The Lockheed XR6O was a massive transport aircraft that was produced for the US Navy during the Second World War, but that had a low priority and wasn’t completed until after the end of the war.
Lockheed began work on the Model 89 early in 1942 in response to a suggestion from Pan American. The airline was able to get the US Navy to sponsor the design, and two prototypes were ordered as the XR6O-1.
The Model 89 was designed by a team led by Willis Hawkins and W.A. Pulver. Work began in earnest in June 1942, and twenty eight different layouts were considered before they settled on a largely conventional four engined mid wing aircraft. The most unusual feature was its double-deck layout, which gave the fuselage a figure of 8 profile, looking like two standard aircraft were stacked on top of each other. Each deck was pressurized, and could carry 204 passengers in maximum military density or 168 passengers in normal military density. A planned post war version would have carried 51 seated passengers and 58 sleeper passengers, along with 11 crew members. The two decks were linked by circular staircases at each end. The lower deck could also be used for cargo, including vehicles up to the jeep.
The two prototypes weren’t completed until fifteen months after the end of the war. The first prototype, powered by four 3,000hp R-4360-18 engines, made its maiden flight on 9 November 1946. Soon after this the engines were replaced with water injected R-4360-22W engines, each providing 3,500hp.
The second prototype was given the new engines before its maiden flight of June 1948.
The two aircraft were delivered to Transport Squadron VR-44 at Alameda in 1949. In service the aircraft was something of a disappointment. It was underpowered and suffered from engine cooling problems that meant that it often had to be flown with the cooling gills on the engines open, which increased drag and reduced range. It also lacked range, and could only reach Hawaii from California with a reduced payload.
The two aircraft were redesignated as the XR6V-1 in 1950. They underwent a major overhaul at Lockheed in 1951-52, but despite this they were retired in 1953 and placed into storage. They were sold off in 1955, and were soon scrapped by their new owners. Lockheed attempted to produce more commercially viable civilian versions, but the promising Model 289 had to be abandoned after the planned Wright Typhoon engines were scrapped.
Engine: R-4360-18 or R-4360-22W
Power: 3,000hp or 3,500hp each
Wing span: 189ft 1.25in
Length: 156ft 1in
Height: 50ft 4.5in
Empty weight: 114,575lb
Loaded weight: 184,000lb
Maximum weight: 143,600lb
Maximum speed: 303mph at 20,000ft
Cruising speed: 269mph
Rate of climb: 1,010ft/ min
Service ceiling: 27,600ft
Maximum range: 6,300 miles