[caldrail]

On the contrary, there are thousands of details to sort out. As I mentioned, the P67 has aerodynamic flaws and was altered structurally in an attempt to solve them before flight testing resumed in September 1944. Note that testing originally began in December 1943 and the plane wasn't flown until January, the aircraft needing to be tested for ground handling, systems, all sorts of things. Some aircraft had ventilation problems. Others had problems with hydraulics. The Me209-I for instance (the fighter version, not the racer) had appalling handling characteristics and allowed lethal amounts of carbon monoxide into the cockpit. That's why aircraft manufacturers need to build prototypes - to find out what the flaws are before they embarras themselves or cause death and injury to others.

One important point to notice is the habitual secrecy of american technology was well rooted in the 1940's and has it's roots in intense commercial competition. The Germans on the other hand had a centrally controlled system in that period and sometimes used prototypes for public propaganda - they created myths about theirs whilst America kept everything under wraps as much as they could.