Reaction Engines To Fly Reusable Spaceplane

RobGoldsmith writes "Reaction Engines have designed a 'reusable spaceplane' to provide inexpensive and reliable access to space. The Star Wars-looking 'Skylon' reusable spaceplane has already been designed and the team are well into engine testing. They have taken some time out from building spaceships to talk about their background, their goals, and their recent engine tests. This article shows new images of their STERN Engine, an experimental rocket motor which explores the flow in Expansion Deflection (ED) nozzles. They also discuss their Sabre air-breathing engine technology. View the Skylon Spaceplane concept, the STERN Engine and much more in this in-depth interview with the team."

Comments

Red stories

[Anonymous Coward]

Red stories makes baby kdawson cry.

anal sex

[Anonymous Coward]

it won't do anything but make your dick stink

Re:anal sex

[Anonymous Coward]

It also makes the Grand Dragon smile when he sees his next treat.

Dollars per kg?

[rift321]

Can anyone find a cost per kg (or lb) of cargo estimate on that website? Not trying to detract from its value, just wanted it for comparative purposes.

Re:Dollars per kg?

[denzacar]

From http://www.reactionengines.co.uk/skylon_dev.html :

The total development program will cost about $10 billion.

Also... http://www.reactionengines.co.uk/skylon_vehicle.html

Skylon Statistics

Length: 82m
Fuselage Diameter: 6.25m
Wingspan: 25m
Unladen Mass: 41,000kg
Fuel Mass: 220,000kg
Maximum Payload Mass: 12,000kg

At the start of the take-off roll the vehicle weighs 275 tonnes, whilst maximum landing weight is 55 tonnes.
At take-off the vehicle carries approximately 66 tonnes of liquid hydrogen and approximately 150 tonnes of liquid oxygen for the ascent.
.
.
.
Payload Capabilities

The Sklyon payload bay is 4.6m diameter and 12.3m long. It has been designed to be compatible with expendable launcher payloads but in addition to accept standard aero transport containers which are 8 foot square in cross section and 10, 20, 30 or 40 feet long.
It is anticipated that cargo containerisation will be an important step forward in space transport operations, enabling the "clean" payload bay to be dispensed with.

The vehicle can deliver 12 tonnes to a 300km equatorial orbit, 10.5 tonnes to a 460km equatorial spacestation or 9.5 tonnes to a 460km x 28.5 deg spacestation when operating from an equatorial site.

You do the per flight math.

Re:Dollars per kg?

[khallow]

Problem here is that they don't (like virtually everyone in the business world) throw out costs for the launches themselves. Still a development budget of $10 billion indicates to me that they're expecting operating profit to be somewhere around $1-2 billion a year. Suppose they make a profit of $10 million average per flight (that's $1000 profit per kg or so). That means 100-200 flights per year. If the profit is only a tenth that, then they have to make 1000-2000 flights a year.

Re:Dollars per kg?

[Rakishi]

You also need to add in maintenance, staff (someone has to manage and test this thing), facilities (you're housing and launching it where?), fuel, insurance and other such costs.

Also there are only something like 20 commercial satellite launches a year and I think that includes geosynchronous orbit ones. Maybe you could double that if you add in government satellites but it's still not much.

Re:Dollars per kg?

[Anonymous Coward]

100% Off-topic: Why does the slash-code take me to the subscriber page when I click on the "tag" link under Firefox?

Re:Dollars per kg?

[WindBourne]

THe hard part is that we did this already; The shuttle had the same issue.

Re:Dollars per kg?

[khallow]

Yes, lot of stuff needs to be added. At a glance, it looks like they can use a convention runway (though it might need to be reinforced, apparently a loaded vehicle generates a lot of impact on landing). Insurance isn't much of a cost for the launch provider. Insurance against third party harm is rather low since US launch providers need to demonstrate a ridiculously low risk of harm before they can launch anyway. Insurance for the payload should be pretty good for an RLV with the kind of launch frequency this will need. Fuel costs are pretty low. Probably going to be something like $20-50 per kg of payload depending what they get the LH2 for, I think.

