The Pfalz D.XV was the last, and probably the best, fighter design produced by Pfalz, but was about to reach the front when the war ended and thus never got a chance to prove itself.
Throughout the war Pfalz designs had appeared later than similar Fokker designs, and had generally proved to be inferior to them. This was the case with the last Pfalz aircraft to enter large scale production, the Pfalz D.XII. This aircraft had used twin bay biplane wings developed from those of the French SPAD S.VII, and had been powered by a 160hp Mercedes engine, with a nose radiator. It was a clear improvement on the Pfalz D.III and D.IIIa and other older fighters still in use when it entered service in the summer of 1918, but was clearly inferior to the Fokker D.VII, which had beaten it into service by several months. As a result the D.XII earned a reputation as a second rate aircraft and was normally unwelcome when it reached the front line.
The D.XV was produced in an attempt to close the gap with the Fokker machine. It was powered by the superior 185hp BMW IIIa engine which improved its speed. The fuselage was similar to that of the D.XII, but the biggest changes came in the wings. The Fokker D.VII had thick wings with a rounded front, which meant that it gave plenty of warning before going into a stall. In contrast the Pfalz used the same thin wings as most First World War aircraft, which gave very little warning before stalling (the same was true of many Allied fighters). As a result pilots of the Fokker D.VII were more willing to push their aircraft to its limits as they knew they’d get plenty of warning before the stall. Pfalz responded by giving the D.XV wings that were thicker than on the Pfalz D.XII although not as thick as on the Fokker D.VII. Unlike on most biplanes, the lower wing was mounted below the bottom of the fuselage.
The overall layout of the aircraft went through a number of changes. Pfalz ‘experimental D.XV No.1’ had single streamlined I struts between the wings and simple wire bracing. The lower wing was connected to the fuselage by a small keel. It was powered by a 180hp Mercedes D.IIIa engine. The wings had square tips, with horn balanced ailerons on the upper wing.
On Pfalz ‘experimental D.XV No.2’ the I struts were replaced with more conventional N struts, which were less streamlined but also gave the pilot a better view. The lower wing was connected to the fuselage by struts. The wing bracing had been removed, reducing drag. The wings remained the same.
The next prototype, Pfalz D.XVf serial number 8364/17, was powered by the 185hp BMW IIIa engine. Unlike the earlier experimental aircraft and later production aircraft it had rounded wingtips without horn balances on the ailerons.
Production aircraft kept the BMW engine but reverted to the rectangular wings with horn balanced ailerons on the upper wings. They used the N struts, the lower wing was connected to the fuselage by struts, and there were no bracing wires.
Production of the D.XV began in October 1918. It completed its type tests on 4 November, and some of the production aircraft may have reached the supply depots before the end of the war. However none entered combat. Austro-Hungary had also been interested in the type and had planned licence construction of it, but those plans also ended with the war.
The D.XV was reported to be fast and manoeuvrable, and the equal of the excellent Fokker D.VII. However it never had a chance to prove itself in combat, so its true capabilities remain unknown.
After the war at least one D.XV reached Argentina, where it was used for barnstorming by Max Holtzem, a Pfalz acceptance test pilot and Pfalz D.IIIa combat pilot. Examples were also examined by the French.
Engine: BMW IIIa
Span: 8.6m upper, 7.2m lower
Chord: 1.45m upper, 1.2m lower
Empty weight: 738kg
Loaded weight: 928kg
Max speed: 200km/ hr
Climb Rate: 2min to 1,000m, 16min to 5,000m
Armament: Two machine guns