Focke Wulf FW 190, vol. I

Focke Wulf FW 190, vol. I

On the afternoon of January 19, 1937  a glistening aircraft flew, engine roaring, over Newark airport in the suburbs of New York. Reflecting the sun’s rays on its smooth fuselage, it descended at full throttle toward the tarmac to pass between two masts that served as a control gate.

The many applauding onlookers in the grandstand jumped to their feet, their shouts drowning the fading hum of the engine. Hats went up, while the radio commentators, shouting one over another into their microphones, tried to reach the listeners over the general uproar: “Howard Hughes has established a new speed record! A distance of 2,490 miles from Los Angeles covered in just 7 hours, 28 minutes and 25 seconds! Unbelievable! The fastest man in the world...”
Professor Kurt Tank of the audience was watching amazed the landing racing aircraft owned by American eccentric billionaire Howard Hughes. Although his H-1 was propelled by a radial engine and did not feature a streamlined bullet-like body, the great engine power aided by other aerodynamic features made it one of the fastest aircraft on earth. Tank’s attention was also attracted by the wide wheel track, allowing safer landing. The German aircraft designer, who was then looking for an inspiration to create his own incredible machine, reached an enlightenment. The entire audience only saw one of the many experimental toys for breaking records, but Kurt Tank was the only individual in this crowd who saw the future creation of his life in his imagination – the Focke Wulf FW 190 fighter aircraft – a terrible weapon which would change the status quo in aircraft engineering. This vision kept haunting him for the next several years, equipping him with a great persistence and the patience of a man who is certain of the potential of his design.

 

FW 190 V1 in the assembly room. Despite its streamline shape, the tunel spinner failed to improve the cooling of the BMW 139 engine [photo via Marian Krzyżan]


The new German fighter appearing in the second half of 1941 – the FW 190 – became another obstacle in the Allies’ advance towards victory. This unusually agile, fast and heavily armed aircraft was from the very beginning the curse of the RAF and the pride of the Luftwaffe. The bloody fights to exhaustion saw the FW 190 defeated not because of its inferior quality but a great enemy advantage in number. Therefore, it still is a surprising fact today that two years earlier one of the best WW2 fighters should have been unwanted. It was partly due to the Germans already having their “wonderful weapon” in the form of the Messerschmitt Bf 109, and offering the Luftwaffe one more fighter – which, on top of that, existed only on paper – seemed a crazy idea. Not a soul in 1941, and even more so before the war, suspected that this fighter, modeled on an American racing design, would soon become the symbol of German power...
* * *
The FW 190 saw the light of day thanks to the great tenacity and Herculean toil of a single man – professor Kurt Tank. This charismatic, natural-born leader gathered a team of talented engineers around him. Among his helpers was an equally skilled engineer, Rudolf Blaser, who worked with him on a single-engined high-wing monoplane, the FW 159 fighter, and the twin-engined FW 187 Falke. Both constructions were propelled by Junkers Jumo inline engines but proved inferior to Willi Messerschmitt’s designs.
When the Messerschmitt Bf 109 fighter began to equip the Luftwaffe, it was announced a “wonder of technology”. The unquestionable success was undoubtedly owed to the Daimler Benz inline engine, which allowed the Bf 109 to receive a very streamlined body and attain higher speeds. It was in accordance with the constructional trends of the period, with preference for inline engines, which offered less drag and, as a result, attaining higher speeds. Speed was considered the most important quality of a thoroughbred fighter.
The radial engine was not the choice in most countries for, along with greater power, it gave greater aerodynamic drag. It was commonly considered an anachronism from the times of WW1 which was only suitable for the obsolete biplane and which on top of that greatly hampered visibility during take-off and landing. The German engineers were not the only ones who believed that a metal low-wing monoplane should be fitted with an inline engine. Great Britain’s engineers conceived the fast Supermarine Spitfire and agile Hawker Hurricane – both fitted with Rolls-Royce Merlin inline motors. The French also preferred this type of power plant for their Morane Saulnier 406 fighter, fitting it with a Hispano Suiza and, for further improvement of the aircraft’s aerodynamics, they used a glycol cooler partly embedded into the fuselage. Also in Soviet Russia work on new aircraft generally assumed the use of inline engines, which resulted in such aircraft as the Yak-1, MiG-1 or LaGG-3.

