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Skylon’s SABRE Engine Passes a Big Test

universetoday.com

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Re: Skylon’s SABRE Engine Passes a Big Test

#11

Post by trhway »

nickpinkston wrote: post #5

In case anyone was confused by the article's description, here's the Wikipedia: "SABRE (Synergetic Air Breathing Rocket Engine) is a concept under development by Reaction Engines Limited for a hypersonic precooled hybrid air-breathing rocket engine. The engine is being designed to achieve single-stage-to-orbit capability, propelling the proposed Skylon spaceplane to low Earth orbit. SABRE is an evolution of Alan Bond…

>After shutting the inlet cone off at Mach 5.14, and at an altitude of 28.5 km, the system continues as a closed-cycle high-performance rocket engine burning liquid oxygen and liquid hydrogen from on-board fuel tanks

the benchmark of today - SpaceX - separates the first stage at Mach6-8 at 65-80km height. Thus, the SpaceX second stage has less delta-v to add and don't have to carry all that weight - the SABRE would naturally be bigger than the 2nd stage for the same payload. The economical space related case of HOTOL/SABRE single-stage-to-orbit pretty much disappeared for a foreseeable future when SpaceX started to recover the 1st stage. That not to say about suborbital flights SF-Shanghai though. Or even "just" hypersonic as SABRE tech seems to successfully deal with one of the major/key obstacles for it (and that is huge, i'm in no way trying to dismiss their work). And one can see how SABRE can be used in some cases as a convenient 1st stage, i.e. by being able to launch from any big airport instead of only specially designed spaceports (such a 1st stage would probably be better than that https://en.wikipedia.org/wiki/Pegasus_(rocket)#Carrier_aircr...).

Re: Skylon’s SABRE Engine Passes a Big Test

#13

Post by SECProto »

trhway wrote: post #11
nickpinkston wrote: post #5

In case anyone was confused by the article's description, here's the Wikipedia: "SABRE (Synergetic Air Breathing Rocket Engine) is a concept under development by Reaction Engines Limited for a hypersonic precooled hybrid air-breathing rocket engine. The engine is being designed to achieve single-stage-to-orbit capability, propelling the proposed Skylon spaceplane to low Earth orbit. SABRE is an evolution of Alan Bond…

>After shutting the inlet cone off at Mach 5.14, and at an altitude of 28.5 km, the system continues as a closed-cycle high-performance rocket engine burning liquid oxygen and liquid hydrogen from on-board fuel tanks the benchmark of today - SpaceX - separates the first stage at Mach6-8 at 65-80km height. Thus, the SpaceX second stage has less delta-v to add and don't have to carry all that weight - the SABRE would n…

Imagine putting SABRE on the first stage though - the engines would be heavier, but using air instead of carrying oxygen, for the full burn of the first stage. The payload mass fraction would be dramatically higher without carrying the oxidizer mass on board.

Re: Skylon’s SABRE Engine Passes a Big Test

#14

Post by ggm »

zer0sugar wrote: post #9

Isn't it inevitable the SpaceX will (and already does) dominate the entire space industry? Won't it be cheaper to launch on starship than anythign else even for very small payloads? Yes, I know about RocketLab but I wonder if they will be able to survive once starship is up and running.

European governments will continue to back Ariane because strategically it makes sense. Russia will bankroll energyia likewise. Dominance is not static and private capital will not entirely replace state actions.

Re: Skylon’s SABRE Engine Passes a Big Test

#15

Post by [deleted] »

SECProto wrote: post #13
trhway wrote: post #11

Earlier quoted context omitted.

>After shutting the inlet cone off at Mach 5.14, and at an altitude of 28.5 km, the system continues as a closed-cycle high-performance rocket engine burning liquid oxygen and liquid hydrogen from on-board fuel tanks the benchmark of today - SpaceX - separates the first stage at Mach6-8 at 65-80km height. Thus, the SpaceX second stage has less delta-v to add and don't have to carry all that weight - the SABRE would n…

Imagine putting SABRE on the first stage though - the engines would be heavier, but using air instead of carrying oxygen, for the full burn of the first stage. The payload mass fraction would be dramatically higher without carrying the oxidizer mass on board.

[deleted]

Re: Skylon’s SABRE Engine Passes a Big Test

#16

Post by trhway »

SECProto wrote: post #13
trhway wrote: post #11

Earlier quoted context omitted.

