Life in the Fast Lane

Welcome back!

Could Jet Packs — the recent rage for extreme sports — be the wave of the future in quick personal transportation? Two companies are currently selling the world’s most advanced personal flying machine Jet Packs which have long been a staple of science fiction in comic books and novels, but the technology has a long way to go.

Photo Dan Schlund

Known as Jet Packs, rocket belts, rocket packs and a range of similar names, they’re various forms of devices usually worn on the back that use jets of escaping gases to propel the user to fly. The concept of these devices evolved from the 1920′s when Buck Rogers — science fiction comic strip hero — used a rocket pack for travel.

The jet of gas in the original Bell Rocketbelt was provided by a hydrogen-peroxide powered rocket, but the jet can also be provided by a turbojet engine, a ducted fan, or other types of rockets powered by solid fuel, liquid fuel or compressed gas.

The “Go Fast Jet Pack” has been the vision of founder Troy Widgery for Jetpack International since his childhood memories of the jetpack that James Bond flew in ‘Thunderball’ on the big screen.

Two high-profile jetpacks are currently offered by Jetpack International. Jet Pack H202 was flown for thirty seconds in Central Park on the April 9th, 2007 episode of the Today Show, and retails for $155,000. The unit operates on H2O2 with a maximum distance of 500 feet, maximum height of 120 feet, at 70 MPH, weighing in at 180 pounds. Its improved version H2O2-Z can stay aloft for 43 seconds with a max distance of 1,500 feet, height of 250 feet, at 77 MPH also weighing 180 pounds.

Left TAM Rocket Belt, right Go Fast Jet Pack H2O2

The new Jetpack T-13 model will burn jet fuel, allowing it to stay airborne for 9 minutes. It has an estimated distance of 27 miles at 83 MPH, but the weight still plays a significant factor at 180 pounds. For trend setters with deep pockets, the unit is said to retail for $200,000, complete with flight class training and all. Oh ya, baby. The jetpack is slated for release early to mid-2008.

Tecnologia Aeroespacial Mexicana (TAM) in Mexico retails its TAM Rocket Belt for $250,000, including flight and maintenance training. With a full tank of hydrogen peroxide the belt weighs 124 to 139 pounds — the bigger the pilot, the bigger the belt — and supplies 30 seconds of flight time at 60 MPH. TAM is working on a propane-burning jet belt, but hasn’t said when it will be set to market.

Until these start-ups can improve the technology to invent a jetpack — which for many is a childhood dream come true — with longer flight times and lighter units, it can leave an inexperienced pilot feeling jittery about when and where to land.

Hydrogen Peroxide Powered Rockets
A hydrogen peroxide powered motor is based on the decomposition reaction of hydrogen peroxide. Nearly pure (90% in the Bell Rocket Belt) hydrogen peroxide is used. Pure hydrogen peroxide is relatively stable, but in contact with the catalyst — such as silver — it decomposes into a mixture of superheated steam and oxygen in less than 1/10 millisecond increasing in volume 5000 times. The reaction is exothermic, i.e. with liberation of much heat, forming in this case a steam-gas mixture at 740 °C. This hot gas is used exclusively as the reaction mass and is directly led to one or more jet nozzles.

The major disadvantage is the limited operating time. The jet of steam and oxygen can provide significant thrust from lightweight rockets, but the jet has a low exhaust velocity and thus a poor impulse. A person’s carrying capacity sets the boundaries on weight of propellant that can be used, and so currently they can only fly for about 30 seconds.

A more conventional bipropellant could more than double the impulse, but with peroxide, while the exhaust is very hot, it’s much cooler than other propellants that could be used and greatly reduces the risk of fire and injury.

In contrast to jet engines which mainly expel atmospheric air to produce thrust, rocket packs are far simpler to build than devices using turbojets.

The foremost faults of the rocket pack is short duration of flight, high cost of peroxide propellant, danger of flying below minimum parachute altitude, the sheer difficulty of manually flying such a device, and little or no safety equipment. Such conditions limit the sphere of the application of rocket packs to spectacular public demonstration flights and stunts. A flight was performed for the opening ceremony of the summer Olympic Games 1984 in Los Angeles, US.

Photos Jetpack International

German Flightpack of World War II
During World War II, Germany made late-war experiments of strapping two wearable shortened Schmidt pulse jet tubes of low thrust — called “Himmelstürmer” (Skystormer) — to the body of a pilot. The working principle was the same as the Schmidt-Argus pulse jet that powered the Fieseler Fi 103 flying bomb but was much smaller in size.

When the flier ignited both engines simultaneously the tubes began to pulse modulate. The angled rear tube strapped to the flier’s back provided both lift and forward thrust while the chest mounted deflector tube of lower thrust maintained a constant upward thrust. This lifted the flier up and forward. By opening the throttle to the rear tube, calculated ‘jumps’ could be made of up to 180 feet (60 meters) at low altitude under 50 feet (15 meters). The tubes consumed very little fuel, but not much could be carried anyway.

