> At that speed, the engines are assumed to have been scraped after each flight. > One could make assumptions that the ram-jet elements of an SR-71's J-58s coul

> At that speed, the engines are assumed to have been scraped after each flight. > One could make assumptions that the ram-jet elements of an SR-71's J-58s could allow for a few minutes...far beyond that I would expect the SR-71 to stay at speed longer and for the engines to be capable of higher power (assuming the airframe and intake can handle it). US engines were generally higher quality, while Soviet engines were expected to be replaced very quickly relatively. However, this was a conscious decision on the part of the USSR: instead of making expensive engines with good maintainability in the field, they chose to make cheap engines that were easy to replace. As a result, while a MiG-25 may have only been able to maintain Mach 3 for a few minutes and ruin the engine in the process, they built 1,186 of them, with probably >5,000 Mach 3 capable engines. Not particularly relevant, but always interesting to discuss how different people think