Me 109 F subtypes

[klemchen]

Hi everybody,

I am interested in EXTERNAL features by which the four Me109 F subtypes can be distinguished. These were defined by INTERNAL features: F-1/2 were fitted with the DB 601 N engine, F-3/4 with the DB 601 E. F-1/3 were equipped wit the MG FF as engine cannon, F-2/4 with the MG 151. During production a few technical modifications were introduced, but without affecting the designation. Some of them occurred exclusively on only one subtype but not on all specimen of those.
In the literature it is claimed that the only external feature distinguishing between F-1/2 and F-3/4 is the inscription of the fuel triangle: The DB 601 N needed C3 type fuel of 96 or 100 octane while the DB 601 E could do with B4 of 87 octane. However, another such feature ought to be the propeller: F-1/2 were fitted with the VDM 11207A, F-3/4 with the VDM 12010A (except some F-4s which got the VDM 12087A with distinctly wider blades). The trouble is that I am absolutely unable to detect any visible difference between these two prop types. Could it be that both had the same blades but different pitch setting mechanisms? Is there anybody who knows the difference?
For completeness, there seems to be another such distinguishing feature: On the starboard upper cowling of some Fs there was a small scoop just behind the hole for the starter, on others not. Now the same scoop appeared on all Me 109 Es I know. Since all these were equipped with the DB 601 A or N, I have come to believe that scoop was needed for the DB 601 N but not for the DB 601 E. If so that scoop would be another external distinguishing feature between F-1/2 and F-3/4.

Regards,
klemchen