Piasecki H-25/HUP

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H-25/HUP Retriever
US Army H-25 Army Mule
Type	Utility helicopter
Manufacturer	Piasecki Helicopter
Maiden flight	March 1948
Introduced	1949
Retired	1964
Primary users	United States Navy United States Army

The Piasecki H-25 Army Mule/HUP Retriever was a compact single radial engine, twin overlapping tandem rotor utility helicopter developed by the Piasecki Helicopter Corporation of Morton, Pennsylvania during the late 1940s and produced during the early 1950s. The company changed its name in the 1956 to Vertol Aircraft Corporation and subsequently was bought by Boeing Aircraft Company in 1960, and became Boeing-Vertol.

Contents 1 Development 2 Operational history 3 Variants 4 Operators 5 Specifications (HUP-2) 6 Specifications (HUP-3) 7 References 8 External links 9 Related content

[edit] Development

The design was a product of a competition by the U.S. Navy in 1945 for a compact utility/rescue helicopter to operate from Navy ships including aircraft carriers, battleships, and cruisers. The prototype was designated by the Navy as the XHJP-1, and first flew in March 1948. It was selected by the Navy for production, as the HUP-1 in a side-by-side flight evaluation against the Sikorsky XHJS-1. It entered service with the Navy and USMC from 1949.

[edit] Operational history

Versions of the HUP built for the U.S. Army were designated H-25 Army Mule. The tandem overlapping rotor configuration was a development by Piasecki and was used in future helicopter designs by the company and successors including the H-21, HRB-1/CH-46, and CH-47.

The design featured two three bladed 35 foot diameter rotors in tandem in which blades could be folded for storage in ships’ hangars. The HUPs were powered by a single Continental R975-46 radial engine, with a take-off rating of 550 hp. To provide rescue without crew assistance, an electrically operated door, available after folding the copilot’s seat forward, opened through which a rescue sling could be lowered from an overhead winch.

The HUP was produced for the Navy in four versions: HUP-1, -2, -3, and -4. The HUP-2 was the first production helicopter equipped with an auto-pilot. In addition to those delivered to the U.S. Navy and Army the HUP/H-25 helicopter was also delivered to the Canadian and French Navies. A total of 339 aircraft were delivered over the 20 year life of the aircraft.

The US Army H-25 designation was adopted by the other services in 1962. The final units were withdrawn from US service in 1964. It also served with the French Navy from 1953 to 1965.

[edit] Variants

• HUP-1

• HUP-2

  Featured a 550 hp Continental R975-42 engine.

• HUP-3

  Featured a 550 hp Continental R-975-46A engine.

• HUP-4

• H-25

  Army version called the "Army Mule".

[edit] Operators

•  Canada
•  France
•  United States: US Army, US Navy

[edit] Specifications (HUP-2)

Data from {name of first source}^[1]

General characteristics

• Crew: 2 pilots
• Capacity: 4 passengers
• Length: 32 ft 0 in (9.8 m)
• Rotor diameter: 35 ft 0 in (10.7 m)
• Height: 12 ft 6 in (3.8 m)
• Empty weight: 4,100 lb (1,864 kg)
• Loaded weight: lb (kg)
• Useful load: 1,650 lb (341 kg)
• Max takeoff weight: lb (kg)
• Powerplant: 1× Continental R975-42 radial engine, 550 hp (737 kW)

Performance

• Maximum speed: 108 mph (174 km/h)
• Range: 360 mi (580 km)
• Service ceiling: 10,200 ft (3,110 m)

[edit] Specifications (HUP-3)

Data from {name of first source}^[2]

General characteristics

• Crew: 2 pilots
• Capacity: 4 passengers
• Length: 56 ft 11 in (17.35 m)
• Rotor diameter: 35 ft 0 in (10.67 m)
• Height: 12 ft 6 in (3.81 m)
• Disc area: 1,924 ft² (179 m²)
• Empty weight: 3,928 lb (1,782 kg)
• Loaded weight: 5,750 lb (2,608 kg)
• Useful load: lb (kg)
• Max takeoff weight: 6,100 lb (2,767 kg)
• Powerplant: 1× Continental R-975-46A radial, 550 hp (410 kW)

Performance

• Maximum speed: knots (105 mph, 169 km/h)
• Range: nm (340 mi, 547 km)
• Service ceiling: 10,000 ft (3,048 m)
• Rate of climb: 100 ft/min (5.01 m/s)
• Disc loading: 3 lb/ft² (15 kg/m²)
• Power/mass: 0.09 hp/lb (0.16 kW/kg)

[edit] References

[edit] External links

[edit] Related content

Related development

• Piasecki H-21
• CH-46 Sea Knight

 

Designation sequence

• YH-22 - OH-23 - YH-24 - H-25 - XH-26 - H-27 - XH-28