The Pfalz D.VIII was one of a pair of Pfalz biplane fighters powered by the same Seimens-Halske engine, and was produced in small numbers during 1918.
In 1917 Pfalz produced their first purpose built triplane, the Pfalz Dr.I. This had an elegantly streamlined fuselage, and a very impressive rate of climb, but it used a new engine, the 160hp Seimens-Halske Sh.III counter-rotary engine. Normal rotary engines had a fixed crankshaft which the crankcase and cylinders rotated around. The propeller was normally attached to the crankcase and thus rotated at the same speed as the engine. However to get most power out of the engine it had to rotate at a higher speed than the most efficient speed for the propellers. On the Sh.III the cylinders and crankcase rotated at 1,800rpm in one direction, and were connected by bevel gears to the crankshaft, which rotated at 900rpm in the opposite direction, thus reducing the speed of the cylinders and crankcase to 900rpm. As a result the overall speed of the propeller was reduced to 900rpm, where the propeller was more effective. As a result aircraft powered by the Sh.III such as the Pfalz Dr.I had a high rate of climb. However the slower speed of rotation meant that the flow of cooling air was also reduced, so the Sh.III was prone to overheating.
The Dr.I was ready for evaluation by the start of 1918, but its triplane configuration increased drag and interference between the wings, and it was slower and less manoeuvrable than the Fokker triplane and also slower than Allied fighters.
The problems with the Dr.I had been obvious during 1917, and Pfalz responded with two related biplane designs, the D.VII and D.VIII. Both used the Sh.III engine and a fuselage that was very similar to that of the Dr.I. By this point Pfalz had a successful biplane in production, the sesquiplane D.III, but they chose to develop more standard biplane wings for the two new fighters. On both aircraft the upper wing had a span of 7.52m and the lower wing a span of 6.98m, while both had a chord of 1.30m. The D.VII was a single bay biplane, while the D.VIII used a stronger but heavier twin bay wing.
The prototype D.VIII underwent its type tests at Adlershof in January 1918. Like the D.VII the prototype had unbalanced ailerons on the upper wing, and a balanced rudder. However while the D.VII was tested unarmed, the D.VIII was given two Spandau LMG 08/15 machine guns carried above the engine. It used a Wotan four bladed propeller, which was manufactured in a single piece.
Pfalz entered three designs in the First Fighter Competition at Adlershof in February 1918 – the D.VIII, D.VII and D.VI (an earlier biplane powered by an Oberursel rotary engine). The D.VI was eliminated because it was too slow, while engine problems meant that the D.VIII was unable complete. The contest was won by the Fokker D.VII and Pfalz D.VII.
However the Idflieg decided to carry out further tests with the two related Pfalz designs, with the winner to be chosen by the result of static load tests, which would reveal which could cope better with aerial combat. This time the D.VIII won, and was ordered into production. However problems with the Sh.III meant that only 120 D.VIII were ordered, with serial numbers 100/18 to 219/18.
Some production aircraft differed from the prototypes by using a propeller that was built by combining a pair of two bladed propellers. This was easier to build, but slightly heavier.
The first of these aircraft reached the front in April 1918, but they didn’t enter front line service until June, when examples were serving with Jasta Boelcke, Jasta 29 and Jasta 56. Little is know about its performance in combat, but it was entered in the Second Fighter Competition of May-June 1918. Pilot compared it to the Siemens-Schuckert D.IV, which used the same engine. The D.VIII was reported as having the same speed and rate of climb but being less manoeuvrable. The pilots recommended using in on Kampfeinsitzer Staffeln or home defence flights, where its excellent speed would make it a good interceptor.
Fourteen aircraft were reported at the front on 30 June 1918 and 19 on 31 August 1918.
Details of its combat record are unclear as it was used in units that operated several types of aircraft and didn’t record which aircraft pilots were using when they scored victories. It was flown by the air Paul Baumer when he served with Jasta Boelcke in the summer of 1918. He was injured when crashing a Pfalz D.VIII on 29 May 1918 and didn’t return to action until September 1918. He was then shot down, but was able to parachute to safety.
At least one Pfalz D.VIII (157/18) was given the new 200hp Goebel Goe.III rotary engine during the summer of 1918. This was another experimental engine that was used in several designs, but appeared too late to reach combat.
Engine: Siemens-Halske Sh.III
Span: 7.52m (upper), 6.98m (lower)
Empty weight: 542kg
Loaded weight: 767kg
Max speed: 180km/ hr
Climb Rate: 1.5min to 1,000m, 11.1min to 5,000m