consists of a forward-facing chair mounted on rails that point at an angle of up to 80 [degrees]. Powered by compressed air, the foolhardy "payload" would shoot up until the saddle reaches the end of the rails, at which point he would flail free skyward.
The application is extremely detailed, with proposals for computer control, feedback mechanisms, and valve pneumatics….the designers reckon a four metre high launcher could put a man on the top of a five storey building in less than two seconds.
Here's the patent, in case you want to build your own, in blatant violation of patent law.
[Hat tip: Jim Mason]