Scientists unveil plans for a

[Vice]

Sure looks cool and that engine looks innovative. Exciting.

I am curious though how does it move once it goes outside our atmosphere where theres no air for its engines does it then switch to a conventional rocket?

[DocM]

The SABRE engine is a combined cycle rocket, not a jet or scramjet.

At high speeds in the atmosphere it breathes air, liquefying it on the fly to support combustion in the rocket thrust chambers (several per engine.) At liftoff & low speeds and outside the atmosphere it uses stored liquid oxygen stored in internal tanks. This minimizes liftoff mass while maximizing the payload mass.

In both cases the fuel is liquid hydrogen stored in low boil-off tanks in the airframe.

[neoadorable]

this is a very complex and awesome approach to engines. how cost effective is this? how much is the Skylon supposed to carry? Forty people with equipment would be quite hefty!

[DocM]

It should carry 20+ metric tons of payload (think: a Russian Proton) with costs limited to payload integration, maintenance and fuel, which are the cheapest parts of orbital spaceflight. Throw-away hardware is the expensive part, which is why SpaceX is doing the Grasshopper research.

If they pull it off it'll be a really-big-deal.

Just to keep diagrams up with the story - here's a longitudinal section of SABRE and the fluid cycles. The critical component is the pre-cooler, which is made up of the 4 silver cylinders in the sectional image.

[neoadorable]

the curved design of the engine is interesting...but 20 tons isn't much for a ship that big!

[DocM]

The curve helps get an upwards angle of thrust on the way up.

20 MT would be enough to loft 90%+ of all launched payloads, and perhaps several at once.

[neoadorable]

i demand 100 metric tons or more!!!

[DocM]

This gets the parts for something large up cheaply, plus it could do hypersonic intercontinental flights.

[neoadorable]

if it can do double duty as a passenger plane, then obviously this will help with expediting adoption and decrease the price significantly. i hope we can have these flying around soon!

[Original Poster]

I dunno, how many people are going to be willing to travel in an unmanned spaceplane? I mean I'm sure it's perfectly safe but still..

MEMEMEMEMEMEEE I would be happy to be the test subject! even if i never came back It would be cool :D

[DocM]

We have to remember that the flight crew on most new airliners are redundant - they can take off, fly the route and land robotically now - and often once they're off the ground that's exactly what they do.

[DocM]

BBC articles on the Skylon and the tests of a key part of its SABRE dual-mode engine. SABRE alone could revolutionize high speed intercontinental transport even if it never flies to orbit.

http://www.bbc.co.uk/news/science-environment-17864782

http://www.bbc.co.uk/news/science-environment-17851603

[neoadorable]

you realize we didn't have any updates on this since January? what have they been doing in those four months? i demand more action! :angry:

[DocM]

Reaction Engines has been testing the pre-cooler that long, plus they're pretty tight lipped because of intellectual property concerns. Just the tech for making that pre-cooler is a major advance, not to mention its LH2 cooled skin.

[neoadorable]

when will we see this plane fly Doc? WHEN? i've been hearing Skylon this and Skylon that for years! i want action!

[DocM]

It take a long time go develop game-changing, bleeding-edge single stage to orbit tech like the SABRE engine and Skylon's refrigerated skin, but if it works out we may well see test flights by 2020. It'll be one helluva sight when Skylon finally rolls out.

[DocM]

Skylon Personnel Logistics Module (SPLM)

Note there is a "Pilot Cabin"

[DocM]

New website & video

Heat exchanger cooling rate: 400 megawatts :woot:

[DocM]

Reaction Engines has received more funding, rumors are ?200 million, and appears ready to scale up operations to a much higher level. Thesr kinds of people are what you'd hire to build prototypes....

Senior Engineers....

Contracts manager....

Program manager....

Design engineers....

[*RedBull*]

Next up.....Cylons!

[neoadorable]

thanks for keeping this going Doc! Those pics look cool. How high of an orbit are we talking about, remind me?

[DocM]

They spec 85,000 ft air breathing and >124 miles onexoatmospheric, but they also talk of visiting the ISS and that's 250 miles.

[SharpGreen]

What does being able to rapidly cool air have to do with extremely fast flight?

[Zlain]

What does being able to rapidly cool air have to do with extremely fast flight?

All fluid flow, if assumed a continuum and constant viscosity, is governed by the Navier-Stokes equations. The three sets of equations are continuity, momentum and energy. At most speeds under say, Mach 0.3, we can generally ignore the energy equation because we can assume the density remains constant. This "decouples" one equation from the three, so we can decouple the energy equation since we only have two unknowns and two variables, pressure and velocity. At higher Mach numbers, compressibility becomes more important and we can't assume a constant density anymore. Moreover, at very high Mach numbers, say M = 5 (hypersonic), the flow regime is dominated by heating effects. I have never studied hypersonic aerodynamics but I'm sure you'll appreciate, with re-entry of the space shuttle for instance, the vehicle speed s substantially high such that the aerodynamic heating effects are very important - hence one reason we might have to cool the materials. In terms of the air, we may have to cool that so that we can actually slow it down fast enough to react with the fuel - at least that is what they do in ramjets. Bare in mind too that the higher you go in the atmosphere, the less true the assumption of a continuum holds, and you begin to enter low density flows or even free molecular flows so this will all change the properties of the flow regime.

[DocM]

What does being able to rapidly cool air have to do with extremely fast flight?

The power produced in an engine depends largely on the quantity of fuel burned with the available oxidizer (air, liquid oxygen, nitrous oxide etc.) in it the engines combustion chamber(s.)

Roughly, more fuel burned/second = more power produced = more speed.

In air breathing turbojet engines this fuel quantity is limited by the density of the air breathed in after it's compressed by the turbines. However, no matter how good the turbines are the air will always be a gas.

In a SABRE engine the air breathed into the precooler is supercooled into a liquid, massively increasing its density and therefore how much fuel can be burned with it. It burns the fuel / oxidizer mix in an array of rocket thrusters.

At 85,000 feet it runs out of enough air to be useful so SABRE switches over to liquid oxygen stored onboard before launch to run its thrusters. This makes it a dual-cycle engine. When in this second cycle it can fly in space.

Why a dual-cycle? By using atmospheric air for the first cycle the amount of stowed oxidized for the rockets is reduced, which increases the amount of cargo that can be flown.