07/20/2026. Remarks by Johan Visschedijk: "By late 1937, the design department at Fokker was already thinking about a successor to the D.XXI and the G.1. The D.XXIII single-seat fighter was unusual in employing a fore-and-aft tandem engine arrangement, the prototype being powered by two 528 hp Walter Sagitta I-SR engines. Although all-metal construction was intended, the prototype was fitted with a wooden wing of greater thickness/chord ratio in order to expedite the test program.

Carrying the manufacturers test marking X-4, the D.XXIII made its first flight on May 30, 1939, with Fokker test pilot Gerben Sonderman at the controls. After the outbreak of WW II in September, the registration was changed to 998 for at least a short period. Owing to various problems, including rear engine cooling, the flight test program was somewhat protracted and the German invasion of the Netherlands on May 10, 1940, brought the program to a sudden halt, as the D.XXIII was damaged during the bombing of Schiphol.

Since May 30, 1939, Sonderman had accumulated only four hours during the course of eleven flights. In 1941, the engines were removed and the rest was scrapped.

The proposed armament comprised two 0.311 in (7.9 mm) and two 0.52 in (13.2 mm) FN-Browning machine guns."

Span: 37 ft 8.75 in (11,50 m)
Length: 33 ft 5.5 in (10,20 m)
Height: 12 ft 5.67 in (3,80 m)
Wing area: 199.13 sq.ft (18,50 sq.m)
Loaded weight: 6,614 lb (3,000 kg)
Max speed: 326 mph (525 kmh)