Albatros D.IV

The Albatros D.IV was an experimental German fighter aircraft built and tested during World War I. It was designed to test a geared version of the 120 kW (160 hp) Mercedes D.III engine. Unlike the ungeared version, the geared engine was completely enclosed within the fuselage. The airframe basically combined the D.II wing cellule with the D.Va fuselage along with minor alterations to the rudder balance and the horizontal stabilizer.

Three examples were ordered in November 1916, but only one was flown, which was tested with several types of propeller, but excessive vibration problems and limited performance increase precluded further development.

Variants
Though two D.IVs were destroyed after the Armistice, one was retained by the Deutsche Versuchsanstalt fur Luftfahrt (German Aeronautical Experimental Institute) and in 1926 was modified for high altitude flight research. Changes included longer span, reinforced wings, revised empennage and a propeller specifically design for operation at height, driven by a 160 hp Siemens-Halske Sh.IIIa rotary engine. This aircraft, now designated the Albatros H.1, was never flown as its was judged to be structurally vulnerable. Its wingless fuselage and engine are on display at the Polish Aviation Museum at Crakow.