Igor Sikorsky demonstrating his helicopter. He utilised the pontoons to make a water landing and take-off the next day, 17 April, and stayed aloft for 92 minutes on 6 May 1941. The sole VS-300 first flew tethered on 14 September 1939. It was modified to VS-300A in 1940. Photo by: Dmitri Kessel / Life

'Helicopter Show, San Francisco'. Stanley Hiller, on the ground, demonstrating his UH-4. Photo by: Charles Steinheimer / Life

Brazilian licence-built version of the SA 315B Lama. Destroyed in a fatal crash into a building near Cochabamba in 2009.

The P.64 looks like a low-res computer graphic with its angular engine nacelles. The sole example dived into the ground at Martlesham Heath on 21 October 1933. Two examples of the P.71A derivative did see service with Imperial Airways. Photo from: Nationaal Archief (Netherlands)

Served until 1940 when it was struck off charge. Photo from: Canada Science and Technology Museum

This coaxial, contra-rotating helicopter was built by the Marquis Raúl Pateras Pescara de Castelluccio and is the only survivor to illustrate the work of this giant pioneer of rotary flight. The Pescara Model 2R was the first helicoopter capable of hovering for 1 minute at a height of 1 m. This exhibit is one of the oldest in the museum and one of the last machines built by Pescara, probably from elements taken from its previous helicopters. The museum do not attribute it as a 4S but it contains the Salmson 9 radial engine with a small cooling propeller, so possibly a pre-4S test frame.

A helicopter project initiated by Bernard Sznyce and Selma Gottlieb was financed by Montreal investor group Intercity Airways in 1944. First flight of the SC-VI-C CF-FGG-X was made in 1947. The second production aircraft, SG-VI-D Grey Gull with the same registration, flew in 1948 and later became the SG-VI-E with a 200 hp Franklin engine. Funding problems delayed certification until 1951 and ran out before production began. The project disappeared for over 30 years until discovered in a Manhattan warehouse in 1987. The vintage helicopter was acquired by the Reynolds Museum in 2002.

Now in the Letecké Muzeum Metoděje Vlacha.

The progenitor of the Burnelli CBY-3 Loadmaster was the Burnelli UB-14 which first flew in the USA in 1934. A very similar but structurally different aircraft, the Cunliffe-Owen OA-1, first flew from Eastleigh on 12 January 1939 and is seen over the Eastern Docks in Southampton. A&AEE were critical of the design and building quality of the prototype. It was flown to Africa in 1941, apparently by Jim Mollison, to be used as a transport by the Free French. It was burnt in a victory bonfire in Egypt in August 1945. Photo from: Nationaal Archief (Netherlands)

15m span, designed by Paul Siebert in the late 60s only 27 were built.

The one and only Totem was designed and built by Boeing of Canada. It flew with Canadian Airways for almost three years. Certificate of Airworthiness lapsed in 1942 and it is presumed to have been scrapped. Photo from: City of Vancouver Archives

Designer Walter Binder about to take off for a test flight.

'Boeing airplane C-11', perhaps at the factory. The Boeing Model 3 was a slightly revised version of the Model 2. The other two Model 3 airframes, C-5 and C-6, were sold to the US Navy and C-11, modified from airframe C-4, was reportedly delivered to a private owner in Bremerton, Washington in July 1918. Photo source says 1917 but that seems unlikely. Photo from: Katherine Stinson Pictorial Collection / University of New Mexico

A tandem-seat elementary trainer, the S.III served in the Netherlands navy between 1924 and 1938. Photo from: Nederlands Instituut voor Militaire Historie

Prototype for Westland Wasp, delivered to the Royal Navy in October 1959. Eventually became A2525. It was found awaiting restoration at the back of the Fleet Air Arm Museum. In the background is Cushioncraft CC-7 Mk.2 XX101.

The Farfadet (elf) convertiplane had separate engines driving the propeller and - through compressed air fed to the tips - the rotor for vertical take-off and landing. In horizontal flight the compressor engine was shut down and the aircraft flew as an autogyro with most lift generated by the fixed wing. According to the French Wikipedia, first vertical flight on 29 April 1953 without nose engine; Artouste nose engine fitted summer 1954; first transition to horizontal flight 2 December 1954; speeds of 260 km/h reached; aircraft damaged a few months later and not repaired, by then re-registered F-BBGD. Prototype 02 damaged during ground test and never flown. Photo from: Nationaal Archief (Netherlands)

Only two Kormorans were built. This example was previously in the main hangar but is currently in the main museum building, although that doesn't appear to be its permanent display position.

In 2002, Polish engineer Edward Margański deverloped the EM-10 "Bielik" aircraft (also SP-YEM) with a flight control system called Margański's Wing, a modification of the canard layout. Małgosia II is a further experimental development of the concept and first flew in May 2014. It is now on display at this super museum.

Originally built as a Heyford II. The Heyford was already obsolete when built, but was still in use in secondary roles during the first years of WW2. This picture could well be taken at the Handley Page factory at Radlett. Photo via RAF Scampton Heritage Center