The performance of the Bf 109 F-4

Limitation of the performance of the DB 601 E

Similiar as on the introduction of the DB 601 N for the Bf 109 F-1/-2 there was also at the begin for the DB 601 E problems with the reliability. Also for this new engine the same measure as for the DB 601 N was taken by prohibiting the take off/emergency power setting at first.

The author hasn't seen any document with a corresponding service instruction. But there are documents proving the existance and the time point of the end of this measure.

There is also no original document known, which tells the details of the reliability problems. Secondary sources tell of a problem with overheating.

Range table of the Bf 109 F-4

Range tables served to plan flights before and during a flight. For several altitudes and engine operational modes were for several fuel volumes the resulting ranges and speeds listed. As a rule for security the fuel consumption was set 15% higher when it should have been for an optimal maintained plane. On the last page the permitted engine operational modes during the validity of the table and their durations were listed.

Fig. 4: Page 1 of the range table for Bf 109 F-4, edition 4th September 1941 - Quelle: BAMA Freiburg

Fig. 5: Page 2 of the range table for Bf 109 F-4, edition 4th September 1941 - Quelle: BAMA Freiburg

Fig. 6: Page 4 of the range table for Bf 109 F-4, edition 4th September 1941 - Quelle: BAMA Freiburg

The table shows clearly that during its validity the take off/emergency power of the DB 601 E was limited on a boost pressure of 1.3 ata and 2500 rpm. This way the take off/emergency power was equal to the 30-minute climb/combat power. The speeds told for maximum permitted permanent power complete the picture.

The begin of the validity of the table is clearly determined with the imprinted date of 4th September 1941. However luckily also the end of validity is documented by a handwritten note.

On the first page (fig. 4) you can read below the character "Nur für den Dienstgebrauch" (translation: only for official use) "Vereinnahmt gem. Br.Bo. 2765/41, <Kürzel des Ausführenden> 6.12.1941" (translation: collected according to Br.Bo. 2765/41, <token of the executor> 6th December 1941). This way on one hand the document, declaring this edition of the range table as invalid, is identified and on the other hand the date, on which this edition was drawn back, told with 6th December 1941. Unfortunately the above told document could not be found yet. Since the signature was numbered continously, a temporal ranging in of the giving of the order will perhaps be possible in the future by documents with signatures lying in proximity.