Here's a useful tip to keep in mind for the future. If, at any point, you have the desire to run comparative siege engine projectile experiments involving oversized public transports and military aircraft, just do it.
You're not going to get permission for that sort of thing. Trust me on this, there's a threshold beyond which no bureaucrat or elected official is capable of rationalizing what you've written on the Application for Special Use Permit. At best, you've made next Christmas very painful for the bureaucrat's family that has to feed their institutionalized and straightjacketed father turkey purée through a straw. At worst you'll be shot immediately.
However, if you're bold, and somehow manage to acquire all the elements necessary for your experiment, it's highly unlikely anyone will stop you. Firstly, it's just never a good idea to interfere with people who can round up a giant bus, a fighter aircraft and an enormous catapult in the same place. Common sense will shield you. Secondly, even the thickest, most aggressive and well armed person is going to want to see what happens. If it's impressive enough you'll remain safe. If you blow it you'll probably be shot, but being shot for just for asking was a real risk you've already sidestepped, so you're 100% further than you would have been. Carp Areadime!