MOL
BERN -In the 1920s, Buck Rogers used a jetpack to fight crime in the comic Amazing Stories, offering a glimpse into a future where humans could fly.
But in the real world, jetpacks have traditionally been too large and cumbersome to be worn by a person. Now, however, thanks to a number of technological breakthroughs it seems the age of the jetpack could finally be upon us.
A jet engine typically generates thrust by taking in air, mixing it with fuel, compressing it and igniting it. This hot, high-pressure gas is then passed through a turbine and out through a narrow nozzle, producing thrust. The gold standard for a jetpack would be to mount one or more of these powerful engines onto a backpack, enabling the wearer to fly freely in any direction.
However, early jet engines were too large to be worn by a person, so the only alternative was to use rockets. Rockets work on a similar principle to jet engines, but instead of taking in air, the rocket uses self-contained chemical reactions to generate power. The first proper attempt at a jetpack - the rocket belt - was invented by Wendell Moore in 1953, and flew using hydrogen peroxide rockets.
A tank of nitrogen gas forced hydrogen peroxide through a silver catalyst, causing it to rapidly break down into steam and oxygen. The gas shot out of the nozzles at 33,280ft (1,000 metres) per second, producing over 280 pounds (125kg) of thrust. This was powerful enough to lift the rocket belt and its wearer into the air for just over 20 seconds.
However, 70 per cent of the fuel in a rocket belt is required just to overcome the force of gravity, severely limiting flight time. Adding more fuel made the rocket belt too heavy to fly, so even with improvements in design and weight reductions using lighter modern materials, hydrogen peroxide rocket packs still cannot fly for more than a minute. One solution to the problem of heavy fuel is to attach the jetpack to a flexible supply hose, tethered to a fuel source on the ground.
While this seems impractical for a jetpack built for long-range transport, for recreational models, like the water-powered JetLev, this technique works well to extend airtime without weighing the pilot down. The other alternative is to use a more efficient engine.