B-17's had a typical service altitude limit of around 31,000 feet,same for the B-29, but the 29 was pressurized,carried more payload and was quite a bit faster.
If ya talk to the men who flew the planes,the facts listed are often meaningless,the plane's speed and altitude depended on engine condition,weather and payload.Top speed of piston engine fighter planes might vary as much as 35 MPH due to dents in the sheet metal,or the pilot's ability to get the most from the engine.The fastest WW2 fighter was the last models of the P-47,powered by a 2800 cubic inch Pratt and Whitney 18 cylinder radial,2800-3000 hp with water injection,495 MPH in level flight. The pilot,besides the throttle,he had to control prop speed,carb mixture,control surface trim and on some ,supercharger boost,all while trying to avoid being shot up.These men relied on crude flight instruments,and how the plane felt in flight,still they could pull over 5 g's in diving turns.
