The Piasecki HRP Rescuer (also called Harp) is a United States tandem-rotor transport or rescue helicopter designed by Frank Piasecki and built by Piasecki Helicopter. The Piasecki PV-3 was adopted as the HRP-1 Rescuer by the United States Navy, United States Marine Corps, and United States Coast Guard. An improved PV-17 variant was later produced as the HRP-2. As one of the first transport helicopters in military service, the HRP-1 was capable of carrying two crewmen and 8–10 passengers or 2,000 lb. (907 kg) of cargo. It was first flown in early 1945, entered service in 1947. The prototype helicopter (designated PV-3 by Piasecki, though commonly known to test personnel as "The Dogship") first flew at Morton, Pennsylvania in 7 March 1945 following a development contract from the United States Navy in February 1944. The "Dogship" was a novel tandem-rotor helicopter with a fixed tricycle landing gear, powered by a 600 hp (447 kW) Pratt & Whitney R-1340-AN-1 engine. To ensure that the rotors did not hit each other, the rear end of the fuselage curved upwards so the rear rotor was higher than the forward rotor. The fuselage was constructed of ordinary mild steel tubing, filled out with wooden ribs, and covered with doped fabric. Following a series of mechanical incidents with the prototype, including stripped transmission gears, it was determined that use of common automotive parts in the helicopter transmission were inadequate to the severe loads imposed by flight; subsequent prototypes built after the war used stronger components. Two prototypes designated XHRP-1 were constructed; one was used as a static test aircraft and the other was used for development flying. The helicopter got the nicknames " Harp" and "flying banana", a name also carried on by its successor. Number built 28 Variants PV-3 Prototype tandem-rotor helicopter powered by a Wright R-975 piston engine, one built. XHRP-1 Military designation for two further PV-3s, one for static testing and one for flight trials. HRP-1 Production variant, 20 built including three HRP-1Gs. HRP-1G Three United States Navy HRP-1s for the United States Coast Guard. HRP-2 Metal skinned variant, five built.
