Since this is a "what if" and we don't have to piddle with actual assets I figured only one way to success- early concentration on aerospace tech and a dedicated will to take GB.

If Hitler had decided, say in 1936, that Germany would/should invade GB and began designing and engineering landing craft in addition to the ample number of Ju 52s actually on hand around in early 1940 they could have air lifted 10,000 troops in one assault to take a couple airfields and build a parimeter. The Ju 52s then would be making round trips with more troops as fast as possible. Once that happens they could have flown in and carved out a coastal landing zone for amphibious landers.

If in 1939 Germany had occupied the GB there would be no later "island aircraft carrier" for the Yanks to use and they'd have go back to the drawing boards to get going on future B-32s and B-36s. If they even chose to combat Germany there would be no escorts so they'd suffer greater causlaties as would occupied England's population being bombed by US planes.

From the time he became Chancellor in 1933 had Hitler immediately taken the Weimar Republic's progress in rockets from the 1920s and seized it for future possibilities he would have been having the success with the V-1 and V-2 in 1936. In actuality the V-2's 1st successful flight was 1941. In 1939 it was finished only awaiting the warhead and rocket engine.

Our Me 262 design was set in 1939. It flew in 1941 was finished with Reichlin testing with the 1st 15 production examples slated for late 1942. It languished only because of the moritorium on longer term projects at that particular time. The Reichsters believed the war would conclude quickly so why invest in long term hi-tech? So we'll say they didn't feel that way and pursued aerospace tech as soon as Hitler seized power. In pre-war Germany as it was there were a great many advanced aircraft designs being tested in wind tunnels and as small scale gliders.

Accelerate the aerospace tech coupled with taking England before any putzing about with Russia or points east and you'd have a great advantage before the US got out of the starting blocks.

So by 1939-40 we have the first generation jets, Me 262 and Ar 234 plus the A-4 (V-2) program would have been in its next phase of development of a true ICBM with the A-10/A-11 vehicles that could reach the US. It wouldn't matter a bit if missiles were costly or not because Germany would have never had expenses or losses in North Africa or Russia. They would still have the wealth of Europe at any rate. The treasuries of these nations and GB's were substantial enough to best any other one country's.

If and when the Americans fielded trans-oceanic bombers they would be met by the Luftwaffe's 2nd generation jets and, more importantly, SAMs along with an array of AAMs. And as it was in 1943 radiation-spreading devices could have been deployed we can imagine one delivered to New York by ICBM missile when the uranium commences meltdown. Once the material bores through to the water table a mass of superheated water will arise in a colossal cloud of radioactive steam that will poison the area for decades hence.

In reality all that would have had to happen is that GB sued for peace with Germany as Hitler imagined they would do. A weak sister like Neville Chamberlain in charge would have really changed things. There'd have been no US presence in Europe. They coulda had fun devoting all their resources and manpower to defeating Japan. What about Russia, and Italy free to develop and build?- are other questions.

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