Flight Report Fw 190/528
High Altitude Fighter
Bad Eilsan 
  Take-off: Landing: Duration: Pilot:
16.8.42 1045 1130 45' Märschel
18.8.42 1000 1056 56' Siedenbiedel
18.8.42 1221 1259 38' Märschel
21.8.42 1054 1142 48' Siedenbiedel

Condition of the machine:
Weight G = 8,025 lbs (3640 kg)
Engine BMW 801 D/2 fully rated
Machine painted, not polished
Armament 2 x MG 151 without MG FF and without MG 17
Split flaps to regulate the cooling air flow
Exterior air intake.
Tight engine cowling

1.) Determination of the rate of climb with open and closed split flaps at cruise, combat and take-off power.
2.) Determination of full throttle heights in climb and level flight.
3.) Determination of speed performance with combat and take-off power.

1.) The results of the climbs are plotted on graph 1. The following service ceiling heights were obtained at a flying weight of G = 8,025 lbs (3640 kg):

34,941 ft. (10650 m) with combat power and split flaps open.
37,238 ft. (11350 m) with combat power and split flaps closed.
39,042 ft. (11900 m) at take-off power and open split flaps.

The rates of climb near the ground are:

3,543 ft./min. (18 m/sec) at combat power and split flaps closed
3,248 ft./min.(16.5 m/sec) in combat power and open split flaps
2,972 ft./min.(15.1 m/sec) at cruise power and split flaps closed

The reduction of climb rate due to open split flaps is 295 ft./min. (1.5 m/sec.) The service ceiling is thus reduced by 2,297 ft. (700 m.) Consequently, the service ceiling using take-off power and closed split flaps should be 41,339 ft. (12600 m.) It would only be necessary to clarify whether the cylinder temperatures are within the permissible values while climbing above 32,808 ft. (10000 m) with this power.

The climb rates with cruise power and closed split flaps above the full throttle heights are just below the ones with combat power with open split flaps. The climb time up to 26,247 ft. (8000 m) height is, for example 11.7 min at cruise power with closed flaps and 10.6 min at combat performance with open split flaps.

2.) The full throttle heights for high supercharger compared to the normal production variant (with open gills and interior air intake) as flown are compiled in the following table. The values are converted to INA temperatures.

    Fw 190 high-altitude fighter
  exterior air intake
  and split flaps
  Fw 190 standard production
  interior air intake and gills.
  Climb with combat power
  full throttle height:
19,357' (5900 m) 17,717' (5400 m)
  Climb with cruise power
  full throttle height:
20,341' (6200 m) -
  Level flight with combat power
  full throttle height:
22,638' (6900 m) 18,701 - 19,029' (5700 - 5800 m)
  Level flight with take-off power
  full throttle height:
24,278' (7400 m) 20,997' (6400 m)

  A considerable gain in full throttle height has been obtained from the exterior intake compared to the production version. The increase between climb and level flight, which is a measure of the quality of intake duct set up, is now 3,281' (1000 m). In the standard production version it is only 1,312' (400 m). Placing this increase in relation to the level ram pressure, with the outer duct 60% and in the production variant 22% ram utilization is obtained. The full throttle height level is inexplicably high in this machine; compared to the information in the engine manual, after which the full throttle height at combat power without ram is given as 17,388' (5300 m), the ram utilization amounts to 95%. It is assumed that, the more so as the full throttle height in climb is also higher by 1,969' (600 m) than stated in the engine manual, a particularly good  supercharger has been installed and that ~984 - 1,312' (300-400 m) lower full throttle heights are to be expected with normal supercharger set-ups.
3.) The plot of graph 2 shows the speed profile at altitude with the corresponding measured data. Top speed with combat power (n = 2,400 rpm pL = 1,32 ata) is 416 mph (670 km/h) at full throttle height and with take-off power (n = 2700 rpm pL = 1,42 ata) is 431 mph (694 km/h) at full throttle height.

The analysis of the ram pressure calibration shows, that the airspeed indicator error for the flown speed range is 0 km/h.

The speed performance of the high altitude fighter in comparison with the standard production version (gills and interior air intake) is plotted in Figure 3. The speed curves match below the full throttle heights. Since the two versions only differ aerodynamically, from a practical point of view, by the different air intakes, it can be concluded that the amount of drag increase of the exterior intakes corresponds to the one of the gills. The greater maximum speed of the high altitude fighter is attributable only to the higher full throttle height.

W'dorf, 27.8.42

Level speeds in comparison with production version


Flugbericht Fw 190/528 Höhenjäger (pdf)

Translation by Jörn Dietrich and Mike Williams

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