The Junkers D.I (factory designation J 9) was a monoplane fighter aircraft produced in Germany late in World War I, significant for becoming 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, going through nearly a half-dozen detail changes in its design during its tests.^[1] When it was demonstrated to the Idflieg early the following year it proved impressive enough to result in an order for three additional aircraft for trials. The changes made by Junkers were significant enough for the firm to rename the next example the J 9, which was supplied to the Idflieg instead of the three J 7s ordered.

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Quick Facts J 7 and J 9 (D.I), Role ...

J 7 and J 9 (D.I)
Junkers D.I survivor at Musée de l'Air et de l'Espace
Role	Fighter
National origin	Germany
Manufacturer	Junkers
Designer	Hugo Junkers
First flight	17 September 1917
Introduction	1918
Status	retired
Primary user	Imperial German Navy
Produced	1918
Number built	41

Close

During tests, the J 9 lacked the manoeuvrability necessary for a front-line fighter but was judged fit for a naval fighter and a batch of 12 was ordered. These were supplied to a naval unit by September 1918, which then moved to the Eastern Front after the Armistice.

J 7

company designation for early prototype variants, one built (three completed as J 9s).

J 9

company designation for late prototypes and production models

J 9/II

company designation for lengthened fuselage version

D.I

Idflieg designation

One example survives and is on display in the Musée de l'Air et de l'Espace, at the Paris–Le Bourget Airport, 11km north of Paris, France. Several replicas have been built, including one on display at the Militärhistorisches Museum Flugplatz Berlin-Gatow.

Data from Holmes, 2005. p 32

General characteristics

• Crew: One pilot
• Length: 7.25 m (23 ft 9.4 in)
• Wingspan: 9.00 m (29 ft 6.3 in)
• Height: 2.60 m (8 ft 6 in)
• Empty weight: 654 kg (1,438 lb)
• Gross weight: 834 kg (1,834 lb)
• Powerplant: 1 × BMW IIIa water-cooled 6-cylinder inline , 138 kW (185 hp)

Performance

• Maximum speed: 176 km/h (109 mph, 95 kn) ^[2]
• Endurance: 1.5 hours^[3]
• Service ceiling: 6,000 m (19,700 ft)
• Rate of climb: 3.5 m/s (683 ft/min) ^[3]

Armament

• 2 × fixed, forward-firing Spandau machine guns

Related development

• Junkers J.I
• Junkers CL.I

Aircraft of comparable role, configuration, and era

• Fokker V.25
• Zeppelin-Lindau D.I