Piasecki VZ-8 Flying Jeep / VZ-8P AirGeep / Model 59K Sky Car
In 1958, Frank Piasecki built the VZ-8 for the U.S. Army which was a single place demonstrator. It used two 7.5 ft diameter ducted fans driven by two 180 HP Lycoming reciprocating engines. Fan blades used cyclic control, but the vehicle proved underpowered. It did exhibit excellent operation in ground effect, but needed artificial stabilization for flight. The powerplants were later replaced with two 425 HP Turbomeca Artouste turboshafts and performance improved.
In 1957, Piasecki Aircraft was awarded an Army Transportation Command contract to develop a "flying jeep." It was to be a VTOL (Vertical Take-Off and Landing) vehicle capable of operating at low altitudes at speeds up to 70 mph to deliver atomic weapons. The first model was the Model 59K Sky Car, built around two tandem, three-bladed, ducted rotors driven by two 180 hp Lycoming piston engines. It had fairly conventional helicopter-type controls that provided directional stability. The landing gear was a fixed tricycle wheel, and the vehicle accommodated a single pilot and one passenger in seats located between two rotor ducts. The first Model 59K Sky Car ordered by the Army made its initial free flight in October 1958. Piasecki renamed it the Airgeep, and turned it over to the Army shortly thereafter, and the Army designated it the VZ-8P. The Army upgraded the engine to a more powerful turbine engine, and test flew it in June 1959.
Piasecki wanted to build a more efficient Airgeep, and the Army Transportation Research Command agreed to issue them another contract. The result was the VZ-8P (B) Airgeep II. The Airgeep II made its first non-tethered flight in the summer of 1962. It was similar in design to the first Airgeep, except that it was bent in the middle so the rotors were tilted, reducing drag in forward flight.
The Airgeep II used twin 400-hp Turbomeca Artouste IIC turbo-shaft engines that were linked, so if one failed the other would drive both rotors. One engine was linked to the landing wheels to move the machine around on the ground. The second model also had ejection seats for both pilot and co-pilot/gunner, and there was additional seating for three passengers.
Neither version of the VZ-8P was dependent upon the surface underneath for flight. Despite the fact that the Airgeeps were intended to operate within a few feet of the ground, both were capable of flying at altitudes of several thousand feet. They were stable and able to hover or fly beneath trees or between buildings. In addition, the Airgeep was surprisingly effective as a weapons platform.
Despite its many positive qualities, the Airgeep, like other ground effects machines developed during this period, was ultimately judged by the Army to be mechanically ill-suited to the rigors of field operations. The "flying jeep" concept was eventually abandoned in favor of further development of conventional battlefield helicopters.
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