Key Test For Skylon Spaceplane Engine Technology

Ogi_UnixNut writes "The Skylon spaceplane is an ambitious project to develop a single-stage-to-orbit craft that can take off and land like a normal airplane. Part of this project requires an engine that can work both as a rocket engine and a normal air-breathing engine (a hybrid approach, essentially). This would reduce the amount of oxidizer required to send stuff into space, and thus greatly reduce the cost. Now, some key experimental parts of the engine have been built, and are to be tested in public at the Farnborough Air Show in the UK in July. The BBC has video of the cooling system being tested."

Comments

Reaction Engines Ltd, SABRE Engine

[xirtam_work]

I've been following the guys down at Reaction Engines and their SABRE engine concept for a few years. These are the same guys who came up with the HOTOL concept at Rolls Royce in the 1980's. No word on what they'd use for thermal protection on re-entry but they're a clever bunch and if I came into a billion pounds I'd shove a fair chunk of it at these guys to build me a fleet of spaceships to rule the world ;-)

If they could get government funding we could lead the world in launch capabilities. However, what would probably happen is that we'd end up handing it over the the USA as our leaders are too short sighted and too cheap to fund anything truly visionary or world beating.

Re:Reaction Engines Ltd, SABRE Engine

[bigtone78]

Not to worry I'm sure we'd bring you Brits along for the ride, just like we'd bring along the Cunucks, Aussies, etc. Ruling the world isn't any fun without a posse.

Re:Reaction Engines Ltd, SABRE Engine

[ScentCone]

At which point our leaders would promptly turn it over to venture capitalists, who would immediately strip the company of any and all value and sell what's left off for their own personal profit.

It's true. That's why promising companies started out by rich people venturing their capital have all been picked clean, and are now gone. I was so hoping that Space-X, Virgin, Orbital Sciences, and others would survive past their first couple of years, but the Eeeeevil Rich People just sold 'em off to buy gold plated spinning hubcaps for the Bentleys they use to drive over the poor people they use as speedbumps on the private estates where they hunt endangered cheetahs for sport.

Or maybe your meme is pure BS.

Re:Reaction Engines Ltd, SABRE Engine

[ScentCone]

What is par for the course? The dismantling of companies like Virgin by evil US investors?

The meme I'm referring to is that nice popular one, where venture investors don't build anything, don't see the money they risk ever put to good use, and that nothing good comes from them pushing small or dying companies into a healthy, viable condition. That's pure BS, on the face of it. But that image, that meme, is trotted around as if it were true - all because people who don't have money to invest and who don't understand how it works resent and villify those who do. The GP played that card in this scenario specifically to keep that false meme alive, to hope that it will keep rattling around in discussions as if it were an accurate portrayal of reality. Why? People have different reasons for wanting to lie about other people. Hard to say. Regardless of his motivation, it's worth calling him on it, and pointing out that it's false.

Re:Reaction Engines Ltd, SABRE Engine

[nitehawk214]

No word on what they'd use for thermal protection on re-entry

IOn the website it currently suggests the will use excess hydrogen to cool to the surfaces and dump in over board.

They hydrogen will at that point become superheated and immediately react with any oxygen in the rather thin air up there... At least this is what I hope would happen, because it would look awesome on re-entry.

So, what is your heat shield made of?

Fire.

I'm impressed

[Baloroth]

At high speeds, the Sabre engines must cope with 1,000-degree gases entering their intakes... Reaction Engines' breakthrough is a module containing arrays of extremely fine piping that can extract the heat and plunge the intake gases to minus 140C in just 1/100th of a second.

That is... impressive, to say the very least. It sounds from Wikipedia like they are even using the heat energy to power the turbo compressor (wondering if it was possible to convert the heat to useful energy was one of my first thoughts). I'm curious how efficient the jet is at low speeds, though. Typically, most jet engines work well at either low or high speeds, not both.

These kinds of engines are definitely needed to make space travel cheaper. Much cheaper, potentially, than solid-state rockets.

I thought that was not the hard part....

[Lumpy]

I though the hard part of making a space plane was that reentry is still a burn in problem. There is no way to slowly glide into the atmosphere without having to be fire and melt proof. and those requirements make it hard to build a plane that can take off enter space, re-enter and land.

I'm betting we can make one now that can take off and make it to orbit, it's the coming home part that is the problem.

Re:I thought that was not the hard part....

[ColdWetDog]

it's the coming home part that is the problem.

Capt. Malcolm Reynolds: Just get us on the ground!
Hoban 'Wash' Washburn: That part'll happen pretty definitely.

