SABRE rocket engine could fly at ultrafast Mach 25!

[Red Stapler]

Of course, I immediately thought of KSP after seeing this article because that is how my brain has been wired ever since I launched my 1st career rocket circa 2016. 

Ultrafast, air-breathing rocket engine moves a step closer to reality...

Cool image btw...I think I know what I'll be designing in the SPH tonight. 

Link to Article: https://www.cnn.com/travel/article/air-breathing-rocket-scli-intl-gbr-scn/index.html

Cheers, RS

Edited April 10, 2019 by Red Stapler
added linky

[tater]

Would be cool if they had some real money to accelerate things.

[kerbiloid]

Sounds familiar

https://translate.google.com.tr/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=https://riafan.ru/1136887-27-makhov-kompleksa-avangard-nedoverchivym-kritikam-stoit-poduchit-kurs-fiziki

[Cunjo Carl]

2 hours ago, kerbiloid said:

Sounds familiar

https://translate.google.com.tr/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=https://riafan.ru/1136887-27-makhov-kompleksa-avangard-nedoverchivym-kritikam-stoit-poduchit-kurs-fiziki

Fortunately for any prospective passengers on Skylon, the Sabre engine's only designed to go up to mach 5-6 while air breathing, and then slowly leave the atmosphere burning fuel like a normal rocket to reach "Mach 25" orbital speeds. In the case of Skylon, it's kindof a misnomer to use 'mach 25' because the plane should be well up into space by the time it reaches those speeds. That missile on the other hand is something else!

 

4 hours ago, tater said:

Would be cool if they had some real money to accelerate things.

Totally agreed. They did get that bit of DARPA funding for the precooler test facility in Colorado, but yeah, funding for the rest of the project would be amazing. That said, major funding from the British government would probably be difficult, and making sure it doesn't get cut the day before their first successful launch would be even harder! ... Alright, I guess I'm just salty about Black Arrow.

[DDE]

SABRE is like fusion, always twenty years away.

[p1t1o]

SABRE performs very well in the Mach0-6 range, but for space applications its just too easy and simple to do that part with a regular rocket.

I do think that SABRE represents an important advance in air-breathing propulsion though, its just that I expect it to have applications that involve more...well, more air breathing.

And also, not for a while, we are not ready for hypersonic airliners.

[Nuke]

19 hours ago, tater said:

Would be cool if they had some real money to accelerate things.

if fringe fusion could get the kind of money that rel can get we would have fusion power plants now. or you can give it to iter which makes the skylon look a lot like a much more viable goal in the short term. iter only fuses money into broken dreams.

14 hours ago, Cunjo Carl said:

Totally agreed. They did get that bit of DARPA funding for the precooler test facility in Colorado, but yeah, funding for the rest of the project would be amazing. That said, major funding from the British government would probably be difficult, and making sure it doesn't get cut the day before their first successful launch would be even harder! ... Alright, I guess I'm just salty about Black Arrow.

i think the successful end goal hear is not the skylon space plane, but to get the engine itself to the point where it can be purchased by the private sector with the military likely getting first dibs. the precooler design itself will likely find uses all over the place. biggest potential i see is for things like more efficient and/or higher capacity heat exchangers, which have applications from hvac and refridgeration to more efficient power plants. not to mention licensing their manufacturing techniques. if the engine is successful then much of the money to build the skylon itself is going to start pouring in. i think they got what they need to finish the engine. 

3 hours ago, DDE said:

SABRE is like fusion, always twenty years away.

i blame tokamaks for that analogy. 20 years is just how long it takes to fund, build, run, and come to the conclusion that it wasn't big enough and that you need a bigger one. this causes the whole thing to repeat thus adding the 'always' part. saber on the other hand is pretty much all known and proven technology. the only real secret sauce in the engine is the anti-icing solution that they have come up with to keep the precooler from becoming useless in short order. that is the thing they need to prove and demonstrate. eliminate that and its just a systems integration problem. 

[YNM]

17 minutes ago, Nuke said:

the only real secret sauce in the engine is the anti-icing solution that they have come up with to keep the precooler from becoming useless in short order. that is the thing they need to prove and demonstrate.

Is this always 20 years further away or not ?

[Xd the great]

58 minutes ago, YNM said:

Is this always 20 years further away or not ?

I guess it used to be 30 years away.

[Nuke]

1 hour ago, YNM said:

Is this always 20 years further away or not ?

it works in the lab and they are doing test runs with it, which is lightyears beyond where iter is right now. testing it under all conditions it would encounter during actual use is something else. that probably requires actually flying it on some kind of test bed that can operate up to mach 5 (sr71, if you can get one out of mothballs). there will be holdups, like if you need to design a completely new aircraft to test it.

but i dont see it being the same circular pattern as with high budget fusion research. you have to realize with all the money that it pulls in, you have a bunch of scientists with cushy jobs that would vanish if they ever got the damn thing working.

