I’m sure you remember the old-style jet packs – the sort of thing you tended to see in early James Bond films. These used to look incredibly exciting and tremendously dangerous – and of course they were both. But now there is a modern jet pack that is amazingly cool, (relatively) affordable, and is capable of travelling 30 miles in 30 minutes on a full tank of fuel (regular automotive gasoline)...
When I hear the term "Jet Pack," my knee-jerk reaction is to think of the 1960s-type units with the two pipes hanging out of either side. As I recall, in addition to generating enough noise to deafen you, the jet engine in these things could last only around 30 seconds to 1 minute, which made them impractical for anything except the occasional sequence in a James Bond film.
Actually, since this sort of pack used liquid hydrogen, maybe this should more properly be considered to be a rocket engine (rocket pack) than a jet pack, but this really doesn’t matter for the purposes of these discussions.
It would take a brave man or woman to fly one of these. As I recall, if you took your hands off the controls, the result was much the same as letting go of a balloon you’d just inflated but not yet tied-off – scary!
Now, before we proceed to look at the modern jet pack I would love to own, below are four videos. The first two show old jet packs in the context that I remember them. The third is similar, but it provides a much better impression as to things like noise level, safety (or lack thereof), and the (very) short flight durations of which this beast is capable. And the third is a really funny one that purports to be of a young kid building a jet pack as a school project, and which immediately makes other kids say “Dad, can you make one of these for me?”
But let's not dilly-dally any longer. I can’t remember when I first heard about this – I think it was a year or so ago – but the folks at the Martin Aircraft Company, in Christchurch, New Zealand, have developed an ultra-modern jet pack that makes me drool with desire.
This little beauty requires only five gallons of the same premium gasoline used in automobiles. The 200 horsepower, dual-propeller pack can fly for 30 miles in 30 minutes on a full tank of fuel, with a top speed of 60 MPH.
With regard to safety, if the uses "let go" of the controls and goes "hands free", the jet pack stops and maintains a stable hover (the machine is also equipped with a Ballistic Parachute in the unlikely eventuality that the engine cuts out for any reason.
The Martin Jetpack complies with the FAA Part 103 Ultralight Regulations, and the Ultralight class does not require an FAA recognized pilot's license. Having said this, it would be extremely silly for anyone to attempt to fly anything like this without professional instruction, and the Martin Aircraft Company have devised a training program which all owners are required to pass (they don’t want to be sued [grin]).
Well, I don’t know about you, but I would LOVE to own one of these little beauties. My office is only about 10 miles away from my home, but it takes me about 25 minutes to drive each way because of all the traffic (Huntsville is a booming town with lots of new folks moving in, and the infrastructure is struggling to keep up). Using one of these jet packs I could be at work in only 5 to 10 minutes.
Yes I know it would take more time to suit-up and then change clothes at the office ... but that's the price one has to pay to be a trend-setter and leader of fashion (it's a hard job, but someone has to do it). Of course I don’t currently have the $50,000 purchase price (this was the number that was quoted when I first heard about this little beauty … but I can no longer find a price on their website), but if I did, I would be sorely tempted.
The funny thing is that as I drive back and forth to my office these days, I look at things like a water tower and think to myself “I wonder what that would look like from above,” or I see a really large tree and think “I’d love to fly around that,” or I see electric cables and telephone wires and think “I’d have to watch out for those” (grin).
The system using two of the Williams Research engines sounds like the best choice, since jet fuel is safer than gasoline, and one whole lot safer than either that 90% hydrogen peroxide, or the hydazine used in one other unit not mentioned here. Of course, the turbine engines are sort of expensive, and Williams will not sell them to just anyone, even for cash. I found that irritating indeed. But surplus should be a bit cheaper. I did consider twin pulsejet engines, but they are incredibly loud, and very hot, and more work to get started, beside, synchronizing them takes more work.
Just at the moment it's been interrupted by gainful, yet fun, employment. But hey, a guy can dream, and being in Sydney, it's not too hard to go over there and have a burl on their unit. To Jim: Cold and rain don't scare me, I learned to fly in an open-frame Eipper MXL ultralight. Errant geese and pheasants tend to scare me a bit, though.
The '60s Bell rocket belts ran on purified hydrogen peroxide. The nozzles had silver screens in them which broke the H2O2 down to steam and oxygen. The Blue Flame (speed record car) used that plus liquified natural gas (added to burn in the hot O2 into CO2 and more H2O for higher specific impulse).
Later in the '60s Bell made a jet belt using a tiny Williams Research fanjet. Since the oxidizer was the air, it had a much longer duration of flight but was still very limited and much more complex. Of course, the kerosene based fuel was much more docile than the notoriously unstable purified peroxide.
Since F=d(mv)/dt, the larger diameter of airstream you aim downwards decreases the power used per unit thrust (a non-obvious but simple derivation). Thus, helicopters have relatively large rotors versus VTOL aircraft like the Harrier which, like rockets, flies as airfoil maestro John Roncz so eloquently put: It turns fuel into noise. And it rises on piles and piles of noise.
Like you, I've often lusted after a rocket / jet belt. But considering cold / rainy / etc. weather and the above, I suspect a combination of NASA's Puffin proposal, Rutan's proposals for aircraft navigation and control, and Moore's law will be what we (or our grandkids) will be using in the forseeable future.
Join our online Radio Show on Friday 11th July starting at 2:00pm Eastern, when EETimes editor of all things fun and interesting, Max Maxfield, and embedded systems expert, Jack Ganssle, will debate as to just what is, and is not, and embedded system.