Aircraft were the domain of the army. US Army Air Corps is what they were called. The reason certain aircraft were not developed, or that certain aircraft fought bueracracy along the way, is because the Army had a VERY limited view of what aircraft should do (forget flying 1000+ mile escort missions over Europe!). I don't know the exact date, but the USAAC was turned into the USAF. One is the precursor to the other.