Aircraft
1. United States = 324,750
2. Germany = 189,307
3. Soviet Union = 157,261
4. United Kingdom = 131,549
5. Japan = 76,320
6. Canada = 16,431
7. Italy = 11,122
8. Other Commonwealth = 3,081
9. Hungary = 1,046
10. Romania = 1,000
The figures look a bit off, especially for Germany. I wouldn't trust Wikipedia as a resource, particularly when other wikipedia pages contradict that one.
The USSBS gave German aircraft production 1939 - 1944 as 111,247, with production of just under 40,000 in 1944. Production collapsed fairly early in 1945.
The usual figure given for German production is just under 120,000.
The USAAF reported US aircraft production of 264,200 from July 1940 - Feb 1945. Production was running about 1,000 per quarter at the start of that period, so assume a max of about 4,000 aircraft between the start of the war and July 1940. Production in the 4th quarter of 1944 was just over 20,000 a quarter, and falling very quickly (about 26,000 in the first quarter of 1944).
If you assume 270,000 up to the beginning of 1945, then production would have had to increase sharply again in 1945, and I've never seen anything to suggest it did.
In 1944, the US was building aircraft at a rate that was quadruple that of the commonwealth combined.
It was actually about 3 times Commonwealth production in 1944.
Again, another statistic indicating just how the lack of manufacturing capacity the Commonwealth had, in trying to build an airforce large enough to take on the LW.
Well, the UK produced more aircraft than Germany in WW2. When you factor in weight, as the British produced lots of heavy bombers, the Germans lots of fighters, the UK greatly outproduced Germany, about 615 million pounds structure weight in the period 1941 - 1944, compared to 470 million pounds.
Britain produced more aircraft engines as well, about 242,000 1939 - 1944, compared to 185,000 in Germany.
The Luftwaffe would have had a much easier time time defending the Reich and would be able to divert substanial resources to the Eastern Front. The troops tied up in Italy and France also would be heading east ,and I'd garrison France and the low countries with some of the other axis troops Romania , Hungary etc .
The problem is, by the time the US buildup in Europe really started to gather steam, the Germans had already lost in Russia.
If you look at the high point of the German advance, it was in the summer of 1942. By that time, the US army presence in Europe was negligible, the USAAF were flying only tiny numbers of sorties to easy targets in France.
By the end of 1942 the Germans were on the ropes in Russia, and still the US presence in Europe was negligible
Certainly without the US the Germans could have diverted some forces to the eastern front in 1943 and 1944, but the German's position was well beyond recovery by that time, and it was really only a question of how fast they retreated.
Italy would be quite capable of defending itself
Italy was completely incapable of defending itself against Britain.
Without German assistance, the British and Commonwealth forces in Italy would have taken the country in short order.
Without US involvement in Europe/North Africa, the war would have gone much the same up to the summer of 1942. Torch would have gone ahead solely with British/Commonwealth forces, and probably taken a bit longer, but by summer 1943 the British would have been in a position to menace Italy, although not to invade whilst the Germans still had substantial numbers of troops in the country.
The German offensive at Kursk would have failed regardless, and from that point on they would be on the retreat in Russia even if every single German soldier, tank and aircraft was committed against them.
I should think the Germans would hold on longer in such a scenario, probably until the autumn of 1945, maybe even the end of the year.
As to speaking Russian, I'd expect the zones of influence agreed between the British and Russians to give almost all of Germany to the Russians, but not France, Belgium and the Netherlands.