Monday, 18 April 2016

Focke-Wulf Fw190 + Dora - some facts. Part 4 - Compiled by German Dzib

Trainer versions

Fw 190 A-5/U1 — Several old Fw 190 A-5s were converted by replacing the MW 50 tank with a second cockpit. The canopy was modified, replaced with a new three-section unit that opened to the side. The rear portion of the fuselage was closed off with sheet metal.
Focke-Wulf Fw190S-8 Trainer version
Fw 190 A-8/U1 — A similar conversion to the A-5/U1.
Fw 190 S-5 — A-5/U1 trainers re-designated.
Fw 190 S-8  A-8/U1 trainers re-designated. An estimated 58 Fw 190 S-5 and S-8 models were converted or built. (42)

Combat history

The Fw 190 participated on every major combat front where the Luftwaffe operated after 1941, and did so with success in a variety of roles. Luftwaffe pilots who flew both the Fw 190 and the Bf 109 generally felt that, with the exception of high altitude capability, the Fw 190 was superior.

Production

A 0.40 km² (100 acre) Focke-Wulf plant east of Marienburg was bombed by the Eighth Air Force on 9 October 1944. (43) In addition, one of the most important sub-contractors for the radial-engined Fw 190s was AGO Flugzeugwerke, which from 1941 through to the end of the war produced enough Fw 190s to earn it major attention from the USAAF, with the AGO plant in Oschersleben being attacked at least five times during the war from 1943 onwards.

FW 190, Dora Series

The Focke-Wulf Fw 190 is widely regarded as Germany's best fighter aircraft of World War II. Its appearance in the skies over France in August 1941 was a rude shock to the Allies, as it was clearly superior to any other plane. For nearly a year, the Fw 190 was the unmatched champion of the air war in Europe. The Fw 190 had speed and high altitude performance as its two great assets.
The development of advanced allied fighters resulted in the Fw 190 D–9 variant which first saw service in September 1944. This variant had a larger nose that housed a more powerful Junkers Jumo engine that produced 2,100 hp with the MW-50. The D-9 was designed for high altitude aerial combat and is a worthy adversary to the P-51D Mustang.

Introduction

The D for Dora variant of the famous Fw 190 fighter was nicknamed the Long-Nose by German pilots as well as the Allies. It was a departure from the radial-engine earlier variants and featured a more powerful inline engine, which gave the aircraft its characteristic long-nose shape compared to the iconic Fw 190A. While experts may still argue about the Dora's looks, the performance gains were clear. While the earlier variants excelled at lower altitudes but suffered higher up, at the most crucial altitudes where Allied bombers operated, the Long-Nosed 190 could easily match the best the Allies had to offer at all altitudes.
The Focke-Wulf Fw 190 is not just one of Germany's greatest fighter planes; it is perhaps one of the famous aircraft of the entire Second World War. Featuring many advances and innovations, it broke new ground in terms of pilot comfort, ease of use, and versatility. First appearing in 1941, it was a rude awakening fighter of the time, the British Spitfire Mk V. In the skies over France, it had no equal for many months as the British scrambled to produce its to the Allies, easily outclassing the best-Allied answer, the Spitfire Mk IX almost a year later.
The work on the D series began in 1942. As the new Junkers Jumo 213 engine offered clear improvements in performance, the decision was made to use it with the 190 airframe. While Kurt Tank, the Fw 190's lead designer preferred the Daimler-Benz DB 600 series, the engines were already used in Messerschmitt fighters, while a surplus of the Jumo 213 bomber engines were readily available. The brand-new 213, an improvement on the earlier Jumo 211, offered 1,750 hp (1,287 kW) of take-off power that could be boosted up to an astonishing 2,100 hp (1,508 kW) of emergency power with MW-50 injection.
While originally intended to serve as a bomber interceptor, changing realities of the war in the air meant that by the time the Dora entered production in August of 1944, it mostly saw combat against enemy fighters or in a ground attack role.
The earliest pre-production variants designated D-0 had the external wing guns removed; this was often reversed and future D variants were produced with the wing guns. Most D-9s intended for lighter anti-fighter role were still built without the outer wing guns, featuring a pair of 13mm MG 141 machine-guns and twin 20mm MG 151/20E cannon.
Initial opinion of the upcoming Dora was not very high. Kurt Tank always stated that the D-9 was intended only as an interim stop-gap until a more perfect Ta-152 design could enter production. However, once Luftwaffe pilots got their hands on the stop-gap Long-Nosed Dora, they were pleasantly surprised. The performance and handling was good. When flown by capable pilots, the aircraft was more than a match to Allied fighters.
The Long-Nosed Dora is considered the best mass-produced late-war Luftwaffe fighter. In total, over 700 Doras were produced out of a total Fw 190 production run of over 20,000.
To this day it remains one of the most recognizable shapes in the skies, and one of the most influential aircraft designs of the entire aviation era.