Maintenance could be a hidden problem. I think the DC-X, an unmanned prototype (for SSTO eventually) had composite tanks. There were serious problems with thermal flexing and penetration by cryogenic fluids that weakened the tanks. If I recall the blurb for the Reaction vehicle, it would use aluminum lined tanks, which addresses most of that problem.

Re:Dollars per kg?

[khallow]

THe hard part is that we did this already; The shuttle had the same issue.

The Shuttle had serious issues aside from lack of demand (it would take the entire US launch market to achieve the design launch rate of 50 launches per year for the Shuttle). Particularly, the 1-2% failure rate and the monstrous overhead. These guys are hoping that they can get the operating costs down to a very cheap level, achieve a high reliability rate, *and* that the launch market will improve significantly to the point that by the time the vehicle flies, they can find enough demand for the vehicle.

Re:Dollars per kg?

[CarpetShark]

The vehicle can deliver 12 tonnes to a 300km equatorial orbit, 10.5 tonnes to a 460km equatorial spacestation or 9.5 tonnes to a 460km x 28.5 deg spacestation when operating from an equatorial site.

You do the per flight math.

I'm more worried about the fact that it can only go in two directions: to the equator, to to 28.5deg.

Re:Dollars per kg?

[Anonymous Coward]

Insurance against third party harm is rather low since US launch providers need to demonstrate a ridiculously low risk of harm before they can launch anyway.

Well, but it's an Euro company. Anyone know the regulations within the EU ?

Re:Dollars per kg?

[CrimsonAvenger]

it looks like they can use a convention runway (though it might need to be reinforced, apparently a loaded vehicle generates a lot of impact on landing).

Even fully loaded, this vehicle is better than 150 tons lighter than a 747. Much less at its designed landing weight (about 1/8th the takeoff weight of a 747). So I doubt the runway will need reinforcement.

Re:Dollars per kg?

[khallow]

Problem is the narrowness of the vehicle. Up to 273 tons concentrated in a narrow band. They even mention it on the website (which is why I brought it up, wouldn't have thought about it on my own). And an abort and return to airport shortly after takeoff would result in a fully loaded landing. That has to be part of the design as well.

Re:Dollars per kg?

[Hal_Porter]

Because only subscribers can add tags?

Re:Dollars per kg?

[CrimsonAvenger]

Problem is the narrowness of the vehicle. Up to 273 tons concentrated in a narrow band.

Width of the undercarriage might be an issue, but probably not. The entire vehicle puts a load on a narrow strip of runway only slightly higher than the load that either side of a 747's undercarriage put on a runway (273 tons versus 220 tons per side). While reinforcement might be desirable, doesn't look to be mandatory.

And an abort and return to airport shortly after takeoff would result in a fully loaded landing. That has to be part of the design as well.

Not really. You can dump fuel if necessary. If you don't have time to dump fuel, then you probably don't have time to turn around and get back to the airport.

Re:Dollars per kg?

[trenien]

It may be naïve of me, but wouldn't there be a huge difference between development cost and construction cost?

What's keeping them from buildng more than one unit?

Re:Dollars per kg?

[khallow]

I completely ignored construction cost. It gets a lot more difficult once you take that into account. The point is, if you spend $10 billion on something risky, you are expecting considerable return. A constant rate of 20% per year in the not so distant future isn't unreasonable and may be low given the circumstances. Or maybe some sort of high growth effect (low or negative rate in the near future with huge growth rate years later), say if they built an large number of these for market a number of years after they are first developed.

Re:Dollars per kg?

[AJWM]

I think the DC-X, an unmanned prototype (for SSTO eventually) had composite tanks. There were serious problems with thermal flexing and penetration by cryogenic fluids that weakened the tanks.

No, DC-X had metal tanks (I forget whether straight Al or Al-Li). You're thinking of the X-33 (VentureStar prototype), that not only had composite tanks but the hydrogen tank was V shaped, putting extreme stresses on the joint (and leading to the flex/leakage problems). Reinforcing that joint overwhelmed the weight savings of using a composite tank.

