Five years ago, this classified ad appeared in a Canadian newspaper: "Jet Pack – Jumps You 10 Feet in the Air. Handcrafted by myself using car and airplane parts. I spent 15 years as a mechanic. Can use for two High Jumps, 10 feet in the air, with a safe landing before overheating, takes about an hour to cool down after that ... Serious buyers only can test out on my property and of course watch me first for safety reasons and training."
Technology blog Gizmodo celebrated the invention with the headline: "$2500 Homemade Jetpack Will Either Get You Laid or Kill You."
That anonymous Canadian may seem a little nutty, but he is one in a long history of tool-shed dreamers of a Buck Rogers bent.
This week, one of those dreamers, New Zealander Glenn Martin, appears to have cracked the code – or at least won the confidence of investors such that his jetpack business was listed on the Australian Stock Exchange for $100 million. Perhaps the most remarkable thing about Martin's machine isn't t that it's travelled to 5000 feet and can stay aloft for half an hour – but that it runs on lawn mower fuel. We'll get back to that.
It's said the first attempt at making a jetpack was in 2000BC, when a Chinese official named Wan Hu fixed 41 rockets to a chair and blew himself into space. The MythBusters program showed that Wan Hu (if he ever existed) most likely ended up a barbecued duck who went nowhere.
Incredibly, Mr Hu may be the jetpack's only fatality in 4000 years – although US engineer Wendell F. Moore injured his kneecap and was permanently grounded during a botched test flight of a rocket-belt in 1961.
Mr Moore – who also worked on the plane that broke the sound barrier – should have been awarded a Purple Heart. His jetpack research for the Bell Aircraft Corporation was part of a push by the US military, beginning in 1949, to create a fleet of flying soldiers for the Cold War.
Apparently the communists had the same idea, sort of. A Romanian inventor, Justin Capra, said he invented a "flying rucksack" in 1956. The first test flight crashed, but the pilot was able to try again a couple of years later. Mr Capra was apparently sanctioned by his Communist government for attempting to sell the device to the Americans.
However, by the early 1960s Uncle Sam had lost interest because no matter how much the Bell Corp boffins tinkered, their rocket-belt, at best, stayed aloft for 30 seconds before running out of fuel.
While this early work was probably useful in developing jetpacks used by astronauts in space walks – where overcoming gravity wasn't an issue – the Bell rocket-belt went on to be a novelty item at state fairs, football games and the opening scene of a James Bond flick, Thunderball.
In 1967, two Bell test pilots jetpacked into the first Super Bowl and shook hands on the 50-yard line. One of those pilots, Bill Suitor, repeated the stunt at the 1984 Los Angeles Olympics, watched by billions of people on TV. His career has consisted of 30-second bursts of glory.
Meanwhile, a young Glenn Martin had already been at work for three years on his jetpack. And the question of fuel remained a roadblock.
The Bell rocket belt ran on hydrogen peroxide, and it's amazing Bill Suitor's legs weren't broiled. According to howstuffworks.com, when combined with pressurised liquid nitrogen and a silver catalyst, hydrogen peroxide generates superheated steam (704.4 degrees Celsius) and 800 horsepower. The only by-product is water.
However, it's very expensive, and it gets used up very quickly.
The Martin jetpack instead uses petrol combined with two-stroke, just like your old lawnmower. It doesn't, however, rely on jet propulsion, but two ducted fans. Strictly speaking, it isn't a jetpack per se but has more in common with another US military Cold War invention, the Hiller flying platform.
The Hiller, tested in 1955, was like a circular fan-blown surfboard that flew through the air – making it, in effect, a prototype of the Hoverboard from Back to The Future. It was steered by the pilot shifting his body weight.
The idea was to have soldiers hide behind trees and buildings, and zoom up in the air for a quick peek at what the enemy was doing. The military scrapped the idea because it was too slow crossing open ground and made their soldiers sitting ducks.
But it seems the US military didn't give up on their jetpack dreams after all. They have a new genius at work: Glenn Martin has teamed up with US company Avwatch to develop gadgets for the Department of Homeland Security.