[wumpus]

5 hours ago, p1t1o said:

SABRE performs very well in the Mach0-6 range, but for space applications its just too easy and simple to do that part with a regular rocket.

I do think that SABRE represents an important advance in air-breathing propulsion though, its just that I expect it to have applications that involve more...well, more air breathing.

And also, not for a while, we are not ready for hypersonic airliners.

My understanding is that it is typical for 75% of a normal rocket to be used to get to mach 6 (obviously mainly fuel.  But if you started at mach 6 you'd need a rocket 25% the size for the same payload.  Of course this assumes that either SABRE doesn't weigh significantly more than a normal rocket engine or it gets staged).  For high cadence flight, SABRE (or SCRAMJETs) might begin to make sense.

The other more recent claim I heard about a funded test (prototype?) of SABRE was that it was cooled by liquid helium.  Is this vented/stored/recooled or what?  Presumably *something* (probably liquid hydrogen fuel) needs to cool the helium, but the article wasn't clear about that [presumably the author didn't follow up the obvious "what cools the coolant" question when the problem was the air rushing by].

[p1t1o]

10 minutes ago, wumpus said:

My understanding is that it is typical for 75% of a normal rocket to be used to get to mach 6 (obviously mainly fuel.  But if you started at mach 6 you'd need a rocket 25% the size for the same payload.  Of course this assumes that either SABRE doesn't weigh significantly more than a normal rocket engine or it gets staged).  For high cadence flight, SABRE (or SCRAMJETs) might begin to make sense.

It does make large weight savings, but those weight savings dont save much money. And a SABRE spaceplane requires an enormous investment in terms of infrastructure (Current SKYLON plans cant use existing runways because of weight/pressure restrictions). It makes a lot more sense to spend a bit more on a larger rocket that to try and convert all of modern space travel to spaceplane basis. Technically the SABRE might give significant savings, but if a large rocket can do the same thing cheaper (and it is significant that rocketry is a mature science with a great deal of experience in the field) then it doesnt make any sense.

 

10 minutes ago, wumpus said:

The other more recent claim I heard about a funded test (prototype?) of SABRE was that it was cooled by liquid helium.  Is this vented/stored/recooled or what?  Presumably *something* (probably liquid hydrogen fuel) needs to cool the helium, but the article wasn't clear about that [presumably the author didn't follow up the obvious "what cools the coolant" question when the problem was the air rushing by].

Helium coolant loop (closed) transfers heat to liquid hydrogen which is burned as fuel. More hydrogen is needed for cooling than is needed for fuel so excess is burned in ramjet burners (which dont really provide much thrust, but provide significant fluid-dynamic drag reductions).

Edited April 11, 2019 by p1t1o

[Bill Phil]

28 minutes ago, wumpus said:

My understanding is that it is typical for 75% of a normal rocket to be used to get to mach 6 (obviously mainly fuel.  But if you started at mach 6 you'd need a rocket 25% the size for the same payload.  Of course this assumes that either SABRE doesn't weigh significantly more than a normal rocket engine or it gets staged).  For high cadence flight, SABRE (or SCRAMJETs) might begin to make sense.

Not quite.

It depends on the specific impulse, of course.

But let's look at Mach 6: that's about 2000 meters per second, or roughly 1/5 of the delta-v needed to enter low orbit.

If we use a 4000 m/s specific impulse we can calculate the needed mass ratio for an SSTO: about 12.2.

Now we can cut out 2000 m/s from that 10000 and calculate it again: about 7.4.

Pretty decent reduction in mass ratio. Of course, you still need to bring all the extra equipment for the jet engines and the fuel to accelerate using the jet engines, but depending on fuel use and how quickly the vehicle reaches Mach 6, it could make an SSTO practical using chemical rockets. If they can squeeze out just a bit more velocity and retain it they could get an even lower mass ratio. Depends on many things. And of course a higher specific impulse would mean even lower mass ratios. 4500 m/s would lower the required mass ratio from 7.4 to 5.9. Using 4500 m/s for ISP, about 36% of propellant seems to be used just to reach 2000 m/s. The rocket equation is exponential.

If SABRE works there's a good chance they can build an SSTO.

24 minutes ago, p1t1o said:

It does make large weight savings, but those weight savings dont save much money. And a SABRE spaceplane requires an enormous investment in terms of infrastructure (Current SKYLON plans cant use existing runways because of weight/pressure restrictions). It makes a lot more sense to spend a bit more on a larger rocket that to try and convert all of modern space travel to spaceplane basis. Technically the SABRE might give significant savings, but if a large rocket can do the same thing cheaper (and it is significant that rocketry is a mature science with a great deal of experience in the field) then it doesnt make any sense.

Yeah. But there's a common thread among reuse: SSTO. Large weight savings (or rather mass ratio savings) make building an SSTO less difficult.

Skylon appears to be a decent proposal, as long as it doesn't get mired in red tape and bad project management.

