FOCKE-WULF 190 A-3
Beginning in the spring of 1942, series production of a more powerful engine version BMW 801D-2 that replaced previous versions in the Fw 190Fighter created a new plane version designated as Fw 190A-3. The increase in the BMW 801D-2 engine power (to 1730 kW) was due to a higher compression ratio and higher pressure two-speed compressor. A higher compression ratio and charging pressure made it necessary to use high-octane (96 octane) C3 fuel in place of B4 (87 octane) fuel. Armament of standard Fw 190A-3 planes was the same as in the previous version. Starting from this version, A series airframes were widely used in a big development program with the aim of finding the optimum armament and equipment mix that made it possible to broaden the operational capabilities of the plane beyond fighter operations. The largest part of these modifications were in the form of Umrustbausatz kits, but some did not have special designations and can be recognized only from photographs. The total number of such modified planes is unknown. The best known are the Fw 190A-3 with an under-fuselage mounted bomb rack ETC 501 for carriage of 500 kg of bombs (1x500 kg, 2x250 kg or 4x50 kg on the ER4 adapter) or an external drop tank of 300 liters capacity for long range fighters. Some planes used only for fighter operations (without bomb racks) had a reduced armament by removal of wing mounted MG FF cannons, which was not reflected in a designation. Moreover, 72 Fw 190Aa-3 (a=auslandisch-foreign) planes were produced. These were exported to Turkey during October 1942 - March 1943. Most of them had the same armament as the A-1 version e.g. 1x4 MG 17 machine guns and 2x1 MG FF cannon, and for obvious reason there was no FuG 25 IFF device in the radio equipment.
In addition to the previously described modification kits designed for the Fw 190A-3 and later versions other kits Umrustbausatz were prepared; but we must admit that most were unrealized projects or experimental planes that existed only in one or two copies: Fw 190A-3/U1 - only one built, experimental plane (W.Nr. 130270, PG+GY) with engine mount extended for 15 cm. It was used as a prototype of the A-5 version, Fw 190A-3/U2 - underwing mounted unguided missile RZ 65 73 mm racks tested on the plane W.Nr. 130386, Fw 190A-3/U3 - reconnaissance fighter with Rb 50/30 cameras mounted in the fuselage; armament reduced by removing MG FF cannons, one built, Fw 190A-3/U4 reconnaissance fighter with two Rb 12.5/7x9 cameras mounted in the fuselage and camera gun EK 16 or miniature camera Robot II in the leading edge of the left wing root; armament as in U3 version, additional under fuselage mounted ETC 501 bomb rack with stabilizer strips for 300 liter fuel tank.
Twelve planes built, Fw 190A-3/U7 - attempt to create a new high altitude fighter, with reduced weight, with armament consisting of only two MG 151/20 E cannons. Only three planes built (W.Nr. 130528, -530 and -531); they can be recognized by external charger air inlets on both engine cowling sides.
FOCKE-WULF 190 A-4
In July 1942, the A-3 was replaced on the production lines by the newer Fw 190A-4 version. The main difference was an BMW 801 D-2 engine adapted to use with a MW 50 system for short period engine power increase by injection of a water-methanol (methyl alcohol CH3OH) mixture in the proportion of 1:1. In this way it was possible to raise engine power to 2100 kW for 10 minutes, after which a high probability of engine failure prevented longer use. Due to delays in MW 50 device production, this system was not mounted on the Fw 190A-4 engines, which had the capability to accept this system. It was not used and only A-8 and later series planes would use the advantages of this invention.
Another difference in the A-4 variant was the replacement of the FuG 7a radio set by the more modern FuG 16z. A less important change was that the vertical line antenna mount was placed on the fin; this made it easier to distinguish between A-4 and A-3 versions. In the case of the A-2 and A-3 versions, it is often difficult to tell them apart. During production, in some Fw 190s another modification was applied. In place of the ventilation slots, engine cowling shutters controlled from the cockpit were installed. The pilot could precisely control the engine temperature by regulation of the shutters. In consideration of increasing number of planes ordered another group of factories and companies started licence production (among others Fiesler in Kassel-Waldau).
Most Fw 190A-4 planes were used with reduced armament, without MG FF cannons. Trials with different variants of armament and equipment, generally with Umrustbausatz kits use, produced the following versions: Fw 190A-4/U1 - bomber-fighter with an under-fuselage mounted ETC 501 bomb rack and reduced armament (without MG FF cannons). As a result of small deliveries of BMW 801 D-2 engines in the autumn of 1943, several dozens of these planes got older C-2 version engines, Fw 190A-4/U3 - bomber-fighter with armament as in the U1 version, but with BMW 801 D-2 engine. Planes for night operation got a landing light, mounted in the leading edge of the left wing root. Designation was later changed to F-1 and in the future the plane was developed as a new attack Fw 190F version, Fw 190A-4/U4 - reconnaissance fighter with two Rb 12.5/7x9 cameras and without MG FF cannons, Fw 190A-4/U8 - long range fighter-bomber with two drop tanks of 300 liter capacity each, mounted under the wings (on the VTr-Ju 87 racks produced by Weserflug company, with duralumin fairings); bombs were placed on the under-fuselage ETC 501 rack. In an attempt to reduce weight, only two MG 151/20 E cannons were retained. This modification was a prototype of a new fighter-bomber Fw 190G version and its first variant (G-1) simultaneously. There also existed a transitional variant (probably in one copy) with modernized V. Mtt-Schlos type racks for underwing fuel tanks; armament: 2x1 MG 17 and 2x1 MG 151/20E, In addition to the Umrustbausatz modifications, from the Fw 190A-4 planes, easier to install Rustsatz (R) kits were produced. Sometimes, the set could be mounted in the field workshops but the plane could also be previously prepared in the factory for such kit application. We must refute the myth of the exceptional ease of application and interchangeability with other kits in particular planes, especially since some of them were as complicated as U kits, More than once, classification to U or R group was just for convenience, later most of the U versions was redesignated as R versions. The first kit widely used was a two tube air-to-air missile launcher W.Gr. 21 210 mm destined for destroying defence formations used by USAAF bomber aircraft. Planes so equipped were designated Fw 190A-4/R6. Some authors have told about the existence of a Fw 190A-4/R1 variant, with the FuG 16 ZE radioset and Morane type antenna installed under the left wing. Very small numbers of such planes existed, but it has not been fully confirmed that it had its own destination in U or R kits. Total production of Fw 190A-4 planes came to more than 900 .
FOCKE-WULF 190 A-5
On the basis of data collected during tests of the experimental Fw 190A3/U1, Blaser's designer team became convinced that the planned additional armament would move the plane center of gravity forward. The best solution to offset this was to move the engine forward. This was done with a 15 cm steel tube engine mount extension. This change (new engine mount) was introduced on the all production lines. This also led to an increase of the plane length to 9.10 m and gave life to the new Fw 190A-5 variant that from November 1942 replaced previous the A-4. In the A-5 also introduced small changes in the equipment (e.g. a new electrical artificial horizon and modernized oxygen respirator, and wide use of the FuG 25a IFF device). In the rear fuselage section was slightly moved back and the equipment compartment cover was enlarged. Standard armament did not change and it remained 2x1 MG 17, 2x1 MG 151/20 E , 2x1 MG FF. Proper airframe design provisions meant that the Fw 190A-5 plane was prepared from the beginning to accommodate a large number of Umrustbausatz kits
Should be all the info you need on the Fw190 A3-A4-A5
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