Fokker D.VII

The Fokker D.VII was a German World War I fighter aircraft designed by Reinhold Platz of the Fokker-Flugzeugwerke. Germany produced around 3,300 D.VII aircraft in the summer and autumn of 1918. In service with the Luftstreitkräfte, the D.VII quickly proved itself to be a formidable aircraft. The Armistice ending the war specifically required Germany to surrender all D.VIIs to the Allies at the conclusion of hostilities.[1] Surviving aircraft saw continued widespread service with many other countries in the years after World War I.

Development and production


Fokker's chief designer, Reinhold Platz, had been working on a series of experimental planes, the V-series, since 1916. These planes were characterized by the use of cantilever wings. Junkers had originated the idea in 1915 with the first all-metal aircraft, the Junkers J 1, nicknamedBlechesel ("Sheet Metal Donkey" or "Tin Donkey"). The resulting wings were thick, with a rounded leading edge. This gave greater lift and more docilestalling behavior than the thin wings commonly used at the time.

Late in 1917, Fokker built the experimental V 11 biplane, fitted with the standard Mercedes D.IIIa engine. In January 1918, Idflieg held a fighter competition at Adlershof. For the first time, frontline pilots would directly participate in the evaluation and selection of new fighters. Fokker submitted the V 11 along with several other prototypes. Manfred von Richthofen flew the V 11 and found it tricky, unpleasant, and directionally unstable in a dive. In response to these complaints, Reinhold Platz lengthened the rear fuselage by one structural bay, and added a triangular fixed vertical fin in front of its Fokker Dr.I-like "comma" shape, all-moving rudder. Upon flying the modified V 11, Richthofen praised it as the best aircraft of the competition. It offered excellent performance from the outdated Mercedes engine, yet it was safe and easy to fly. Richthofen's recommendation virtually decided the competition, but he was not alone in recommending it. Fokker immediately received a provisional order for 400 production aircraft, which were designated D.VII by Idflieg.

Fokker's factory was not up to the task of meeting all D.VII production orders. Idfliegtherefore directed Albatros and AEG to build the D.VII under license, though AEG did not ultimately produce any aircraft. Because the Fokker factory did not use detailed plans as part of its production process, Fokker simply sent a completed D.VII airframe for Albatros to copy. Albatros paid Fokker a five percent royalty for every D.VII built under license. Albatros Flugzeugwerke and its subsidiary, Ostdeutsche Albatros Werke (OAW), built the D.VII at factories in Johannisthal(designated Fokker D.VII (Alb)) and Schneidemühl (Fokker D.VII (OAW)), respectively. Aircraft markings included the type designation and factory suffix, immediately before the individual serial number.

Some parts were not interchangeable between aircraft produced at different factories, even between Albatros and OAW.[2] Additionally each manufacturer tended to differ in nose paint styles. OAW produced examples were delivered with distinctive mauve and green splotches on the cowling. All D.VIIs were produced with the lozenge camouflage covering except for early Fokker-produced D.VIIs, which had a streaked green fuselage. Factory camouflage finishes were often overpainted with colorful paint schemes or insignia for the Jasta, or the individual pilot.

Albatros soon surpassed Fokker in the quantity and workmanship quality of aircraft produced[citation needed]. With a massive production program, over 3,000 to 3,300 D.VII aircraft were delivered from all three plants, considerably more than the commonly quoted but incorrect production figure of 1,700[citation needed].

In September 1918, eight D.VIIs were delivered to Bulgaria. Late in 1918, theAustro-Hungarian company MÁG (Magyar Általános Gépgyár - Hungarian General Machine Company) commenced licensed production of the D.VII with Austro-Daimler engines. Production continued after the end of the war, with as many as 50 aircraft completed.[3]

Powerplants


Many sources erroneously state that the D.VII was equipped with the 120 kW (160 hp) Mercedes D.III engine. The Germans themselves used the generic D.III designation to describe later versions of that engine. In fact, the earliest production D.VIIs were equipped with 170-180 hp Mercedes D.IIIa. Production quickly switched to the intended standard engine, the higher-compression 134 kW (180-200 hp) Mercedes D.IIIaü. It appears that some early production D.VIIs delivered with the Mercedes D.IIIa were later re-engined with the D.IIIaü.

By the summer of 1918, a number of D.VIIs received the "overcompressed" 138 kW (185 hp) BMW IIIa, the first product of the BMW firm. The BMW IIIa followed theSOHC, straight-six configuration of the Mercedes D.III, but incorporated several improvements. Increased displacement, higher compression, and an altitude-adjusting carburetor produced a marked increase in speed and climb rate at high altitude. Because the BMW IIIa was overcompressed, using full throttle at altitudes below 2,000 m (6,700 ft) risked premature detonation in the cylinders and damage to the engine. At low altitudes, full throttle could produce up to 179 kW (240 hp) for a short time. Fokker-built aircraft with the new BMW engine were designated D.VII(F), the suffix "F" standing for Max Friz, the engine's designer.

