<human>:  When did the US Air Force become a separate branch of the military?
<bot>: The US Air Force was established as a separate branch of the military in 1947. The US Air Force was formed after the United States Army Air Corps was disbanded, and was made up of several of the branches of the army that had aircraft. The Air Force became a separate branch of the military in 1947, and the Air Force Academy was founded in 1954.