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Fokker F.I / F.II

Страна: Германия

Год: 1919

Fokker - V39/V40 - 1918 - Германия<– –>Fokker - FG-1 - FG-4 - 1919 - Германия

A.Weyl Fokker: The Creative Years (Putnam)

The transport monoplane, V.44 and V.45

   The post-war development of air transport in Germany had been foreseen in 1917. In that year the Deutsche Luftreederei, a transport enterprise, had been founded by a powerful shipping combine in conjunction with the A.E.G. This company announced that passenger and mail transport services would be organized immediately after the war ended.
   When the Armistice was signed, Platz at once started work on the design of an aeroplane specifically intended for passenger transport. In the early post-war months, most of the would-be transport companies in Germany and elsewhere were content to convert the plentiful unwanted bombers or reconnaissance aircraft by adding seats, ashtrays and, occasionally, a cockpit canopy. However, a few of the less conventional German designers shared Platz’s opinion that transport aeroplanes had to be specifically designed for their purpose. These were Junkers, where Mader and Reuter developed an excellent all-metal monoplane, Dornier, Dorner, and Sablatnig. All these firms had constructed aircraft with enclosed cabins; all but the Dorner were monoplanes. The Sablatnig product was a parasol monoplane designed by Seehaase.
   Platz’s first project was the V.44, a parasol monoplane rather like an enlarged Fok. D.VIII with a 185-h.p. B.M.W.IIIa engine. It had seats for six passengers arranged in three side-by-side pairs; the passengers were expected to climb over the fuselage side to enter the cockpit.
   While the V.44 was under construction Platz discovered one morning that some practical joker had put into the nearly-completed fuselage a sign-board announcing “Facklam’s Sight-seeing Excursions”. Facklam was the alcoholic proprietor of a modest transport undertaking at Schwerin; he operated an antique horse-drawn char-a-banc with open seats. This vehicle spent most of its time as the transport for proletarian pub-crawls, and had a reputation all its own.
   Platz was dismayed to see his new passenger transport treated with such facetiousness. But on reflection he realized that the unknown wag had done him a service: this aircraft was too primitive for its purpose. The V.44 was abandoned without more ado. It was replaced by a new design, the V.45, which had a completely enclosed cabin for the passengers. The wing of the V.44 was adapted for use on the V.45. The V.44 fuselage was subjected to a series of strength tests and then scrapped.
   In the V.45 the rear spar of the mainplane rested on the upper longerons, but the front spar was supported by two typical tripods of struts. This arrangement facilitated access to the pilot’s cockpit, which was open; there was no connecting door to the passenger cabin.
   Work on the V.44 had begun in December 1918. Owing to various circumstances of a non-technical nature, nearly a full year elapsed before Parge made the first test flights of the V.45. The V.44 was to have been named Fokker I or F.I; the V.45 was therefore designated Fokker F.II.
   Parge was delighted with the new aeroplane and was soon at home in it. He took up nine passengers on one occasion, a considerable load for the 185-h.p. B.M.W.IIIa.
   Platz suggested he should try to loop the F.II when flying it solo. Parge tried several times but failed. The aircraft would begin each attempted loop in normal response to the controls but, instead of going over the top, it would put the nose down on its own and dive gently out, even with the stick held firmly back.
   On the next flight Platz accompanied Parge to try for himself, using the dual controls. Platz was more muscular than Parge, but even their combined forces on the stick failed to coax the F.II over the top.
   Under the new regulations, passenger-transport aeroplanes had to obtain a Certificate of Airworthiness, after being technically approved by the D.V.L. (the German Research Establishment for Aeronautics) at Adlershof. The D.V.L. were prepared to accept a comprehensive stress analysis in lieu of a test to destruction in their laboratory. Platz was reluctant to submit his own stressing: he thought the D.V.L. would ridicule his home-made methods and reject his stress analysis. He therefore cautiously suggested that the D.V.L. send one of their experts to prepare the necessary stress analysis at the firm’s expense. Hoff, now director of the D.V.L., readily obliged, and sent Dipl. Ing. Bethge.
   Bethge was surprised to discover that the Fokker F.II was not only of adequate strength with a comfortable factor of safety, but also economically designed; that is to say, no component was unnecessarily large. However, he raised two minor objections related to the adequacy of the undercarriage structure, and told Platz that it might be necessary to redesign part of it. He was nonplussed when Platz proved conclusively from his own stress assumptions that his calculation was at fault: the central inverted-V members of the four-strut undercarriage legs were, contrary to Bethge’s assertion, sufficiently strong. Before they could buckle, the landing impact would be dissipated into the other struts of the structure, consequently the central connexions to the lower longerons were adequate.
   Bethge reported his findings to Hoff, who was so surprised that the Fokker designer now possessed more reliable stressing methods than the D.V.L. that he urged Platz to write a paper on the subject. This was too much for Platz: overwhelmed by the suggestion, he hastily declined.
   After its approval by the D.V.L., the prototype F.II was flown to Holland by de Waal. A second aircraft was already under construction. De Waal had arrived at Schwerin in disguise, and members of the Workers’ Council helped him to get away in the F.II. On the way to Holland he had three emergency landings owing to engine trouble; Fokker saw the F.II for the first time after it had been damaged by de Waal in making yet another forced landing, this time on Dutch soil.
   When de Waal told him about the F.II’s excellent flying qualities and remarkable performance, Fokker became enthusiastic. The business-man in him was quick to see the possibilities that lay before this latest creation by Platz. He sent Platz a most flattering testimonial: this was the only testimonial or expression of appreciation that Platz ever received from Fokker.
   In his autobiography Fokker wrote:
   “But while I was still in Germany, we built the first really commercial cabin aeroplane, the F-2 (sic), and had it secretly flown over to Holland by de Waal.”
   Apart from the fact that Fokker was not in Germany while the F.II was being built, it is necessary to add that the aircraft was by no means the first “really commercial cabin aeroplane”. In England, the B.A.T. F.K.26 had flown in April 1919. Nearer at hand and more directly comparable was the Junkers F.13, powered by a 185-h.p. B.M.W.IIIa, which had flown on June 25, 1919; on September 13, 1919, in an officially observed flight, it climbed to 6-75 km. (22,200 ft.) with eight people on board.
   The Deutsche Luftreederei soon became interested in the Fokker F.II; their pilot Harry Rother was asked to try the aircraft. In Holland Fokker found it easy to introduce the new transport aeroplane. The Koninklijke Luchtvaart Maatschappij, now internationally known as K.L.M., began operations on May 17, 1920. On the same day, Fokker personally demonstrated the F.II before the Press and the public with all his brilliant showmanship. Afterwards Parge made passenger flights with various highly-placed personages aboard. The occasion was a great success.
   Orders for F.II aeroplanes were immediately placed with the Dutch Fokker firm; these were executed at Schwerin. By September 1920, the K.L.M. had taken delivery of two F.II aircraft. One was flown to Croydon on September 30 by W. G. R. Hinchliffe, K.L.M.’s chief pilot; his passengers were Albert Plesman, later to become President of K.L.M., Henri Hegener, and S. Elleman, a Fokker works mechanic. In addition, the aircraft carried fuel for seven hours. The flight to Croydon took just over three hours; fuel consumption was 118 litres per hr. (26 gals, per hr.). In England the F.II was much admired.
   The prototype V.45 was later acquired by the Dutch Rijksstudiedienst voor de Luchtvaart (Aeronautical Research Establishment) as a flying laboratory. It was extensively used by Dr. van den Maas for his important experimental work. This historic aircraft was still flying up to the outbreak of the Second World War.

