I spent a lot of time at that Pratt facility in the early 1980's observing JT9D engine testing. IIRC, back then Pratt flew a corporate 727 shuttle between there and East Harford every weekday. Heard some interesting sounding jet engines in the distance while working there. At least at the time, security was pretty lax - they even had a rental car desk at that airport (I swapped out my rental there one time when the one I got from the West Palm Beach airport was a POS).
BTW, it appears it's not just LockMart - Boeing is working on something as well.
Boeing Unveils Hypersonic ?Son-Of-Blackbird? Contender | Defense content from Aviation Week