Re:Dollars per kg?

[AJWM]

The 747 is a heavy beast indeed. In the early days of autoland systems (heavily used at airports that tend to be foggy, like Heathrow), the accuracy of the autoland system was so good that the 747s kept touching down on the same spot on the runway, overstressing that one spot. They fixed it by adding some slight dither to the autoland to spread the impacts out.

The landing gear for a 747 uses more wheels than Skylon which reduces the 747 point loads (in terms of PSI).

Re:Dollars per kg?

[cheesybagel]

DC-XA had an Al-Li Oxygen tank and a composite LH2 tank. The think that fscked up X-33 was indeed the shape of the tank in combination with the composite material picked. It was heavier than using Al-Li in the first place.

Re:Dollars per kg?

[MJMullinII]

You know, not to get off topic, but I've always wondered if Aluminum lining wasn't the answer to hydrogen embrittlement?

I bring it up because that has always been (among other things) one of the big barriers to the so-called "Hydrogen Economy".

Re:Dollars per kg?

[khallow]

As I understand it, aluminum is vulnerable to hydrogen embrittlement, maybe even more so than steel. What aluminum guards again here is penetration of the composite material by liquid hydrogen and its subsequent expansion when the tank heats up. Thermal expansion, especially of trapped air, is another problem with composite materials and has bad synergistic effects with the above problem. There's probably ways to develope composite materials without air bubbles, but it wasn't discovered at the time of the X-33. Expansion and contraction (as the tanks are filled and emptied) of the bubbles induces cracks, cryo fluid leaks in and greatly speeds up crack formation when it evaporates. An aluminum liner, prevents leakage and would allow the tank to last longer.

Star Wars looking?

[Anonymous Coward]

That doesn't look like any X-Wing, B-Wing, Tie Fighter or Millenium Falcon that I've ever seen...

Re:Star Wars looking?

[Tubal-Cain]

I think it looks like a cross between a SR-71 Blackbird, and a Naboo Royal Starship (the silver ship from SW episode one).

Re:Star Wars looking?

[MadnessASAP]

Looks like an aircraft meant for hypersonic flight to me... Dunno why it needs to look like anything else.

Re:Star Wars looking?

[Yvan256]

What the hell is an Aluminum Falcon?

Re:Star Wars looking?

[meringuoid]

I think it looks like a cross between a SR-71 Blackbird, and a Naboo Royal Starship (the silver ship from SW episode one)

Looking at that ship, I'm overcome with a sudden urge to fly it to Pleione to track down Mic Turner.

Re:Star Wars looking?

[deimtee]

It's what the Yanks call an Aluminium Falcon.

Re:Star Wars looking?

[decoy256]

Is that what pretentious Brits call Aluminum?

Re:Star Wars looking?

[Yvan256]

The Brits and everybody else on the planet. ;)

Re:Star Wars looking?

[Anonymous Coward]

"Is that what pretentious Brits call Aluminum?"

Our language - if you don't like it you're free to use another one...

Re:Star Wars looking?

[Anonymous Coward]

"Is that what pretentious Brits call Aluminum?"

Our language - if you don't like it you're free to use another one...

Our website - if you don't like it you're free to use another one...

Re:Star Wars looking?

[Anonymous Coward]

Ok, I've had enough.

You don't want me here? I'm taking my language and I'm leaving.....

Re:Star Wars looking?

[decoy256]

Except for Canada... so... we've got the cannucks.

Space Elevator

[Anonymous Coward]

Do not want shuttle 2.1. Do want Space Elevator. Now get to work.

Re:Space Elevator

[khallow]

Do not want shuttle 2.1. Do want Space Elevator. Now get to work.

Are you personally picking up the tab for this space elevator? Even an RLV doesn't have much of a business case to be made. There simply isn't that much demand. A space elevator needs a lot more demand than has been demonstrated to exist. A reasonable plan is to build up the demand to the point that exotic launch systems make business sense. Not develope the exotic launch system and hope someone will use it.

