People, be very careful whether you speak of range or radius! E.g. Milosh statement "Combat range of any a/c would be ~ 1/3 of its flight distance. (1/3 going out, 1/3 for combat, 1/3 for return)" is inaccurate unless the word range is replaced with radius. Another problem with general references is that they often mix. data for maximum air range and the range at maximum continuous speed. One must remember that e.g. at sea level cruising at maximum air range speed a P-38L requires well below 400 hp per engine (1600 rpm/22" Hg, 28" Hg at the same rpm gives 425 hp) while the maximum continuous power at SL is 1100 hp. The latter setting increases TAS from 168 mph to 302 mph while fuel consumption increases from 46 US gph to 245 US gph.So less than doubled speed and over 5 times greater fuel consumption.
BTW, it is regularly laughed that the Me 163's endurance was some 8 minutes or so. Well, check out what endurance modern jets have at sea level if flown at full afterburner...