[p1t1o]

25 minutes ago, Bill Phil said:

Yeah. But there's a common thread among reuse: SSTO. Large weight savings (or rather mass ratio savings) make building an SSTO less difficult.

Skylon appears to be a decent proposal, as long as it doesn't get mired in red tape and bad project management.

Yes, everyone should definitely refer to that much more in-depth thread. If there is something to be said about SSTOs, its been said already there.

But whilst I do count myself as a SABRE/Reaction Engines fanboy, I have lost confidence in SKYLON. Its not that I dont think its both supercool and a huge leap forward in terms of spaceplane-enabling tech - they certainly could build a workable spaceplane if SABRE does what it says on the can -  but its just that normal, comparatively simple rockets, are so much more well known, so much cheaper to make larger - and now they even come in reusable flavours, I just dont think the niche is big enough [YET] for an air-breathing infrastructure when you look at the tonnages of cargo involved and the fact that SKYLON would require an entirely new industry to come into existence.

Maybe in 100 years when we have industry that requires, globally, the monthly shipment of thousands of tons to orbit and beyond, but not yet.

It doesnt matter that SABRE can make a viable spaceplane, it matters if it can make one easier/cheaper to operate than a rocket. Which is not currently possible, IMO.

 

 

Edited April 11, 2019 by p1t1o

[Nuke]

30 minutes ago, p1t1o said:

Yes, everyone should definitely refer to that much more in-depth thread. If there is something to be said about SSTOs, its been said already there.

But whilst I do count myself as a SABRE/Reaction Engines fanboy, I have lost confidence in SKYLON. Its not that I dont think its both supercool and a huge leap forward in terms of spaceplane-enabling tech - they certainly could build a workable spaceplane if SABRE does what it says on the can -  but its just that normal, comparatively simple rockets, are so much more well known, so much cheaper to make larger - and now they even come in reusable flavours, I just dont think the niche is big enough [YET] for an air-breathing infrastructure when you look at the tonnages of cargo involved and the fact that SKYLON would require an entirely new industry to come into existence.

Maybe in 100 years when we have industry that requires, globally, the monthly shipment of thousands of tons to orbit and beyond, but not yet.

It doesnt matter that SABRE can make a viable spaceplane, it matters if it can make one easier/cheaper to operate than a rocket. Which is not currently possible, IMO.

 

 

skylon was always going to be a paper airplane. a marketing tool used in order to secure the funding for their actual ambition, making an air breathing hybrid rocket engine. what becomes of that engine? who knows. seems it would be more viable as a reusable first stage. if you can get it on a sub orbital trajectory and seperate out of the atmosphere it would be a lot more viable than stratolaunch ever will. it would also have to be competitive with what spacex is doing. 

Edited April 11, 2019 by Nuke

[YNM]

9 hours ago, Nuke said:

testing it under all conditions it would encounter during actual use is something else. 

What, you mean ITER doesn't have to actually break even ?

[wumpus]

9 hours ago, p1t1o said:

It does make large weight savings, but those weight savings dont save much money. And a SABRE spaceplane requires an enormous investment in terms of infrastructure (Current SKYLON plans cant use existing runways because of weight/pressure restrictions). It makes a lot more sense to spend a bit more on a larger rocket that to try and convert all of modern space travel to spaceplane basis. Technically the SABRE might give significant savings, but if a large rocket can do the same thing cheaper (and it is significant that rocketry is a mature science with a great deal of experience in the field) then it doesnt make any sense.

It doesn't make sense now and it is unlikely to make sense in a decade or two.  A lot depends on if Musk (and/or Bezos or some other well funded visionary) is pushing hard to reduce costs.  Eliminating building a new rocket appears be the first step in making space travel cheap.  Reducing the army of techs needed to launch a rocket is likely the second step (I believe the program that Bezos built his rocket program around, DC-X, was able to do a lot in this direction).  I doubt that fuel/oxidizer reduction would even be the fourth stage of cost reduction, but as things stand now it represents a definite ceiling in how much it costs to take things (and people) to orbit, and that ceiling is still fairly high.

Still, I wouldn't be too surprised if Starship and/or New Armstrong is outfitted with side boosters that only work in atmospheric flight, possibly scramjets or air-augmented rockets to reduce total fuel costs.  Just don't expect such a thing until a decade of flying or more (or possibly a sufficiently high cadence).

[Nuke]

5 hours ago, YNM said:

What, you mean ITER doesn't have to actually break even ?

its not intended to. 

[YNM]

3 hours ago, Nuke said:

its not intended to. 

Ooh, so the engines doesn't have to actually be able to carry out the mission, yes ? XD

[KerikBalm]

On 4/11/2019 at 10:46 AM, DDE said:

SABRE is like fusion, always twenty years away.

or a mission to mars... That Ares/SLS program has been going on how long and still hasn't flown? Meanwhile, ol' musky has the Falcon heavy (like... basically... a reusable SLS) in the market carrying commercial payloads, and is working on an even bigger rocket.

I have a feeling that ITER is like the SLS...