Re:Space Elevator

[barc0001]

You know, the day Sputnik went up hardly anyone was thinking about a commercial use for space, and now look at us. Space has definitely become a "build it and they will come" scenario. If you make payload lifting even cheaper, there will be more customers because things that didn't make sense before suddenly start to.

Re:Space Elevator

[evanbd]

I don't much like the idea of a space elevator, at least for short- or medium-term applications. (Long term, is 50 years from now, is different... but also not very relevant.) Why, you ask? Simple. Give me a space-elevator class building material, and I'll make rocket tankage out of it long before it's fully developed to space elevator performance levels. Those tanks will be so vastly superior in weight performance to current materials that I can give you a rocket that is not only single stage to orbit, but does it on *pressure fed* engines. Who needs turbopumps and all their associated machinery when you can just put enough pressure in the tanks (and run at a lower chamber pressure... which is more conducive to high reliability anyway)?

For a given payload rate, my pressure fed SSTO will use somewhere between 3 and 10 times the energy (depending on which kool-aid you drink when it comes to getting the power from the ground to the elevator car). It will have a *vastly* lower capital cost. It will be faster (no radiation worries for cargo that spends days passing through the van Allen belts). Perhaps more importantly, it will scale down better. It starts with a lower investment and lower flight rate to prove out demand, and then grows as more customers appear and more rockets get built.

Oh, reusability? It gets a lot easier when you don't have to jettison a stage a third of the way there -- and when your reentry vehicle is as light and fluffy as these building materials imply, it gets even easier. Engine reusability is pretty trivial when you don't have 60,000 rpm turbines wearing out all the time.

There are plenty of engineering problems to be overcome for a space elevator. They're not impossible, but they're far from trivial. But the real problem is the competition from rockets -- it makes zero sense to compare a space elevator built with magic nanotubes to a lithium-aluminum tankage rocket; it should be compared to a magic nanotube rocket. When you do that, you discover that for any unproven market (ie, where capital costs matter) the spaceship fleet is far, far cheaper.

Re:Space Elevator

[Fulcrum of Evil]

Sure, nobody wants to lift cargo at the current price point. Try cutting it by 90% and see what happens.

Re:Space Elevator

[khallow]

You know, the day Sputnik went up hardly anyone was thinking about a commercial use for space, and now look at us. Space has definitely become a "build it and they will come" scenario. If you make payload lifting even cheaper, there will be more customers because things that didn't make sense before suddenly start to.

There was around an eight year lag between Sputnik 1 and the first commercial satellite. My take is that there wasn't enough business to support a commercial launch provider till sometime in the late 70's or early 80's. So it seems odd to me to build a space elevator and then wait 20 years for the elevator to become economically viable. My take is a superior approach is to increase launch demand and reduce launch costs on current and near future vehicles. That will in turn drive demand for RLVs, space elevators, and other launch systems. Some of the decisions that could be made now, don't even have to detract from development of a future space elevator.

For example, the US (so far) has missed an opportunity to transition a good portion of its manned launches to commercial vehicles, the Delta IV Heavy and Atlas V Heavy. The more demand for commercial launch, the lower the cost per launch to the launch providers. You're not going to have the market to justify a space elevator, if you don't bother to sow the seeds.

Re:Space Elevator

[khallow]

Sure, but guess what? I bet even current launch vehicles can do a lot better in cost per kg than they currently do. I figure the limit of expendable launch vehicles are somewhere around $500 per kg in very high launch volume (thousands of launches a year). RLV would drive that to somewhere around $100 per kg. At that point, you have the business to justify that next step to exotic technologies like space elevators, rail launch, etc. This is the point that I think is being missed. There's little reason to fund a lot of space elevator research now. And by the time there is enough reason, it pays for itself.

Re:Space Elevator

[Anonymous Coward]

http://en.wikipedia.org/wiki/TELSTAR

1962 for the first commercial satellite

Re:Space Elevator

[F34nor]

Look into the Space Fountain instead... http://en.wikipedia.org/wiki/Space_fountain

Re:Space Elevator

[EdIII]

There simply isn't that much demand.

