Originally Posted by Capt'n Midnight
How much information was shared ?
Even little things like impressing upon the Japanese the importance of convoys
Despite all the publicity about enigma the Germans were just as good at breaking Allied codes and knew a lot about Allied technology.
Japan lacked widespread radar, didn't use convoys, and easily broken codes.
Radar was also used in proximity shells.
a few submarine loads / few fast ship loads of cargo
plans were shared, but too late to make a difference
the big problem was developing decent kit
far too many prototypes that failed - jets were bumped up because they could run on diesel instead of the scarce petrol
heavy bombers with engines overheating
each V1 took the resources of a fighter to produce , and there was a shortage of potatoes because of the alcohol fuel which has to have knock on effects
at one stage German shells were topped up with 20% salt, because they ran out of explosives
Japan had a few wasteful schemes, the amount of manpower wasted sewing up balloons on the off chance they'd start a forest fire in the US - because that will win the war somehow
Back to codes , on the Eastern front the Russians used the public system of loudspeakers to communicate , so very little radio traffic to eavesdrop on. In Siberia it may have been different, but if the US could break the codes then perhaps the USSR could too ?
Of all the examples of shared tech, I think I'd point to two as being of critical importance - I'm sure there are others, but I'll plump for these two....
Penicillin - the Brits discovered and developed it, shared it with the Yanks who then pioneered its mass production. The Germans knew of penicillin but couldn't produce it in the volumes the Allies could.
The cavity magnetron - again developed by the Brits and mass produced by the Americans, it made centimetric wave radar a reality which allowed for smaller objects to be detected such as submarine periscopes. It also made radar sets smaller meaning they could be incorporated into more aircraft.
A lot of German prototypes didn't fail in as much they were killed by rivals anxious to promote their own designs.
There's another point about artillery shells - a lot of war production in Germany was carried out using forced / slave labour who no doubt had an incentive to mess about if / when they could get away with it.
I saw one study that suggested between 20% and 25% of the shells fired during the Germans 1944 Winter Offensive in Alsace (the Battle of the Bulge) failed to explode on landing. No doubt some of those suffered from poor materials, but the author also suggests that workers in the factories played their part in sabotaging fuzes etc.