Flight Report Fw 190/711
Nr. 2
Werk Flughafen 



Engine BMW 801 D2/25543
Close engine cowl
Split cowl flaps with reinforced drive linkage, with a pre-load of 40 kg at 0° angle.
Split cowl flap adjustment manually by E-motor and automatically by thermostat.
Armament: 2 MG 17, 2 MG 151, MG FF belt hatches.
C-rear fuselage with 1:1,3 differential from 15.1.43.
Landing gear pre-load  spring from 26.1.43.
Cylinder temperature measuring equipment.
Pressure drop in the radial cylinder block Δ px
Pressure in front of radial cylinder block px


1.) Cylinder temperatures in climb and level flight with combat power, depending on the split cowl flap opening angle.
2.) Assessment of the thermostatic split cowl flap control.
3.) Landing gear speed limits for the landing gear with pre-load springs in comparison to the standard production pneumatic pre-load system.
4.) Level speeds with combat power.


1.) For comparison with the cylinder temperature of the previously flown Fw/0028, data in climb and level flight was initially determined for the split flaps positions "open" and "closed.

The results: tzyl = 255 / 260° for climb with combat power and split flaps closed, and tzyl = 220° with flaps fully open, showed good agreement with the measured temperatures of 0028 (Comparison report: "Fw 190 with split flaps from 9.6.42 "). Level flight values were determined at 1,640 feet (500 meters) with tzyl max = 180° or 175° and at 26,247 feet (8000 meters) with tzyl max = 200° or 190° for split flaps "closed" or "open". This shows that the cooling effect of the split flaps in level flight is minor but increases somewhat with increasing height. This fact is, however, not relevant, since the split flaps remain closed in level flight at all altitudes, even in the tropics.

Further investigations, such as the determination of the temperatures in climb with split flap opening angle between 0° and 40° and the determination of, - without exceeding the maximum permissible cylinder temperatures, - flap opening angle for best climb speed at the time period 1.11.42 – 1.2.43, are incorrect and do not appear in this report. From 1.11.42 on the measured temperatures were up to 50° below the level determined at the start of testing. Frequent checking of the measurement equipment, recalibration and replacement of the indicators did not change the result. Only the use of a highly sensitive precision instrument on 1.2. resulted in an improvement and the temperatures were so determined in their old magnitude. (comparison graph of 1.2., and 7.10.).

2.) The first test with thermostatic split flap control with a sensor for 90° control temperature was negative. The position of the sensor, chosen because of the low control temperature of the thermostat, between cylinder head and engine cover, was subject to strongly fluctuating air flows, depending on the size of the split flap opening angle, which caused active swinging of the flap. The testing will now be conducted with a homemade thermostat with a much higher control temperature. The cylinder temperature measuring pin of cylinder 4 was chosen for the location, which causes the indicated temperature of this cylinder to appear somewhat lower.

3.) The established speeds for the production landing gear
When retracting =   270 mph (435 km/h),
When lowering =   146 mph (235 km/h),
With maintenance-free spring,
When retracting =   224 mph (360 km/h),
When lowering <   124 mph (200 km/h),
Thus, the spring pre-load seems to be stronger. The force-displacement diagrams are still being created and will appear in the next report.

4.) In comparison with the level flight speeds with covered gills (winter emergency equipment) documented in Report No. 1, the speeds were flown at altitude with split flaps closed and plotted on the attached graph, corrected for CINA-conditions. There were no significant differences.

Wenzendorf, 6 February 1943

Level speeds with combat power


Flugbericht FW 190/711 Nr. 2 (pdf)

Translation by Jörn Dietrich and Mike Williams

© 2013  WWIIaircraftperformance.org.  All Rights Reserved