 The Breme factory assembly room. The employees are very busy  working on FW190A-1, which confirms great demand with frontline units  [photo via Marian Krzyżan]



Quite the opposite was true of the trends across the Atlantic, in the United States. A fast development of the much lighter air-cooled radial engine also resulted in streamline cowlings for this type of power plant, which greatly improved the aircraft’s aerodynamics. That made these engines much easier to maintain (compared to inline engines), having no complex cooling installations. It was of particular importance to the US Navy: having a shorter length, these engines allowed concentration of a greater number of aircraft onboard aircraft carriers. The greatest contributor to the promotion and development of radial engines was American company Pratt&Whitney, which willingly sold licenses for its products, and this was how the production of radials was launched in early 30s at the German BMW.
In the autumn of 1937 the Reich’s Ministry for Air (Reichsluftfahrministeruim – RLM) ordered the Technical Department (Technisches Amt) to come up with guidelines for a new fighter aircraft. The RLM people were perfectly aware of the fact that one type of fighter with the Luftwaffe might be insufficient in case of an unavoidable military conflict. On top of that, the RLM was notified by the intelligence that other superpowers were going to equip their air forces with at least two types of modern fighter aircraft. Therefore, in the spring of 1938 aircraft factories received the guidelines for a new fighter aircraft that was in the future to join the Bf 109 in combat. As Daimler Benz was working at the top of its capacity, hardly keeping up to its engine delivery schedules, the specs were given to Focke Wulf Flugzeugbau AG in Bremen, a factory preferring radial engines.
Kurt Tank knew that radials were especially liked in Italy, where they were successfully used on newly built Fiat and Macchi aircraft. But the Italian products could provide insufficient power, just like the French Gnôme Rhône, which only encouraged spiteful smiles on the faces of German designers. However, apart from easier handling, radial-fitted fighters were also more resistant to damage. Therefore Italian fighters left a deep imprint on the memories of British airmen in fights over Greece and North Africa.
An even greater surprise to the Allied pilots came from Japan, where the outstanding Mitsubishi A6M Zero carrier-borne fighter was ­introduced into service and outclassed all the enemy constructions over the Pacific in 1941-1942, proving that the proper use of the radial engine could result in high speeds. Apart from its well-designed radial engine, the Zero had a very light construction, and its incredible agility and armament of 20 mm cannons let it quickly rid the Pacific sky of enemy aircraft. Its entering service over China in 1940 supported Tank’s arguments in the promotion of his own novel design.

 Lower part of the FW 190 fuselage. Two main fuel tanks were mounted in these nitches by means of special tapes  [photo via Marian Krzyżan]


When Kurt Tank presented the initial guidlines of his design, it turned out that he would have to fight a real bureaucratic battle for his project. The man responsible for equipping the Luftwaffe at the time was a famous WW1 ace, General Ernst Udet, a very good friend of Willi Messerschmitt, the latter owing him very much. Now all signs seemed to be showing that Tank’s construction was going to die before ever seeing the world. However, disturbing bills that Udet received from the RLM forced him to verify his initial aversion to radial-propelled fighters.
Udet’s biased attitude changed when it came out that the Heinkel 100 and 112 that were being designed turned out to be unsatisfactory constructions and series production was given up. Even more disturbing was that the two chief manufacturers of water-cooled inline engines – Junkers in Dessau and DaimIer-Benz in Stuttgart-Unterturkheim – were unable to increase production volumes in the nearest future and deliver the required number of motors for the hurriedly built aircraft. In view of the problems with production of one type of inline engines used for different aircraft, it was a masterstroke to launch production of a radial-fitted fighter. It allowed manufacture of new aircraft without troubling the factory with engine delivery-related issues, as happened in the case of the He 111. Owing to this unexpected coincidence, the design submitted to the RLM by Kurt Tank was eventually approved.
An engineer team was detached for further development of the project, which was designated FW 190, for Kurt Tank was then technical director at the factory and was unable to devote himself to only one project. But he constantly supervised the team led by engineer Rudolf Blaser, who was assisted by engineers Willi Käther and Ludwig Mittelhuber as well as the chief of design department, engineer Andreas von Fählmann.
In the summer of 1938 the RLM placed an order for three prototypes propelled by the powerful 18-cylinder BMW 139 air-cooled engine. It was a new product from the BMW that had been developed by combining two 9-cylinder banks taken from the BMW 132 engine. This unit delivered a maximum power of 1550 HP (1140 kW), which definitely surpassed the inline DB 601 or Jumo 211. If the design proved satisfactory, it would help avoid overload to the production lines and the Daimler Benz engine delivery schedule. As if by irony, the FW 190 design, which Kurt Tank named Würger (Shrike) and which owed its origin to the BMW engine, almost ceased to exist due to this very power plant.


