Junkers CL.I

J 8, J 10 (CL.I), and J 11 (CLS.I)
J 8, J 10 (CL.I), and J 11 (CLS.I)
	Junkers J 11 (CLS.I)
General information
Type	Ground-attack aircraft
National origin	Germany
Manufacturer	Junkers
Primary user	Luftstreitkräfte
Number built	51
History
First flight	10 December 1917

Last updated January 22, 2026

The Junkers CL.I was a ground-attack aircraft developed in Germany during World War I. Its construction was undertaken by Junkers under the designation J 8 as proof of Hugo Junkers' belief in the monoplane, after his firm had been required by the Idflieg to submit a biplane (the J 4) as its entry in a competition to select a ground-attack aircraft.

Design and development

The J 8 design took the J 7 fighter as its starting point, but had a longer fuselage to accommodate a tail gunner, and larger wings. The prototype flew in late 1917 and was followed over the next few months by three more development aircraft. The Idflieg was sufficiently impressed to want to order the type, but had misgivings about Junkers' ability to manufacture the aircraft in quantity and considered asking Linke-Hoffmann to produce the type under licence. Finally, however, Junkers was allowed to undertake the manufacture as part of a joint venture with Fokker, producing a slightly modified version of the J 8 design as the J 10.

Like the other Junkers designs of the period, the aircraft featured a metal framework that was skinned with corrugated duralumin sheets. 47 examples were delivered before the Armistice, including three built as floatplanes under the designation CLS.I (factory designation J 11). After the war, one or two CL.Is were converted for commercial service by enclosing the rear cockpit under a canopy.

Operators

Germany

Luftstreitkrafte
Kaiserliche Marine

Latvia

Latvian Air Force - Postwar.

Specifications (CL.I)

A passenger-carrying J.10 JunkersJ10.jpg — A passenger-carrying J.10

Data fromGerman Aircraft of the First World War^[1]

General characteristics

Crew: Two, pilot and gunner
Length: 7.90 m (25 ft 11 in)
Wingspan: 12.04 m (39 ft 6 in)
Height: 2.65 m (8 ft 8.25 in)
Wing area: 23.4 m² (253 sq ft)
Empty weight: 710 kg (1,562 lb)
Gross weight: 1,050 kg (2,310 lb)
Powerplant: 1 × Mercedes D.IIIa , 134 kW (180 hp)

Performance

Maximum speed: 161 km/h (100 mph, 87 kn)
Endurance: 2 hours^[2]
Service ceiling: 6,000 m (19,700 ft) ^[3]

Armament

2 × fixed, forward-firing machine guns
1 × trainable, rearward-firing machine gun

References

Notes

↑ Gray and Thetford 1970, p. 440
↑ Green and Swanborough 2001, p. 311
↑ Boucher, W. Ira (10 April 2002). "The Closing Days Of The War". WWIAviation.com. Archived from the original on 2013-02-08. Retrieved 2008-05-20.

Bibliography

Gray, Peter & Thetford, Owen (1987) [1970]. German Aircraft of the First World War (2nd ed.). London: Putnam. ISBN 0-85177-809-7.
Green, William & Swanborough, Gordon (2001) [1994]. The Complete Book of Fighters: An Illustrated Encyclopedia of Every Fighter Built and Flown (Revised and Updated ed.). London: Salamander Books. ISBN 1-84065-269-1.
Herris, Jack (2012). German Seaplane Fighters of WWI: A Centennial Perspective on Great War Seaplanes. Great War Aviation Centennial Series. Vol. 2. Charleston (S.C.): Aeronaut Books. ISBN 978-1-935881-09-4.
Owers, Colin A. (2018). Junkers Aircraft of WWI: Volume 2: Junkers J.5–J.11: A Centennial Perspective on Great War Airplanes. Great War Aviation Centennial Series. Vol. 31. n.p.: Aeronaut Books. ISBN 978-1-935881-66-7.

