Hiller YH-32 Hornet

YH-32 Hornet
Hiller YH-32 Hornet on display in Seattle's Museum of Flight
General information
TypeExperimental helicopter
ManufacturerHiller Aircraft
Primary usersUnited States Army
Number built18[1][2]
History
Introduction date1954
First flight1950

The Hiller YH-32 Hornet (company designation HJ-1) is an American ultralight helicopter built by Hiller Aircraft in the early 1950s. It was a small and unique design because it was powered by two Hiller 8RJ2B ramjet engines mounted on the rotor blade tips which weigh 13 lb (5.9 kg) each and deliver an equivalent of 45 hp (34 kW) for a total of 90 hp (67 kW).[3] 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.[4][5]

The Hiller HOE-1 became the first production ramjet helicopter, and the Army and Navy flew a small number of these aircraft for a short time to test and evaluate the technology.[6]

Design and development

Hiller Hornet with litter attached in flight, 1951

The Hiller HJ-1 Hornet was an early attempt to build a jet-powered helicopter using ramjets, with work beginning in 1948.[6] Before that there had been experiments with the XH-26 Jet Jeep tip rotor pulse jets.The HJ-1 ramjet tipped rotor propels the rotor and the aircraft. Unlike a conventional helicopter, this mechanically simple design avoids the need for a tail rotor.

Unfortunately, the tip speeds on helicopter rotor blades are subsonic, and ramjets are inefficient at subsonic speeds due to low compression ratio of the inlets. Therefore, the Hornet suffered from high fuel consumption and poor range. Also, the vehicle suffered from low translational speeds, and the ramjet tips were extremely noisy. In the event of power loss, autorotation was found to be difficult due to the drag from the ramjet nacelles.[7]

The vehicle exhibited powerful lifting capacity, and there was some hope for military uses, but the high noise, poor range, and high night-time visibility of the ramjet flames failed to attract sales.

The first Hiller Hornets were not ready for delivery until late 1954, due to Hiller certificating the aircraft to Civil Aviation Authority standards rather than military specifications.[6]

Operational history

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 armed helicopters. All the fibreglass cockpit fairings were removed and the tail was modified. The tests were successful in proving the viability of the helicopter as a weapons platform, but due to marginal performance, no further conversions or orders were placed.[1] Also, versions were sent to the U.S. Army's DRC to be evaluated in one of their contests involving the research and development of a light weight, air droppable helicopter for air rescue and reconnaissance, and for a portable, easily put together, and fuel efficient 1 man observation and transport copter. It was competing against the Jet Jeep and its pulse jets. Overall the YH-32 won out over the Jet Jeep, but the concept was considered obsolete, and later the program was canceled.

Variants

Armed "Sally Rand" version on display at the Hiller Aviation Museum
HJ-1
Company designation, one prototype.[1]
YH-32
United States Army, Similar to HJ-1 with two small v-shaped stabilizers, 14 built (2 prototypes and 12 production aircraft).[1]
YH-32A
Two YH-32s modified for trials as an armed helicopter.[6]
XHOE-1
Three HJ-1s for evaluation by the United States Navy in 1951.[2]

Aircraft on display

On display at the Hiller Aviation Museum

Specifications (YH-32)

3-view line drawing of the Hiller YH-32 Hornet
3-view line drawing of the Hiller YH-32 Hornet

Data from Jane's All the World's Aircraft 1958-59[18]

General characteristics

  • Crew: 1
  • Capacity: 1 pax / 536 lb (243 kg) max. payload
  • Length: 23 ft 8 in (7.21 m) [citation needed]
  • Width: 3 ft 9 in (1.14 m) fuselage
  • Height: 7 ft 10 in (2.39 m)
  • Empty weight: 544 lb (247 kg)
  • Gross weight: 1,080 lb (490 kg)
  • Powerplant: 2 × Hiller 8RJ2B ramjet engines, 40 lbf (0.18 kN) thrust each [citation needed]equivalent to 45 hp (33.6 kW)[19]
  • Main rotor diameter: 23 ft (7.0 m)
  • Main rotor area: 491 sq ft (45.6 m2) [citation needed]
  • Blade section:NACA 0012[20]

Performance

  • Cruise speed: 69 mph (111 km/h, 60 kn)
  • Range: 28 mi (45 km, 24 nmi) in still air
  • Endurance: 25 minutes
  • Service ceiling: 6,900 ft (2,100 m)
  • Rate of climb: 700 ft/min (3.6 m/s)
  • Disk loading: 2.7 lb/sq ft (13 kg/m2) [citation needed]

See also

Aircraft of comparable role, configuration, and era

Related lists

Notes

  1. ^ a b c d Andrade 1979, p. 121.
  2. ^ a b Andrade 1979, p. 195.
  3. ^ "H-32." Flight, 21 March 1958, p. 396.
  4. ^ "Hiller 8RJ2B ramjet". Wings of History Air Museum. Retrieved 23 June 2024.
  5. ^ "Collection". Hiller Aviation Museum. Retrieved 2024-06-23.
  6. ^ a b c d e "Hiller XHOE-1 Hornet". Smithsonian National Air and Space Museum. Retrieved 18 March 2017.
  7. ^ "Tip-Jet Rotor Helicopters." Aerospaceweb.org, 14 September 2003. Retrieved: 30 January 2012.
  8. ^ "Airframe Dossier - Hiller YH-32 Hornet, s/n 53-4663 USAF, c/n 2". Aerial Visuals. AerialVisuals.ca. Retrieved 24 March 2017.
  9. ^ "Airframe Dossier - HillerH-32 Hornet, s/n 55-4965 US Army". Aerial Visuals. AerialVisuals.ca. Retrieved 18 March 2017.
  10. ^ "Military and Civil Helicopters Displayed at American Heroes Airshow June 20". The Museum of Flight. 10 June 2009. Retrieved 18 March 2017.
  11. ^ Bogash, Robert. "Seattle Museum of Flight Restoration Center". Retrieved 18 March 2017.
  12. ^ "1956 Hiller Hornet". Fantasy of Flight. 18 September 2013. Retrieved 18 March 2017.
  13. ^ "Airframe Dossier - HillerH-32 Hornet, s/n 55-4973 USAF, c/n 13, c/r NX125JC". Aerial Visuals. AerialVisuals.ca. Retrieved 18 March 2017.
  14. ^ "FAA REGISTRY [N125JC]". Federal Aviation Administration. U.S. Department of Transportation. Archived from the original on 18 March 2017. Retrieved 18 March 2017.
  15. ^ "Hiller H-32 Hornet". Classic Rotors. Archived from the original on 15 August 2017. Retrieved 18 March 2017.
  16. ^ "Airframe Dossier - Hiller YH-32 Hornet, c/n 15, c/r N3955". Aerial Visuals. AerialVisuals.ca. Retrieved 18 March 2017.
  17. ^ "Aircraft on Display". Hiller Aviation Museum. Retrieved 18 March 2017.
  18. ^ Bridgman, Leonard, ed. (1958). Jane's All the World's Aircraft 1958-59. London: Jane's All the World's Aircraft Publishing Co. Ltd. pp. 315–316.
  19. ^ Bridgman, Leonard, ed. (1958). Jane's All the World's Aircraft 1958-59. London: Jane's All the World's Aircraft Publishing Co. Ltd. pp. 485–486.
  20. ^ Lednicer, David. "The Incomplete Guide to Airfoil Usage". m-selig.ae.illinois.edu. Retrieved 16 April 2019.

Bibliography

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