lawyer fees to learn your lesson I bet. And the negative publicity in a press that we've already been warned about by the AMA to refer to them to keep people who are just having normal (they think) conversations with the press are gleefully turned into homeland terrorists.
Keep going down the gun path and see how long it is before flying RC airplanes is illegal.
Devil's advocate note.....
Of course, I regularly drop water-bombs from my airplane. Wonder what the press would do with that? I guess the big difference is that the bombs, unlikely to do damage to people (at least the ones that have hit me haven't) do not propel from the front of the aircraft and are fairly controlled.
If you want to do something about dropping things from your aircraft, we can go down that route. You wanna play combat with your airplane. I can show you safe and legal ways to do it. You want to shoot rockets and guns off your airplane, go somewhere else like the model ship groups that can do this safely.