The idea of the jet or rocket pack has existed in popular culture for a long time, appearing in fiction as early as the 1890s. However, it was not until the development of jet and rocket technology in the 1920s and 30s that man-sized flying machines became a practical reality. One oft-cited candidate for the first working jet pack is the Himmelstürmer or “Heaven Stormer,” a device supposedly tested by the Nazis in 1944 to allow combat engineers and assault troops to jump over trenches, barbed wire, and other obstacles. The Himmelstürmer was based on pulse jet technology, most famously used in the Fieseler F.103 or V-1 cruise missile, some 12,000 of which were launched by the Germans against targets in Britain and the Low Countries between1944 and 1945. Unlike regular jet engines, pulse jets have no rotating compressor or turbine blades and instead use a set of spring-loaded shutters or vanes to burn fuel and air in a series of high-frequency pulses, generating thrust. This simple construction makes pulse jets cheap to manufacture, but also loud and inefficient compared to other jet engines. The Himmelstürmer incorporated two pulse jets: one strapped to the soldier’s back to provide vertical lift, and one mounted to his chest on a swivel, allowing him to steer. In testing, the device allowed soldiers to cover distances of 50 metres at a height of 15 metres.
…only no, it didn’t, for despite being widely covered on the internet, the Himmelstürmer never actually existed. This fanciful piece of Nazi tech was in fact invented out of whole cloth by Canadian author Ernst Zündel, first appearing in his 1976 book German Secret Weapons and Wonder Weapons of World War Two. An ardent conspiracy theorist and holocaust denier, Zündel’s extensive bibliography includes such choice titles as Secret Nazi Polar Explorations; Hitler at the South Pole; The Hitler We Loved & Why, UFOs – Nazi Secret Weapons?; Auschwitz, Dauchau, Buchenwald: the Greatest Fraud in History; and Did Six Million Really Die? – which should give a good idea of the credibility that ought to be attached to his claims. In any case, the Himmelstürmer as commonly described would likely never have worked. The Argus As-014 pulse jet used in the V-1 cruise missile measured 4 metres long and produced only around 270 kilograms of thrust; a pulse jet small enough to strap to a man’s back would not only be too weak to lift him off the ground, but would also become far too hot and inflict serious burns. This, combined with the inherent difficulty of controlling such a device, would have made the Himmelstürmer an impractical death trap. So despite what The Rocketeer, Captain America, and Iron Sky would have you believe, Nazi stormtroopers flying around in jetpacks were never actually a thing.
It was not until after the Second World War that practical jetpack development began in earnest. One early candidate for the inventor of the jetpack is Romanian inventor Justin Capra, who claimed to have built and flown a working “flying rucksack” in 1956. Capra approached both the Romanian military and the American Embassy in Bucharest with his invention, but neither expressed any interest, and Capra was imprisoned by the communist government for approaching the Americans. Capra later claimed that the Americans stole his idea, but was unable to provide any credible evidence that he ever actually built or flew his invention. The invention of the first practical jetpack is thus commonly attributed to Wendell Moore, an engineer at Bell Aircraft of Buffalo, New York. In 1953, Moore began experimenting with a vehicle called the Small Rocket Lift Device or SRLD, a backpack-like contraption designed to carry a single person over a short distance. The technical challenges facing Moore – and, indeed, all jetpack designers to the present day – were daunting. To be practical, a jet pack must be lightweight enough to comfortably wear, produce enough thrust to lift a man off the ground, carry enough fuel to cover a useful distance, and be stable, safe, and easy to fly – requirements that are frequently at odds with one another. While the ideal power source for jet pack is a turbojet engine, which can provide constant thrust over an extended period and operate at reasonable temperatures, in the early 1950s no turbojet engine was simultaneously compact and powerful enough to fit on a man’s back and lift him into the air. The only alternative was to use rocket engines, which presented problems of their own. Rocket engines are notoriously thirsty, severely limiting their endurance, and produce dangerously hot exhaust gases that can potentially injure the pilot.
Moore’s initial SRLD prototype used cold compressed nitrogen gas stored in tanks and vented through a pair of flexible nozzles controlled by twin joysticks. Intended as a testbed for evaluating stability, control, and other technical issues, for initial testing the SRLD was flown tethered to a special rig. While much safer than future iterations, the SRLD nonetheless had its fair share of teething problems. For example, on one occasion the nozzles were found to be mounted too close to the operator, causing the rocket blast to tear his shirtsleeves clean off. These early experiments soon caught the attention of the U.S. Army’s Transportation, Research, and Engineering Command, who in 1958 launched Project Grasshopper, a concerted effort to develop a practical rocket pack to allow combat engineers and assault troops to jump over minefields and other obstacles. Rival companies Aerojet and Thiokol submitted nitrogen-powered “jump belts” very similar to Bell’s SRLD, but Bell eventually won the Government contract to build a combat-ready “rocket belt.”
