Intial company prototype for the HRP-1 Type series. It was also designated PV-3 by the company.
An excellent description of the design and development of the aircraft can be found on the Smithsonian National Air and Space Museum web site,
"P-V Engineering Forum XHRP-X (PV-3)", R. D. Connor, Smithsonian National Air and Space Museum web page, Last accessed 04 November 2018
Latest or last design authority:
Piasecki Helicopter Corporation
Originally designed by P-V Engineering Forum
Primary manufacturer: P-V Engineering Forum
Parent type: P-V Engineering Forum PV-3/HRP-1
Aircraft status: No longer flying
VTOL type: Helicopter
Lift devices: 2 in Tandem (Fore/aft) configuration
Crew required: 2 in Other arrangement
Landing gear: Wheels (non-retractable)