Platt-Le Page XR-1 - Design and Development

Design and Development

Developed during 1939 from an earlier, unsuccessful design, the PL-1, the Platt-LePage Model PL-3 was the winner of a 1940 design competition, held under the terms of the Dorsey-Logan Act, for the supply of a helicopter design to the United States Army Air Corps. Platt-LePage's submission was judged by the Army to be superior to its competitors, which included a helicopter submitted by Vought-Sikorsky, and autogyros developed by Kellett and Pitcairn.

Following the selection of the Platt-LePage design in May 1940, a contract for the construction of a prototype and a static test airframe was issued in July of that year. The contract specified delivery of the flying prototype in January 1941, however the aircraft was not completed until three months later than the contract schedule, a delay that led to Sikorsky receiving Dorsey-Logan Act funding for development of its design, which became the XR-4.

In its design, the XR-1 bore a strong resemblance to the Focke-Wulf Fw 61, a helicopter developed by Henrich Focke in Germany that, flown by Hanna Reitsch, had impressed Platt-LePage co-founder Wynn LePage during a tour of Europe. The XR-1 was powered by a Pratt & Whitney R-985 radial engine, mounted in a buried installation within the fuselage. The aircraft had two, three-bladed rotors, mounted in a side-by-side arrangement on wing-like pylons. The pylons were aerodynamically designed to produce some lift when in forwards flight, slightly unloading the rotors. The construction of the XR-1 was conventional by the standards of the time, with the aircraft's frame consisting of a steel-tube framework, which was covered with fabric. The XR-1 had tail surfaces similar to those of a conventional aircraft, and was equipped with a fixed, taildragger landing gear. The aircraft's wheels freely castered for easier maneuvering on the ground.

The cockpit of the XR-1 seated the aircraft's two crew members in a tandem arrangement, the pilot located ahead of the observer, and was extensively glazed to provide good visibility in the aircraft's intended observation and army co-operation role. During the development of the aircraft, Major General Robert M. Danford proposed to the War Department that the XR-1 be evaluated against the Stinson YO-54 and the Kellett YG-1B autogyro.