François Gissy built this incredibly fast trike propelled simply by water and air.
You don't see many rockets on motorcycles. Typically, rockets either run on supercooled liquid oxygen or hypergolic fuels that create deadly fumes from spontaneous combustion, both of which are difficult to deal with in the small space of a bike. Frenchman François Gissy took a much simpler approach to building his own rocket bike. His fuels were not only safe, but they were also essential to life: water and air. The danger came not from the rocket fuel but from the insane speed and acceleration it could achieve.
I was a serious space nut when I was a kid. Actually, I still am. (A space nut, I mean. You can decide for yourself whether I'm still a kid.) One of my favorite toys was a replica of a Saturn V rocket that actually flew. I filled it with a certain amount of water, then attached it to a special air pump to pressurize it. When I launched it, it would shoot up into the sky from the force of the water being forcibly ejected from the bottom of the rocket. If all went well, the capsule would separate and parachute gently back to Earth. It was not quite a moon shot, but it was close enough for 8-year-old me.
Gissy used exactly the same principle as my toy rocket, supersized, and turned horizontally instead of vertically. The vast majority of the trike was a large tank that stored the water and pressurized air. When Gissy flipped the switch, it opened the valve at the back, resulting in some crazy acceleration. Going 0-100 km/h (0-62 mph) happened in just 0.551 seconds. During the first 60 feet of the run, he pulled over 5 Gs of acceleration forces. It's crazy to think of such massive acceleration numbers, especially on a homemade bike. I thought I had a hard time hanging on when the Energica Ego I rode took off. He hit a top speed of 261 km/h (162 mph).
Sadly, Gissy's creation eventually killed him. He was running the rocket trike not on a track, but on a public road, without permission, for a film crew to shoot some fly-by shots. We don't know exactly what went wrong, only that Gissy suffered a major crash that killed him and destroyed the trike. Keep it on the track, people.
Still, we should appreciate Gissy's rocket trike not only for the massive speeds it achieved but also for its sheer simplicity. Anyone with some fabrication skill could build a similar machine in their garage—not that we'd recommend it.