Piasecki VZ-8
| Piasecki VZ-8 | |
|---|---|
 Airgeep II in the United States Army Transportation Museum |
|
| Type: | Experimental aircraft - VTOL aircraft |
| Design country: | |
| Manufacturer: | |
| First flight: |
Airgeep I: October 12, 1958 (unbound) Airgeep II: mid-1962 |
| Number of pieces: |
2 |
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The Piasecki VZ-8 was an experimental VTOL aircraft made by the US manufacturer Piasecki Aircraft Corporation in the 1950s. Like the VZ-6 and VZ-7 , the VZ-8 was developed as part of the flying jeep competition initiated by the US Army . It is considered the most advanced and most successful of the three designs.
history
prehistory
In the mid-1950s, the US Army investigated the potential uses of VTOL devices that could take over the tasks of helicopters in combat zones, but should be easier and cheaper to manufacture. Among the most interesting of these alternative aircraft were a number of light aircraft that the Army believed should combine the versatility and manageability of a jeep with the ability to fly over dangerous or difficult terrain. The plan envisaged a simple, robust and easy-to-use vehicle that could both hover and move forward at a sufficient speed at a low altitude. Specifically, the transport of a payload of 450 kg at a cruising altitude of 1.5 to 3.6 m (5 to 12 ft) was required for flights over several hours. The request from the US Army prompted a number of companies to submit proposals. In early 1957, Chrysler Corporation , Curtiss-Wright and Piasecki each received a contract to develop prototypes.
VZ-8P Airgeep I (Model 59K Sky Car)
Piasecki received an order from the Army Transportation Research Command to develop a prototype with the factory designation Model 59K Sky Car.
The vehicle was by two consecutive, in each case by a Lycoming - piston motor driven three-bladed ducted propeller built around. For safety reasons, both engines were connected to a central gearbox so that both propellers could still be driven even if one engine failed. The controls largely corresponded to those of conventional helicopters. A number of movable baffles under each propeller outlet ensured directional stability. The Sky Car had a fixed three-wheel chassis. The pilot and optionally three other passengers sat between the air inlets of the propellers.
The first prototype had its first untethered flight in October 1958 and was handed over to the Army for testing in early 1959, where it was given the designation VZ-8P and serial number 58-5510. At the same time, Piasecki renamed the vehicle Airgeep. Shortly after acceptance by the Army, the VZ-8 received a Turboméca Artouste IIB shaft drive instead of the two piston engines. The first flight with the new engine took place on June 28, 1959. The Army then loaned the vehicle to the US Navy for their own evaluation, Piasecki using the factory designation Model 59N. The vehicle was named Seageep by the Navy . During testing, inflatable floats were also used instead of the wheeled undercarriage. After being returned to the Army, the Artouste IIB was replaced by the lighter and more powerful AiResearch TPE331 -6 engine.
VZ-8P (B) Airgeep II (Model 59H)
Unlike the two rival designs, the VZ-6 and VZ-7, the basic version gave rise to another variant that included extensive design improvements. The Piasecki factory name for this was Model 59H Airgeep II and that of the US Army VZ-8P (B) with the serial number 58-5511. The biggest change in the external appearance of the VZ-8P (B) was the upward kinking "fuselage" directly behind the pilot's seat. It was powered by two Artouste IICs, each with 400 WPS and zero-zero ejection seats for the pilot and the copilot, who was also supposed to act as a machine gun operator. The separately driven undercarriage was intended on the one hand to improve handling on the ground, but it should also offer the possibility of cruising. The Airgeep II made its first unrestrained flight in the summer of 1962.
Flight testing
Although both vehicles were intended to be used at a height of only about one meter above the ground in order to make use of the coverage possibilities of the terrain topography, none showed a dependence on the ground effect . It was even possible to fly at altitudes of almost 1000 m. The flight stability was judged to be sufficient. The vehicles could hover under trees and fly safely between buildings and other obstacles. The properties as a weapon platform were also surprisingly good. In a fight, only the machine-gun and the sight would have been visible above the cover. Even modern helicopters offer a larger target for the enemy in this regard, as they have to move further out of cover when firing the weapons below the rotor plane. In addition, the casing of the rotors provided a certain shielding effect against enemy radar, which is not the case with conventional helicopters.
But despite all these positive results, the US Army finally assessed the Airgeep, just like its competitors, as mechanically too complex and susceptible to the requirements of field use. The concept of the flying jeep was finally abandoned in favor of the further development of the conventional battlefield helicopter. In the mid-1960s, both machines then disappeared from the Army's inventory lists.
Piasecki also planned a civil version of the Airgeep I with a closed cabin, driven wheels for road operation and protective grids over the rotors. But even these plans could not be implemented.
Whereabouts
The Airgeep II is on display at the United States Army Transportation Museum in Fort Eustis, Virginia.
Technical specifications
| Parameter | Airgeep I | Airgeep II |
|---|---|---|
| crew | 1 | 2 |
| Passengers | 3 | 3 |
| Length over all | 7.95 m | 7.44 m |
| width | 2.87 m | 2.81 m |
| height | 2.01 m | 1.77 m |
| Propeller diameter | 2.26 m | 2.50 m |
| Reduction ratio rotor / engine | 0.56: 1 | |
| Empty mass | 838 kg | 1184 kg |
| Takeoff mass | 1065 kg | 1664 kg |
| Marching speed | 80 km / h | 112 km / h |
| Top speed | 104 km / h | 136 km / h |
| Service ceiling | 914 m | |
| Engines | 2 × Lycoming O-360 -A2A with 180 HP each 1 × Turboméca Artouste IIB shaft turbine with 425 WPS (373 kW) 1 × AiResearch TPE331 -6 with 550 WPS |
2 × Turboméca Artouste IIC shaft turbine with 400 WPS each (or 530 WPS) |
See also
literature
- Stephen Harding: Flying Jeeps - The US Army's Search for the Ultimate 'Vehicle' . In: AIR Enthusiast No. 73, January / February 1998, pp. 10-12
- Leonard Bridgman (ed.): Jane's All The World's Aircraft - 1959-60 , Sampson Low, Marston & Company Ltd., London, 1959, pp. 368 f.
- John WR Taylor (Ed.): Jane's All The World's Aircraft - 1965-66 , Sampson Low, Marston & Company Ltd., London, 1965, p. 285
Web links
- Brief historical overview on piasecki.com
- Field testing of the VZ-8P (A)
- Piasecki VZ-8 Airgeep
- jaglavaksoldier, youtube.com, published on April 3, 2009, accessed May 9, 2019, video (1:27) - bound and unbound flight of Airgeep I, descriptions of Airgeep I and II
- VZ-8 on aviastar.org (accessed July 23, 2015)
Individual evidence
- ^ John WR Taylor (Ed.): Jane's All The World's Aircraft - 1965-66 , p. 285