 FW 190A-1 at Rechlin airfield. RLM 74/75/76 camouflage is well visible [photo via Marian Krzyżan]


Design work was put in full swing and a wooden model was soon ready, whereupon a prototype began to be built in the fall of 1938. The new aircraft was an all-metal low-wing, cantilever monoplane of a semimonocoque construction with a fully retractable landing gear. The high power delivered by the BMW 139 was also a drawback of a kind – a problem resulted with effective cooling of the aircraft. To resolve this issue, a special tunnel spinner was used which covered the engine air inlet in order to increase the flow of cooling air and at the same time reduce the pressure drag.
The design work was accompanied by great enthusiasm. For the FW 190 was a real masterpiece when still on the designers’ desks. The body worked out by Kurt Tank was elegant, streamlined, of a strong construction, and at the same time very simple. Therefore, soon noone doubted the potential of the aircraft, which Kurt Tank intended to fit with a BMW engine.
The first unit was hand-made. Each piece of metal was cut out and formed using dies, though it was already assumed that the aircraft would be mass-produced.
The prototype fuselage (and later also production aircraft) was a duralumin semimonocoque construction divided into two segments. The entire fuselage consisted of fourteen frames reinforced by perpendicular longerons. Both segments were assembled separately and then joined with rivets. The rear fuselage segment was combined of three matching parts – two side ones and a bottom one. Under the floor were two self-sealing fuel tanks of 524 liters. With special attention put to the pilot’s safety, the windshield on the production aircraft was a steel welded frame which held a 50 mm thick armor pane in the front and laminated glass panels on the sides. The sliding canopy was made of formed plexi spread over a light steel tube frame. A 12 mm thick armor plate was fixed to the canopy behind the pilot’s head. Besides, three additional armor plates of 5 mm were mounted behind the seat of 8 mm sheet metal.
The wings were a two-spar construction – the main web spar ran along the entire length, the rear spar consisted of two parts. The separate (upper and lower) wing surfaces were riveted on and then joined with formed leading edges. Rounded wing tips were added on during the final stage of assembly, being fixed with bolts. The Focke Wulf’s both wings were first assembled together, and then fixed to the bottom part of the fuselage, whereas each of the Messerschmitt Bf 109’s wings was fixed to the fuselage independently. To save power and speed, the bolts connecting the wing unit to the fuselage were covered with a streamlined plate. The landing gear legs, with oleo-pneumatic shock absorbers, were fixed to the main spar. Initially, a hydraulic landing gear retraction and extension mechanism was used, but soon it was replaced by a very efficient electromechanism that retracted it into bays closed by two-piece formed sheet metal covers. The tire ­pressure could be adjusted depending on the aircraft load between 4.5-5.5 atmospheres. The wings featured split landing flaps covered with sheet metal only on the bottom side. Electromachanically controlled, they had a maximum angle of 60o. The slotted ailerons were a metal structure covered with fabric. The trimming strips could be adjusted on the ground, and they were controlled by a system of pushers.
The metal tail unit was a separate part. The horizontal stabilizers were fully cantilevered, with a tapered contour and rounded tips. The sheet metal control surfaces were set in motion by an electromechanism. The single fin was a semimonocoque construction consisting of two halves joined along the symmetry axis. Its spar was placed askew and, with transverse longerons, it was the mount of the tail wheel, which was released by a clever spring mechanism. The wheel was established in a fork with oleopneumatic shock absorption. It was only retracted halfway with a steel cord activated by the right landing gear leg. The tire pressure was adjusted between four and five atmospheres.
As time would soon show, the FW 190’s strong construction could endure even the worst conditions. Every feature of the plane reflected Kurt Tank’s principles – the construction was to be simple, and its components were to be strong. What mattered was reliability and usefulness. When the prototype was being finished, noone must have suspected that it was the top item of the FW 190 family genealogical tree that would comprise 20,000 machines.
The first prototype, FW 190V1 (W.Nr. 0001), left the Bremen factory in May 1939. It was registered under the civil code of D-OPZE and sent for ground tests. The chief Focke-Wulf test pilot, Flugkapitän Hans Sander, performed initial ground tests, which revealed the engine’s tendency to overheat. It was probably intensified by the lack of cooling fan that had still not been installed. As to taxying on the wide landing gear of the FW 190V1 over the factory airfield
tarmac, it was real pleasure, considering similar maneuvers with the Bf 109. No disturbing symptoms were noticed, and on June 1, 1939 the FW 190V1 took off on its maiden flight. Kurt Tank’s theory was now to be finally tested in practice.
When the aircraft disconnected from the ground and began to perform the obligatory test maneuvers, a crowd of interested engineers gathered on the apron. The first flight allowed them to assess the aircraft’s characteristics. Sander felt both admiration and disappointment. The FW 190V1 displayed excellent piloting features, offering accurate responding to the control surfaces’ movements, although the ailerons needed to be redesigned. Despite this, the aircraft was very agile, and the engine power effectively compensated for the greater aerodynamic drag. Backward visibility was just perfect, and a fantastic speed of 595 km/h at 4,000 m was achieved. The most important, however, was that the main concept – a combination of body harmony, high-performance engine and wide landing gear – proved excellent.

