3 ms·
Yes, fuel as coolant worked at around mach 3, but at mach 4+ the kerosene itself may not not be energetic enough to both sink heat, and produce more energy than
by baybal2 5y ago
Yes, fuel as coolant worked at around mach 3, but at mach 4+ the kerosene itself may not not be energetic enough to both sink heat, and produce more energy than the energy of incoming airflow.
Supercooling the fuel may work to some extend.
Having the entire aircraft being a flying liquid hydrogen tank is another least improbable option.
- HPsquared 5y agoI suppose heat flux is still a limiting factor that's independent of scale. Though things like liquid evaporative cooling (by "sweating") also become more practical with larger scale (more mass available). Not sure how big it would have to be though...
- masklinn 5y ago> Yes, fuel as coolant worked at around mach 3, but at mach 4+ the kerosene itself may not not be energetic enough to both sink heat, and produce more energy than the energy of incoming airflow. The blackbird did not use kerosene, it used JP7, specially designed for high range of operation as well as being usable for cooling and hydraulics. > JP-7 is unusual in that it is not a conventional distillate fuel, but is created from special blending stocks in order to have very low (<3%) concentration of highly volatile components like benzene or toluene, and almost no sulfur, oxygen, and nitrogen impurities. JP-7 is famously hard to ignite, the blackbird needed TEB shots to start ignition, and was initially started by driving the engines with a starter cart composed of paired V8s (later replaced with a smaller and simpler compressed-air starter). The Waverider used the same fuel, and fuel-cooling, and reached Mach 5.1.
- baybal2 5y ago> The Waverider used the same fuel, and fuel-cooling, and reached Mach 5.1. Not so much as coolant, but as a thermal mass reservoir, and only for a few minutes.