Description of the Fokker F.II

   In some of its features the F.II wing was identical with that of the Fok. D.VIII. It was covered entirely with plywood. The ailerons originally had no horn balances but were modified at an early stage, before the prototype was flown to Holland.
   The spars by themselves had a load factor of 7 in Case A; the plywood skin raised this to 9 for the whole wing. The maximum wing thickness was 63 cm. (24-8 in.); and the wing weighed 350 kg. (775 lb.). It was secured by only four steel bolts.
   Side-by-side seats for two pilots and dual control were provided in the crew’s cockpit, which was a short distance aft of the engine. For the ailerons Platz provided wheel control, as had been used on all heavier German military aeroplanes at the end of the war. The pilots’ cockpit was open and was entered from the outside via external steps. A small window in the bulkhead wall provided a means of communication with the passenger cabin.
   This cabin was underneath the wing. It had seats for four passengers, two of whom sat facing rearwards with their backs against the bulkhead behind the pilots’ cockpit. There were three Triplex-glass windows in each side of the cabin; all could be opened. The door was in the port side.
   The stern of the fuselage was deep, and no fin was required; the rudder was a squat, balanced surface. The tailplane was braced to the lower longerons, and horn-balanced elevators were fitted.
   In designing the fuel system, Platz avoided pressurized tanks to minimize trouble with leaks and the risk of fire in the event of a crash. The main tank, of 330-litres (73-gals.) capacity, was situated under the front seats of the passenger cabin but insulated by a fume-proof bulkhead. From this tank, fuel was transferred by a small hand-operated Allweiler petrol pump to the 50-litre (11-gal.) gravity tank just behind the engine. The pump could be operated from either seat in the pilots’ cockpit, and the contents of the gravity tank could be read from a stand glass. This arrangement was simple but perfectly reliable.
   The undercarriage had four struts on each side to distribute the landing loads into the fuselage structure. To prevent the wheels from sinking into soft ground Platz fitted a form of double wheel. In this, two standard rims placed side by side were spoke-braced to a common hub. Existing accessories and components could therefore be used, and the double wheel created little more drag than the more conventional wheel. Fokker was very pleased with this idea.
   In 1925 a batch of modified Fokker F.II aeroplanes were built under licence arrangements in Germany for the Deutsche Aero Lloyd airline company. The wings were made by the Albatros Works, while the fuselage construction and final assembly were undertaken in the workshops of the Deutsche Aero Lloyd at Staaken aerodrome. Modification design work was in the hands of Karl Grulich, designer of the Harlan types and many Gotha aeroplanes. The workshops were under the supervision of H. Jeannin, formerly of the Argus Engine Co.
   The Aero Lloyd F.IIs had the 230-h.p. B.M.W. IV engine. They had no cabane struts and were genuine high-wing monoplanes. The crew compartment was neatly incorporated in front of and below the wing, and access to it was via a door from the passenger cabin. The undercarriage had only three struts on each side, and more substantial wheels were used. The speed of this version was 125 km./hr. (77-5 m.p.h.) with a load of 794 kg. (1.750 lb.).
   These Fokker F.IIs and some F.IIIs were extensively flown in the service of the Deutsche Lufthansa on German internal routes. No pilot was promoted to be captain of a passenger aircraft unless he had airline experience on the Fokker F.II.