There isn't a demand because there isn't a supply. That's like the argument, "Which came first, the chicken or the egg?"

I used to live with a little jack terrier dog that would crap all over the place. If there was a space elevator I would have used it.

Re:Space Elevator

[khallow]

I like this idea. SSTO hasn't been attainable so far. But getting an SSTO with a pressure fed propulsion system. That's extremely competitive even for a space elevator.

Re:Space Elevator

[khallow]

Doesn't look like it was a commercial satellite. NASA and publically owned European organizations were involved. Though it did belong to AT&T which was nominally a private company at the time.

Belonging to AT&T, the original Telstar was part of a multi-national agreement between AT&T, Bell Telephone Laboratories, NASA, the British General Post Office, and the French National PTT (Post, Telegraph & Telecom Office) to develop experimental satellite communications over the Atlantic Ocean. Bell Labs also built the Andover Earth Station in Andover, Maine, and it held a contract with NASA, reimbursing the agency three million dollars for each of the two launches, independent of success.

Looks like COMSAT wasn't really commercial either. It was owned by Intelsat which didn't privatize till 2001 according to wikipedia.

Re:Space Elevator

[daveime]

Unobtainium.

Re:Space Elevator

[hitmark]

another thing is that given how we humans are basically running this planet dry, there is only one way to go for future resources.

also, if we are able to spread out over the solar system, there is less of a likelihood that a single big rock will take us out...

Re:Space Elevator

[evanbd]

Actually, if you want a mega-scale engineering project, my personal preference is for the launch loop.

Re:Space Elevator

[evanbd]

Yeah, when you start applying space elevator class building materials to your rocket tankage, the usual assumptions simply don't apply. For example: with 65GPa tensile strength (the low end of the strength range Wikipedia gives for an elevator material) material for tankage, a 1000 psi tank filled with dense propellants (which, depending upon your models, might be better) has a mass ratio of somewhere over 1000. The exact number depends on your assumptions about anisotropic winding strength efficiency, but is probably around 1500 before you include a safety margin.

The helium to pressurize it with is actually the most problematic part -- but with that kind of tank mass ratio, it's not unreasonable to decide you're going to operate in blowdown mode (or regulated, but decaying to a lower final pressure) so that you have less helium mass at burnout. That lets you get the high initial chamber pressure (good atmospheric expansion ratio) without all the helium mass required to pressurize the entire tank. And using the ullage helium for the circularizing burn isn't hard (you could even include a peroxide monoprop heater and get a reasonable Isp out of it).

Re:Space Elevator

[StrawberryFrog]

Space has definitely become a "build it and they will come" scenario.

Except with the space shuttle, which hasn't lived up to expectations.
And the ISS, which is behind schedule.
And the way that no-one has sent a manned mission to the moon in decades.

Re:Space Elevator

[decoy256]

I think what he's saying is that we need to know in what ways we would be using the technology, so it at least has an economically viable proposal. Jack Terrier crap is actually one of those viable proposals that would have to be figured into the whole process... but if all evidence points to very limited use, then we would just be wasting money on a fruitless endeavor. Prove to me that this is economically viable (however you want to do that), and then I'll willing hand over my money. The other way around is just bad business.

Re:Space Elevator

[EdIII]

I think what he's saying is that we need to know in what ways we would be using the technology, so it at least has an economically viable proposal. Jack Terrier crap is actually one of those viable proposals that would have to be figured into the whole process... but if all evidence points to very limited use, then we would just be wasting money on a fruitless endeavor. Prove to me that this is economically viable (however you want to do that), and then I'll willing hand over my money. The other way around is just bad business.

I'm sorry you misunderstood what I was trying to say. I would never send dog crap into space. I wanted to send the dog.

