Here are a number of sites, resources that as an enthusiast, WW historian, serviceman or family member of the 15th Air Force you might enjoy and find relevant.
Army Air Corps Library and Museum A Army Air Corps, Army Air Forces Museum of WW1 and WW2.
15th Air Force History Order of Battle, Commanders, etc.
US National Archives
Air Force Historical Research Agency
Sons of Liberty Museum US Army, US Marines, US Navy, US Air Force. World War I, World War II, Korea, Vietnam History Museum.