Cockpit

The cockpit in the FW 190D-9 was a revolutionary design that attempted to put all levers and instruments easily within reach. It was one of the first examples of ergonomic cockpit design, and can be seen as the early precursor of today's hands on throttle and stick (HOTAS) cockpits.

3D model of Fw 190 D-9

The 3D model is a very precise and accurate of the Fw 190 D-9 that includes:
Full animated surfaces such as flaps, canopy, landing gear, stabilizers, ailerons, etc.
Multiple-texture maps, normal and specular maps, about 80,000 triangles construction.
Damage model includes flight surfaces that can be torn off, bullet holes and structural damage.
Several authentic paint schemes.

Flight Dynamics Model

The flight dynamics of the Fw 190 D-9 are a further develops the Advanced Flight Model principles started with the Su-25 and then later improved to Professional Flight Model (A-10C, P-51D etc.).
A multi-segmented wing provides natural damping; and each aerodynamic surface has a number of airspeed-sensitive points for accurate slipstream effect calculation. Slipstream location and direction depends on plane speed, angle of attack, angle of sideslip, prop thrust and wing lift. All prop side effects, such as slipstream, torque, P-factor are taken in account in overall flight model.
A true thermodynamic engine model for all engine modes from idling to maximal power is provided.
Jumo-213 had its own, very distinctive combination of a variable performance supercharger controlled with a complicated regulator to maintain constant air mass flow. Low power ratings were controlled with a second throttle directly linked to the engine lever. This throttle was used for emergency operation in the case of Engine Control Unit (MBG) malfunction.
The second original feature was that fuel flow was programmed and was a function of engine lever position as the airmass flow regulator maintains the necessary mixture strenght.
The engine model truly simulates all these features providing authentic engine responce to the throttle and ambient conditions.
The second ("slow") model is used for engine start-up and stop. The true thermodynamic model is used for each stroke of each cylinder, providing individual firing in cylinders, natural plane rocking during the start, over-priming, in-flight prop stop, etc.

Fw 190 D-9 Systems

The control system uses differential bell cranks that transfer control movement near the center position into finer control surface movement, while control movement is magnified as the controls approach their limit.
The flight stick can be moved forwards and backwards in conventional fashion to control the elevator. It can be moved 20 degrees forward and 21 degrees rearward. The flight stick can also be moved sideways to control the ailerons in conventional fashion. Aileron deflection is limited by mechanical stops in the control stick mounting base. Flap position is controlled via push buttons on the left-hand side of the cockpit.

Landing Gear

The landing gear is of the inward retracting type, with the main wheels being housed ahead of the front spar when raised. The tail wheel is semi-retractable and is interconnected with the main wheels to synchronize retraction which is achieved by electrical means. The gear is extended or retracted electrically. A cable attached to the right main landing gear unit also retracts the tail wheel simultaneously with the main gear.
The main gear consists of two shock struts, with a scissors unit connecting the upper and lower shock strut members to absorb torque stresses. Each main gear strut is operated individually by a drive unit powered by an electric motor mounted on the main spar. A conventional tail wheel is also provided. It can be rotated 360 degrees and has a centering lock. 

Brake System

The Fw 190 D-9 has hydraulically operated brake shoes on each of the two main wheels. Each has its own hydraulic pump and brake lines. Each wheel can be braked individually. The entire system is conventionally operated via rudder pedals. 

 Engine

The Fw 190 D-9 is powered by a Junkers Jumo 213A-1 engine, a 12-cylinder liquid-cooled inverted inline Vee. The Jumo 213 features a single stage, two speed supercharger and an automatic manifold pressure regulator. The engine drives a three-blade constant-speed propeller.

Bediengerat Engine Control Unit

The Junkers Jumo 213 engine comes equipped with a "Bediengerat" Engine Control Unit. It is 
similar in function to the "Kommandogerat" command device used on BMW-801-powered earlier variants of the Fw 190. The "Bediengerat" is a hydraulic-electric mechanical multifunction integrator that dramatically simplifies engine control. While in most other contemporary aircraft the pilot had to constantly operate a slew of levers to manage throttle level, propeller pitch, fuel mixture, and supercharger stages, the "Bediengerat" takes the majority of the workload away. The pilot simply has to move the throttle lever to set the desired manifold pressure. The "Bediengerat" takes care of the rest, setting all other parameters to allow the engine to properly operate at the desired manifold pressure, given the current flight conditions.
The gauge used to monitor desired supercharger pressure is the Supercharger Pressure Gauge to the right of the front dashboard labeled ATA.
Additional controls are also available that allow for some Engine Control Unit parameters to be manually finetuned. 

Supercharger

The Junkers Jumo 213 engine is equipped with a single stage, two speed centrifugal supercharger with MW-50 Water-Methanol injection into the intake and the after cooler.

