685 - Two 325kW (435hp) Continental GTSIO-520-K geared, turbocharged and fuel injected flat six piston engines driving three blade constant speed propellers.
500S - Two 215kW (290hp) Lycoming IO-540-E1B5.
685 - Max speed 449km/h (242kt) at 20,000ft, max cruising speed 412km/h (222kt), long range cruising speed 281km/h (152kt). Initial rate of climb 1490ft/min. Operational ceiling 25,000ft. Max range at 20,000ft with reserves 2125km (1147nm), with optional fuel 2858km (1543nm).
500S - Max speed 346km/h (187kt), max cruising speed 326km/h (176kt), long range cruise 298km/h (161kt). Initial rate of climb 1340ft/min. Service ceiling 19,400ft. Max range with reserves 1915km (1035nm).
685 - Empty 2742kg (6046lb), max takeoff 4082kg (9000lb).
500S - Empty 2102kg (4635lb), max TO 3060kg (6750lb).
Seating in standard length Commanders for five to seven, including one pilot. Stretched Grand Commander seats up to 11.
Total 1999, including 1 L-3805, 150 520s, 345 560 series, 1 360, 789 500 series, 700 680 series, and 13 720s.
Utility and corporate transports
The origins of this prolific series of twins lies with two former Douglas employees (one of whom was Ted Smith) who formed the Aero Design and Engineering Corporation in December 1944 after failing to interest their employer in a design they were working on.
Their original design was the six to seven seat L-3805, which first flew on April 23 1948. This aircraft formed the basis for the first Aero Commander production model, the 520, which seated five to seven people and was powered by two 195kW (260hp) Lycoming GO-435s. Production began in late 1951.
A total of 150 Aero 520 Commanders were built through to 1954. Subsequent development led to the more powerful 560 series (1954) with geared engines, the 680 series (1955) with supercharged engines, and the direct drive normally aspirated 500 series (1958). Variants, apart from the experimental 360, include the 560A which introduced the 25cm (10in) stretched fuselage that became the standard short fuselage length, the 560E which introduced the definitive wing span, the 720 Alti Cruiser pressurised development of the 680 and the later pressurised 680PF.
The 560 and 680 were joined by the stretched 680FL Grand Commander from 1962. The 500 was introduced to production in 1958 and was originally intended as a low cost model.
In 1967 North American Rockwell took over Aero Commander and the Grand Commander became the Courser Commander and the 500 became the Shrike Commander (gaining its distinctive pointed nose at the same time). The Shrike Commander was the last Commander to remain in production, manufacture ending in 1980.
The final piston powered model to appear was the Rockwell 685 Commander, which was a piston powered Turbo Commander.
In US military service, the designation for the aircraft was originally L-26, in 1962 renamed to U-4 (Air Force) and U-9 (Army). Two U-4Bs (ex L-26Cs), an Air Force version of the 680, were ordered by the USAF as presidential aircraft for President Dwight D. Eisenhower. They were used from 1956 to 1960 for short trips. They had the distinction of being the smallest "Air Force One", the first Presidential aircraft to have only two engines, and the first Presidential aircraft to carry the familiar blue and white colors.