by JOSEPH TREVITHICK
Despite movies and T.V. shows repeatedly telling us that personal jetpacks are right around the corner, the actual products have been expensive and impractical. But one company once tried to sell the U.S. Army on the idea that jetpacks were the wave of the future.
In 1957, the ground combat branch went looking for ways to help move troops around the battlefield. For the next decade, New York-based aircraft maker Bell Aerosystems cooked up various machines that could speed one or two soldiers wherever they might need to go.
“Late in 1957 industry was informed of the Army’s interest in the ‘Jump Belt’ concept as a means for increasing the foot soldier’s mobility,” aeronautics engineer Bernard Lindenbaum wrote in a 1986 U.S. Air Force history of flying machines able to land and take off vertically. “This approach was named the ‘Grasshopper Concept’ by the Army.”
This concept revolved around a general plan to help soldiers run faster, jump higher, fall from great heights without injury and quickly cross bodies of water. The Army eventually settled on jetpacks — which Bell would build — and named them Small Rocket Lift Devices, or SRLDs.
Unfortunately, limited range and other issues eventually killed Bell’s dream of a jetpack-powered fighting force.
Though Bell today is generally associated with helicopters, the company had a long and storied history working on both airplanes and later spaceship components. The company had significant experience in building rocket motors from the X-1 supersonic and X-15 hypersonic test planes.
According to the Air Force history, Bell employee Wendell Moore — who eventually became an assistant to the company’s chief engineer — had first thought up the idea of a personal jetpack in 1953. As a result, “Bell Aerosystems had actually become interested in the Rocket Belt concept spontaneously,” Lindenbaum noted.
When the Army formally asked for ideas five years later, Bell had a distinct advantage over the competition. Aerojet General and the Thiokol Corporation both offered up alternative SRLD designs.
While Aerojet won the first contract, Bell patented Moore’s design as a private venture. With a system already in development, the firm easily beat out the competition for the second phase of the Army’s project in 1960.
But the initial rocket belt prototypes were heavy and underpowered. Altogether, the jetpack weighed more than 100 pounds. The bulky backpack could boost a soldier fewer than 900 feet at most. The fuel wouldn’t even last 30 seconds.
Still, the system worked. That fact was enough to keep the Army interested.
At the ground combat branch’s urging, Bell ditched the rocket motor for a small jet turbine. Thiokol’s “preference for an air-breathing jet engine Flying Belt approach was vindicated by the subsequent shift in military interest,” Lindebaum added.
Bell unimaginatively dubbed the new design the Jet Belt. Unlike what one might imagine — say, jet engines blasting a soldier into the air — the new motor sucked in air from below and then blasted it out through two nozzles arranged along the operator’s shoulders.
The “pilot” would maneuver these exhaust ports with two joysticks. With these controls, the operator could yaw back and forth and pitch left and right.
Plus, it was speedy. These jetpacks could move troops at more than 100 miles per hour — significantly faster than the rocket-powered versions. But the Jet Belt still suffered from limited range and short flight time.
“As the performance increases, the size, complexity, and cost also increase,” Bell wrote in an undated pamphlet on its Light Mobility Systems. “The most cost effective LMS will naturally be the smallest system which could accomplish the mission.”
Given the fact that the literature featured Vietnam motifs in the art and pictures, as well as Bell’s SK-5 hovercraft, the company likely put out the document late in the project’s development. Based on the British Saunders-Roe SR.N5, the U.S. Navy sent SK-5 variants to fight in Southeast Asia in 1966.
By that point, Bell had expanded its LMS product line to include one and two-man rocket-powered “Pogo” flying platforms, including a two-man jet-powered version and a rocket-equipped chair complete with four legs with caster wheels. According to the company’s promotional materials, these flying machine could do anything and everything.
It’s all very sci-fi. Troops with Jet Belts could launch hit and run raids or rush to break up an ambush. Soldiers and Marines might zoom to dry land from ships offshore without having to plod along in landing craft or amphibious vehicles.
A Jet Belt trooper would be an ideal spotter for field artillery or airstrikes. Military police could hover around rear areas — keeping an eye out for saboteurs.
The two-man systems had enough room to pick up injured troops or downed pilots and rush them to safety. Without the burden of a second person, the platforms could even schlep heavy weapons or cargo.
To go along with the pitches, Bell artists cropped in images of jetpack soldiers into existing pictures and artwork. One promotional image depicted troops flying above an apparently staged Vietnamese jungle scene. The giveaway? A “Viet Cong” guerrilla wearing a conical hat in the foreground brandished an American M-14 rifle.
The company released some original artwork, too. Clearly trying to sell a whole new era of warfare, one scene depicted a soldier flying along a riverbank with a Jet Belt while an SK-5 speeds by in the background.
Bell provided a questionnaire for interested parties in the back. “When you have finished reading this report, complete the questionnaire in the envelope at the back of the book, and return it in the self-addressed envelope to Bell Aerosystems Company,” the introduction politely asked the reader.
While we don’t have any completed surveys, it’s clear that the Jet Belts and Pogos couldn’t compete with the range of more conventional systems. Bell’s own UH-1 “Huey” helicopters could easily ferry more men and gear — and do so at greater speeds and longer distances — than the jetpacks.
By 1968, the Army was losing interest in the SRLD project. The ground combat branch never put one of Bell’s systems into service, let alone combat.
Bell’s work did contribute to NASA’s work on lunar landers and maneuvering units for astronauts. And despite the fundamental issues, jetpacks and personal hover devices continue to capture the public imagination.
In the 1990s, hobbyists and engineers began seriously experimenting with special wing suits, which allow parachutists to glide long distances during a free fall. Who knows — jet-powered, rigid-winged versions now on the market might finally offer a practical and affordable tool to rush troops around a battlefield.