Piasecki HUP Retriever - Photos & Videos

Piasecki HUP Retriever
Country	USA
Role	Utility helicopter
First flight	March 1948
Built	339

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 1956 to Vertol Aircraft Corporation and subsequently was bought by Boeing Aircraft Company in 1960, and became Boeing-Vertol.

Source: Piasecki HUP Retriever on Wikipedia

Piasecki HUP-3 (H-25A) Retriever Walk Around
Photographer	Vladimir Yakubov
Localisation	Pima Air and Space Museum, Tuscon
Photos	27

Piasecki HUP-3 Retriever 01

Piasecki HUP-3 Retriever 02

Piasecki HUP-3 Retriever 03

Piasecki HUP-3 Retriever 04

Piasecki HUP-3 Retriever 05

Piasecki HUP-3 Retriever 07

Piasecki HUP-3 Retriever 06

Piasecki HUP-3 Retriever 08

Piasecki HUP-3 Retriever 09

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Piasecki HUP-2 Walk Around
Photographer	Unknow
Localisation	Unknow
Photos	32

Piasecki HUP-2

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The Compact Tandem Workhorse

The Piasecki HUP-3 Retriever (known in the Army as the H-25 Army Mule) was a compact tandem-rotor helicopter designed specifically for the tight confines of aircraft carrier decks. By placing the rotors in a tandem configuration—one at the front and one at the rear—Piasecki eliminated the need for a tail rotor, which allowed the aircraft to be shorter and more stable in crosswinds. The HUP-3 was the refined version of the series, primarily serving in search and rescue (SAR) and utility roles during the early 1950s.

Attribute	Technical Specification (HUP-3)
Role	Search and Rescue (SAR) / Utility Helicopter
Crew / Capacity	2 Pilots / 4-5 Passengers or 3 Litters
First Flight (HUP series)	March 1948
Powerplant	1 × Continental R-975-46A radial engine
Horsepower	550 hp (410 kW)
Maximum Speed	105 mph (169 km/h)
Rotor Diameter	35 ft 0 in (10.67 m) each
Length (Rotors turning)	56 ft 11 in (17.35 m)

Engineering Innovations and Tandem Flight

Overlapping Rotors: To keep the fuselage as short as possible for carrier elevators, the front and rear rotors were designed to overlap. They were synchronized via a drive shaft to ensure the blades never collided.
No Tail Rotor Advantage: Because the two rotors counter-rotated, they cancelled out each other’s torque. This meant all engine power went toward lift and thrust, making the HUP series very efficient for its size and exceptionally stable during hovering.
The Rescue Hatch: The HUP-3 featured a large rectangular hatch in the floor of the cabin. A rescue hoist was mounted directly above it, allowing the crew to lift a person straight up into the center of the aircraft while in a hover.
Canted Vertical Fins: Early models lacked the large vertical fins seen on the HUP-3. These “end plates” on the rear pylon were added to improve directional stability during high-speed forward flight.

Service History and Variants

Carrier Plane Guard: Before the HUP, destroyers often followed carriers to pick up downed pilots. The HUP-3 allowed the helicopter to act as the “Plane Guard,” hovering near the carrier during flight ops to provide immediate rescue capability.
Army “Mule”: The Army version, the H-25A Army Mule, featured power-boosted controls and a reinforced floor for cargo. However, the Army found the tandem design less suited for field operations than the Navy did for sea duty.
All-Metal Blades: The HUP-3 was among the first to benefit from all-metal rotor blades, which were far more durable in the humid, salty conditions of naval service than earlier wooden or fabric-covered versions.
Preservation: Several HUP Retrievers are preserved in museums today, including the National Naval Aviation Museum in Pensacola and the Pima Air & Space Museum in Arizona.