The Flying Banana
The Piasecki HRP Rescuer—usually called the "flying banana"—was the first U.S. helicopter developed under a military contract. The nickname came from the "bent" fuselage with overlapping tandem rotors at either end, the latter a characteristic of Piasecki helicopters.
The HRP-1 design was the second helicopter developed by Frank N. Piasecki's P. V. Engineering Forum, the first being a single-seat, single-rotor craft.1 A privately built Piasecki demonstration helicopter with tandem rotors designated HRP-X flew on 7 March 1945.
The Navy had ordered two XHRP-1 models on 1 February 1944, with the flight-test aircraft delivered in June 1947. The second XHRP-1 was used for static testing. At the time of its appearance, the XHRP-1 was both the world's largest and first tandem-rotor helicopter. The Navy designation HRP indicated helicopter, transport, Piasecki, with the X indicating experimental or prototype.
The tandem rotors were driven by a 600-horsepower Pratt & Whitney R-1340-AN-1 engine installed in the rear of the fuselage along with the clutch and gearbox. Drive shafts ran to reduction gearboxes mounted below each rotor. The rotors, each 41 feet in diameter, folded for shipboard stowage, and the helicopter's tricycle landing gear could be fitted with wheels or floats.
Following the prototypes, 20 HRP-1 production aircraft were built, with the first of these flying on 15 August 1947. Deliveries continued through the end of 1950. The U.S. Navy, Marine Corps, and Coast Guard evaluated the helicopters in a number of roles. The HRP-1 had seats for up to ten passengers or space for six litters, or it could lift 2,000 pounds of cargo.
To accelerate the evaluation of fleet introduction of helicopters, the Navy established what was probably the world's first official all-helicopter squadron—Experimental Squadron (VX) 3—on 1 July 1946. A year later the squadron began receiving the HRP-1s. They were evaluated for the antisubmarine role, being fitted with AN/AQS-4 dipping sonar that was lowered into the water while the aircraft was in hover. VX-1 pilots flying the HRP-1 also demonstrated the feasibility of using helicopters for aerial minesweeping. The first of those tests took place off Panama City, Florida, in November 1952.
Twelve of the HRP-1s served with the Marine Corps from 1948 to 1950, and three with the Coast Guard from 1948 to 1952. The Marines assigned their HRP-1s to Marine Helicopter Squadron (HMX) 1 to develop vertical assault tactics, with operations from the light carrier Saipan (CVL-48) and escort carrier Palau (CVE-122). All three Coast Guard helicopters
designated HRP-1G were assigned to the Coast Guard air station at Elizabeth City, North Carolina. At least one flew with the Rotary Wing Development Unit based there.The last Navy HRP-1 assigned to a squadron was discarded from Helicopter Antisubmarine Squadron 3 in February 1953. Probably six of these ex-military helicopters were then flown as civilian aircraft.
The HRP-2, also named Rescuer by the Navy, was a significantly improved helicopter. While the HRP-1s had fabric coverings, sometimes removed to save weight, the HRP-2 had all-metal fuselage skin, was more streamlined, and had improved performance. The Navy procured only four HRP-2s, the first flying on 10 November 1949. Three of these went to the Marine Corps.
The improved Piasecki design, however, very favorably impressed the U.S. Air Force and Army. The Air Force bought 214 Piasecki H-21 Workhorse helicopters, which were fitted with a more powerful engine that further increased performance. They had a carrying capacity of up to 20 troops. The Army procured 334 as the H-21 Shawnee. The latter name was derived from the Army's scheme of naming helicopters for American Indian tribes.
These aircraft saw service around the world, with the H-21 becoming the Army's "workhorse" of the Vietnam War from December 1961 until late 1963. It was replaced by the HU-1/UH-1 Iroquois series
invariably know as the "Huey." The Army experimented with arming H-21s with various gun and rocket loads in early efforts to develop helicopter gunships, and an Air Force H-21 fitted with floats was used to test minesweeping gear.The HRP-1/2
H-21 design's effectiveness led to Piasecki producing additional helicopters of that series for Canada, France, West Germany, Japan, and Sweden. Although their service life in the U.S. Navy, Marine Corps, and Coast Guard was brief, the HRP Rescuer provided invaluable experience in preparing the Sea Services for the helicopter era. And the derivative H-21 provided the U.S. Air Force and Army with their first major helicopter forces.
1. Mr. Piasecki held the first helicopter pilot's license issued in the United States. The firm was renamed the Piasecki Helicopter Corp. in September 1946. It became known as the Vertol Aircraft Corporation in March 1956, and Boeing Vertol in March 1960. Having left the firm in 1955, Frank Piasecki formed the Piasecki Aircraft Corp. in June of that year.