BMW-engined aircraft entered service with Jasta 11 in late June 1918. Pilots clamored for the D.VII(F), of which about 750 were built. However, production of the BMW IIIa was very limited and the D.VII continued to be produced with the 134 kW (180 hp) Mercedes D.IIIaü until the end of the war.

D.VIIs flew with different propeller designs from different manufacturers. Despite the differing appearances there is no indication these propellers gave disparate performance. Axial, Wolff, Wotan, and Heine propellers have been noted.

Operational history


The D.VII entered squadron service with Jasta 10 in early May 1918. When the Fokker D.VII appeared on the Western Front in April 1918, Allied pilots at first underestimated the new fighter because of its squarish, ungainly appearance, but quickly revised their view. The type quickly proved to have many important advantages over the Albatros and Pfalz scouts. Unlike the Albatros scouts, the D.VII could dive without any fear of structural failure. The D.VII was also noted for its high maneuverability and ability to climb at high angles of attack, its remarkably docile stall, and its reluctance to spin. It could literally "hang on its prop" without stalling for brief periods of time, spraying enemy aircraft from below with machine gun fire. These handling characteristics contrasted with contemporary scouts such as the Camel and SPAD, which stalled sharply and spun vigorously.

However, the D.VII also had problems. Several aircraft suffered rib failures and fabric shedding on the upper wing. Heat from the engine sometimes ignited phosphorus ammunition until cooling vents were installed in the engine cowling, and fuel tanks sometimes broke at the seams. Aircraft built by the Fokker factory at Schwerin were noted for their lower standard of workmanship and materials. Nevertheless, the D.VII proved to be a remarkably successful design, leading to the familiar aphorism that it could turn a mediocre pilot into a good one, and a good pilot into an ace.

Manfred von Richthofen died only days before the D.VII began to reach theJagdstaffeln and never flew it in combat. Other pilots, including Erich Löwenhardt and Hermann Göring, quickly racked up victories and generally lauded the design. Aircraft availability was limited at first, but by July there were 407 on charge. Larger numbers became available by August, when D.VIIs achieved 565 victories. The D.VII eventually equipped 46 Jagdstaffeln. When the war ended in November, 775 D.VII aircraft were in service.

Postwar service


The Allies confiscated large numbers of D.VII aircraft after the Armistice. The United States Army and Navy evaluated 142 captured examples.[4]Several of these aircraft were re-engined with American-built Liberty L-6 motors, very similar in appearance to the D.VII's original German power plants. France, Great Britain, and Canada also received numbers of war prizes.

Other countries used the D.VII operationally. The Polish deployed approximately 50 aircraft during the Polish-Soviet War, using them mainly for ground attack missions.[5] The Hungarian Soviet Republic used a number of D.VIIs, both built by MAG and ex-German aircraft in the Hungarian-Romanian War of 1919.[6]

The Dutch, Swiss, and Belgian air forces also operated the D.VII. The aircraft proved so popular that Fokker completed and sold a large number of D.VII airframes that he had smuggled into the Netherlands after the Armistice. As late as 1929, the Alfred Comte company manufactured eight new D.VII airframes under license for the Swiss Fliegertruppe.

Survivors


The widespread acquisition of the D.VII by Allied countries after the Armistice ensured the survival and preservation of several aircraft. One war prize was captured in 1918 when it accidentally landed at a small American airstrip near Verdun, France. Donated to the Smithsonian Institution by the War Department in 1920, it is now displayed at theNational Air and Space Museum in Washington, D.C.[7] Two other American war prizes were retained by private owners until sold abroad in 1971 and 1981. They are today displayed at the Canada Aviation Museum, in Ottawa, Ontario, and the Militaire Luchtvaart Museum in Soesterberg,Netherlands, respectively. The latter aircraft is painted in fictitious Royal Netherlands Air Forcemarkings.

A former Marine Luchtvaartdienst D.VII was discovered in a German barn in 1948. This aircraft is now displayed at the Deutsches Museum inMunich, Germany.[8]

Both Canada and France also acquired numerous D.VII aircraft. A former war prize, one of 22 acquired by Canada, is displayed at the Brome County Historical Society, in the Knowlton neighborhood of Lac-Brome, Quebec. This unrestored Albatros-built example, serial number D.6810/18, is the only surviving D.VII that retains its original fabric covering. Of the aircraft sent to France, examples are today displayed at theRoyal Air Force Museum in Hendon, England,[9] and the Musée de l'Air et de l'Espace in Paris, France.

