4 ms·
The point is that the shock isn't the air hitting the vanes, it's the air hitting other air. Similar to re-entry heating: the specific kinetic energy of the re
by Tuna-Fish 3y ago
The point is that the shock isn't the air hitting the vanes, it's the air hitting other air.
Similar to re-entry heating: the specific kinetic energy of the returning capsule is many times greater than would be required to melt and vaporize any material. So why do things survive re-entry? Because most of the energy is dissipated in the bow shock, significant distance away from from the capsule, where air gets heated to temperatures higher than the surface of the sun when other air slams into it. The purpose of the heatshield is to protect from radiative heating from the bow shock, not convective heating. Ablative heatshields do not work because ablation consumes energy which removes heat (again, there is sufficient energy going around to ablate the entire craft), but because they place a shade (made of ablated carbon particles) between the bow shock and the craft, which shields it from the radiative heating.
- pfdietz 3y ago> The purpose of the heatshield is to protect from radiative heating from the bow shock, not convective heating. In this case the entry regime was such that convective heating far outweighed radiative heating.
- kragen 3y agoi'm interested to hear more about these heaters. do you know what they are called or what they are made of?
- pfdietz 3y agoSee link in a comment below.
- kragen 3y agogot it, thanks! https://news.ycombinator.com/item?id=39540283 https://news.ycombinator.com/item?id=39540283 https://coolbrook.com/wp-content/uploads/2023/06/REPRINT-2023-04-LR-Coolbrook-Breakthrough-tech-2.5p-MB.pdf https://coolbrook.com/wp-content/uploads/2023/06/REPRINT-202...
- kragen 3y agohmm, that's a good point; so if you run coolant through the vanes they can operate without damage while producing temperatures that would vaporize them?