MW-50 Water-Methanol Injection

MW-50 (MethanolWasser 50) is a 50-50 mixture of methanol and water sprayed into the Fw 190 D-9's supercharger of, allowing the use of increased boost pressures.
The MW-50 tank has a capacity of 115 liters (85 kg). The primary effect of the mixture spray is its anti-detonant effect, which is how the increase in boost pressure is achieved.
The secondary effect of the mixture spray is cooling of the engine.
While the primary boost-increasing effects deteriorate with altitude, the secondary cooling effects are still noticeable. Therefore, the MW-50 system can be used to cool down the engine at all altitudes in an event of an emergency.
The boost provided by the MW-50 begins to decrease in power at altitudes above 6,000 meters.
The boost increase provided by MW 50 can be described with the word "incredible".
Turning the system on immediately increases engine power by almost 100 HP due to the fact that a cooler engine can pull in more air. At the same time, turning on the MW-50 enables much higher supercharger boost levels. In optimal conditions, both effects combined increase engine power by a whopping 350…400 HP.

Fuel System

The Fw 190 D-9 has two main tanks, forward (Vorn) and rear (Hinten), both conveniently located below the cockpit floor underneath the pilot's seat. The fuel tanks and the fuel lines are self-sealing. Engine-driven pumps feed the fuel into the engine at a normal pressure of 1 to 2 kg/cm3. There is also an electrical booster pump in each of the two tanks that prevents vapor lock at altitude, provides improved fuel supply and can serve as a back-up in case of main pump failure.
There is also a primer fuel tank built into the rear fuel tank with a capacity of 3 liters. The tanks have a capacity of 232 liters (172 kg) front (Vorn) and 292 liters (216 kg) rear (Hinten).
The Fw 190 D-9 can also carry an external drop tank under the fuselage with the capacity of 300 liters.

Oil System

A 55-liyrt circular oil tank is located in the nose, protected by an armored ring. The oil cooler is also protected by the ring. Two cockpit gauges are provided, both located on the Front Dash. The Oil Temperature gauge monitors the system with the normal operating temperature range of 110...130 degrees (min – 40, max – 135 degrees). The right-hand side of the Fuel and Oil Pressure gauge monitors the oil system with the normal operating pressure of 5 – 11 kg/cm2.

Coolant System

The D-series of the Fw 190 uses the AJA 180 annular radiator with the capacity of 115 liters. It is installed in front of the engine.
The Jumo 213 coolant system has both the main system, consisting of the coolant pump, engine, radiator, and the heat exchanger; as well as the secondary system with the secondary flow pump, coolant pump, and the coolant tank. The two systems only interact within the coolant pump. The coolant system attempts to operate at the temperatures about 100°C at all altitudes. A built-in electric temperature sensor between the engine and the radiator is used to control the temperature.
Proper pressure is required in the cooling system to prevent unwanted vapor formation. Any steam that may occur is separated in the Vapor Air Separator of the coolant pump and then sent to the secondary system coolant tank where it is condensed.
However, if the boiling limit in the coolant tank is exceeded the pressure begins to rise. Therefore, the pressure and temperature gauges should be watched at all times to avoid overheating and possible engine damage. To avoid excessive pressure the cooling system has a pressure-controlled pressure regulating valve which also performs the task of maintaining pressure at greater altitudes via the evaporation of the coolant in the coolant tank.

Radio Equipment

The aircraft if equipped with a FuG 16ZY radio, a specially-designed airborne VHF transceiver. The FuG 16 can be used for in-flight communication as well as for IFF identification and DF homing. The set operates in frequency range between 38.4 and 42.4 MHz.
The FuG 16ZY can also be set to "Leitjager" or Fighter Formation Leader mode that allows it to use a special "Y-Verfahren" (ground tracking and direction finding method) via the normal headphones.
The AFN2 component of the radio set allows easy navigation to ground-based homing beacons, showing both direction and range on one simple dial.

Armament

The Fw 190 D-9 carries powerful fixed armament that consists of twin synchronized 13mm Rheinemetall-Borsig MG 131 machine guns above the engine cowling with 475 rounds per gun, and twin synchronized Mauser MG 151/20 cannon in the wing roots with 250 rounds per gun. Cockpit equipment for the armament includes the EZ 42 gunsight as well as the SZKK 4 ammunition counter.
The SZKK 4 ammunition counter is from the SZKK (Schalt- Zahl- und Kontrollkasten) family of German indicators used on many Luftwaffe aircraft during WWII. While most pilots from other air forces had to estimate the amount of ammunition remaining in their weapons, German pilots had the luxury of seeing the actual amount of ammunition in their stores right in their cockpit.
The Fw 190 D-9 is also equipped with the pioneering EZ42 gunsight that is roughly equivalent to the well-known K-14 gunsight used on the North American P-51D Mustang.
The design history of the EZ gunsight began before the war, but the Reich Air Ministry continued to focus on conventional reflector sights, installing the ubiquitous REVI sight on most aircraft. "Einheitszielvorrichtung" (Target Predictor Unit) development remained low-priority until captured US aircraft showed that the Allies had predictor gunsights in operational use. Development took two long years, with first production EZ42 units delivered in spring of 1944.
A total of 803 EZ42 was produced in total, production ceasing in March of 1945.