British aerospace company claims biggest engine advance since the jet

The BBC article, <a href="http://www.bbc.co.uk/news/science-environment-20510112" rel="nofollow">http://www.bbc.co.uk/news/science-environment-20510112</a> has some nice explanatory graphics.<p>It appears they are using a liquid nitrogen boiler to chill a helium loop through their heat exchanger and in turn chill the air.<p>So, perhaps someone better at these calculations can help out, cooling incoming air by 160°C by moving nitrogen from -195°C to -15°C is going to require them to haul up liquid nitrogen and cool a bunch of atmospheric nitrogen that they don't really need. The heat of vaporization is the key that will make their solution win, but by what factor? How many grams of nitrogen must they haul to chill a gram of atmospheric oxygen?

Elon Musk was specifically asked about this technology when he was at Martin School last week. He didn't hear about it, but he seemed skeptical that it would work better than rockets. His response here:<p><a href="http://youtu.be/c1HZIQliuoA?t=48m55s" rel="nofollow">http://youtu.be/c1HZIQliuoA?t=48m55s</a><p>SpaceX might still be the first one with a re-usable rocket if they finish the Raptor engine in 3 years. Plus, his could actually be used to land on Mars, while this can only be useful where you still have atmosphere and oxygen - so only for launches to orbit.<p>But it's great to see more private companies competing in this area. And even if nothing comes out of it for space travel, it might still turn out be a useful technology for airplanes.

This is just rocket-based combined-cycle propulsion that has been proposed and studied by various organizations over the years.<p><a href="http://en.wikipedia.org/wiki/Rocket-based_combined_cycle" rel="nofollow">http://en.wikipedia.org/wiki/Rocket-based_combined_cycle</a><p><a href="http://investor.gencorp.com/releasedetail.cfm?ReleaseID=708513" rel="nofollow">http://investor.gencorp.com/releasedetail.cfm?ReleaseID=7085...</a><p><a href="http://www.isset.org/nasa/nano/www.grc.nasa.gov/WWW/AERO/base/ccp.htm" rel="nofollow">http://www.isset.org/nasa/nano/www.grc.nasa.gov/WWW/AERO/bas...</a><p>The concept is not new, but Reaction is probably the closest to a commercial implementation. Also, it's not fair to compare it to the jet when RBCC isn't a fundamentally novel form of propulsion, just a combination of existing ones (like a car that is both gas and electric propelled). This is not something that could supplant the jet.<p>Some people are comparing this to SpaceX's pure-rocket approach. Up until yesterday, SpaceX and Scaled were working on their own type of combined-cycle launch with Stratolaunch: <a href="http://www.flightglobal.com/news/articles/stratolaunch-and-spacex-part-ways-379516/" rel="nofollow">http://www.flightglobal.com/news/articles/stratolaunch-and-s...</a>. The difference is that the jet and rocket would be separate vehicles instead of fitting into one nacelle. It'd have some of the advantages of using air as propellant as with a RBCC engine, but easier to design I think.

The MAGLEV Launcher.<p><a href="http://en.wikipedia.org/wiki/Rocket_sled_launch" rel="nofollow">http://en.wikipedia.org/wiki/Rocket_sled_launch</a><p><a href="http://www.reallyrocketscience.com/node/2393" rel="nofollow">http://www.reallyrocketscience.com/node/2393</a><p>Using MAGLEV as a launch assist technology to offset the amount of energy derived from burning tons and tons of fuel. Some of the articles estimate a potential to increase payload by 80% compared to a conventionally launched rocket.<p>If you want to get a little deeper into it, this is a good read:<p><a href="http://upload.wikimedia.org/wikipedia/commons/5/58/Maglifter_Mankins.pdf" rel="nofollow">http://upload.wikimedia.org/wikipedia/commons/5/58/Maglifter...</a><p>Some fun data points:<p><pre><code> Power for large scale system: 10GW for 20 seconds. Thermal Management system capable of dissipating 40GJ. </code></pre> What's the probability of this ever being built? In the US, my guess is zero. I could see the Chinese throwing money behind such a crazy project if the numbers make any sense at all. If a system like this can significantly reduce cost to orbit it could represent a huge competitive advantage.

From the article: "The company has deliberately avoided filing patents on its heat exchanger technology to avoid details of how it works - particularly the method for preventing the build-up of frost - becoming public."<p>I would think that for something like this, the patent system would actually work fine. Anybody who tries to make this is going to be located in the US, Canada, Western Europe, or Japan. It's not like they're going to make cheap ones in China and India, and if they did it would be easily correctable with the WTO. What am I missing?

Unfortunate title here - British Aerospace was involved in the project some years ago, but Reaction Engines is a distinct company and I believe they exist despite BAe's "assistance"

The problem with these advanced technologies is two fold<p>1. it requires a large amount of hydrogen - which is not heavy so it looks good on paper but is very cold and voluminous, meaning you need huge insulated tanks. They are expensive to build, have bad mass fraction and are aerodynamically problematic. Hydrogen is also expensive to handle in systems and infrastructure.<p>2. the dry mass of an air breathing engine sucks because they process gases (rockets process liquids with 1000x density), though SABRE is better than stuff like scramjets. This is especially bad for an SSTO like they are proposing since you carry the inlets and precoolers and all that all the way to orbit.<p>My bet for cheap spaceflight would be a two stage kerosene-oxygen rocket. A SABRE engine might make a great first stage but I doubt if you would want to carry it to orbit. I haven't performed much calculations though.

