How to Build a Flying Jeep

Add large propellers and turn it into a robot

How to Build a Flying Jeep How to Build a Flying Jeep

Uncategorized January 11, 2015 0

Far-off visions of the future don’t have as many airborne cars like they used to. But flying military jeeps were once very real—if impractical... How to Build a Flying Jeep

Far-off visions of the future don’t have as many airborne cars like they used to. But flying military jeeps were once very real—if impractical and dangerous to their pilots.

From the 1940s to the 1960s, the British and American militaries experimented with such rotorcraft. The jeeps never left the prototype stage. But it seemed like a good idea, at the time.

In theory, a jeep capable of taking flight has advantages to both ground and air vehicles. It could zoom over obstacles, ambushes and improvised explosive devices, without the cost and complexity of a helicopter.

But getting a small truck to fly is a trick engineers have yet to master, despite decades of effort. That may be about to change.

The flying jeep dates back to World War II. The planned invasion of France—and the huge logistical hurdles of such an operation—preoccupied Allied military planners. How do you move vehicles across the rough seas of the English Channel?

You can certainly move them by ship. But the necessity of getting the vehicles into action—and quickly—fostered the first serious attempt at building a flying jeep.

In 1942, the British Airborne Forces Experimental Establishment green-lighted engineer Raoul Hafner’s idea of attaching a free-spinning rotor and a set of tail fins to a Willys jeep.

Known as the Rotabuggy, Hafner’s concept proposed a jeep towed behind a large, propeller-driven airplane. The tow plane provided the forward thrust, while the rotor provided the Rotabuggy’s lift.

A two-man crew controlled the jeep using glider instruments, and swiveled a big upside-down joystick to tilt the rotor.

This being a British invention, ground tests employed a supercharged Bentley as the tow vehicle. Later, a Whitley bomber pulled the jeep through the air during flight tests.

But the Rotabuggy’s crude controls and unstable aerodynamics were dangerously rough on its crew.

After one bouncy landing, the jeep raced out of control down the runway. When the vehicle stopped, the pilot staggered out and lied down in exhaustion.

The Rotabuggy never saw combat. The development of the Horsa and Hamilcar transport gliders—used to carry airborne infantry and small jeeps into battle—served the British military’s requirements instead.

At top—Piasecki Airgeep II on Feb. 15, 1962. San Diego Air and Space Museum Archive photo. Above—The Avrocar. Wikimedia photo

Into the Cold War

During the 1950s and early 1960s, the U.S. Army took up the pursuit, and produced several experimental hybrid prototypes. All looked weird, and most designs were never workable.

Canada’s leading aerospace firm Avro explored the most exotic configuration—the VZ-9 Avrocar. This machine, shaped like a flying disc, used an airflow-control technique called the Coanda effect to generate enclosed lift without exposed rotors.

The VZ-9 resulted from a series of joint efforts by Avro and the Army—beginning during the Korean War—to first develop a high-speed strike fighter, then a tactical aircraft and a flying jeep.

Although it looked zoomy—so much that it inspired conspiracy theories about secret Air Force flying saucers—the VZ-9 proved incredibly disappointing.

It wobbled like a spinning hubcap, screamed like a banshee and never flew higher than a picket fence. The Army canceled the Avrocar in December 1961.

The VZ-6, Chrysler’s entry in the competition, looks positively retro sci-fi by today’s standards—think The Jetsons. But the automaker’s prior experience with military and aerospace hardware didn’t translate into success.

Despite the VZ-6’s 500-horsepower engine, it lacked enough power to move out of its own way. The Chrysler vehicle also handled poorly. The machine flipped over and nearly killed its pilot during the VZ-6’s first and only test flight in 1959.

Curtiss-Wright’s design, the VZ-7, succeeded in flying thanks to four large propellers mounted on the spindly vehicle’s corners. Test pilots reported that the single-seat prototype was easy to fly, and the vehicle could reach altitudes of 200 feet.

But the Army also rejected the VZ-7. It traveled at slow speeds—only 32 miles per hour—and it had exposed rotors. If soldiers approached such a vehicle in a hurry, perhaps when under fire, they risked getting sliced and diced by its blades.

The concepts weren’t all terrible. Piasecki’s VZ-8 Airgeep proved to be the most successful of the flying jeeps.

The Airgeep lifted on two large propellers encased in shrouds placed forward and aft of its two-man cockpit. Like the VZ-6, the VZ-8’s directional control came from louvers mounted within a propeller-generated airstream.

Pilots liked the VZ-8, and it handily outperformed competing designs. With a top speed of 85 miles per hour and a ceiling near 3,000 feet, the Airgeep came close to matching a helicopter in performance.

The VZ-8’s powered undercarriage allowed it to drive along the ground, and it was maneuverable enough to fly under trees—and out of sight from observers.

But by 1963, the Army decided that helicopters provided superior payloads and performance. Airborne jeeps didn’t offer enough advantages to justify further development. The remaining prototypes eventually wound up in museums, and in the pages of books about strange-looking aircraft.

The AirMule. Urban Aeronautics photo

Into the future

One of the main reasons for the flying jeeps’ failure was the inherent danger to human pilots. But half a century later, the space between a terrestrial vehicle and a full-fledged helicopter is attracting interest.

It’s now feasible to simply remove the human pilot completely.

The Israeli military firm Urban Aeronautics is deep into developing the AirMule, a direct robotic descendant of the Airgeep. Designed along similar lines—with front-and-back ducted fans for lift and louvers for maneuvering—the AirMule hopes to go where helicopters and Humvees can’t.

Planned missions include medical and logistics support.

The Pentagon’s wonder lab DARPA also jumped into the field with its Aerial Reconfigurable Embedded System, or ARES. Early designs for the system hearkened back to the Rotabuggy—Humvees sporting giant ducted fans—and looked just as goofy.

ARES follows the Israeli lead by envisioning drone transport craft delivering supplies and evacuating wounded troops. But the latest concept nixes the wheeled jeep idea for a rotorcaft that drops supply pods.

And it’s still an open question whether Urban Aeronautics and DARPA have solved the practical problems. But if they do, the flying jeeps sitting in museums today might look innovative and ahead of their time … instead of as bygone oddities.

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