[jr2]

I stumbled across it and found it interesting.  I would rather have seen it when I found the original article.  Hence; I figured anyone who saw my first post but didn't have the inclination to go searching would find this info useful. 

Basically, if I was reading my own post as someone else and was uninformed, I would appreciate it being done for me.  If I was actually informed, it would just be background noise and I wouldn't really mind.

[The E]

You're either not seeing or ignoring the point.

You were necroing this thread for basically no good reason, ou did not post information that was in any way new. Presumably, given that we have no running discussion about Skylon's tech, I would have assumed that everyone who wanted to know about it back when this topic was current has already informed himself.

You bringing this topic back from the dead is a nono. Don't do it again.

[jr2]

Is there a way to update your posts without marking it as new/edited?  I actually would have done that if I knew how.  I didn't bother to edit the first post because it will just show up in the updated topics anyways.

[Thaeris]

For the record, I thought that was an interesting snippet that I would not have been looking for at this time, jr2. Thank you.

[Nuke]

i think their next step is actually building a complete engine, which is going to take time. then they are likely going to o through a validation process before they start building the ship.

[FreeSpaceFreak]

Hmm, so they're using helium as an intermediary, rather than cooling the air directly with LH2? Interesting, anyone have an idea on the advantage of that? I just see it adding weight and complexity... Most of today's rocket engine nozzles are cooled with LH2 as well, so it'd not like it couldn't be done (although the use case here is different, of course).

[Klaustrophobia]

jesus christ E, calm down.  i found it interesting and i'm glad he posted it.  unlike your responses to him.

[Nuke]

Hmm, so they're using helium as an intermediary, rather than cooling the air directly with LH2? Interesting, anyone have an idea on the advantage of that? I just see it adding weight and complexity... Most of today's rocket engine nozzles are cooled with LH2 as well, so it'd not like it couldn't be done (although the use case here is different, of course).

the helium loop is essentially a heat engine. heat sucked out of the air is used to power turbo pumps and the compressor. you still use a lot more lh2 to cool the helium than the engine can burn. even that is put to use in a ring of ramjets who's job is not to produce usable thrust but to reduce intake drag by accelerating surplus intake air. this engine design is ****ing awesome.

[Thaeris]

I finally got around to watching that BBC documentary you posted back-in-the-day, Nuke. I think the engine actually might be even more f-ing awesome if they used an annular aerospike nozzle for the exhaust.

As per helium... it is heavier than hydrogen, and thus less likely to escape its containment. Being as active a gas as it is, well, it will still do a lot of escaping. But it's also non-reactive. If your heat exchangers are as fragile as they are, and they're being used to channel mass amounts of air to be combusted... you probably do not want to use a highly active, reactive gas like hydrogen to pump through the exhangers. Granted, carrying a separate set of gas tanks is a bit lossy, but when it comes to mitigating disaster, the weight gain is really worth it.

[Nuke]

they are using an expansion-deflection nozzel called stern. i cant find any information on this particular nozzel. but it will have some of the features of an aerospike engine. both nozzels have altitude compensation features.