I think the first article I read about Sabre was on HN so it's nice to see it getting followed up.<p>The technology sounds like it's progressing, even if parts of it are still heavily conceptual, and getting a sign off from the ESA is quite a big step (even if certain space company founders have dissed them recently). The last I read was they were struggling to find funding, which is on one hand utterly surprising as if it works properly then it's got the potential to revolutionise travel and who wouldn't like to say "yeah, I put money in before they were famous", and on the other isn't a surprise at all as the returns are probably a decade out.<p>Still, I wait patiently and optimistically for when Britain is showing everyone that whilst we were slow off the mark on the space race we aren't out of it yet.

Here's a documentary that was broadcast on BBC4 a couple of months ago about Bond and his quixotic journey to get HOTOL/Skylon into the sky:<p><a href="http://www.youtube.com/watch?v=vZ_a21fPkYM" rel="nofollow">http://www.youtube.com/watch?v=vZ_a21fPkYM</a><p>It includes a test-firing of the new heat-exchanger at the end.

Article from the BCC at <a href="http://www.bbc.co.uk/news/science-environment-20510112" rel="nofollow">http://www.bbc.co.uk/news/science-environment-20510112</a>

Someone asked on another list for an explanation of the press release. This is my try.<p>Hypersonic engines are up against hard physics. The ram air heats so much in the inlet that it's hard for combustion to add much energy to make it go faster out the back.<p>The idea behind the SABRE engines is to cool the ram air before it is compressed. The heat exchanger to do this is what the press release is all about. With not much more than a ton of mass, it sucks 400 MW of heat out of the incoming air, dropping the temperature from 1500 C to -150 C in a few inches of heat exchanger that looks much like fabric because the tubes are so tiny.<p>The engine cycle also uses the temperature difference between the ram air and the LH2 to run the compressor. It takes close to 2/5th of the energy from burning hydrogen to liquefy it. The engines recover much of this by running a helium turbine on the temperature difference between the ram air and the liquid hydrogen flow to the engines. The turbine powers the compressor stage that raises the pressure of the -150 C air to rocket chamber pressure.<p>The design is extremely clever thermodynamics which also avoids most of the metallurgical problems of high temperature. Fabricating the air to helium heat exchanger was a very hard task. They have miles of tiny tubing, tens of thousands of brazed joints and they don't leak!<p>Using these engines and breathing air, the vehicle reaches 26 km and about a quarter of the velocity to orbit giving an equivalent exhaust velocity (back calculate from hydrogen consumption) of 9 km/s. That's twice as good as the space shuttle main engines. It is expected to go into orbit with 15 tons of payload out of 300 or 5% even though the rest of the acceleration is on internal oxygen that only gives 4.5 km/s exhaust velocity.<p>Leaving out the oxygen and using big propulsion lasers to heat hydrogen reaction mass, such a vehicle would get 25% of takeoff mass to LEO, reducing the already low cost by a factor of 5. That's enough to change the economics of power satellites from being too expensive to consider to a cost substantially less expensive than any fossil fuel.<p>But try explaining any of this in a press release.

I wonder how this will impact air travel. It is a real shame that after Concord retired there is no supersonic jetliner in service, which at least kept the dream alive even if Concord is expensive and short legged. I believe no viable program exists right now for supersonic jetliners. The problem, if I recall correctly from my aerospace professor, is not the jet engine's thrust but heat generated from friction with air. If this Sabre engine can get the airplane mostly out of atmosphere cheaply, heat problem can be alleviated. I don't know how practical my guess is, but if it works, the market potential is immense.

This guy has been at this in various forms for 30 years. Amazing story and for once not completely fucked up by the British Govt, unlike our aerospace industry after WWII that was world leading.

&#62; This core piece of technology solves one of the constraints that limit jet engines to a top speed of about 2.5 times the speed of sound, which Reaction Engines believes it could double<p>Is that 2.5 times the speed of sound limit just for jets at low altitude? At high altitude it is certainly not true. Both the SR-71 and MiG 25 did well over Mach 3.

Does anyone have guesses on how the heat exchanger might work to prevent frost?<p>Perhaps ultrasound?

Sounds like quite a disruptive innovation in the aerospace industry. Always wondered how much it cost to get innovations like this off the ground. $400m funding round sounds pretty serious...

Personally I'm always more intrigued by the prospect of getting around the world quicker. Making the world a smaller place, and more accessible to all, would do wonders for humanity.

I don't see where this technology "fits". When you're going to orbit, 90% of the flight takes place outside the atmosphere, so an air-breathing engine doesn't do much for you.<p>For commercial sub-orbital hops, they'll have to bring the cost down considerably to compete with existing air service. Sure, we'd all love to be able to go from NYC to Frankfurt in an hour. But how many people will pay ten thousand dollars for the privilege?

I'll maybe believe it when I learn more. That it's an idea on paper only means it's way too early to tell. I'm also wondering if they are relying on exotic building materials being developed in the future for this to work, like a previous expensive but failed US space-plane program.

This is great news, but it also makes me a bit sad - because all this innovation died down in the 80's when everyone lost interest in the space race. We could be 30 years further down the road already and many of us probably won't live to see people setting foot on Mars.

Another discussion of this has broken out here:<p><a href="http://news.ycombinator.com/item?id=4856986" rel="nofollow">http://news.ycombinator.com/item?id=4856986</a>

"The company has deliberately avoided filing patents on its heat exchanger technology to avoid details of how it works - particularly the method for preventing the build-up of frost - becoming public."<p>Evidence that the main use case for patents - protecting true innovation and development - does not even need the patent system.

I was skeptic about them so far, I would love to be proven wrong here.

I'm sure some of you chuckleheads are going to figure out how to use this to OC some poor unassuming Ivy Bridge CPU...