The "rocketman" post

As mentioned a couple of posts back, I was delighted (much more so than my wife, children, or any other person in the vicinity, it seemed) to see a "rocketman" again last Sunday.  Here's video of him doing a daytime practice at the same Brisbane showgrounds where we were:



The guy doing the flying is David Clarke, who calls himself "Ozrocketman."  (Not sure I'm keen on the name, but it hardly matters.)   He has his own website, and is an ex RAAF aeronautical maintenance engineer who appears to have decided to try to make a business out of promotional flying using his own, homebuilt jetpack rocketpack.  Good luck to him.

On his site there's an excellent video from a kid's TV show explaining how this old "rocketbelt" design (famously built by Bell Laboratories in the late 1950's) works:



For a simplified illustration of why there are three tanks, see this:

David Clarke refers to "ten years" of research to make his own personal rocketpack, although it's a little hard to see why it would take so long these days - there seem to be many enthusiasts on the Web.  I think I have mentioned before on this blog that you can even order one from a Mexican aviation company.  Their website looks flashy, but honestly,  I wouldn't be paying the deposit without some good reassurance that they are still in business.  It would also appear that you might still be able to buy one from an American company which claims their model can fly for up to 75 seconds.  (That seems optimistic - most sites talk of a about a 30 second maximum.) 

Interestingly, it's via the Mexican company's website that I found an ad for a 2010 Discovery documentary about another Australian named David who wanted his own rocketbelt.  Here's the blurb:

Australian jet pilot David Mayman builds and flies his own Rocket Belt. This is the story of a tenacious Australian Jet Pilot, David Mayman, as he strives to achieve his childhood dream of building and free-flying his very own Rocket Belt, only to discover he faces a nearly impossible task. Collaborating with the world’s leading Rocket Belt engineers David risks life and limb to become the world’s next Rocketman. ROCKET COMPULSION will take the audience on a ride that shows point blank why less people have flown Rocket Belts than have walked on the Moon.

In fact, the documentary has its own website too, with a page of short video clips from it, including this one talking about the history of its design:



But by far the oddest tale of what has happened with a rocketbelt is the story of three Americans in the 1990's who went into a partnership to build their own one for profit.  They had a spectacular falling out; one of them was murdered, the rocketbelt went missing, and the partner who had taken it was kidnapped, kept in a box and threatened with it being thrown in the sea.

The story has been the subject of a book, but you can read about it at this site, or just watch the embedded videos there summarising the story.   Pretty amazing.

But going back to technical stuff:  Howstuffworks explains the dangers and expense involved in the hydrogen peroxide rocketbelt:

 Rocket belts run on hydrogen peroxide fuel, which is not explosive on its own. This makes rocket belts slightly safer than jet packs. When the hydrogen peroxide is combined with pressurized liquid nitrogen and a silver catalyst, the chemical reaction generates superheated steam that shoots out of twin rocket nozzles at 1,300 degrees Fahrenheit (704.4 degrees Celsius). There's no flame, but it's still extremely dangerous. The result is 800 horsepower or about 300 pounds of thrust [source: CNN.com]. Hydrogen peroxide is a good, reliable fuel, and it's only by-product is water. However, it's very expensive, costing about $250 per gallon (3.78-liters). Each flight uses almost all of the fuel in the tank -- about seven gallons (26.5-liters) per flight.

Some other sites make mention of the pilot having insulated pants legs to make sure the superheated steam doesn't burn them.  I guess you certainly wouldn't want to be too close under a "rocketman" hovering over you. 

 But given their limited flight time, it was interesting to read of an attempt in the 1960's to develop an actual jet powered backpack, which I might have read about before, but forgotten:

In 1969 Wendell Moore and John K. Hulbert of Bell Aerosystems had Williams Research Corporation design a turbojet small enough to be carried on a man's back. The jet was mounted with the intake facing the ground and the exhaust shooting upward to a pipe that split the outflow and pointed back down. Two nozzles were located just in back of the pilot's shoulders similar to those on the rocket belt. The jet had less power for its weight than the rocket engine, but also used much less fuel. Tests were carried out that showed that the pack could carry a man in the air for ten minutes, and with improvements the flight time might reach as long as a half hour (This device turns out to be the one I'd actually seen on the cover of Popular Science). The jet pack seemed to solve the biggest problem associated with the rocket belt: range. Twenty-one seconds was now thirty minutes. 

Here's a photo of this shortlived device from the same site:

Wikipedia (under the entry "Jet pack", but which also talks of the hydrogen peroxide rocketbelt, which just goes to show how confused the terminology in this field has become) gives some further details as to what happened with the turbojet pack:

In 1965 Bell Aerosystems concluded a new contract with the Defense Advanced Research Projects Agency (DARPA) to develop a jet pack with a turbojet engine. This project was called the "Jet Flying Belt", or simply the "Jet Belt". Wendell Moore and John K. Hulbert, a specialist in gas turbines, worked to design a new turbojet pack. Williams Research Corporation (now Williams International) in Walled Lake, Michigan, designed and built a new turbojet engine to Bell's specifications in 1969. It was called the WR19, had a rated thrust of 430 pounds of thrust (195 kgf, 1,910 newtons) and weighed 68 pounds (31 kg).

The first free flight of the Jet Belt took place on 7 April 1969 at the Niagara Falls Municipal Airport. Pilot Robert Courter flew about 100 meters in a circle at an altitude of 7 meters, reaching a speed of 45 km/h. The following flights were longer, up to 5 minutes. Theoretically, this new pack could fly for 25 minutes at velocities up to 135 km/h.

In spite of successful tests, the U.S. Army lost interest. The pack was complex to maintain and too heavy. Landing with its weight on his back was hazardous to the pilot, and catastrophic loss of a turbine blade could have been lethal.

Thus, the Bell Jet Flying Belt remained an experimental model. On 29 May 1969, Wendell Moore died of complications from a heart attack he had suffered six months earlier, and work on the turbojet pack was ended. Bell sold the sole version of the "Bell pack", together with the patents and technical documentation, to Williams Research Corporation. This pack is now in the Williams International company museum.

 How sad.   Of course, flying with your spine mere centimetres from spinning turbine blades which have been known, from time to time, to shatter and spray out in all directions does make this a design one which few might like to risk.   Still, I assume turbines have improved a hell of a lot since 1969, and I wonder if it will ever be reattempted.

It's taken me a while to find it, but here's some video of the jetpack being flown (and not just in a test setting either: it looks like it got a PR outing to the public):



As it happens, while reading about all of this, news turned up that the New Zealand developed "jetpack" (more like a mini personal flying vehicle, really, but it still looks awesome) has advanced:

The New Zealand makers of a one-person jetpack hope to have it on sale by the middle of next year. The Martin Aircraft company says its jetpack can reach speeds of up to 70 kilometres per hour and soar 1 kilometre high. 

The Christchurch-based firm has been testing its prototype 12 via remote control. 

The New Zealand Civil Aviation Authority said the jetpack has now been issued with an experimental flight permit for development test flying, which allows someone to pilot the aircraft.

 In case you have missed it, this is what they look like:

  

I'm seriously looking forward to seeing one of these at the Ekka in the future.