>After shutting the inlet cone off at Mach 5.14, and at an altitude of 28.5 km, the system continues as a closed-cycle high-performance rocket engine burning liquid oxygen and liquid hydrogen from on-board fuel tanks the benchmark of today - SpaceX - separates the first stage at Mach6-8 at 65-80km height. Thus, the SpaceX second stage has less delta-v to add and don't have to carry all that weight - the SABRE would n…

Imagine putting SABRE on the first stage though - the engines would be heavier, but using air instead of carrying oxygen, for the full burn of the first stage. The payload mass fraction would be dramatically higher without carrying the oxidizer mass on board.

It is possible though cost&complexity seems high - we theoretically can even today bundle a bunch of SR-71 engines and probably stretch them beyond designed Mach 3.3 for the short time. Having low thrust-to-weight (SABRE promises up to 14, SR-71 had 6) we'd need either a lot of them for VTOL which leads to high cost, or we're limited by the size of maximum realistically possible hypersonic capable plane, plus the plane body being the additional weight. For example VTOL calculation - say engine weights 1 ton, we can lift off 13 ton of fuel and payload. It will use 40 ton of O2 from the air. For rocket engine - 1 ton engine can lift off 100+ ton, and if we just take the 13 ton fuel plus 40 ton O2 we'd have 45 ton budget for the rest (body plus payload). In reality you'd need higher fuel ratio, and this is why VTOL for atmospheric breathing engine pretty much isn't an option .

Going beyond pure rocket engine for the 1st stage i think air-augmented rocket (http://astronautix.com/g/gnom.html) being simpler (thus cheaper) would be the next step that would get us closer (specific impulse wise) to what SABRE is targeting.

Re: Skylon’s SABRE Engine Passes a Big Test

#17

Post by privateSFacct »

These guys don't disappear - they have been around forever with their Skylon plane.

Just a heads up, it's a long way from testing one component of an engine on the ground to getting a full engine demo going to then testing it in the air to then build the plane then integrating engine - then getting orbital trips working with reentry!

I am curious how much private capital they have been able to attract (outside of govt contract players). Obviously if this is really revolutionary then they will but this always felt like a long term / govt kinda of cool - tech forward but pork barrel project for the UK.

More of their background from a somewhat more balanced source - at least the headline put revolutionary in quotes.

https://www.bbc.com/news/science-environment-36773074

They do claim to have the "best engineers" in the industry - so beating out big players like rolls royce, PW, CFM, spacex, blue origin, ariane aerospace - so that is a positive they have.

Re: Skylon’s SABRE Engine Passes a Big Test

#18

Post by btbuilder »

travisporter wrote: post #10

Here’s to a single stage to orbit craft a la Kerbal space program’s RAPIER engine (although it’s probably still not realistic to expect better than two stage due to the rocket equation)

Pretty sure KSP RAPIER is a fictional copy of the described SABRE engine.

Re: Skylon’s SABRE Engine Passes a Big Test

#19

Post by riffraff »

btbuilder wrote: post #18
travisporter wrote: post #10

Here’s to a single stage to orbit craft a la Kerbal space program’s RAPIER engine (although it’s probably still not realistic to expect better than two stage due to the rocket equation)

Pretty sure KSP RAPIER is a fictional copy of the described SABRE engine.

The names seem to indicate that, both being similar kind of weapons.

Re: Skylon’s SABRE Engine Passes a Big Test

#20

Post by avmich »

ggm wrote: post #14
zer0sugar wrote: post #9

Isn't it inevitable the SpaceX will (and already does) dominate the entire space industry? Won't it be cheaper to launch on starship than anythign else even for very small payloads? Yes, I know about RocketLab but I wonder if they will be able to survive once starship is up and running.

European governments will continue to back Ariane because strategically it makes sense. Russia will bankroll energyia likewise. Dominance is not static and private capital will not entirely replace state actions.

A nitpick, Energiya doesn't make rockets this days, rather Soyuzes, Progresses, satellites, upper stages (Block D)... Launchers are made mostly by Khrunichev (Proton) and Progress (Soyuz-2).

Russia tries to develop new rockets, but so far it's really slow and quite expensive. It's possible that when NASA will stop paying for Soyuz transport to ISS, it will become even slower. It's not a particularly good time in Russia for new rockets paid by the state.

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