Re:I thought that was not the hard part....

[jacknifetoaswan]

The issue isn't necessarily protecting the bulk of the spacecraft, it's protecting those parts that have openings to the outside world. It's easy to design an ablative thermal protection system, or a ceramic-based one, but the tough part is sealing the air inlets, docking ports, etc, etc, etc, such that superheated gasses can't melt the turbine blades or fuel nozzles within the engines. Yeah, you can have moveable doors that would swing open to block the ports, but you've got to make sure they're SEALED, and you've got to make sure that they can open again, reliably, after re-entry, so that you're able to start up your engines on the air cycle and make a safe landing.

Re:I thought that was not the hard part....

[osu-neko]

There is no way to slowly glide into the atmosphere without having to be fire and melt proof.

Your sentence is twice as long as it ought to be. If you could manage to slowly glide into the atmosphere, you wouldn't need to be fire and melt proof. The problem is, you simply can't slowly glide into the atmosphere to begin with. Among other things, until you enter the atmosphere, you can't glide at all, and you're likely to be coming in at near orbital velocity, and even if you did slow down before hitting the atmosphere, gravity will helpfully~ accelerate you back up to ludicrous speed.

In any case, that's a long solved problem. A single-stage to orbit craft has to solve much more difficult problems than surviving reentry. There's a reason that even the space shuttle still used an external launch rocket. Being able to get to orbit without the vast majority of your launch weight being devoted to getting into orbit is a far, far more difficult problem.

Re:I thought that was not the hard part....

[bughunter]

STS didn't need to have air intakes that hang out in the breeze... that simple difference makes the engineering problems a whole lot more difficult.

I've worked in commercial and government space for nearly 30 years, and one thing I've learned is that most, nay almost every, new launch system idea that sounds promising and brilliant in the concept stage runs aground on shoals of engineering problems with the result of either grossly inflated cost and schedule, or catastrophic failure. Layman frequently underestimate how much of the technology space has been explored and found to be dead ends due to either unsurmountable technical difficulties or simple economics. Incremental materials improvements are the most common route to innovation, but they can only do so much to open up new avenues.

In other words, it's not always possible to identify technical risks early on. The history of launch systems is full of "oh, shits." The cliche "the devil is in the details" may very well have been coined by a rocket scientist.

That said, I wish them luck and good fortune. If there's a way that we haven't yet achieved of bumping up the payload fraction of conventional launch systems, this is it. Hybrid jet/rocket engine approaches are also one place where I believe the introduction of improved materials can be disruptive. REL may have found a new route to orbit, and I hope it works for them.

Re:I thought that was not the hard part....

[FSWKU]

This is largely due to my ignorance of how space travel actually works, but why can't you descend gradually (or more gradually than we already do)? Wouldn't that reduce the overall maximum heat that the craft is exposed to?

It all comes down to available fuel. Spacecraft burn most of their fuel getting into orbit, meaning that they usually have just enough left to drop their orbit into the atmosphere, where aerodynamic drag takes over. To descend gradually, you would need to have just as much (if not more) fuel as required to get into orbit in the first place, since you would have to slow down a LOT more than currently feasible. And after that you would need even more fuel to control your descent rate, since even if you stopped on a dime, gravity is going to accelerate you back to the point where thermal protection is required.

For reference, Joe Kittinger jumped from a balloon somewhere in the 100,000 foot (18.9 mile) range. The air is pretty thin up there, but he was into the thicker part before his velocity got too high. A spacecraft coming from, say, 190 miles has 10x farther to accelerate before the air becomes thick enough to act upon it. 190 miles is a long way, and even discounting the 19 miles from the balloon, that's still another 172 miles. By the time you get to where drag is a factor, you would be travelling upwards of 5,200mph (just under mach 16 at sea level). And that's just your vertical velocity assuming you managed to somehow bleed off ALL of your orbital velocity. So you would still need either thermal protection, or a lot more fuel to keep your descent rate below suicidal velocities.

TROY & Mission to Mars

[xirtam_work]

Just thought I'd point you in the direction of Reaction Engines ideas for a mission to Mars. Take a look at the detailed PDF and the movie.

http://www.reactionengines.co.uk/troy.html

Re:Where's the warp drive?

[nervouscat]

You need to wait another 50 years or so for Zefram Cochrane to invent the warp drive.

Cylons?

[cstacy]

All this has happened before, and it will happen again... http://en.wikipedia.org/wiki/Rockwell_X-30

Re:Where's the warp drive?

[w_dragon]

So all we need is to develop walls that can keep out gravity. Brilliant!