Re:Space Elevator

[drinkypoo]

Rockets suck because they burn fuel. Energy goes into making the fuel one way or another and there is generally a significant environmental cost. The space elevator has a massive initial capital cost, but if you're spinning it down from orbit and making it out of something that's already up there (carbon is easy to come by, anyway) then the environmental cost is low. Once the elevator is built, it requires a fraction of the energy to operate that it takes to launch your rockets, as long as you're sending up as much mass as you're bringing down. That should be easy - we can start with hazardous wastes and power satellites. Then we can move on to masses of people going to Mars, I hope :) You are thinking of "cheaper" in terms of energy costs. But as you use the elevator, the overall cost decreases. And as you use the rockets, the overall cost increases. The more you use the space elevator, the cheaper space gets. The more you use the rockets, the more money you've spent on launches.

Re:Space Elevator

[Cowmonaut]

And what pray tell does that have to do exactly with what the OP said, of "if you build it they will come"? No one said this stuff had to come immediately. The space shuttle is the first re-usable spacecraft the US created. Many of the first escort fighters (Allison-engined P-51 mustangs didn't live up to expectations either, nor did the first assault rifle for the US (M-16 before they lined the barrel and chamber with chrome).

First and early attempts rarely tend to their tasks as well as people hope or require. Typically you have to go through several revisions while the old models are still "in the field" as it were. Really the only difference is the expense of space exploration. NASA has been able to do some slick stuff on a low budget since the 60's or 70's, but its been a hamper.

You mention no one has gone back to the moon in the last few decades. What, may I ask, exactly would you have them do there? They still have the moon rocks from Apollo. We've gotten pretty handy with a spectrometer, being able to tell chemical compositions of planets and stars light-years away. What exactly were they to do there besides build a telescope, which we have easily done in orbit anyways (see Hubble).

The economics of space exploration are slowly changing to make it as feasible as deep ocean exploration (which is also hurting from lack of interest, outside of oil companies). The politics of it are leading to like what? Three manned missions from countries outside the US? I believe Russian, India, and China were all discussing targeting the southern end of Luna.

Anyways, manned space exploration will continue to happen and eventually we will colonize other planets. The pace of space is different. The amount of resources it takes to leave Earth and head for another system are unlike anything we've had to deal with before. The distances likewise, with it easier to measure it light-seconds and light-minutes or AU within the solar system than kilometers.

How long has it taken humanity as a whole to explore the bulk of the dry surface of Earth? You do realize I hope that there are large uncharted tracts of land. This is why we still discover new species as we cut down the rain forests. And don't even get me started on the sea, we don't even know what all is living in our oceans and can't even reach the bottom in some places.

Personally I say do as much as we can from remote without sending people out as possible. Saves lives, saves money, saves time. Voyager 1 and Voyager 2 are still sending information back occasionally. They haven't left the solar system entirely yet. In the last 10-15 years we've uncovered more information about our solar system than in the previous hundred. We're learning more about all the planets every day, and we haven't been sending out people.

May as well find out what we can know before sending someone out since we may not have too many shots to do so.

Re:Space Elevator

[LingNoi]

Once one is up it's easier to put others up.

Re:Space Elevator

[Anonymous Coward]

As long as we are talking about 'magic' technology, the 'magical' space elevator is still necessarily more efficient than a 'magical' chemical rocket because however light and efficient the rocket's tank is, it still has to contain the fuel and a large part of that fuel will go into lifting the fuel itself.

The space elevator can run on fusion on the ground or solar up in the space, and all the energy goes into moving the payload.

Re:Space Elevator

[khallow]

There isn't a demand because there isn't a supply. That's like the argument, "Which came first, the chicken or the egg?"

There's no paradox if there's neither a chicken nor an egg.

Re:Space Elevator

[evanbd]

Have you actually run the numbers on efficiency? I have. A rocket (built from space elevator class magic nanotubes, of course) is somewhere around 5-8% efficient at converting energy on the ground to energy in the payload; somewhat more if you use hydrogen instead of dense propellants, and somewhat more if you count the rocket bits in orbit as useful rather than dead weight.

