Halberstadt CL.IV

The Halberstadt CL.IV was one of the most effective ground attack aircraft of the First World War. It appeared on the Western Front towards the end of the German offensives in 1918. Flights of four to six aircraft flew close support missions, at an altitude of less than one hundred feet, suppressing enemy infantry and artillery fire just ahead of the advancing German troops. After these late German offensives stalled, Halberstadt CL.IVs were used to disrupt advancing Allied offensives by striking at enemy troop assembly points.

Karl Thies, chief designer of the Halberstadter Flugzeug-Werke, G.m.b.H., designed the CL.IV as a replacement for the Halberstadt CL.II. The CL.II had been developed in mid-1917 to meet the new CL (light C-type) specification for a manoeuvrable, two-seater to serve as an escort for C-type reconnaissance and photographic patrol aircraft. Powered by a 160-horsepower Mercedes D.III engine, the CL.II was tested in May1917, at Adlershof, and was found to be aerodynamically sound with fine performance. The design also permitted excellent visibility and easy crew communication because the pilot and the observer/gunner shared a common cockpit. Approximately 900 CL.IIs were built. Production continued though the summer of 1918.

The ground attack capabilities of the Halberstadt CL.II were demonstrated late in 1917 when it was deployed with great success in coordinated attacks against British forces during the Battle of Cambrai. The low-flying Halberstadt CL.IIs were an effective support weapon and a tremendous morale booster for counterattacking German troops. With this successful adaptation of the CL.II, design work began on an improved version, specifically intended for the ground attack role.

Designated the CL.IV, the new airplane had a strengthened and shortened fuselage, with a horizontal tail surface of greater span and higher aspect ratio than the CL.II. These changes, along with a one-piece, horn-balanced elevator, gave the CL.IV much greater manoeuvrability than its predecessor. Like the CL.II, its fuselage was plywood-skinned and still incorporated the shared cockpit. The CL.IV retained the 160-horsepower Mercedes D.III engine of the earlier model, although the spinner was omitted in favour of rounded cowls that enclosed the engine completely, giving the airplane a more aggressive look. Two fixed, forward-firing, Spandau machine guns could be mounted on the CL.IV, but typically only one was fitted. The observer/gunner had a Parabellum machine gun on an elevated, movable mount. Anti-personnel grenades in boxes were carried on the fuselage sides, and rows of cartridges for a Very pistol were often strapped across the rear fuselage decking. After tests were completed of the Halberstadt CL.IV prototype in April 1918, at least 450 were ordered from Halberstadt, and an additional 250 aircraft from a subcontractor, L.F.G. (Roland).

The Halberstadt CL.IV performed well in combat as a low-level attack airplane, relying on its good manoeuvrability to avoid ground fire. When not on close support or ground attack missions, it was used as a standard two-seat fighter for escort work. Towards the end of the war, on bright, moonlit nights, CL.IV squadrons attempted to intercept and destroy Allied bombers as they returned from their missions. Night sorties against Allied airfields were also made with the CL.IV.