4 ms·

Its interesting to know that they are finally testing. I remember reading about Reaction Engines back in 2012 (I was in college) and them working in this techno

Its interesting to know that they are finally testing. I remember reading about Reaction Engines back in 2012 (I was in college) and them working in this technology. Back then it was in primordial stages. How does this technology compare with Ramjet technology and X51? https://en.m.wikipedia.org/wiki/Ramjet https://en.m.wikipedia.org/wiki/Ramjet https://en.m.wikipedia.org/wiki/Boeing_X-51_Waverider https://en.m.wikipedia.org/wiki/Boeing_X-51_Waverider

baybal2 8y ago
Scramjets minimise compression losses by minimising compression... Sabre minimisies compression losses by instantly cooling incoming hypersonic air stream with their tricky heat exchanger, thus not doing compression. The turbocompressor after the precooler is pretty much a pump.
- igravious 8y ago
  Interesting, thanks? You seem knowledgeble on the subject, what's your take on the commercial and technical viability of this tech in general and REL's abilities to execute more specifically in the case the tech is viable.
  - baybal2 8y ago
    My common sense says that tech is not viable, but reality shows otherwise. Thus, I can't tell much about it from my common sense. The company must be staffed by much more competent engineers in their domain than I am. The most tricky parts in my view are the pre-cooler just for the giant mass flow and temperature difference, and the helium/lh2 heat exchanger, but those two seem to been done. O_O
    - igravious 8y ago
      I see what you're saying but innovation in high-speed mass transport is going to take a breakthrough in tech: could be sabre, could be hyperloop, could be superconducting maglev. Despite what your spidey-sense is telling you, maybe this is one of the breakthroughs we need. Having said that I think we should be aiming for low environmental footprint with all our tech from now on given what we know about the damage we're doing. I'd like to see these breakthrough techs compared in terms of environmental costs. My ideal combo would be superconducting maglev high-speed trains coupled with nuclear power to deliver the electricity.
      - close04 8y ago
        For mass transit high speed only makes sense for longer distances. Most mass transit is relatively short haul where the acceleration/deceleration times (that still provides a comfortable ride) prevent you from saving any time. Over the speed of sound is great if you want to fly half way around the world. But from Paris to London it doesn't really save you much. Unless it becomes cheaper than regular air travel.
        igravious 8y ago
        > For mass transit high speed only makes sense for longer distances. Most mass transit is relatively short haul where the acceleration/deceleration times (that still provides a comfortable ride) prevent you from saving any time. Probably I just should have said superconducting maglev trains. I guess you're right that they only need to be properly high speed over longer distances. Superconducting maglev would be a win for acceleration/deceleration as well so would benefit short haul. Realistically speaking, inexpensive superconductors would be a total game changer for many fields, not just mass transport. > Over the speed of sound is great if you want to fly half way around the world. But from Paris to London it doesn't really save you much. Unless it becomes cheaper than regular air travel. I kind of feel that in general it'd be better to replace planes with trains, than to replace planes with better or faster planes. Better security-wise. Better for the environment in the long run I believe. I'm totally open to correction though.
        close04 8y ago
        > Superconducting maglev would be a win for acceleration/deceleration as well This limitation isn't at all technological. You just can't accelerate or decelerate much faster than today's high speed trains without causing discomfort to your passengers. And the radius of any turn increases with speed. Otherwise first you just produce noticeable discomfort while turning, and beyond that you risk derailment (no matter the rail type). So you're basically stuck with having really long and very straight stretches of rail where you have to gently accelerate and decelerate. On any short trip this would kill any economy of high top speed. > I kind of feel that in general it'd be better to replace planes with trains The advantage of flight is that you are free to take a more or less straight path between the 2 points without caring about what's below. But with any kind of land transportation you need to deal with rivers, mountains, lakes and seas (not to mention oceans), cities and other man made structures, etc. Without a breakthrough in engineering I don't see how you can go from London to Los Angeles in a reasonable time.
grondilu 8y ago
> I remember reading about Reaction Engines back in 2012 I'm not sure but I think I first watched a CGI rendering of Skylon in the early 2000s (back when I was still a student). I've tried to find the video on YouTube to find out its publication date but it appeared more difficult than I expected. Anyone can find the original video I'm talking about? It's definitely not on the official RE Youtube channel anymore.
- Hendrikto 8y ago
  Are you sure it was ever on YouTube? In the early 2000s yt did not exist yet.
  - taf2 8y ago
    A lot of pre YouTube content is now available on YouTube....
  - grondilu 8y ago
    Yeah, my bad. I guess my memory is failing me.
bloopernova 8y ago
If you are interested, Kerbal Space Program has mods for ramjets/scramjets, and the air-breathing rockets are part of the base game now. You can build your own Waverider and mess around with all sorts of fun explosions and crashes!