How efficient the space elevator is varies depending on your assumptions about beamed power efficiency (or other means of getting power to the climber). You still have to put the vast majority of the energy into the payload directly. At geosynchronous altitude, the vast majority of your energy is in the form of gravitational potential energy that comes from your climber, not kinetic energy that comes from Coriolis forces. The climber will probably have an unexciting payload fraction (motors and energy collectors are heavy), and less than stellar conversion efficiencies. 50% overall would imply roughly 70% payload fraction and 70% conversion efficiency; that seems optimistic to me. 25% efficiency seems much more reasonable, but still a definite engineering challenge (especially if you want to climb quickly).

That says that a rocket launch uses only 5x the energy of the elevator for a given payload. The capital costs are dramatically reduced. A notional nanotube SSTO has a nanotube tankage mass noticeably less than its payload mass. It can fly several times per day, if you have an equatorial launch site or aren't too picky about destination orbit. A space elevator is *massive* compared to its payload, and has a limited number of climbers launching each day (weight limits on the lower portion of the cable are severe). The capital cost per lofted kg per day is vastly lower with the rockets than the elevator. For unproven markets, this difference is important. For current rocket launches, and any sane model for early elevator launches, the capital costs dominate the energy costs. Until there is enough of a proven launch market that you can take a business plan to investors that reasonably assumes near-100% utilization of your elevator for several years of useful life, the rockets win. The fact that the rocket version of the business plan can be made workable at much lower launch rates is a nontrivial benefit.

Sure, the space elevator makes sense many years from now, when there is a thriving space-based economy with regular demand and plenty of destinations. That world is not the one we live in today. For the near term, and even medium term, rockets will beat space elevators on price per kg launched -- especially if you give the rocket engineers space-elevator class building materials.

Re:Space Elevator

[evanbd]

The rocket is not perfectly efficient; neither is the elevator. As I explained above, plausible estimates put the efficiency difference at about a factor of 5. That number can vary by a factor of at least 3 (in either direction) depending on which kool-aid you prefer. The implication of this is that for the short and medium term, the reduced capital cost of the rockets dominates. For the long term, where energy costs are actually relevant, the elevator wins -- but that problem is properly classed as "a very nice problem to have." It will be a long time before we do, and until then, rockets make more sense.

Re:Space Elevator

[timeOday]

You know, the day Sputnik went up hardly anyone was thinking about a commercial use for space, and now look at us. Space has definitely become a "build it and they will come" scenario.

On the other hand, when we went to the moon it was emotionally a "giant leap for mankind," but it really didn't lead to anything or change anything in practice. Neither has the ISS paid off. Motorolla's Irridium communications constellation seemed incredibly awesome and well-timed, and promptly went out of business. How do we know which situation we're looking at with a space elevator?

Re:Space Elevator

[mac1235]

I was always a fan of the surface-to-orbit 30km long rail gun.

Re:Space Elevator

[Fulcrum of Evil]

Hey, if you think you can get those numbers, go ahead. I haven't seen anything other than a skyhook that does $100/kg. Also, once you have 2 skyhooks, you can build 20 while lifting cargo.

Re:Space Elevator

[khallow]

Hey, if you think you can get those numbers, go ahead. I haven't seen anything other than a skyhook that does $100/kg.

To be honest, nobody has seen anything that can do $1000 per kg much less $100 per kg. But once you get any launch system to the point where virtually all of the cost is reaction mass and energy, then it's going to be $100 per kg or lower. RLVs, skyhooks, and space elevators can do that. If your launch system only runs mass up to orbit, then RLVs remain rather competitive. The only weakness is that chemical motors have a much lower isp than what you can use in vacuum (where most of the space elevator and skyhook would be). That means a lot more reaction mass and somewhat more energy.

Re:Space Elevator

[jamstar7]

OK, I don't see the numbers working for a launch loop too easily. How do you hang a 2000 km loop 80 km up in the atmosphere to begin with???

I'm more of a fan of the laser launcher concept myself. Problem is, it takes a lot of energy to make one of these work right, so we're probably looking at a couple geosync power sats feeding microwaves to the site. Talk about bootstrapping. Development costs would be a helluva lot lower than 'magic materials' to build a loop or a fountain, I'd think, and if something screwed up, you've still got a nice shirtsleeve environment to work on...

