A glorious pair of Lockheed monoplanes is ready to deliver your Saturday Air Mail.
Both were a development of Northrop-designed Lockheed Vega. Developed originally to meet a requirement of Charles Lindbergh for a low-wing monoplane of high performance, the Lockheed 8 Sirius combined what was basically a Vega wooden fuselage with a new low-set cantilever wing. First flown in November 1929, and then powered by a 336kW Pratt & Whitney Wasp radial engine, the Sirius had non-retractable tailwheel landing gear and two open cockpits in tandem.
In the following year, before Lindbergh set out on a survey flight for Pan American Airways, a 429kW Wright Cyclone engine and twin-float landing gear were installed (see this configuration below - two inflight photos from Charles M. Daniels collection, via SDASM, plus one more, also from San Diego Air & Space Museum photostream).
The success of Lindbergh's aircraft led to the construction of 13 more by Lockheed, comprising four similar Sirius 8, eight Sirius 8A with enlarged tail surfaces, and a single four-seat Sirius 8C aircraft (above, via Bill Larkins, on Flickr) which had an enclosed cabin for two between the engine and pilot's cockpit. One Sirius built by the Detroit Aircraft Corporation, with a metal fuselage and Lockheed wooden wing, had the designation DL-2 Lindbergh's Sirius spanned 13.04m, weighed a maximum of 3220kg, was capable of a maximum of 298km/h, and had a range of 1570km, all in landplane configuration.
In 1933, the Lindberghs set out again with the plane, now upgraded with a more powerful engine, a new directional gyro, and an artificial horizon. This time their route would take them across the northern Atlantic, with no particular destination, but primarily to scout for potential new airline routes for Pan Am. While at a refueling stop in Angmagssalik, Greenland, the Inuit of the area gave the plane a nickname, "Tingmissartoq" or "one who flies like a bird". They continued on their flight and travelled to many stops in Europe, Russia, then south to Africa, back across the southern Atlantic to Brazil and appeared back over the skies of New York City at the end of 1933, after 30,000 miles and 21 countries, where droves of people turned out to greet them as they landed.
The aircraft was in the American Museum of Natural History in New York City until 1955, when ownership of it was transferred to the National Museum of the United States Air Force in Dayton, Ohio. It was given to the Smithsonian Institution in 1959, and it went on display at the National Air and Space Museum when the original facility opened on the National Mall in 1976.
When acquiring his Sirius, Charles Lindbergh had intimated that he might be interested in having retractable landing gear, with a result that the company designed an alternative wing to accept inward-retracting main landing gear units. Although this feature was not adopted by Lindbergh, it became available as a retrofit for Sirius aircraft, first flown on a company-owned Sirius 8A during September 1930.
Redesignated Lockheed Altair 8D in this form, the aircraft was loaned to the US Army Air Corps during 1931 and in November of that year, with a new 336kW Pratt & Whitney R-1340-17 engine installed, was acquired by the USAAC under the designation Y1C-25. Four more aircraft were converted, two Sirius 8As becoming Altair 8D aircraft, the Detroit Aircraft DL-2 being redesignated Altair DL-2A and, most famous of all, one Sirius receiving the designation Sirius 8 Special.
This last aircraft was later acquired by Sir Charles Kingsford Smith and, modified to Altair 8D configuration and named Lady Southern Cross, was used by this pilot, with P. G. Taylor as his navigator, to make the first crossing of the Pacific Ocean from Australia to the United States between 20 October and 4 November 1934.
In addition to the conversions, six Altairs were built as new, one of them an Altair DL-2A built by Detroit Aircraft and powered by a 481kW Wright R-1820E Cyclone which was acquired by the US Navy under the designation XRO-1.
Headline picture: Shigeo Koike