FW 190A-8 of JGr 10. RLM 74/75/76. Parchim airfield (Germany), Autumn of 1944 [Drawings Arkadiusz Wróbel]


Still, the tunnel spinner turned out to be a complete misapplication – the engine tended to overheat and the cockpit temperature rose to 55°C. Later, Hans Sander stated that while flying he “felt as if both feet were kept in a stove”, but at the same time that he was “flying the most beautiful aircraft of those times and the delight in flying the FW 190 was the only memory that remained of this first flight” – a very positive statement, indeed, notwithstanding an unpleasant surprise experienced during the first flight. A great amount of exhaust fumes entered the cockpit through the numerous leaks, and only by immediate use of oxygen mask did he save himself from asphyxia. It was imperative to seal the cockpit.
After a few test flights and slight modifications, the FW 190V1 was sent to the Luftwaffe’s main test and development center at Rechlin. The tests completed there confirmed both the good and bad sides of the new construction, and it is noteworthy that the Rechlin center was the most important advisory body to the RLM. Next, the aircraft was sent back to the manufacturer for the required modifications, the chief one being correction of the cooling installation. As any prototype, the FW 190V1 needed much more time for its construction to be elaborated and series production to be prepared. Of course, mutual accusations were not avoided – Tank accused the engine manufacturer of having delivered a faulty product, while the BMW blamed the engineers for having failed to design a correct cooling system. In the meantime the aircraft was re-registered from civil to military – first as WL-FOLY, and later as FO+LY.
The first thing the engineers did was to check the performance of the tunnel spinner. For this, they used the wind tunnel, and it soon turned out the item did not allow the necessary air flow inside the engine. Besides, its contribution to reduced pressure drag was minimal, so it was eventually given up and replaced by a standard small spinner for protection of the propeller hub. Still, this failed to solve all the issues and the unreliable BMW 139 engine retained its tendency to overheat. Now, the only reasonable solution was to intensify the air flow by employing a ten-bladed fan placed just behind the spinner.
All these innovations were applied to the FW 190V1 and used when building the second prototype, FW 190V2 (W.Nr. 0002, FO+LZ), which became airborne for the first time on October 31, 1939. Aside of the new “regular” spinner and a fan behind, the FW 190 was the first aircraft in history to be armed with MG 17 cal. 7.9 mm and MG 131 cal. 13 mm machine guns. This allowed shooting tests at the Tarnewitz center firing ground. […]

 

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