4 ms·

How do you shed 400Mwh of heat in an area that small? I would imagine the surrounding air would take some of the heat, but that's an incredible amount of energ

How do you shed 400Mwh of heat in an area that small? I would imagine the surrounding air would take some of the heat, but that's an incredible amount of energy to dissipate in such a small area. Call me skeptical.

nickhalfasleep 9y ago
This is at least an order of magnitude more complexity and heat exchange than the Shuttle Main Engines (SME's) ever succeeded in doing. And were constantly maintained and babied by NASA staff for less than a dozen flights a year. Cryogenic hydrogen is a really nasty chemical. It's so small it'll worm into your linings, plumbing, metal walls, and flake them apart with the temperature swings. Other combustible fluids condense on the outside of the plumbing if you're not careful.
- nickhalfasleep 9y ago
  NASA and the DOD tried to make this with Copper Canyon / NASP / X-30. They couldn't make it fly, and they had cubic billions of dollars to try with. Today, the children of Von Braun, tail-sitting rockets like the DC-X, which is Blue Origin and Space-X, are progressing towards the amazing reality of boring reliable transport to space without crazy wings and dwelling in thick atmosphere. https://thehighfrontier.blog/2016/01/02/reagans-impossible-dream-the-x-30-national-aerospace-plane/ https://thehighfrontier.blog/2016/01/02/reagans-impossible-d...
semi-extrinsic 9y ago
Maybe they're going liquid hydrogen for the fuel? Or another cryogenic? That gives you a lot of "waste cold" that you can use for cooling charge air and the rest of the engine. I'm a big fan of LH2 planes. Tupolev actually built one just before the wall fell [1]. Airbus did a big concept study in the 2000s that indicated it would be on par with normal airliners once you eked out all the optimizations. Then everyone decided to go gradual biofuel phase-in instead, which I'm decidedly skeptical of. Sure I get that the CAPEX of going LH2 is a lot worse, so for someone optimizing on a < 10 year horizon it looks better. But are biofuels really going to get us all the way we need to go eventually? [1] https://en.wikipedia.org/wiki/Tupolev_Tu-155 https://en.wikipedia.org/wiki/Tupolev_Tu-155

nickhalfasleep 9y ago

This is at least an order of magnitude more complexity and heat exchange than the Shuttle Main Engines (SME's) ever succeeded in doing. And were constantly maintained and babied by NASA staff for less than a dozen flights a year. Cryogenic hydrogen is a really nasty chemical. It's so small it'll worm into your linings, plumbing, metal walls, and flake them apart with the temperature swings. Other combustible fluids condense on the outside of the plumbing if you're not careful.

nickhalfasleep 9y ago
NASA and the DOD tried to make this with Copper Canyon / NASP / X-30. They couldn't make it fly, and they had cubic billions of dollars to try with. Today, the children of Von Braun, tail-sitting rockets like the DC-X, which is Blue Origin and Space-X, are progressing towards the amazing reality of boring reliable transport to space without crazy wings and dwelling in thick atmosphere. https://thehighfrontier.blog/2016/01/02/reagans-impossible-dream-the-x-30-national-aerospace-plane/ https://thehighfrontier.blog/2016/01/02/reagans-impossible-d...

semi-extrinsic 9y ago

Maybe they're going liquid hydrogen for the fuel? Or another cryogenic? That gives you a lot of "waste cold" that you can use for cooling charge air and the rest of the engine. I'm a big fan of LH2 planes. Tupolev actually built one just before the wall fell [1]. Airbus did a big concept study in the 2000s that indicated it would be on par with normal airliners once you eked out all the optimizations. Then everyone decided to go gradual biofuel phase-in instead, which I'm decidedly skeptical of. Sure I get that the CAPEX of going LH2 is a lot worse, so for someone optimizing on a < 10 year horizon it looks better. But are biofuels really going to get us all the way we need to go eventually? [1] https://en.wikipedia.org/wiki/Tupolev_Tu-155 https://en.wikipedia.org/wiki/Tupolev_Tu-155