[KenWittlief]

If this is really intended to launch a law enforcement officer onto the roof of a 5 story building, then what happens if the 'perp' steps in his way, and give the officer a slight push backwards as he is about to land?

or pops up at the edge of the roof with a sheet of plywood?

I can think of other uses for it though, like delivering groceries to a 5th floor window

or it would be great for shooting bundles of roofing shingles onto the roof of your house (instead of carrying each 50 pound bundle up a ladder)

Ill bet UPS and FEDEX would buy one for each delivery truck - just pick an open window and yell "INCOMING!"

could also greatly speed up olympic events, like the high dive - instead of having to climb the ladder for the 10 meter high dive, the athletes could be launched up in two seconds

I can even see new sporting events - with one of these, and lets say... about ten trampolenes, spaced out about 50 feet apart....

BTW, since the forces involved would be identical, shouldnt it be possble for someone to jump off a 5 story building onto the raised chair, and have the system catch him? Shouldnt it work in both directions?