J.Herris, J.Leckscheid Fokker Aircraft of WWI. Vol.5: 1918 Designs Part 1: Prototypes & D.VI (A Centennial Perspective on Great War Airplanes 55)

Fokker V44 & V45

  The Fokker V44 was essentially an enlarged V43 powered by a 185 hp BMW IIIa having a wing span of 20 m and length of 13 m. The V45 (work number 1500) was a more advanced aircraft, also powered by a 185 hp BMW IIIa, with enclosed cabin for the pilot and passengers. V45 was slightly smaller and more streamlined than the V44 and was the prototype of the production Fokker F.II transport.

Fokker V45 Specifications
Engine: 185 hp BMW IIIa
Wing: Span 17.24 m
Area 42.0 m2
General: Length 11.63 m
Height 3.67 m
Empty Weight 1200 kg
Loaded Weight 1900 kg
Maximum Speed: 150 km/h
Endurance: 7 hrs

J.Stroud The World's Airliners (Putnam)

The Netherlands has played a great part in the development of aviation and two names stand out as symbols of Dutch achievement. They are KLM as the world’s oldest airline to retain its original name and Fokker as a great aircraft manufacturer.
   Fokker developed a system of welded steel-tube fuselages and tail units married to deep ply-covered wood-framed wings and used these constructional methods for a series of outstanding transport aeroplanes which were in production until 1935 and in service until after the 1939 45 war. Most of these Fokker transport monoplanes were single-engined or three-engined, but there was one twin-engined type and two types with four engines. All but one of these aircraft had non-retractable undercarriages.
   First of the Fokker transports was the V.44 (F.I) with open cockpits, but its construction was abandoned in favour of the V.45 (F.II) which had an enclosed cabin for four passengers and a two-seat open cockpit. Like all the subsequent inter-wars Fokker transports it was a high-wing monoplane with thick-section wing covered by plywood. The fuselage was a welded steel structure with fabric covering. The original engine was a 185 hp BMW IIIa water-cooled unit but production examples had various kinds of engines including the 240 hp Siddeley Puma.
   The prototype F.II was built in Germany, made its first flight in October 1919, and in March 1920 was flown to the Netherlands. The type was subsequently produced in Amsterdam and Germany and it appears that about two dozen were built. F.IIs served KLM Royal Dutch Airlines, Deutsche Luft-Reederei, Deutscher Aero Lloyd, Lufthansa, Sabena and, on charter, DDL Danish Air Lines, and one was still in the Lufthansa fleet at the end of 1936. The prototype survived until the German invasion of the Netherlands in 1940.

A.Weyl - Fokker: The Creative Years /Putnam/
The Fokker V.45 or F.II at Schwerin.
J.Herris, J.Leckscheid - Fokker Aircraft of WWI. Vol.5: 1918 Designs Part 1: Prototypes & D.VI /Centennial Perspective/ (1)
The V45 (Works Number 1500) was given the German civil registration issues in May 1920. The V45, powered by a 185 hp BMW IIIa, was the prototype commercial aircraft from which the Fokker F II production aircraft was derived. In contemporary documents and publications, the V45 is also referred to as 'V1' or 'F I', where the letter 'V' here stands for 'commercial aircraft'. The crew was one or two pilots with four or five passengers. (Peter M. Grosz Collection/STDB)
J.Herris, J.Leckscheid - Fokker Aircraft of WWI. Vol.5: 1918 Designs Part 1: Prototypes & D.VI /Centennial Perspective/ (1)
For the transfer to the Netherlands, the V45 was given a modified livery and the lettering 'Fokker.' The V40 is at left. (Peter M. Grosz Collection/STDB)
J.Stroud - The World's Airliners /Putnam/
Lufthansa’s German-built Fokker F.II Weichsel.
A.Weyl - Fokker: The Creative Years /Putnam/
Wing spars of the Fokker F.II.
A.Weyl - Fokker: The Creative Years /Putnam/
Fuselage stern and tailplane of the Fokker F.II.
A.Weyl - Fokker: The Creative Years /Putnam/
Fokker V.45