As compressed nitrogen had insufficient energy density to meet the Army’s requirements, Wendell Moore switched to a more potent propellant: High-Test Hydrogen Peroxide, or HTP. Ten times more concentrated than the peroxide used to bleach hair, when passed over a suitable catalyst, HTP decomposes violently into hot, high-pressure steam and oxygen. It is also highly corrosive, capable of stripping flesh from bone in seconds. Nonetheless, throughout the 1940s HTP was widely used in torpedoes and a variety of rocket-powered vehicles, including the German V-2 ballistic missile and Messerschmitt Me-163 Komet interceptor – and for more on this, please check out our previous video, The German Rocket Fighter That Dissolved its Pilots Alive.
Weighing 57 kilograms fully-fuelled, the Bell Rocket belt was built around a fibreglass frame moulded to fit the operator’s body. To this was mounted two tanks holding 19 litres of HTP plus a tank of compressed nitrogen to push the propellant through the system. HTP passed from the tanks over a platinum catalyst, converting it to high-pressure steam and oxygen, which exited through a pair of flexible nozzles mounted on either side of the pack, producing 127 kilograms of thrust. The angle of these nozzles was controlled by a pair of joysticks, allowing the pack to be directed forward, backward, left, and right. Thrust was controlled by twisting the throttle on the right-hand joystick. Tethered test flights began in early 1961, mostly flown by Moore himself. Once more the pack and its control system proved temperamental, with one flight on February 17 nearly ending in disaster when the Rocket Belt ran away and snapped its tether, causing Moore to crash to the ground and break his kneecap. Eventually, however, most of the kinks were ironed out, and on April 20, 1961 the Bell Rocket belt made its first free flight at Niagara Falls Municipal Airport with engineer Harold Graham at the controls. While this flight lasted only 13 seconds, subsequent tests further expanded the device’s flight envelope, with Graham ultimately achieving distances of 262 metres, altitudes of 60 metres, and speeds of 96 kilometres per hour. Once satisfied with its reliability, the Bell team began demonstrating the Rocket Belt before military officials across the United States and around the world. Some of these displays were more successful than others. While demonstrating the Rocket Belt as a potential means for NASA personnel to escape a rocket launch tower in an emergency, Harold Graham plummeted 6 metres onto his head and knocked himself unconscious. More encouraging was an October 11, 1961 flight in which Graham took off from a landing craft anchored off Fort Bragg, North Carolina, flew across the water, and landed in front of an astonished President John F. Kennedy.
But while outwardly futuristic and impressive, the Rocket Belt was hardly the safest or most practical vehicle. For one thing, despite the greater energy density of hydrogen peroxide compared to nitrogen, the Rocket Belt only carried enough fuel for 21 seconds of operation. This, along with the fact that the Rocket Belt flew at altitudes too low to use a parachute, meant that running out of fuel was almost inevitably fatal, forcing operators to carefully monitor their fuel consumption throughout each flight. To help avoid mishaps, the Rocket belt incorporated a special timer with a buzzer mounted in the operator’s helmet, which sounded every second as soon as the throttle was opened. After 15 seconds the intermittent buzz became a continuous tone, warning the pilot that he had just 6 seconds to land. The Rocket Belt was also deafeningly loud – exceeding 130 decibels – and while cooler-running than most rocket engines, the hot peroxide exhaust could still inflict severe burns, forcing operators to wear special heat-resistant Nomex clothing. These limitations made the Rocket Belt impractical for use in combat, and in 1962 the Army, having spent nearly $150,000 on what was essentially an expensive toy, pulled the plug on the project. But the Rocket Belt had already captured the public’s imagination, and the Bell Rocket Belt Flying Team enjoyed a long career as a novelty act for special events, making dramatic appearances at the 1964 World’s Fair, the first Super Bowl in 1967, the opening ceremonies of the 1984 Los Angeles and 1996 Atlanta Summer Olympics, and – of course – in the James Bond film Thunderball. Today, a handful of qualified pilots, including stunt performer Dan Schlund – AKA “Rocketman” – continue to fly updated versions of the Bell Rocket Belt for movies, TV, and special events.
Despite the commercial failure of the Rocket Belt, Bell Aircraft continued to develop personal flying machines for the military. Their next attempt was the POGO, a small rocket-powered flying platform designed to carry two people. Originally intended for use by Apollo astronauts on the moon, POGO was also pitched to the Army as a “flying jeep” for carrying soldiers over rough or dangerous terrain. While Bell managed to make the POGO extremely reliable, stable, and easy to fly, NASA turned it down in favour of the more conventional Lunar Roving Vehicle, while the Army decided the POGO was insufficiently “GI proof” for combat use and the project, like the Rocket Belt, was eventually cancelled. Undaunted, Bell abandoned the use of hydrogen peroxide and teamed up with the Williams Research Corporation of Walled Lake, Michigan, to develop a turbojet engine compact and powerful enough for individual manned flight. The result was the WR19, which weighed only 31 kilograms and could produce over 193 kilograms of thrust. Bell incorporated the WR19 into a single-man flying machine, imaginatively named the “Jet Belt”, which, like the earlier Rocket Belt, was steered by moving a pair of flexible jet nozzles using joysticks. The Jet Belt first flew on April 7, 1969 at Niagara Falls, piloted by Robert Courter. Subsequent flights revealed the device to be capable of flying for up to 25 minutes at speeds of up to 135 kilometres per hour – making it far more practical for military use. Despite this, however, the U.S. Army saw the Jet Belt as too heavy, complex, and temperamental, and like all its predecessors the device never entered service.
