Once the Americans had escorting Mustangs it became too costly for the Germans to put up singles seat fighters since there was a higher priority for fighters on the eastern front. Galland was always trying to hold back deployment of fighters against bombers so he could build up a large enough force of daylight fighters to take on the bombers streams. But nightfighter technology steadily increased on both sides till the end of the war. Another idea worth mentioning was Schrange Musik where guns on nightfighters were angled upward to fire on the bombers from underneath

Now here’s a what if. What if Barnes Wallis had come up with the idea of converting a squadron or two of wellington bombers as gun ships with bristling with guns that could shoot in any direction and with a longer range then the German guns. And these Wellingtons with fighter protect were patrolling the areas where the Germans were approaching from, with the radar etc which we had at the time, they could then be in a good position to do max damage on meeting the Luftwaffe. The scrapmen in Kent would have a field day.

The US did experiment with the idea of fitting B-17s with heavy 20mm cannons and have them fly along in bomber formations as dedicated gunships. I dont know how successful the idea was. Recall though that both the Germans and British had discovered that the Me-110 and Mosiquito twin engine fighters were devastating against bomber formations with their heavy concentration of cannon fire, in daylight when there was no fighter cover and of course as nightfighters.

As well as having the disadvantages of hitler and goering running the show – the german procurement ‘system’ was riddled with politics and some fairly bizarre decisions….they could have built more aircraft quite early on but did not really sort out their priorities properly.
Many of their top brass were not of the same calibre of many senior RAF officers (Our internal politics was bad enough but not a patch on theirs).
Dowding and Park were the right men for the job and we were lucky to have had them,Dowding had overseen the setting up of our air defence system and was a dedicated professional – Goering was not !!

I think Ernst Udet was more at fault for incompetent handling of aircraft production than Goering. Udet was a WW1 ace and stunt pilot in the 30s. He took the job in the air ministry only because he enjoyed test flying new aircraft prototypes. He was said to be a very likeable and happy-go-lucky type of personality. He was forced to stop doing test flights and do only administration work which caused him to become miserable and he went into depression and alcoholism. He completely mismanaged aircraft production, it wasnt till he finally commit suicide and Milch took over that aircraft production really took off on a full industrial level footing.

The all out assault on the UK mainland was unsustainable but it’s probable that the Luftwaffe had strength that could outlast the RAF.

The opportunity for invasion was over due to the weather and the RAF could simply have chosen not to be drawn into unproductive combat until it had regained, at least, some of its strength.

It should be noted that Germany’s window of opportunity for invading Russia with such a small force was 1941 and if they had waited a year or two, Russia would have become impregnable with up to date equipment. In 1941 the Me-109 completely outclassed the Polikarpov I-16 and they pretty much wiped out the entire Russian air force in the first couple of weeks. The Panzer III made equally easy work of obsolete russian tanks. A year later with obsolete hardware getting replaced by Yak-1s and T-34s such a quick invasion would have been impossible. Russia basically started the war with nothing and was able to outproduce Germany in the long run, all thanks to part to the russian winter, muddy spring, stretched supply lines, Hitler interfering with his insane battle strategy