Brief summary of the developmental history of the Fw 190 A-4
Approximately 900 Fw 190 A-4s were produced between June 1942 and March 1943. While equipped with the same BMW 801 D engine and same basic armament as the Fw 190 A-3, the Fw 190 A-4 differed from the A-3 in the use of a different radio, FuG VII up to A-3 and FuG 16 from A-4 on. This gave the A-4 a different antenna, a tail fin with a litte horn on top and a 6.5 kg increased weight. Consequently the (early) A-4 was very close to the A-3 in terms of performance. With the A-4 occured the transition from the gills to the split cooling flaps and the multi-purpose use (various U kits). The R1 designation for the FuG 16ZE variant seems to have been used by Fw originally, but doesn't seem to have made it into Luftwaffe use. However, as opposed to R6 the R1 definitely existed in (limited) numbers. The A-4 was also the subversion where the external air intakes became popular.
Trials with different variants of armament and equipment, generally with Umrustbausatz kits 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 litre 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 similar to the U8 (probably in one copy) with modernized V. Mtt-Schlos type racks for underwing fuel tanks; armament: 2x1 MG 17 and 2x1 MG 151/20E.