After the 1960s, military research into jetpacks effectively stopped, but over the following decades various inventors have attempted to push the technology forward. In 1992, insurance salesman Brad Barker, businessman Joe Wright, engineer Larry Stanley, and professional inventor Doug Malewicki formed a company to develop an updated version of the original Bell Rocket Belt using lightweight alloys and composite materials. The resulting design, dubbed the RB 2000, was first flown on June 12, 1995 by Bell test pilot Bill Suitor, and succeeded in increasing the design’s maximum endurance from 21 to 30 seconds. Unfortunately, like the rocket pack’s hydrogen peroxide fuel, the four men’s business partnership proved dangerously volatile, and the whole venture collapsed into a bizarre maelstrom of paranoia, intrigue, and lawsuits, culminating in Barker being kidnapped by Stanley for eight days and Wright being murdered by an unknown assailant. But the allure of the Rocket Belt survived even this outlandish soap opera, and today modernized examples are sold commercially by both Mexico’s Tecnological Aeroespacial Mexicana or TAM and Colorado’s Jet Pack H2O2. So if you have access to hydrogen peroxide, a quarter million dollars burning a hole in your pocket, and a death wish, you too can experience the thrill of untethered human flight for 30 seconds at a time.
Far safer and more practical are the wide array of turbojet-powered jetpacks made possible by recent advancements in gas turbine technology. Among the most famous of these are the jet packs designed and flown by Swiss pilot Yves Rossy, known around the world as “Jetman.” His packs, consisting of 2-metre-wide carbon fibre wings strapped to his back and powered by four Jetcat P400 compact turbojet engines, have reached speeds of up to 304 kilometres per hour and carried Rossy across the Grand Canyon, the Alps, the English Channel, and other landmarks. As impressive as they are, however, Rossy’s creations do not quite fit the classic image of a jetpack, being incapable of taking off under their own power. Instead, Rossy must be carried aloft by a separate aircraft and jump free before igniting his engines. He also cannot land while wearing the wing and must instead jettison it and parachute separately to earth.
More in keeping with the popular conception of a jet pack is JetPack Aviation’s JB-9, which made its public debut in November 2015 by flying around the Statue of Liberty. Developed by Australian businessman David Mayman and American engineer and inventor Nelson Tyler, the JB-9 is powered by two AMT Nike jet engines producing 160 kilograms of thrust and can achieve speeds of 100 kilometres an hour for around 10 minutes. Even more science-fiction is the Daedalus Flight Pack developed by British inventor Richard Browning. More real-life Iron Man suit than jet pack, the Daedalus consists of a metal exoskeleton fitted with six 22-kilogram-thrust micro turbojet engines – two on the back and two on each arm, allowing the wearer to maneuver the suit by simply moving their arms. On November 9, 2017, Browning set a Guinness World Record for jet engine powered flying suits, reaching a speed of 51.5 kilometres per hour over Lagoona Park in Reading [“Redd-ing”], England. On the more accessible end of things, in 2008 Canadian inventor Raymond Li patented the JetLev, a rocket pack that uses jet-ski technology to levitate the wearer on jets of water pumped from a lake or ocean below. JetLevs are available for rental at dozens of tourist resorts around the world and, in possibly the first practical deployment of jetpacks in history, have recently been adopted by the Dubai fire department to avoid traffic congestion and access hard-to-reach fires.
So, contrary to popular belief, real-life jet packs have been around for a long time, are surprisingly common, and are rapidly catching up to their fictional counterparts. Why then, isn’t everyone flying one to work? Well, aside from the obscene cost, the simple answer is that despite nearly 60 years of development, jetpacks are still too difficult and dangerous for the average person to fly without extensive training. Automobiles, which only drive in two dimensions on constrained roads, are relatively simple to operate, and are highly regulated, still cause millions of serious accidents each year; add in the third dimension, tricky flight controls, and a limited fuel supply, and the risk of a deadly mishap increases exponentially. So the next time you bemoan the current state of technology by asking “where’s my jet pack?”, take a step back and ask yourself: if you don’t even trust your neighbours with a car, why on earth would you trust them with a jet pack?
If you like this article, you might also enjoy:
- A Harrier Jet, Pepsi, and John Leonard
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The post The Race to Create Working, Practical Personal Jetpacks appeared first on Today I Found Out.
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by Gilles Messier - December 13, 2022 at 04:14PM
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