London To Sydney In 4 Hours

[Revolver]

http://www.wimp.com/prototypeengine/

What does TF reckon to this?

It would be great to be able to go to Australia so quickly. But the Gs at Mach 5 have to be crippling, surely?

[Luke Dunstan]

But the Gs at Mach 5 have to be crippling, surely?

Not if the passengers chairs rotate during acceleration.

[Skoze]

But surely you'd not really notice seeing as it'd build up to it gradually?

[Revolver]

So mental Gs won't kill you if they sneak up on you slowly?

[Luke Rainbird]

"G"s are an acceleration, so if there's no major acceleration, no.

[Duncy H]

Mental G's are caused by you accelerating. The higher the acceleration the more g generated. So if it increases speed slowly you won't notice much of a difference and once you reach that certain high speed you won't need to accelerate no more so you won't be subjected to any g forces

Edit: gosh dang it rainbird!

Edited September 21, 2012 by Duncy H

[Luke Rainbird]

[Revolver]

Oh, that's cool then. 4 hours to Australia, wahey!

[Greetings]

So, who can dumb this down?

[JT!]

I went from Minneapolis to Amsterdam in 6 hours 10 mins airtime.

[Rusevelt]

Like to see that tech used for the world land speed record.

[CurtisRider]

The noise that thing makes is soooooo cool

[LukasMcNeal]

Mach 5 passenger plane? Id like to see this! The engineering on it would be phenominal.

[Martin Reynolds]

If the main feature of the engine is to rapidly drop the temperature of air over 1000C, then couldn't this technology be used elsewhere?

Obviously they don't give any details on what environments it can work in, at what speed ect.

[LukasMcNeal]

Really cold really quick freezers?

[JT!]

Really cold really quick freezers?

More like aircon.

[Revolver]

That's what a freezer is.

[RobinJI]

There was a documentary on this the other day on the BBC called 'The Three Rocketeers' it was good, but more about their struggle to get funding and get on with developing it, there was very little talk of the actual technology.

So, who can dumb this down?

I can have a go, but that's the first real explanation of how the thing works I've seen too! If I seem patronising or like I'm simplifying it too much, it's just because writing this helps me get my head around it too!

Looking at it, it appears that it's essentially a jet/rocket that provides thrust by burning liquid hydrogen, and it burns it using atmospheric oxygen when available (like a jet engine) and then liquid oxygen when it gets out of the atmosphere (like a rocket engine).

There's basically 3 substances being used in it, the Air/liquid oxygen, the Hydrogen fuel, and then there's helium which is used within it to transport heat and pressure around then engine to where it's needed. It's probably easiest to explain the path/use of each substance:

Air:

Air enters the engine and is immediately cooled massively (entering the engine at mach 5 would heat the air to a ridiculous temperature, as it'll be highly compressed by the forward motion, and when you compress a gas it's temperature increases, kind of like needing an intercooler on a turbo car.) A compressor driven by a flow of helium then compresses the air, before it's flow's split and it's partly used to burn hydrogen (to provide the propulsive force by exiting through a jet engine style exhaust labeled 'rocket') and partly just chucked into the exhaust. As the engine's designed to be used to exit the atmosphere, there's also a supply of liquid oxygen on board for when it runs out of atmospheric oxygen to burn, which is introduced when needed by the 'LOX pump'.

Helium:

The helium used to drive the 'Turbo compressor' and the 'LOX pump' appears to work like a steam engine, where it's converted from a liquid form to a gas by heating it using the heat exchanger labeled 'HX3', and the resulting pressure/flow is used to drive the pump/compressor. (The heat used in 'HX3' is taken from the hot exhaust/propulsion gasses.) Once it's driven these, it's then cooled back to being a liquid by 'HX4', before being pumped back to the start of the system by the 'He circulator' While it's a liquid, its very low temperature is used by the 'precooler' to cool the intake air.

Hydrogen:

The hydrogen that is eventually burned is first used to cool the helium in 'HX4' while it does this the heat it's removed from the helium appears to convert it from a liquid to a gas, this causes an expansion, causing a pressure/flow which is used to drive the hydrogen pump 'LH2 pump', as well as helium circulator 'He Circulator', once it's driven these it's burned.

I think that kind of explains it, it's basically a jet engine which uses helium to transport some of the energy created through combustion around the engine, where it can be used for the specific tasks it's needed for to allow the engine to operate at ridiculous speeds. Then when it runs out of atmospheric air to use for the jet engine, it just uses stored liquid oxygen instead, essentially operating as a simple rocket.

It looks like some seriously interesting technology that really will open some doors that were previously closed with regards to high speed travel and space travel. There's already engines that'll operate at these sorts of speeds, and in fact much higher, (SCRAM Jet's being the most heavily developed one) but this looks like it's the first one that's capable of propelling its self to those speeds. A SCRAM Jet will only work at speeds of several times the speed of sound upwards, so tends to need a piggyback or disposable rocket engine to get it up to speed, making it cripplingly expensive for any commercial flight use.

Edited September 23, 2012 by RobinJI

[Greetings]

Thanks for that, well explained. Also the reason behind having an intercooler is something new to me, I always thought it was due to there being poor thermal insulation between the exhaust and compressor in the turbo. Makes sense now.

What I don't get though is how you can cool such huge masses of air from 1000C to -150 in the speed it enters the engine. Surely at Mach 5 there must be unbelievable amounts of air going in there?

edit: Also, to simplify what's amazing about this engine is that it's a rocket engine which can take the oxygen from the atmosphere, as opposed to conventional rocket engines which need it in liquid form?

