A guy did a similar stunt in Long Beach, years ago, except he used a pellet gun, and just kept popping the balloons in order for his lawn chair to descend. Feds prosecuted him, he was near LGB airport’s flight path. A commercial flight passed him, the pilot and first officer couldn’t believe their eyes ! He made it to 15,000 ft. “Lawnchair” Larry:
http://en.wikipedia.org/wiki/Larry_Walters
I’m planning to be Barcalounger Larry.