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British Skylon Engine Passes Its Tests
An anonymous reader writes "The BBC reports that the SABRE hybrid (part air-breathing jet, part rocket) that is intended to power the Skylon single-stage-to-orbit space plane has passed its final technical demonstration test, and is now looking for money (only £250m!) to prepare for manufacturing. If this goes ahead, travel into orbit from local airports (ideally, those close to the equator) will be possible. And quite cheaply. But might it have the same legal difficulties flying from U.S. airports as the Concorde did?"
I sense a Kickstarter in the offing...
Last I read, developing Skylon was going to cost about ten billion pounds (or maybe dollars, though it's a big number either way). So there's a big jump from having an engine to being able to fly into space from your local airport.
Is the strobing red light on the front. Seriously, what the frak?
And their legal (read: environmental) difficulties.
Launch from somewhere accessible to the market via other modes, but with sane local regulations.
Problem solved.
Scruting the inscrutable for over 50 years.
Citation needed.
Why would throwing away half the craft and having to carry many tons of oxidizer, which the skylon does not need, be cheaper?
Good show, old chaps, but change the name. Sooner or later, a Skylon will turn on you.
Fuel is cheap: rocket designers dream of a future where fuel will be the primary cost of launching things into space. Developing a space plane is not, and you have to invest all that money before you even know if it will work.
SpaceX estimates for launches on a reusable Falcon are similar to the estimates for Skylon, and they can build up to it, starting with expendable versions that are proving the technology and making money. Skylon has the tricky 'give us ten billion and it will probably work' hurdle to jump over.
The engine doesn't exist yet. This was a test of the pre-cooler. It is a critical component and it was important.
I love Jesus, except for his foreign policy.
Fuel is cheap: rocket designers dream of a future where fuel will be the primary cost of launching things into space.
That will only happen, if you're not throwing away a vehicle every time you launch. Else you have to add the cost of the vehicle to the launch. This is where Skylon comes in. It's a completely reusable vehicle. What it doesn't have currently is a market which justifies spending ten billion dollars or euros. You have to have a lot of launches before the development costs become a small part of overall launch costs.
Wrong!
Rockets can't be cheap. They are not reusable (you can try to reuse certain parts, but you're going to disassemble and reassemble them in any case) and that is ALWAYS going to put a high lower limit for their price. In the best case, you'll be paying millions of dollars for person to get to a lower orbit.
Skylon spaceplanes can, in theory, lower that to perhaps several tens of thousands dollars. Definitely to the level of hundreds of thousands.
That will only happen, if you're not throwing away a vehicle every time you launch.
Sure. But if Skylon meets the launch cost estimates I've seen, fuel will still be only a few percent of that cost.
As I understand it, they want to use air during launch to allow them to carry a bigger payload in an SSTO, not to save money.
Why does the input air need to be chilled? Does this have something to do with using hydrogen in a turbine engine?
Covered here. It's actually an interesting read. Put succinctly, as speed increases, the temperature of the air increases, reducing efficiency.
Oliver's law of assumed responsibility: If you're seen fixing it, you will be blamed for breaking it.
clip from online article regarding this intercooler:
But its success depends on the Sabre engine's ability to manage the very hot air entering its intakes at high speed.
These gases have to be cooled prior to being compressed and burnt with the onboard hydrogen.
Skylon would do the job of a big rocket but operate like an airliner from a conventional runway
REL's solution is a module containing arrays of extremely fine piping that can extract the heat and plunge the inrushing air to about -140C in just 1/100th of a second.
Ordinarily, the moisture in the air would be expected to freeze out rapidly, covering the piping in a blanket of frost and dislocating their operation.
But the company's engineers have also devised a means to control the frosting, permitting the Sabre engine to run in jet mode for as long as is needed before making the transition to full rocket mode to take the Skylon spaceplane into orbit.
It is the innovative helium cooling loop with its pre-cooler heat-exchanger that REL has been validating on an experimental rig.
"We completed the programme by getting down to -150C, running for 10 minutes," said Mr Bond. "We've demonstrated that the pre-cooler is behaving absolutely as predicted."
If I sound stupid, it's not me talking....
Why should we care about it being able to fly at US airports if it needs to launch from the equator?
This is a very neat concept, and it has implications in regular jet travel as well as space travel. The ability to cool air and compress it that much in a regular jet engine could increase efficiency astronomically! The fact that this concept works could mean we see more economical jets before we see this in space travel.
How's that going for disposable cars and airplanes?
Things are disposable _because_ they can be made very cheaply. Not the other way, generally.
Far from advising xenophobia, I'd still like to point out that US is a fucking big country. Most people in Europe, for example, have no idea what a "fucking big country" is.
You mean like Russia that is actually in Europe (at least the part that fits given that it is so large it spreads over two continents), contains 10 time zones, and has a land area almost twice that of the US?
Many years ago in high school I think, I wrote a report on the X-15 rocket plane. The impression I got was that, while vertical rocket technology got us further faster in the short term, a more gradual development of hypersonic planes would've been better in the long run. We might have had a whole generation of space planes lobbing satellites and even space tourists capsules cheaper, more safely, and with faster turn-around time. I'm not an engineer, so I could be completely full of crap, too.
I swear to God...I swear to God! That is NOT how you treat your human!
But if Skylon meets the launch cost estimates I've seen, fuel will still be only a few percent of that cost.
Doesn't matter. Lets say you blow $10B on R+D for a launch platform. Over the life of that platform, no matter how low the fuel cost, you MUST gross more than $10B revenue before you can dream of profit.
Competitor? Traditional tech means $2B in R+D for a launch platform. Over the life of that platform, no matter how low the fuel cost, you MUST gross more than $2B revenue before you can dream of profit.
Normally, in aerospace, you spend more money on R+D than on vehicles. So the vehicle cost doesn't really matter. Maybe the $10B project will actually be $10.5B because they build 5 reusable vehicles each costing $100M delivered, and, the $2B project will actually be $3B delivered because they build 100 disposable rockets each costing $10M delivered. Side by side competition, the disposable rocket platform earns a profit for every penny of revenue after $3B and the reusable gets no profit until after $10.5B
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
"The junkyards are full of disposable cars and airplanes. Like the disposable razor, they last for a while then stop being useful."
No, cars are not disposable - almost all cars work for more than 10 years (average age of a car in the US is 8.5 years). And planes most _definitely_ are not disposable - they can easily have 30-40 years of service. Most rocket components, on the other hand, are used exactly once.
On another list someone asked me to explain the press release. Here is my try.
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.
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.
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.
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!
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.
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.
But try explaining any of this in a press release.
End MGM. Get prospective parents of boys to Google: Men do complain