Halberstadt based the CLS.I on the earlier CL.IV design, with modifications including a modified wing profile of a lower curvature and a more streamlined rear fuselage. All these improvements were introduced to obtain a higher flight speed, (hence "S" in CLS standing for schnell, meaning "fast" in German). The prototype flew on 2 October 1918, but the aircraft didn't enter production due to the Armistice.[1]
Halberstadt had plans for derivatives of the CLS.I armed with 3.5 cm (1.378 in) revolver cannon, the CLS II and CLS X, but these designs never left the drawing board by the end of World War I.[1]
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Cowin, H.W. (2000). German and Austrian aviation of World War I : a pictorial chronicle of the airmen and aircraft that forged German airpower. Oxford: Osprey Pub. ISBN1-84176-069-2.
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