Junkers J.I

The Junkers J.I, called the J 4 by its maker, was a German armoured sesquiplane of the First World War, built for low-level ground attack, observation and army cooperation. A single steel bathtub running from just behind the propeller to the rear crew position formed both the main fuselage structure and the armour, which was 5 mm thick, weighed 470 kg and protected the crew, engine, fuel tanks and radio equipment from small arms fire. It is noted as the first all-metal aircraft to enter mass production. Its upper wing had more than double the area of its lower wing, and the aircraft could be taken apart for rail or road transport and reassembled by a ground crew of six to eight in four to six hours. It entered front service in August 1917 and was used on the Western Front in the German spring offensive of 1918, where crews liked it despite handling so ponderous that it earned the nickname furniture van. Only 227 were built before production ended in January 1919.