The Albatros D.XI was a German single-seat fighterbiplane first flown in February 1918. It was the first Albatros design to use a rotary engine, in the form of the 120 kW (160 hp) Siemens-Halske Sh.III, and also featured a new wing construction with diagonal struts from the fuselage replacing traditional wire bracing.
The wings had unequal spans with the upper planes having greater span than the lower ones, and were braced by I-struts with an aerofoil cross-section, additional rigidity being provided by twinned diagonal struts from the base of these to the top of the fuselage, located where the "landing wires" of a normal wire-braced biplane would be. The use of a rotary engine necessitated a large-diameter propeller and a correspondingly tall undercarriage.
The D.XI was armed with the same twin 7.92 mm (.312 in) Spandau LMG 08/15machine guns employed on other Albatros fighters. Two prototypes were built, the first having balanced, parallel-chord ailerons and a four-blade propeller; and the second with inversely tapered, unbalanced ailerons and a two-blade propeller. The D.XI was not put into production.