The intended purpose for this device was to cross minefields, barbed wire obstacles, and bridgeless waters, but was never intended for troop use.

At the end of the war the device was handed over to Bell which tested it on a tether from fear of harm, as no test flier was willing to risk his life with the German machine. What became of the device is unknown.

Turbojets
Packs with the turbojet engine work on traditional kerosene. They have higher efficiency, greater height and many minutes for flight duration, but they’re complex in construction and very expensive. Only one working model of this pack was made — it underwent flight tests in the 1960′s and no longer flies.

In Space
Rocket packs were tested during mission STS-64. Mission Specialists Carl Meade and Mark Lee tested the SAFER Rocket Pack while Hammond remained inside the Orbiter.

Bruce McCandless II operating the Manned Maneuvering Unit (MMU), a few meters away from the cabin of the shuttle Challenger without being tethered to the shuttle.
Photo NASA

Rocket packs can be useful in outer space, where much less thrust is needed, because the weightlessness of space removes the need to continually fight against gravity.

NASA demonstrated the Manned Maneuvering Unit in the 1980′s — a rocket pack that allowed an astronaut to function as their own spacecraft — but the system was retired before the end of the decade. The MMU’s propulsion was produced by high-pressure nitrogen gas discharged through its 24 nozzles. It was used in 3 Space Shuttle missions — STS-41-B, STS-41-C and STS-51-A.

NASA has recently introduced the SAFER, a smaller simpler version of the MMU meant to be used in case of accidental separation from spacecraft or station. With only small amounts of thrust needed, safety and temperature are much more manageable in the atmosphere than in Earth gravity.

Control of transport studies of the U.S. Army Transportation Research Command (TRECOM) believed that personal jet apparatuses could find the most diverse uses for reconnaissance, crossing rivers, amphibious landing, access to steep mountain slopes, overcoming minefields, and tactical maneuvering. The concept was named Small Rocket Lift Device (SRLD).

Photos Jetpack International

Making a Rocket Pack at Home
In Episode 32 of MythBusters, according to urban legend a jetpack or rocket pack could be built affordably from plans purchased off the Internet. The jetpack produced by the MythBusters using 2 ducted fans were powered by a Rotax 583 ultralight engine wasn’t powerful enough to lift a person off the ground and expensive to build.

Even if a rocket pack could be built, flying a pack is both extraordinarily difficult and extremely dangerous. It takes countless hours of practice to learn to fly the pack, and training carries a high cost in propellant. Even when trained, the low flight time of any peroxide-based pack means that the entire flight is below the minimum parachute altitude so any loss of control or failure of the pack is highly likely to be fatal.

One of the largest stumbling blocks that would-be rocket pack builders have faced is the difficulty of obtaining concentrated hydrogen peroxide, which is no longer produced by very many chemical companies. The companies who do produce high concentration hydrogen peroxide typically sell to large corporations or governments, forcing some amateurs and professionals to make their own hydrogen peroxide distillation installations. But since 2005, hydrogen peroxide has become more readily available since more rocket packs are being built and tested out.

Jet Pack International H2O2

Jetpack Accident

Jet Pack – Monster Jam

Jet-man: Human powered flight
The Jet Man, Yves Rossy, a former Swiss military pilot, designed and built a deployable 3-meter wing, holding kerosene fuel for 2 jet engines fixed to
the tips and attached it to his back. Rossy launched from an airplane and
flew for 4 minutes, traveling over 100 mph, landing by parachute.

Power Bike Jet Pack Demonstration
A demonstration of the Pacificwind Thrustpac for use as a power assist for riding a bicycle, reported to get 150 MPG. Some have considered to use them on skates and skateboards.

Sources: Go Fast Jet PI, Tecnologia Aeroespacial Mexicana, and Wikipedia

Related stories:
BASE Jumping in Wingsuits for Extreme Sport
Extreme Aerobatics – No Room for Error

Tags:flying Go Fast Jet PI jet apparatuses Jet Packs jetpacks odd rocket belts rocket packs science Tecnologia Aeroespacial Mexicana

Random Posts

• Lunar Behavior during Full Moons
• Dolphins Walk on Water in the Wild
• Panda-monium for Kissing Red Panda Pair
• Weirdest Things Found in Sewers and Drains
• Astounding Brawny Brain Power – 15 Things You May Not Know About the Human Brain
• Chimps Play Computer Games Too
• One Small Disc for Man One Giant Message for Mankind
• Beat the Heat – Frozen Beer on a Stick and Beer Ice Cream
• Bizarre and Strange Things Confiscated at Airports Throughout the World
• Egyptians Discover Queen Hatshepsut Mummy