Reproductions


Many modern D.VII reproductions have been built. Most flyable examples are powered by Ranger or Gipsy Queen inverted inline engines. These engines must be turned upright to produce the correct thrust line, thus requiring a new oiling system. A few flying reproductions, such as the one at New York State's Old Rhinebeck Aerodrome, are equipped with original Mercedes D.IIIa engines.[10]

Variants

 * V 11 : Prototype
 * V 21 : Prototype with tapered wings
 * V 22 : Prototype with four-bladed propeller
 * V 24 : Prototype with 179 kW (240 hp) Benz Bz.IVü engine
 * V 31 : One D.VII aircraft fitted with a hook to tow the V 30 glider
 * V 34 : D.VII development with 138 kW (185 hp) BMW IIIa engine
 * V 35 : Two-seat development with 138 kW (185 hp) BMW IIIa engine and undercarriage fuel tank
 * V 36 : D.VII development with 138 kW (185 hp) BMW IIIa engine and undercarriage fuel tank
 * V 38 : Prototype Fokker C.I

Operators

 * Argentina
 * Argentine Naval Aviation (one ex-French captured aircraft postwar)


 * Austria-Hungary
 * Austro-Hungarian Navy


 * Belgium
 * Belgian Air Force
 * 9 Squadron (postwar)
 * Kingdom of Bulgaria
 * Bulgarian Air Force


 * Czechoslovakia
 * (postwar)


 * Denmark
 * Royal Danish Air Force (postwar)


 * Finland
 * Finnish Air Force (postwar)


 * German Empire
 * Luftstreitkrafte
 * Kaiserliche Marine
 * Kingdom of Hungary
 * Hungarian Air Force (postwar)


 * Netherlands
 * (postwar)


 * Latvia
 * Latvian Air Force (postwar)


 * Lithuania
 * (postwar)


 * Poland
 * Polish Air Force (postwar)


 * Kingdom of Romania
 * Royal Romanian Air Force (postwar)


 * Soviet Union
 * Soviet Air Force (postwar)


 * Sweden
 * Swedish Air Force (postwar)


 * Switzerland
 * Swiss Air Force


 * Ottoman Empire
 * Ottoman Air Force


 * United States
 * United States Army Air Service (postwar)
 * United States Marine Corps (postwar)

Specifications (D.VII with Mercedes D.III engine)
Data from [11]

General characteristics Performance Armament
 * Crew: 1
 * Length: 6.954 m (22 ft 10 in)
 * Wingspan: 8.9 m (29 ft 2 in)
 * Height: 2.75 m (9 ft 0 in)
 * Wing area: 20.5 m2 (221 sq ft)
 * Empty weight: 670 kg (1,477 lb)
 * Gross weight: 906 kg (1,997 lb)
 * Powerplant: 1 × Mercedes D.III 6-cyl. water-cooled in-line piston engine, 120 kW (160 hp)
 * or 1 × 130.5 kW (175 hp) Mercedes D.IIIa 6-cyl. water-cooled in-line piston engine
 * or 1 × 137.95 kW (185 hp) BMW IIIa 6-cyl. water-cooled in-line piston engine (240hp rating at low level, emergency only, risk of engine damage.)
 * Maximum speed: 189 km/h (117 mph; 102 kn)
 * BMW IIIa engine - 200 km/h (124 mph)
 * Service ceiling: 6,000 m (19,685 ft) [12]
 * Rate of climb: 3.92 m/s (772 ft/min)
 * BMW IIIa engine – 9.52 metres per second (1,874 ft/min)
 * Time to altitude:
 * 1,000 m (3,281 ft) in 4 minutes 15 seconds (1 minutes 40 seconds w/ BMW IIIa)[13]
 * 2,000 m (6,562 ft) in 8 minutes 18 seconds (4 minutes 5 seconds w/ BMW IIIa)[13]
 * 3,000 m (9,843 ft) in 13 minutes 49 seconds (7 minutes 0 seconds w/ BMW IIIa)[13]
 * 4,000 m (13,123 ft) in 22 minutes 48 seconds (10 minutes 15 seconds w/ BMW IIIa)[13]
 * 5,000 m (16,404 ft) in 38 minutes 5 seconds (14 minutes 0 seconds w/ BMW IIIa)[13]
 * 6,000 m (19,685 ft) (18 minutes 45 seconds w/ BMW IIIa) [13]


 * Guns: 2 × 7.92 mm (.312 in) LMG 08/15 "Spandau" machine guns