The Albatros D.IV was an experimental German fighter aircraft built and tested during World War I.
The D.IV 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.[1]