Edited September 24, 2012 by Greetings

[LukasMcNeal]

It takes it from the atmosphere so doesnt have to carry it as a fuel? I think thats what you mean!

[RobinJI]

Cheers, I'm glad my explanation made some sense!

Yeah, it's essentially a cross between a rocket engine and a jet engine, what's groundbreaking about it is that it's capable of running using air as its combustion material at speed ranges that I don't think were previously possible from a single air-breathing engine, as well as being able to operate as a liquid fuel rocket engine, so basically it's a single engine that can power a craft from the runway, to mach 5 within the atmosphere burning atmospheric oxygen, and then adapt to burning liquid oxygen and continue to operate in a vacuum. Crucially though, because of this it's capable of providing the speeds require to exit the grip of earths gravity without the need for external boosters, and is efficient enough with its use of fuel that it can power a craft into space without the need for any external booster rockets/fuel tanks. The guys developing it have been trying to make a 'single stage to orbit' space craft for decades, and this is basically the biggest thing that's been in their way for a while. If they get their way, this engine will essentially power the replacement for the space-shuttle, and won't need the huge launching dramatics the shuttle does, it'll just take-off from a runway like a normal plane, bugger off into space for a while, fly back down and land. Pretty awesome if you ask me!

I really do hope this is as big leap as they seem to think, if it is then it looks really exciting in terms of providing much more accessible space travel. Space exploration, (and in fact purely experimental/exploritory science in general) is an area that I think's depressingly under-invested at the moment, the modern mentality seems to simply be that money = success, and nothing else, there's no real sense of want for progress, unless that progress allows you to make money off it. It seems like there's no true pioneers anymore, people are just happy to just aim for the top of the current society, rather than improve society as a whole. If this can provide a bit of spark to re-ignite the public's interest in the advancement of the human race, then I've got nothing but praise for it.

In fact the same seems to apply for technology as a whole, people seem to aim to be the best within the current technology much more so than they seem to want to re-invent it (I guess it's easier to sell something that's an improved version of something people already understand than it is something truly ground-breaking and different). Refinement seems to have taken over from development, and it's a bit of a shame really, as in my eyes it's holding us back. This SABRE engine is an example of what happens when that mindset is broken and people take a whole new approach, which is something I thoroughly approve of.

I'm not really sure on how the coolers work either. Like you say there must be mental amounts of air-flow through it at those sorts of speeds, so they're trying to cool massive amounts of air in the fraction of a second it spends within the cooler, impressive stuff that they've made it work!

PS, intercoolers are for that use too, but simply compressing the air will cause an increase in its temperature even if the turbo was somehow operating at ambient temperatures, just because of its increase in pressure. It's a thermodynamic relationship that's used a lot in engines, I guess the most obvious example being diesel engines, which compress the air in them so much that its temperature's high enough to cause spontaneous combustion as soon as a fuels added to it, removing the need for a separate combustion source like a spark-plug, hence the name 'compression ignition'. An interesting example in my eyes is one of the formula one cars Cosworth developed during the turbo-era, it boosted the intake air to 4 bar, inter-cooled it down to near ambient temperature, and then decreased the airs pressure to around 2 bar, this pressure-drop reduced the intake temperature to well bellow ambient (approaching zero apparently), effectively giving them chilled air entering the engine at twice atmospheric pressure, clever stuff. Another obvious example's aerosols getting cold as their contents expand when you use them. It may even be that the coolers in this thing utilise this and use a clever chamber shape to provice a pressure drop/temperature drop to help them out.

Edited September 24, 2012 by RobinJI

[Pete.M]

An interesting example in my eyes is one of the formula one cars Cosworth developed during the turbo-era, it boosted the intake air to 4 bar, inter-cooled it down to near ambient temperature, and then decreased the airs pressure to around 2 bar, this pressure-drop reduced the intake temperature to well bellow ambient (approaching zero apparently), effectively giving them chilled air entering the engine at twice atmospheric pressure, clever stuff.

I'm definitely going to read more into that, sounds awesome.

How much more efficient will these SABRE engines really be compared to typical current jet engines when attached to a jumbo? Are we looking at as much as 50% more efficient?

[RobinJI]

I'm definitely going to read more into that, sounds awesome.

How much more efficient will these SABRE engines really be compared to typical current jet engines when attached to a jumbo? Are we looking at as much as 50% more efficient?

I'm trying to remember what car used it, and if it even made it to a race or not, I was told about it by Geoff Goddard who use to be pretty high up the design team at Cosworth, and had a lot to do with its development (along with some other pretty damn cool stuff), all I remember is that it was the result of a rule change; they'd developed an engine to run at 4 bar, and the rules were changed to require a max of 2 bar, so they made the intake pressure 2 bar but kept a turbo output pressure of 4 bar, giving them the bonus of a huge temperature drop. I'm guessing it had some disadvantages/issues or it'd be a more commonly used concept.

As for strapping them to a Jumbo, no idea, it'd be interesting to find out more about them. I'd guess that it wouldn't be much benefit, as they're designed around being used at speeds about 7 times faster than a jumbos cruising speed. In my mind they seem to be more an advancement in rocket technology rather than jets, although it'd be interesting to see if they'd be capable of replacing jets effectively too. I guess the main issue would be using hydrogen as a fuel, as we know from the debate over hydrogen fuel-cell powered cars, it's not easy stuff to collect/make/store.

[Jake.]

tl:dr

Something about jet engines?

[Revolver]

tl:dr

Something about jet engines?

Jet engines what makes u go ded fast cus of crammin more air in but mekkin it ded coled wich is the trick.