Kinetic Heating vs Mach Number

[KJ_Lesnick]

Well, that would depend on how long the V-2 spends in the lower, denser air. Also, going up there'll be the fuel and oxidiser available as heat sinks, and as I mentioned going down the V-2 will be lighter - lowering the thermal loading.

Yeah, but the X-15 spends far more time in a straight-line, almost all at high-altitude. Virtually no time spent in thick air going up or going down (except gliding for landing after burn-out)

In regards to the V-2, while you might have the fuel as a heat-sink on the way up on the way down though you'll have *no* fuel at all, and you'd still be moving hypersonic on the way down.

The X-15 is a heavy plane that spends almost all of its time in the atmosphere travelling at up to Mach 6.7, if I recall correctly.

Yeah, but it doesn't fly though very thick air on the way up and reaches peak speed while at altitude and is already slowing down quite a bit as it heads for the runway to land. All the time spent in the dense lower atmosphere is not spent at any significantly high-speed. It's engine burn time is only 90-seconds on all but the X-15A2 which carries two large tanks.

Of course it will get hot at such speeds, but I'm just wondering how the hell they'd get that hot (peak temperatures pretty much) if they were spending a very tiny amount of time at peak-speed and largely in thin air (heating occurs slower and to an extent slightly less) The X-15 seemed to take serious thermal abuse during it's flights!

From what I remember a plane takes a certain amount of time to heat up, which depends on the atmosphere and the velocity (the lower the altitude and the higher the velocity -- either one or both the faster it happens, but still heating occuring almost instantly seems a bit odd even at that speed especially considering the Mach 6 flights were done around 130,000 feet)

Another point - the V-2 is a one-shot weapon. You can put it through a lot more stress than a vehicle which is designed to be reused.

I suppose that's true. However stainless steel can take Mach 5 flight repeatedly and could be used on a vehicle designed to repeatedly fly at Mach 5. Which still might make my question valid anyway.


KJ_Lesnick


KJ_Lesnick