Fw 190 A-9

Memorandum, Neuhausen near Cottbus, 17.9.1944


Subject: Start of serial production of BMW 801 TS in Fw 190 A-9.

1.) Low oil temperature:
FW Cottbus complains, that the engine oil inlet temperatures of the 801 TS (and TU) are at about 55° C. compared to about 70° C with the 801 D 2 in climbs with climb and combat power. Die differences between individual B 1 oil coolers are up to 10° C. The actual nose ring gap difference is 9 - 16 mm, the nominal value is 4 - 6 mm. Only about 3° C higher oil temperatures were reached by reducing the nose ring gap to 4 - 6 mm.
BMW states, that the 801-engines without cold start additives can be run at all powers down to 25°C oil temperature (at high oil pressure), if the engine runs normal when doing so. The difference of the above mentioned oil temperatures between the D 2 and the TS (and TU) results from the fact, that the oil cooler for the former engine is not sufficient for hottest summer day conditions, while it is alright for the TS (and TU).
BMW has a fixed ring cover behind fan in production and cooler cover sheets in testing for achieving higher oil temperatures in winter.
2.) Air screw settings:
With the air screw settings given by BMW for the 9-12176 hub with the 9-30341 blade, Heine Holz (Heine wood), with a basic setting of 25° = 12.25 o'clock, limit low pitch 12.25 o'clock, high pitch 8.05, satisfactory results have been achieved with so far 34 TS-engines. Power test are done at 12.00 o'clock setting with climb and combat power, where engine revolutions are supposed to be 2400 ± 40 rpm. With automatic 2700 rpm have to be reached at 1.65 ata. The power checks gave a mean value of 2430 rpm with narrow bladed fans (used in TS during production start), with wide bladed fans (TS-production standard) a mean value of 2380 rpm. (Current outside temperatures 7.00 o'clock 6°C, 14.00 o'clock 22°C at 1015 to 1023 mbar).  The catching up of the revolutions during take off is controllable.
3.) Low-High supercharger gear set up:
In order to avoid power loss at the high power settings mostly used in fighters by switching between LG/HG, which is no longer power dependent on the 801 TS engines (except for the first 100 engines), BMW sets the gear change altitude to 3.8 km ± 150 m, with the boost expected to drop to about 1.15 ata at climb and combat power. The gear change altitudes flown so far with the TS engines (with BMW test setting of 4.2 km) were in between 3.1 and 3.8 km. Since the gear change altitudes have not been flown under the same conditions, FW Cottbus is going to provide BMW with further values in the near future.
4.) Fluggeschwindigkeiten:
With the TS engine a speed gain of about 30 km/h at 1 km altitude compared to the TU-engine was so far achieved. At full throttle height the indicated speed was 460 - 480 km/h, where the full throttle altitude was at 5.9 to 6.05 km.
Since it is known from flight testing, that the speed increases by about 5 km/h when the nose gap is reduced (from 20 to 10 mm), BMW has to set up a gap of 5-6 mm.
5.) Pressure point:
It is being suggested to remove the pressure point for combat and climb power on the cabins side, since it is already present in the Kommandogerät (somewhat lower forces) and the armed forces probably do not particularly appreciate it. Through that, working hourse and fuel could be saved.
6.) Fuel balance:
The introduction of the higher powered TS-engines into serial production, for which no tests results exist, will result in initially higher average fuel consumptions per aircraft for stationary set up and commissioning, which are subdivided as follows:
a.) Testing for increasing the oil temperature.
b.) Testing of full throttle heights, speeds, supercharger gear change altitude at various power settings with several aircraft. Tests for the latter point, determining the gear change altitude for fuel savings at most economic power, were without result.
c.) General training of pilots and mechanics.
d.) Determination of the proper air screw settings.
Generally it must not be overlooked that the engine with increased power requires a higher fuel consumption. On the other hand, fuel saving measures for serial commissioning have been taken:
a.) Engine warm up (without cold start additives) only up to 25°C engine oil temperature.
b.) Take off with climb and combat power instead of take off power (excess power),
c.) Possibly removal of pressure point on instrument panel.
7.) Miscellaneous:
a.) On 10.9.44 a prelimary flight report has been issued to allow approval flights.
b.) For pilots of serial commissioning a "document for commissioning the BMW 801 TS" has been created on 16.9.44, which contains the stipulation for the cooling flaps to be opened at least 30 mm for climb and take off.
8.) Summary:
From todays point of view there are no difficulties stemming from the use of the 801 TS for the achievment of the serial production programm.

Memorandum, Neuhausen near Cottbus, 17.9.1944

Translation by Jörn Dietrich and Mike Williams

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