Like the V.1, the V.4 triplane was a rotary-engine machine with unbraced cantilever wings of thick airfoil section, supported by plywood double-box spars. Unlike the V.1, however, the triplane had wings covered with fabric rather than plywood. With its short wingspan, short fuselage and a vertical tail surface that was all rudder, the Fokker proved to be very maneuverable, and its three wings endowed it with a superlative rate of climb. In its original form, the triplane was devoid of interplane bracing. After the wingspan was subsequently lengthened, the action of the ailerons tended to flex the upper wing, so simple, planktype interplane struts had to be added.

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In late June 1917, Leutnant Werner Voss, then acting commander of Jasta 14, test-flew the Fokker triplane prototype at Schwerin and was extremely enthusiastic about it. He recommended it to Manfred von Richthofen, then commander of Jagdgeschwader (JG) I, Germany’s first permanent fighter wing. On July 18, Richthofen, who was recuperating from a head wound suffered on July 6, wrote his superiors from the hospital, demanding to know why the Fokker triplane was not in production.

Unknown to Richthofen, the Fokker had already proved itself by far the best of all prototypes the Germans had developed in response to the Sopwith Triplane scare, and Idflieg had placed an order on July 14 for 20 Fokker F.Is, as the type was initially designated. On July 26, Richthofen informed his pilots that they would soon be receiving new Fokker triplanes that are maneuverable as the devil and climb like monkeys. On August 11, a refined version of the F.I, redesignated the Dr.I, was approved for full-scale production.

The first two preproduction Fokker F.Is, bearing the serial numbers 102/17 and 103/17, were issued to Richthofen and Voss, respectively. Neither plane lasted very long. Richthofen scored his 60th and 61st victories with F.I 102/17, but on September 15, the Baron’s friend OberLeutnant Kurt Wolff, commander of Jasta 11 and a 33-victory ace, was killed while flying it, shot down by Flight Lt. Norman M. MacGregor of Naval 10. Ironically, by that time the British squadron had traded in its Tripehounds for a new, more potent biplane design by Herbert Smith-the Sopwith Camel.

Voss, then commanding Jasta 10 in Richthofen’s JG.I, flew F.1 103/17 for the first time on August 28. Delighted with his new mount, he went on a rampage, shooting down nine enemy aircraft by September 11. On September 23, Voss scored his 48th victory, but he was killed later in the day in an epic, single-handed dogfight against seven SE-5a’s of No. 56 Squadron, a crack RFC unit. In the course of his last fight, Voss executed seemingly impossible maneuvers and damaged all of his antagonists’ machines.

The spectacular performance of Voss’ new Fokker triplane was as jarring to the British as their Sopwith Triplane had previously been to the Germans. Unfortunately for the Germans, that advantage was to prove short-lived. On October 30, 1917, Leutnant Heinrich Gontermann, commander of Jasta 15 and a 39-victory ace, was killed when the top wing of his new Fokker Dr.I 115/17, disintegrated. The next day, Leutnant Gnther Pastor, a pilot from Jasta 11, was killed under similar circumstances in Dr.I 121/17.

All Fokker triplanes were promptly grounded. Upon investigation, it was found that the main wing spar was more than sufficiently strong, but the attachments of the ribs, wingtips and ailerons were weak. Worse yet, there was evidence of poor quality control in both the doping of the fabric and the varnishing of the wooden wing components, causing wood rot in the wingstructure after a short time.

The Fokker triplanes would remain grounded until redesigned and better constructed wings could be fitted. German pilots then continued to fly them with great success during the first half of 1918, but the rapid tempo of aircraft development had caught up with the Dr.I, and only 320 were built. Fast-climbing and maneuverable though they may have been, the triplanes were only effective when engaged on their own terms. With a top speed of only 102 mph, they were simply too slow, due to interference drag between the three wings. Occasional structural failures continued to occur as well, one instance of which put Richthofen’s brother Lothar in the hospital on March 13 1918.

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