Along with the long held dream many folks have about flying cars you can add the fantasy of soaring through the skies with your own personal jet pack strapped to your back. If you grew up in the 60s, you probably remember seeing the Bell Jet Pack (more appropriately called a rocket belt or rocket pack) demonstrated at major sporting events or Disneyland.  Or maybe your dream began after you watched James Bond as agent 007 rocket away from the bad guys using a Jet Pack in the movie "Thunderball".  Was the jet pack just another tease of space age technology we were told would available in "the near future"?  Well the dream still lives for some entrepreneurs, but the engineering obstacles that made the Bell jet pack just a novelty over 50 years ago still remain.

One of the companies actively flying and marketing a jet pack is JetPack International which has developed their own jet pack that they fly regularly at numerous venues throughout the world. Another company that offers a product for demonstration purposes is  The Rocket Man. Then you have just a regular guy from Mexico, who has spent much of his adult life developing his own jet pack design. Juan Manuel Lozano Gallegos has been tinkering, building, testing and funding his effort for almost 30 years. You can listen to him interviewed as he talks about his life-long obsession with rocket belts. And finally, you have your Jet Man, who uses small jet engines developed for radio controlled airplanes to maintain level flight for a few minutes. If you watch the videos, he looks like he is flying around like the hero in the movie "The Rocketeer".  It's not really a jet pack, though, since he is using some small wings to produce lift aerodynamically.  Plus, the small engines don't produce enough thrust for you to take off from the ground. You have to jump out of an airplane, deploy the wings and start the engines. After the fuel runs out (minutes) landing is accomplished by deploying a parachute. As for buying a jet pack of your own, get ready to cash in your 401K. Gallegos will reportedly sell you one of his prototypes for $125K, and the JetPack International web site says they are taking pre-orders for a jet turbine engine version for about $200K.

While these folks are to be admired for their tenacity and ability to build flyable rocket belts, don't think there have been any major engineering breakthroughs in jet pack design since the Bell jet pack of the 1960s. Just like the Bell design, the jet packs flying today use simple rocket engines to produce the thrust, with the main fuel source being hydrogen peroxide. After reacting with a catalyst, the hydrogen peroxide breaks down and basically produces high velocity steam. This steam is then sent through rocket nozzles where it produces thrust.  (Jet packs using a real jet engine have been tried, and though they are more fuel efficient that a rocket engine, they are also much heavier and complicated. Heavy enough that you really couldn't wear it on your back.) While being relatively simple, because of few moving parts, rocket packs still have very short durations, typically less than a minute, and can be pretty tricky to learn how to fly. Not to mention the safety aspect. At least with an airplane if the engine quits, the wings still provide aerodynamic lift to allow the pilot to glide under control to the ground. Even if the engine stops on a helicopter, it can autorotate (the air passing through the blades still causes them to rotate) as you descend to a safe landing. In both cases aerodynamics is your friend and safety net. Not so with the jet pack. With all the lift for flight provided only by rocket or jet engine thrust, and nothing provided by aerodynamics, if the jet pack quits in the air, you are going to drop like a stone. (I recall once talking with an F-14 pilot who I had just briefed on the latest developments of ejection seats. He very seriously asked me why we couldn't get rid of such antiquated technology as ejection seats and parachutes to recover pilots, and instead have a jet pack installed in the cockpit so the pilot could just fly away from his crippled plane.  I had to politely point out to him some of the engineering difficulties I just mentioned.) Basically, when using a jet pack, you probably don't want to fly higher than you are willing to fall.  (I guess you could add a ballistic parachute as emergency backup, but that of course adds weight and complexity, which will probably shorten your flight duration even further.)

Dreams die hard. So unless there are fundamental technical breakthroughs that lead to a light weight, high thrust, fuel efficient power source, you can keep dreaming. Just don't expect to be flying your own personal jet pack anytime soon.