Sorry, I didn't mean to imply that at all -- I didn't really have anything intelligent to add so just hand-waved, I'm afraid.

Don:

Indeed, quantity has a quality all its own, as Stalin is supposed to have said.

For example re JG26. From '40 through '43 JG26 had an enviable and favourable claim/loss rate (and that's confirmed two sighting or crash site claims as was the German approach, markedly unlike the Allies, but that's another story). But day after day they (indeed Western defenses at large) were up against the sheer weight of American production. You can be a great marksman but when it's a staffel or two against 300, 500, 800 enemy aircraft - what can you do? And of course the same on the ground and sea, and the Eastern front.

My view is that the war was inevitably lost from taking on two huge enemies (Russia, USA). That view BTW not based on this single reading! It might have gone quicker or slower, and perhaps that pace affected by procurement and training, but Germany was on a hiding for nothing.

But to return to Ian's initial point ... was there ever an example of the fortress concept working in practice? Ie bomber formations successfully defending themselves without fighter escort. Not in WWII, I don't think. The Gothas in WWI? I don't that counts -- even though British fighters shot down only 6 Gothas, the Gothas shot down only 2 fighters ... and after a few daylight raids they switched to night bombing, which is suggestive in itself. Maybe the Russians?

I agree about the D-551 being a racer prototype, however I did get an e-mail from a Jean Emile Cassin from France that told me that the French had built 3 operational D-550s with 6 wing MGs (7.5 mm) and a 20 mm high velocity moteur-cannon. M. Cassin told me the three 550s actually fought from May 27 to June 21, 1940, and one may have been responsible for 15 or 16 kills of Me-109Es. He told me the name of the pilot and I believe it was Doriot.

Two D-550s were apparently destroyed by French pilots before being captured by the Nazis and the last one was hidden in a building and apparently destroyed by Allied bombs prior to the liberation of Southern France.

Also, looking back at September 1940 to May 1941, didn't the German's copy the moteur-cannon from captured French designs for the 20 mm on the later Me-109E-3s that got into it with the Spits and Hurricanes over GB, making the Me-109E more effective than its predecesors even though slower than the Spits.

The Germans upgrading and making their fighters heavier was not the key reason why the German fighter force become so vulnerable to allied fighters. The main problem is training and the human drain caused by several years of fighting. The launch in late 1940 of intruder ops moving onto the 'Big Week' of 1944 gradually degraded the quality of the german fighter force to the point of no return. Most experienced pilots survived quite well in the fighters of 1944 where as the newly trained pilots had a high mortality rate.