Flight Report Fw 190/711
Nr. 5
Werk Flughafen 

Condition: Engine BMW 801 D2/25543.
Old fan with wide rectangular blades or
new fan with narrow rectangular blades.
Tight engine cowling
Split flaps with reinforced actuator
Armament: 2 MG 17, two MG 151 (without ammunition).
MG FF belt hatches.
Maintenance-free undercarriage pre load springs.
Operable wheel doors.
Flap actuator without synchronization and coasting
(no take-off position).
Armored ring mounting in accordance with BSK 897
Oil cooler 140 x 6/7 with 10 mm air outlet gap
without cover.

1. Recording the pressure before and the pressure drop in the radial cylinder with the old and new fans in climb and level flight.
2. px and Δ px as a function of rpm and ram pressure at different heights.
3. Check of oil temperatures with low power and very low outside air temperatures.

1. As a preliminary investigation for the aircraft with GM 1 - accessory (non-pressurized liquid) the cooling pressure gradient was measured with two different fans in climb and level flight at combat power (n-2400 U / min). The recorded values of the cooling pressure gradient for the old fan are, for unknown reasons, lower, compared to the measured results, laid down in Flight Report 190/711 No. 2, to be precise in climbing corrected to 0 m height by 50 mm water column. An increase of 40 mm water column was achieved with the new fan, (see graph) so that the installation of this fan in the GM 1 machine is well worth it.
2. The cooling pressure gradients obtained in level flights at steadied speeds with various rpm are shown on the attached graph for the corresponding altitudes. The speeds obtained here correspond to the plotted values in Flight Report 190/711 No. 2.
3. On the basis of a complaint by the troops, after which the motor runs with too cold oil at very low outdoor temperatures, the oil temperatures were determined with stock oil cooler thermostat (switching temperature ~ 57°) compared to Rö 11 with a switching temperature of 65 +/- 5° for 8000 m altitude with low power:

    190/711 Production thermostat
Production radiator 140 x 7/8
Cooling air outlet gap 10 mm without cover
HB = 8000 m, n = 1700 rpm, tL = - 40°, töKA=48°
    190/711 Production thermostat
Production radiator 140 x 7/8 with cover
Cooling air outlet gap 10 mm with stock cover
HB = 8000 m, n = 1700 U/min, tL = - 40°, töKA=54°
    190/382 New thermostat (switching temperature 65 + - 5 °)
Experimental cooler 140 x 6/7
Cooling air outlet gap 15 mm with stock cover
HB = 8000 m, n = 1700 U/min, tL = - 40°, töKA=58°

  Although a direct comparison is not possible due to the different conditions and the different machines, the following statement can be made: In spite of the radiator 140 x 6/7 with better cooling effect as well as the 15 mm air gap, the cooler outlet temperature is ~ 4° higher when using the new thermostats and when using a 10 mm gap should be increased so far, that the installation of the proposed Rechlin 3 mm cooling air gap does not seem necessary.
Since the steady-state temperatures were flown at high altitude with relatively low ram pressure, slightly lower oil temperatures are to be expected at similar temperatures and flights near the ground. However, please note that the oil is heated up by another ~ 5° prior to the engine inlet and that this temperature is shown by the standard Fw-measuring point. Further experiments in these areas are to be conducted with the GM 1 - machine.

Langenhagen, 7 June 1943


Flugbericht FW 190/711 Nr. 5 (pdf)

Translation by Jörn Dietrich and Mike Williams

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