Brilliant! Oh, there is so much one can do with bungee chords. At this amusement park they had this catapultoid contraption with the seat secured to the ground while the chord was tightened by a crane. Release the seat and the thrill seekers were shot upwards. Now I propose that is now old news and thrill seekers need new kicks so: Invert it. Have the chord secured to the ground while the seats are hoisted by crane.