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

Prototype DC-7. Delivered to American Airlines. Scrapped in 1957. Photo from: David Caughey Collection

On 19 May 1939 the new DC-4E was flown from the Douglas factory to the United Air Lines base at Oakland, before leaving on a nationwide publicity tour. This photo was taken during a press event the next day.

The very distinctive triple tail of the original Douglas DC-4E, photographed during a press event prior to the aircraft's nationwide publicity tour in 1939.

The DC-8 prototype, first flown on 30 May 1958. Predominantly C-124 Globemasters and C-133 Cargomasters in the background.

Built in 1935 for Pan Am as NC14296. Preserved airworthy by the Douglas Foundation.

This early production convertible DC-8-54F first flew on 1 February 1964 and was initially used by Douglas as a test aircraft and demonstrator. Note the large forward freight door, with windows - indicating its dual role. Sold to Airlift International and delivered 17 June 1964. From Douglas over 40 years ago.

Newly built outside the LGB factory. Used for tests by Douglas with 'Experimental' wording placed next to the forward passenger door. From Douglas over 40 years ago.