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Piasecki PV-14 / PV-18 / HUP Retriever / UH-25

Piask-HUP-1

 

Piasecki set to work on a specification, issued by the US Navy Bureau of Aeronautics in 1945, for a shipboard helicopter to be used on aircraft carriers and larger vessels for SAR, liaison, replenishment and plane guard duties.

Designated PV-14 (XHJP-1 by the US Navy), two XHJP-1 prototypes (37976 and '77) were completed for US navy evaluation and three pre-production aircraft, the HUP-1, were ordered in 1948. From 1950-52 a further twenty-two HUP-1 Retrievers (PV-18) were delivered to the U.S. Navy. They differed little from the original XHJP-1, the major apparent change being the addition of inward-sloping endplate fins to the horizontal stabilisers below the rear rotor head. Both sets of 3-blade rotors could be folded for shipboard stowage and the HUP-1, powered by a single 391kW / 525hp Continental R-975-34 piston engine, could accommodate 4-5 passengers or 3 casualty litters in addition to the 2-man crew. The power-plant was installed at the center of the fuselage, which had a steel tube framework with particularly strong, fixed tricycle landing gear. The fin of the HUP-1 was subsequently eliminated, as further improved versions were fitted with an autopilot. The US Navy versions had all-weather instrumentation and some were equipped with sonar for antisubmarine warfare.

The HUP-1 had a smaller, more compact fuselage than its predecessors. This enabled the helicopter to be stowed without having to fold back the rotor blades. Once acceptance trials were over, the US Navy ordered 32 aircraft, followed by another 165 of the HUP-2, which was fitted with a more powerful engine. The first squadron, HU-2, took delivery of its initial aircraft in February 1951.

Successful tests with a Sperry autopilot in the XHJP-1 enabled the HUP-2, to be built without tail surfaces and the more powerful 410kW Continental R-975-46 was installed in this and all subsequent production models. Another feature of the Retriever was a large rectangular rescue hatch offset to starboard in the floor of the front fuselage, through which a winch inside the cabin could lift weights of up to 181kg / 400 lb at a time. The U.S. Navy machines included some completed as HUP-2S submarine-hunting aircraft with dunking sonar equipment. Another HUP-2 was given a sealed, watertight hull and outrigged twin floats for waterborne tests, presumably as part of the development programme for the Boeing-Vertol 107 / CH-46 helicopter.

The Marines also used 13 HUP-2, while the Army acquired 70, designated H-25A (serials 51-16572 to -16641) powered by the R-975-46A engine, 50 of which were later transferred to the Navy as HUP-3s, three serving with the Royal Canadian Navy's Squadron VH-21. The first H-25A entering regular Army service in early 1953. Those Army Mules that remained in Army service were used mainly as training or medical evacuation aircraft, and the type was totally withdrawn from Army service by 1958.

 

piask-hup


The Army H-25 Mule was basically similar in general layout to the HUP-2, sharing that aircraft's all-metal fuselage, fixed three-point landing gear, and 550hp Continental R-975-42 engine. The H-25A differed from the Navy variant primarily in having hydraulically-boosted controls, a strengthened floor with cargo tie-down fittings, and modified doors intended to ease the loading and unloading of stretchers.

 

Piask-H25A
Piasecki H-25A Army Mule


In 1951 the U.S. Army ordered a version of the HUP-2 with a reinforced cabin floor and hydraulically boosted controls, for general support and evacuation work. Seventy of these were delivered as H-25A Army Mule from 1953, as were fifty similar Naval HUP-3's (including three for the Royal Canadian Navy) for ambulance and light cargo duties. Production of the three hundred and thirty-ninth and last aircraft was completed in July 1954. Shortly after this a proposal was made to boost the speed, range and payload of all H-25/HUP aircraft still in service by refitting them with 700hp Wright R-1300-3 engines. However, this did not take place and by the time the new tri-service designation system was introduced in July 1962 only the HUP-2 and HUP-3 remained in service; these became the UH-25B and UH-25C respectively. Neither type is now in U.S. front-line service, and the French and Canadian HUP types were withdrawn from service in 1966.

 

The HUP-4 has the 800-h:p. Wright R-1300-3 engine, and earlier versions cou be modified to that standard. 

 

 

An amphibious conversion of the HUP-2 was used for research by the Edo corporation in New York. It had a reinforced hull-type lower fuselage, all-metal outrigger floats and a new engine cooling system.
 
 
Pias-HUP-Edo
 
Edo Corporation HUP-2

 

 

 

H-25A Army Mule
Engine: 550 hp Continental R975-42
Rotor dia: 35 ft
Weight: 5,750 lb
Max. Speed: over 103 mph
Seats: 6
 
HUP-1
Engine: 525 h.p. Continental R-975-34
Rotor diameter: 35 ft.
Rotors: 2 x 3-blade main rotors in tandem
Fuselage length: 32 ft
Loaded weight: 5,750 lb
Max speed: Over 103 mph
Ceiling: Over 10,000 ft
Typical range: 395 miles at 80 mph
Seats: 6.
 
HUP-2
Engine: 550 h.p. Continental R-975-46
Rotor diameter: 35 ft.
Rotors: 2 x 3-blade main rotors in tandem
Fuselage length: 32 ft
Loaded weight: 5,750 lb
Max speed: Over 103 mph
Ceiling: Over 10,000 ft
Typical range: 395 miles at 80 mph
Seats: 6.
 
HUP-3
Engines: 1 x 550 hp Continental R-975-42, 410kW
Speed: Max: 170 km/h
Range: Max 550 km
Weight: Empty: 1780 kg
Max weight: 2770 kg
Rotor diameter: 10.67 m
Length rotors turning: 17.35 m
Height: 3.80 m
Disc Area: 179 sq.m
Service ceiling: 3050m
Height: 3.80 m
Disc Area: 179 sq.m
Service ceiling: 3050m
 
HUP-4
Engine: 800h.p.Wright R-1300-3
Rotor diameter: 35 ft.
Rotors: 2 x 3-blade main rotors in tandem
Fuselage length: 32 ft
Loaded weight: 5,750 lb
Max speed: Over 103 mph
Ceiling: Over 10,000 ft
Typical range: 395 miles at 80 mph
Seats: 6.

 

Piask-HUP-ld

 

 

 

 

 

 

 

 


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