IOTL, the Nazis were the first to research and develop thermobaric warheads (aka 'fuel-air bombs'), courtesy of Projekt Hexenkessel, carrying out its first successful test in 1943; however, none of these actually saw use in combat in WW2. So then, what if Adolf Hitler and the Nazis gave their approval to a proposed Projekt Hexenkessel several years earlier, with these thermobaric warheads starting to entering full production from mid-1940 onward ITTL? How much of an impact might this have upon the passage of the war, and the effectiveness of the Luftwaffe in particular?