The Stinson Model U was a slightly enlarged 1932 development of the SM-6000, with the side engines mounted on stub wings. American Airlines was the main operator. The last airframe off the line in June 1933, NC12196 served as an executive transport for San Francisco Examiner executives, including the newspaper's famous owner William Randolph Hearst. It is seen here against the backdrop of Mt Shasta near Dunsmuir. One of Hearst's estates was nearby at Wyntoon. NC12196 to Aerovías Nacionales of Costa Rica in 1938 as TI-34. Photo from: San Diego Air & Space Museum

Under the US military aid programme the Netherlands received thirty-five H-23B helicopters between June 1955 and late 1958. They wore permanent 8A codes, indicating 298 Sqn, although they were also used by other units. Used as a trainer by the US Army, the H-23B had marginal engine power and could barely lift three persons including the pilot. This one is seen flying near Arnhem. Photo from: Nederlands Instituut voor Militaire Historie

The US Army got a limited number of four-seat (O)H-23F Ravens, equivalent to the civilian UH-12E-4, apparently from 1962. There were four with fiscal year 1959 serials, 17 with 1961 serials, of which 61-3218 was changed to an OH-23G, and six with 1962 serials. Powered by a 305-hp engine they were intended for hot and high environments according to Hiller. The OH-23G went back to three seats. Hiller seems to have ignored the quirky tail number system in which the decade digit of the serial should be left out. Photo from: Hiller

This was the first UH-12E for the Canadian army and the first to arrive at the helicopter flying school at Rivers, Manitoba, on 22 August 1961. The post-1968 designation CH-112 is worn along with Army titles despite the unification of the Canada's armed forces. The serial number was changed to 112264 in 1970. Withdrawn in 1972. To Evergreen as N28872. Photo from: Department of National Defence (Canada)

A new H-23D for the US Army. Photo from: Hiller

Data for the helicopter on the left, which has been preserved at Fort Rucker. The medical evacuation pods seen here were too small for a stretcher, so the wounded had to be transferred by hand. The H-23A was quickly withdrawn from Korea. Photo from: Hiller

VP-40 operated the Martin Marlin from 1953 until 1967 when it was the last seaplane squadron in the US Navy. Photo from: San Diego Air & Space Museum

Registered in New Zealand as ZK-AGO in September 1938. Impressed by the RNZAF as NZ583 a year later but was found to be unsuitable. Returned to its owner and in accordance with policy at the time, received a new registration. In August 1941 it was stored at Timaru due to World War II restrictions. ZK-AGR written off when floodwaters entered the hangar. The location of the photo is unknown but does not appear to be Timaru where it was based. Photo from: Air Force Museum of New Zealand

Pan Am wartime operations. NC25642 was delivered in May 1940. Later supplied to Cubana as CU-T138 - see other photo of this construction number. Destroyed in CIA-backed B-26 Invader raid on eve of Bay of Pigs invasion on 15 April 1961. Photo from: SFO Museum

Marked 'YHJ-1', this is the prototype of the YH-32 Hornet, but not the original HJ-1 Hornet model as seen in photo 677702. Testing of the extremely noisy ramjets terrified the neighbourhoods surrounding the Hiller factory. Photo from: Vertical Flight Society

Following the GCA-2A Helidyne compound helicopter variant, the GCA-2 was developed further as the more conventional GCA-2C, capable of carrying three litters. According to the Gyrodyne Helicopter Historical Foundation, this airframe, which has been preserved at the Cradle of Aviation Museum, was still the rebuilt original GCA-2 prototype N74101, and thus probably the original Bendix J prototype. First flight of the GCA-2C on 25 April 1952. The photo was published in January 1953 when flight testing under a US Navy contract was complete. This took place at Flowerfield, Long Island, where the Gyrodyne company moved in 1951. Photo from: National Museum of the US Navy

In 1946, the Gyrodyne company acquired rights to the Bendix Model J and developed it into the GCA-2. N74101 was reportedly the same airframe as the Bendix J prototype, N74102. The aircraft was reworked again in 1949 as the GCA-2A Helidyne compound helicopter with auxiliary engines on outriggers. Testing took place at small Fitzmaurice Field on Long Island. Photo from: Vertical Flight Society

Hovering in front of the water tower at CFB Trenton. Helo destroyed by fire following an engine failure and forced landing at Bancroft, Ontario on 6 March 1957. Photo from: Royal Canadian Air Force

It seems that Hawthorne Nevada Airlines was only so named in 1968 and early 1969. Earlier it was Mineral County Airlines. Hawthorne is a small town but a casino on Walker Lake drew gamblers from California. N15570 fatally crashed into Mount Whitney on 18 February 1969. Our other photo of N33639 suggests the airline was renamed Air Nevada immediately thereafter. The DC-3A was originally NC28305 of Pan Am. Photo from: San Diego Air & Space Museum

Built for Pan Am in 1941. To Cubana de Aviación as CU-P38 in 1946. Photo from: San Diego Air & Space Museum

N number 30000 has been worn by five different DC-3s. NC30000 was issued regularly in 1941 to a DC-3A (c/n 4809) which the Douglas company decided to keep as a demonstrator and executive transport. Douglas kept the mark and used it for the first remanufactured DC-3C (old c/n 13825, new c/n 43073) and then for the first Super DC-3 (c/n 6017/43158). When that one was sold, the reg of the plane in the photo, the second Super DC-3 (c/n 4122/43159) was changed from N15579 to N30000. Another Super DC-3, VC-117D BuNo 17175 (c/n 12779/43301) also wore N30000 in the 1990s. Photo from: San Diego Air & Space Museum

Delivered to Pan Am as a seaplane trainer in November 1941. Bought by the US Navy in 1942, but leased back to Pan Am and allocated BuNo 99076 not applied. Had a long list of owners after the war. Converted to McKinnon Super Widgeon, N37189. Crashed at Pilot Point, Alaska on 14 February 1978 as the right gear collapsed on take-off. Photo from: SFO Museum

The first aircraft built by Allan Loughead (later Lockheed), the Model G, was first flown on 15 June 1913. During the 1915 Panama-Pacific International Exposition, the Loughead brothers sold passenger rides operating from San Francisco's Marina Yacht Harbor. The adjacent Marina Green was used by landplanes during the fair and was known as Montgomery Field from 1919 until 1924. The cruiser USS Milwaukee is seen in the background. Photo from: SFO Museum

This was the first DC-8-61, first flown on 14 March 1966. The stretched DC-8 entered service on United Air Lines' California to Hawaii routes from February 1967. Photo by: Marshall Moxom / SFO Museum

The DC-6 still carried United Air Lines passengers in the late 1960s. N37528 served with them from 1947 until 1968. This is a small fragment of an overview photo, still of decent quality thanks to a large scan of a good 4×5 in negative. Photo by: Marshall Moxom / SFO Museum