[Test Pilot]

We have more details and we know the differences in the motor setups.

The top speed on SL can not grow from 540 km/h up to 560 km/h just because you have radiator flaps. If you have ever seen the radiators flaps of the Fw-190 and you have a little bit knowlege of aerodynamics you will see that the jump from 540 up to 560 km/h is something different.

An ETC 501, the bomb rack of a Fw 190 for exampel reduces the top speed up to 10-13 km/h. Compared with the radiator flaps the bomb rack is directly in he wind. So why should the flaps have an effect that reduces the top speed nearly 10 km/h more?

In early 1942 the BMW 801-D2 was derated and the A-3 made 540 km/h on SL. With the raise of the loading pressure in Summer 1942 upt to 1.42 ata the A-3 made 560 km/h on SL. The top speed of 565-567 Km/h on SL is a result of the updated BMW 801D-2 in summer 1943.

Still i cant see any info about motor update. From 1942 till 1943 BMW 801 D-2 got 1.42 Ata 2700 RPM only upgrade which is known is C3 injection which rise bost pressure for 1.65 Ata and have major inpact in speed at sea level. See also Fw 190 A-8 - there is still the same motor with 1.42 Ata 2700 RPM and some of these version use C3 injection ( which was upgrade for H blower also) or MW 50.

Initialy Fw 190 A-3 had derated engine for 1.35 Ata 2450 RMP. You could compare Fw 190 Aa-3 data at steigt und kamp. :

0km - 520 km/h
5,7 km - 630 km/h
7 km - 620 km/h

And these should be performance of derated Fw 190 A-3 version. These confirm RAF test of Faber derated Fw 190 A-3 ( with very good condition) which reach even little worse results.

Really i didnt saw any confirmation that Fw 190 A-4 reach 560 km/h even with manually operated colling slots. So it could be also just 550 km/h comparing to Fw 190 A-3 with fixed slots with only 10 km/h incrase. The only reliable data which i found was for Fw 190 A-5 and A-6 with 1.42 Ata 2700 RPM

A-5
0km - 567 km/h
6.3 km - 656km/h

A-6
0km - 565 km/h
6,3km- 651 km/h



Still there is a question what really casue speed incrased in Fw 190 A-5 comparing to A-3/A-4 early. I suppose these could be colling slots and longer airframe - it is possible that they reached ~25 km/h incrase using the same engine settings ( still 1.42 Ata , 2700 RPM)

German manual of Fw 190 A-5 state:




Start und Notle. - 1.42 Ata 2700 RMP
0km - 560 km/h
6.3 - 660 km/h

Steig und Kamp - 1.32 Ata 2400 RMP
0km - 530 km/h
5.9 km - 634 km/h

These really are close for Fw 190 Aa-3 ( export version) data and could explain rise of speed due to longer airframe and manualy cooling slots in A5. Remember that at higher atlitutde drag is lees then lower that why could be not much difference in speed at high altitudes.