Hiller YH-32 Hornet

YH-32 Hornet
Hiller YH-32 Hornet in museum display
Type	Experimental helicopter
Manufacturer	Hiller Aircraft
Maiden flight	1950
Introduced	1954
Primary users	United States Army United States Navy
Number built	18

The Hiller YH-32 Hornet (company designation HJ-1) was an American ultralight helicopter built by Hiller Aircraft in the early 1950's. It was a small and unique design because it was powered by two Hiller 8RJ2B ramjet engines mounted on the rotor blade tips. Versions of the HJ-1 Hornet were built for the United States Army and the United States Navy in the early 1950s.

The Hiller Museum identifies the YH-32A, named the Sally Rand, as the first helicopter gunship.

Design and development

The Hiller HJ-1 Hornet was an early attempt to build a jet powered helicopter. It is notable for its ramjet tipped rotor, which propels the rotor and the aircraft. Unlike a conventional helicopter this layout avoids the need for a tail rotor, and is mechanically simple.

Unfortunately the tip speeds on helicopters are subsonic, and ramjets are very inefficient at subsonic speeds, due to low compression ratio of the inlets, and thus the Hornet suffered from poor fuel consumption and range. Additionally, the vehicle suffered from low translational speeds and the ramjet tips were extremely noisy. Autorotation recovery if the ramjets flamed out in flight was also found to be difficult due to the drag from the ramjet nacelles.

The vehicle was relatively powerful as regards lifting capacity, and there was some hope for military uses, but the high noise, poor range and at high night time visibility of the flames from the ramjet tips meant very few if any sales were made.

Operational service

The HJ-1 was evaluated by the United States Army as the YH-32, and the United States Navy as the XHOE-1. In 1957 two YH-32s were modified as the YH-32A for trials as an armed helicopter, all the fibreglass cockpit fairing were removed and the tail was modified. The test were successful in proving the viability of a helicopter as a weapons platform, but due to marginal performance no further conversions or orders were placed.

Variants

HJ-1

Company designation, one prototype.

YH-32

United States Army, Similar to HJ.1 with two small v-shaped stabilisers, 14 built.

YH-32A

Two YH-32s modified for trials as an armed helicopter.

XHOE-1

Three HJ-1s for evaluation by the United States Navy in 1951.

Specifications (YH-32)

General characteristics

• Crew: two pilots
• Length: ()
• Rotor diameter: 23 ft (6.9 m)
• Height: 7 ft 10 in (2.4 m)
• Disc area: 402 ft² (37.4 m²)
• Empty weight: 544 lb (247 kg)
• Loaded weight: 1,080 lb (490 kg)
• Powerplant: 2× Hiller 8RJ2B ramjets, 40 lbf (178 N) each

Performance

• Range: 28 miles (52 km)
• Service ceiling: 6,900 ft (2,100 m)
• Rate of climb: 700 ft/min (213 m/min)
• Disc loading: 2.7 lb/ft² (13 kg/m²)

References

• Display information at Museum of Flight in Seattle, Washington.
• Hiller Aviation Museum timeline "The First 100 Years of Aviation" [1]

External links

• Hiller Aviation Museum: The First 100 Years of Aviation
• National Air and Space Museum Hiller HOE page

See also

See also

• Fairey Rotodyne - a gyrodyne (jet tipped rotor driven at take off and landing only)
• Rotary Rocket - with rocket tipped rotor blades

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Hiller YH-32 Hornet".