Hiller YH-32 Hornet
The Hiller HJ -1 Hornet is a helicopter blade tip drive of the U.S. helicopter manufacturer Hiller Aircraft.
History
The civil prototype
Stanley Hiller began in 1948 with the development of HJ -1 Hornet as einsitzigem sports helicopter. Significant development work was in its 5 per kilogram heavy ramjet engines, which each developed nearly 14 kgf (137 N ) of thrust. Early ideas with Verpuffungsstrahltriebwerken were abandoned in favor of the ramjet engines; long-term goal, however, was - despite the high g - load - the use of small jet engines.
The first prototype with a cell made of steel and aluminum tubes flew in 1950 without any fuselage fairing. The second prototype was already provided with two seats arranged side by side and a cabin of fiberglass - one of the first applications of the material in aircraft construction. The third HJ -1 was built as a model for mass production, which was scheduled at a price of U.S. $ 5,000; which corresponded to the equivalent of a full-size Cadillacs. The cockpit was significantly increased at the same time the empty weight increased from 160 to 230 kg; the possible cruising altitude dropped to 2100 m. The rotor blades were first made entirely of steel.
Military development
The one with the start of the Korean War following military orders for the Hiller UH -12 with a total of 2,000 units produced blocked the planned production capacities for civil helicopters. 1952 sold Hiller three " HJ -1" under the name " XHOE -1" to the U.S. Navy, which sought an ultralight aircraft for the Marine Corps. The U.S. Army, which had been left behind in comparison to the Marine Corps in the use of helicopters, also ordered two " HJ -1" under the name " YH -32 " as a potentially low-cost replacement of the jeep for compound tasks, for laying cables and as an observation platform. Before delivery to the military end of 1954, the tail boom was still somewhat extended and supplemented by two horizontal stabilizing fins to improve stability in forward flight. The late delivery was also due to the authorization for " Civil Aviation Authority standards," in addition to the military license of further led Hiller.
The U.S. Army ordered 12 more YH -32 for detailed field tests. Due to the system-related limitations, the well-developed project was abandoned around 1956.
Construction
To start the ramjet engines brought a gasoline engine with 50 horsepower the rotor to a speed of 150 min -1. This corresponded to a peripheral speed of about 200 km / h with each of a glow plug lit the engines that were already burdened with nearly 90 g. The glow plugs were, the term "flame - holder", as they support the combustion after the starting. As fuel gasoline, kerosene or diesel oil could be used, other sources also give alcohol to. The operating speed was 550 min-1, corresponding to a tip speed of 715 km / h and nearly 1,200 grams of the ramjet engines. The high g - load also explains why gas turbines could not be used here.
It is assumed that the controllability of the vertical axis is generally not satisfied, since the initially used conventional rudder is replaced by a downwardly angled V-tail in the YH -32. In principle, no tail rotor was actually necessary because the blade tip drive via wore no torque on the cell. In at least one Y is H -32, however, the tail was removed and replaced with a conventional tail rotor.
Use
Big problems in the operation prepared the demanding flight characteristics during autorotation in the event of an engine failure. The ramjet engines produced in the absence of a significant push air resistance; was according to the rate of descent during autorotation of 15 m / s, about twice as high as in conventional helicopters.
Fuel consumption was about ten times of that which would be expected for a conventional design. The maximum amount of fuel of 136 kg was enough for 30 minutes - including takeoff and landing. This could only reach a maximum of 50 km can be realized. The planned military operation also focused on the design-related extreme noise and the bright flames from the Staustrahtriebwerken that night were united in a radiant circle counter.
Specifications
Together with 27 kg thrust