baybal2 8y ago

Scramjets minimise compression losses by minimising compression... Sabre minimisies compression losses by instantly cooling incoming hypersonic air stream with their tricky heat exchanger, thus not doing compression. The turbocompressor after the precooler is pretty much a pump.

igravious 8y ago
Interesting, thanks? You seem knowledgeble on the subject, what's your take on the commercial and technical viability of this tech in general and REL's abilities to execute more specifically in the case the tech is viable.
- baybal2 8y ago
  My common sense says that tech is not viable, but reality shows otherwise. Thus, I can't tell much about it from my common sense. The company must be staffed by much more competent engineers in their domain than I am. The most tricky parts in my view are the pre-cooler just for the giant mass flow and temperature difference, and the helium/lh2 heat exchanger, but those two seem to been done. O_O
  - igravious 8y ago
    I see what you're saying but innovation in high-speed mass transport is going to take a breakthrough in tech: could be sabre, could be hyperloop, could be superconducting maglev. Despite what your spidey-sense is telling you, maybe this is one of the breakthroughs we need. Having said that I think we should be aiming for low environmental footprint with all our tech from now on given what we know about the damage we're doing. I'd like to see these breakthrough techs compared in terms of environmental costs. My ideal combo would be superconducting maglev high-speed trains coupled with nuclear power to deliver the electricity.
    - close04 8y ago
      For mass transit high speed only makes sense for longer distances. Most mass transit is relatively short haul where the acceleration/deceleration times (that still provides a comfortable ride) prevent you from saving any time. Over the speed of sound is great if you want to fly half way around the world. But from Paris to London it doesn't really save you much. Unless it becomes cheaper than regular air travel.
      - igravious 8y ago
        > For mass transit high speed only makes sense for longer distances. Most mass transit is relatively short haul where the acceleration/deceleration times (that still provides a comfortable ride) prevent you from saving any time. Probably I just should have said superconducting maglev trains. I guess you're right that they only need to be properly high speed over longer distances. Superconducting maglev would be a win for acceleration/deceleration as well so would benefit short haul. Realistically speaking, inexpensive superconductors would be a total game changer for many fields, not just mass transport. > Over the speed of sound is great if you want to fly half way around the world. But from Paris to London it doesn't really save you much. Unless it becomes cheaper than regular air travel. I kind of feel that in general it'd be better to replace planes with trains, than to replace planes with better or faster planes. Better security-wise. Better for the environment in the long run I believe. I'm totally open to correction though.
        close04 8y ago
        > Superconducting maglev would be a win for acceleration/deceleration as well This limitation isn't at all technological. You just can't accelerate or decelerate much faster than today's high speed trains without causing discomfort to your passengers. And the radius of any turn increases with speed. Otherwise first you just produce noticeable discomfort while turning, and beyond that you risk derailment (no matter the rail type). So you're basically stuck with having really long and very straight stretches of rail where you have to gently accelerate and decelerate. On any short trip this would kill any economy of high top speed. > I kind of feel that in general it'd be better to replace planes with trains The advantage of flight is that you are free to take a more or less straight path between the 2 points without caring about what's below. But with any kind of land transportation you need to deal with rivers, mountains, lakes and seas (not to mention oceans), cities and other man made structures, etc. Without a breakthrough in engineering I don't see how you can go from London to Los Angeles in a reasonable time.

grondilu 8y ago

> I remember reading about Reaction Engines back in 2012 I'm not sure but I think I first watched a CGI rendering of Skylon in the early 2000s (back when I was still a student). I've tried to find the video on YouTube to find out its publication date but it appeared more difficult than I expected. Anyone can find the original video I'm talking about? It's definitely not on the official RE Youtube channel anymore.

Hendrikto 8y ago
Are you sure it was ever on YouTube? In the early 2000s yt did not exist yet.
- taf2 8y ago
  A lot of pre YouTube content is now available on YouTube....
- grondilu 8y ago
  Yeah, my bad. I guess my memory is failing me.

bloopernova 8y ago

If you are interested, Kerbal Space Program has mods for ramjets/scramjets, and the air-breathing rockets are part of the base game now. You can build your own Waverider and mess around with all sorts of fun explosions and crashes!