This calculated performance sheet was prepeared 8 months after the release of the previous datasheet containing flight tested values in November 1941 (IV/43/42). Both datasets are undertood for 30-minute power settings (Steig und Kampfleistung) of the DB 601 E engine, ie. 1.3ata manifold pressure and 2500 rpm, or about 1200 PS (static) output at Sea Level.

        The performance data contained the calculated Datenblatt shown on this page is far more conservative than stated in the predating flight tested datasheet - as seen in the comparison table below.

It is noticable that while the associated horsepower and the level speed results at Sea Level are practically identical, the two datasets show increasing seperation as altitude increases. Considering the aformentioned charasteristics observations of the two sets of data, and that most other Bf 109F-4 performance sheets and grahps repeatadly claim the 635 km/h value at the same power setting in agreement with the IV/78/42 calculated datasheet, it seems likely that the flight tested datasheet IV/43/42 is without compressibilty correction - the lack of such correction would characteristically result in increasingly higher instrument reading error with the increase of altitude, the read error levels peaking out at maximum speed at the rated altitude.

Comparison of level speed results
IV/78/42 - Calculations			IV/43/42 - Test flight
Date	1 July 1942		Date	29 November 1941
H (km)	N (PS)	V (km/h)	H (km)	N (PS)	V (km/h)
0 2 4 6 8	1165 1250 1250 1185 940	523 572 611 635 620	0 2 4 6,2 8	1170 1250 1260 1180 950	526 586 614 660 649

Another noteworthy point of interest is that this more recent calculated datasheet, reproduced below, dating from July 1942 no longer notes the banning of the Start und Notleistungs power for the DB 601 E engine as opposed to the previous datasheet from the end of November 1941, points to that the full power has been cleared for the engine.

This clearance is in fact also supported by the February 1942 release of the Bf 109F Flugzeughandbuch, which no longer notes any limitation in regards to the DB 601 E. The new Hanbuch part 7 (Powerplant) was likely to have been re-issued because of this clearance.
See D.(Luft) T. 2109F-1 bis F-4, 'Bf 109F-1 bis F-4 Flugzeug-Handbuch', Teil 6 'Triebwerksanlage', page 7., authorized in Berlin, 24 February 1942.

Flight measurements performed in E-Stelle Rechlin with a Bf 109F-4 with DB 601 E using the full power (Start- u. Notleistung, 1,42 ata 2700 rpm, for 1350 PS at Sea Level), reported by a GL/A-Rü IA datesheet dated 1 June 1942, note the following level speed performance :

537 km/h at Sea Level,
670 km/h at 6200 m,
625 km/h at 10 000 m.

Rechlin's figures appear to have been corrected for compressibilty, ie. compare the 10 km level speeds between Rechlin and IV/78/42 calculated datasheet which are in reasonable agreement.