The R-4 became the world's first production helicopter and the USAAF's first service helicopter. This R-4B on display at the National Museum of the USAF was donated to the museum by the University of Illinois in 1967.

R-4B Hoverfly I on loan to Fairey Aviation for development work for their helicopter designs. This made the first visit of a helicopter to Manchester Ringway, still wearing wartime camouflage and RAF code letter. Image obtained from Fairey's about 60 years ago.

Ex US Army 43-46560. I believe this to be the only R-4 ever modified as a crop duster in the U.S.

The prototype of the R-4, one of the first practical helicopters. It first flew on 14 January 1942.

This was officially accepted in May, 1942 and although not the first helicopter to see military service, the XR-4 was the first mass-produced helicopter and the first successful production rotorcraft of single-rotor configuration. The XR-4C came to the Smithsonian Institution in 1947 as part of a larger gift of aircraft transferred from the USAF to the new National Air Museum. It is now on display at the Udvar-Hazy Center.

This Hoverfly is really RAF serial KL110, US serial 43-46596, but it has parts of KK995.

This Hoverfly I was the first helicopter to visit Ringway. It was loaned to Fairey Aviation for development work on the rotor systems of the company's Gyrodyne helicopter. US serial 43-46545. Obtained from Faireys many years ago.

Ex USAAF Hoverfly 43-46596 delivered direct from the production line to the UK as KL110 in October 1945. Served the RAF and Navy until retirement in May 1951. Exhibited at the RAF 50th Anniversary exhibition incorrectly marked as KK995. Now preserved at the RAF Hendon Museum.