[Kjetil Aakra]

I also think Andreas got it right.

The old notion that the "square" canopy signifies an E-4 while the older "rounded" was a feature of the E-1 and E-3 has been abandoned now, as far as I know. At least it should be.

These two types were readily interchangeable which is proved by the fact that there are even some Bf 109Fs with the "rounded" canopy. Rather than being early examples of Bf 109Fs as some sources have stated I think these are in-the-field modifications. The best know examples are the Fs flown by Horst Carganico. On his F-4s you can easily see these old canopies and as they were also a feature of his Emils (which is otherwise in E-7 configuration, with capped spinners), it is likely Carganico simply preferred these older versions, probably feeling they provided him with a better view from the cockpit.

Rabe Anton's ideas of the Emil modification program is also in line with my findings. I agree fully that there was probably no single standard set down for this upgrade, except to upgrade armament. In all likelyhood the main modifcation to be carried out was the fitment of droptank piping, MG FF cannon (on E-1s) and, in most cases it would seem, the capped spinner. The external armoured windscreen glazing was also fitted to most of these older models.

The attached photos are indicative of this practice. They show what was originally W.Nr 6274, an E-1 built by Fieseler at Kassel (note the black exhaust shrouds which is a feature of Fieseler-built Bf 109Es & Ts) and later modified into an E-7 with capped spinner, windscreen armour and MG FFs (and probably droptank piping). The photos show it in service with 5./JG 5 as Red 19 in 1942. Note the round metal sheet covering the original MG 17 port.

This one still retains the "round" canopy and this must have been the least important feature of the modification so I am not surprised that it was ignored for quite a few conversions. At least there are several examples to be seen in the JG 5 invetory of 1941-42.

Kjetil Aakra