Junkers D.I

The Junkers D.I, factory designation J 9, was a German monoplane fighter built late in the First World War and is significant as the first all-metal fighter to enter service. The prototype, a private venture by Junkers named the J 7, first flew on 17 September 1917 and went through nearly half a dozen detail changes during its tests. When it was shown to the army inspectorate, the Idflieg, early the following year it impressed enough to bring an order for three more aircraft, but Junkers renamed the changed next example the J 9 and supplied that instead. In tests the J 9 lacked the manoeuvrability needed for a front-line fighter, yet it was judged fit for a naval fighter and a batch of 12 was ordered, supplied to a naval unit by September 1918 that moved to the Eastern Front after the Armistice. It was a single-seater with a BMW IIIa six-cylinder inline engine and two forward-firing machine guns. One original survives at the Musée de l'Air et de l'Espace at Le Bourget near Paris.