v t e Junkers aircraft
Company designations	J 1 J 2 J 3 J 4 J 5 J 6 J 7 J 8 J 9 J 10 J 11 J 12 F 13 J 15 K 16 K 17 J 18 T 19 A 20 H 21 / J 21 / T 21 J 22 T 23 G 23 F 24 / G 24 A 25 T 26 T 27 J 28 T 29 K 30 G 31 A 32 W 33 W 34 A 35 S 36 K 37 G 38 K 39 K 47 A 48 J 49 A 50 K 51 K 53 K 85
Company EF designations (experimental aircraft)	EF 29 EF 31 EF 52 EF 61 EF 72 EF 73 EF 74 EF 77 EF 94 EF 126 EF 127 EF 128 EF 130 EF 131 EF 132 EF 140 EF 150
Idflieg designations	CL.I CLS.I D.I E.I E.I (2) J.I
RLM designations	Ju 46 Ju 49 Ju 52 Ju 60 Ju 85 Ju 86 Ju 87 Ju 88 Ju 89 Ju 90 Ju 160 Ju 187 Ju 188 Ju 248 Ju 252 Ju 268 Ju 287 Ju 288 Ju 290 Ju 322 Ju 352 Ju 388 Ju 390 Ju 452 Ju 488 Ju 635

v t e World War I aircraft of the Central Powers
Fighters	AEG D.I AEG Dr.I Albatros D.I Albatros D.II Albatros D.III Albatros D.V Aviatik D.I Aviatik C.VI Daimler L.6 Euler D.I Euler D.II Fokker D.I Fokker D.II Fokker D.III Fokker D.IV Fokker D.V Fokker D.VI Fokker D.VII Fokker D.VIII Fokker Dr.I Fokker E.I Fokker E.II Fokker E.III Fokker E.IV Fokker E.V Halberstadt D.II Hannover CL.II Hannover CL.III Hannover CL.IV Hannover CL.V Hansa-Brandenburg W.12 Hansa-Brandenburg W.29 Junkers D.I Kondor D.6 Kondor E.III Naglo D.II Pfalz D.III Pfalz D.XII Pfalz Dr.I Pfalz E.I Pfalz E.II Phönix D.I LFG Roland D.II LFG Roland D.VI Siemens-Schuckert D.I Siemens-Schuckert D.II Siemens-Schuckert D.III Siemens-Schuckert D.IV Zeppelin-Lindau D.I
Bombers and ground attack	AEG DJ.I AEG G.I AEG G.II AEG G.III AEG G.IV AEG G.V AEG J.I AEG J.II AEG R.I Friedrichshafen G.II Friedrichshafen G.III Gotha G.I Gotha G.II Gotha G.III Gotha G.IV Gotha G.V Gotha GL.VII Gotha G.IX Hannover CL.II Junkers CL.I Junkers J.I Rumpler G.I Rumpler G.II Rumpler G.III Siemens-Schuckert L.I Zeppelin-Lindau Rs.II Zeppelin-Lindau Rs.III Zeppelin-Lindau Rs.IV Zeppelin-Staaken R.VI
Reconnaissance	AEG B.I AEG B.II AEG B.III AEG C.I AEG C.II AEG C.III AEG C.IV AEG C.V AEG C.VI AEG C.VII AEG C.VIII AGO C.I AGO C.II AGO C.III AGO C.IV AGO C.VII AGO C.VIII Albatros B.I Albatros B.II Albatros C.I Albatros C.III Albatros C.V Albatros C.VII Albatros C.IX Albatros C.X Albatros C.XII Aviatik B.I Aviatik B.II Aviatik C.I Aviatik C.VI DFW C.V LFG Roland C.II LVG B.I LVG C.II Rumpler C.I Rumpler C.IV Rumpler Taube
Trainers	Euler D.I
Prototypes	Albatros C.II Fokker V.1 Fokker V.2 Junkers J 1 Junkers J 2 Zeppelin-Lindau Rs.I