Re:Space Elevator

[evanbd]

You don't have to hang it up there; it stays up by itself. The ribbon is moving faster than orbital velocity (14 km/s -- orbital is a bit over 7), so its natural tendency to go in a straight line means that the Earth's surface curves away from it. You then have to apply tension with cables to hold it down and make it follow the curvature of the Earth (from 80 km up, of course). The problems with the launch loop lie in things like the control systems and the quantity of stored energy, not the basic physics. Wrapping your head around it takes a little work, but in many ways it works for the same reason that the space elevator counterweight does -- both the ribbon and the counterweight are moving at a higher velocity than orbital velocity for their altitude, so they try to "fall" away from the Earth and thus maintain tension in the cable[s].

IMHO the laser launcher is yet another result of the common fallacy that mass ratio actually matters. It doesn't; cost does. If you save a lot of mass while making the whole thing more expensive, that's not a win. I should add the caveat that I'm not current on the detailed numbers, so I may be mistaken, but that's my general impression of it. (Obviously mass ratio matters to the extent it has an impact on cost; but that is the *full* extent to which it matters.)

Re:Space Elevator

[decoy256]

Either way, I'm saying there is a market there... just prove the viability before we start spending money.

Re:Space Elevator

[jamstar7]

OK, Earth's circumference is 40,075 km & change. Rotates once every 24 hours. That's 1669.79 km per hour, which means, any point on the equator moves at .46 km per second according to my calculator here. You're talking a supraorbital velocity of 14 km/sec, on the order of 30 times the rotational speed of the Earth at the equator. I repeat my question: How do you hang it up there? How do you keep it from flying away with those cables and maintain a speed 30 times faster than the rotational velocity of the planet? Do you put it in a track? If so, what do you make those cables out of? Hell, how do you anchor the track??? You DO realise the track would have to be 40,075 km long, right? What about expansion and contraction? How much energy do you figure it'll take to get that loop up to speed? How do you keep Luddites, terrorists, Earth Firsters, tax collectors, and herd animals from damaging the track? The loop itself will be moving at 50,400 km/hr, a mere 80 km up. How do you intend to keep pumping energy into a 2000 km long tube to offset speed loss due to air resistance? What do you mean, 'What air resistance?' Put something into LEO under 200 km up, and it'll come down due to orbital decay from air resistance. There isn't much air at 80 km, but it's not a vacuum.

Hell, how do you catch up to the loop moving at 50k km/hr? If you can do that, why bother with the tube at all?

With the laser launcher, the big investment is in the lasers, mirrors, mirror guidance & controls and all the stuff that stays on the ground. The cheap part of it, the capsual, reaction mass & payload, is what goes up. So, once you get the system into place and working, the more you use it, the more you amortise the cost across each launch until someday you get down to a per-launch cost of the capsual, payload, maintanance, and electricity to push that sucker up.

Re:Space Elevator

[evanbd]

Surprising as it may seem, every one of your questions is addressed in published papers. Many of them can be found in the references section of the Wikipedia article I linked to.

Your argument in favor of laser launchers has no meaning without either some numbers to back it up or at least some sound logic as to why the expensive capital investment is less than for a [launch loop|space elevator|rocket fleet] or is made up for by reduced operating costs (including but not limited to energy consumption).

Re:Space Elevator

[jamstar7]

From TOFA:

A running loop would have an extremely large amount of energy in the form of linear momentum. While the magnetic suspension system would be highly redundant, with failures of small sections having essentially no effect at all; if a major failure did occur the energy in the loop (1.5×1015 joules or 1.5 petajoules) would be approaching the same total energy release as a nuclear bomb explosion (350 kilotons of TNT equivalent), although not emitting nuclear radiation.

While this is a large amount of energy, it is unlikely that this would destroy very much of the structure due to its very large size, and because the energy release would be spread out over several minutes. Steps might need to be taken to lower the cable down from 80 km altitude with minimal damage, such as parachutes.

Therefore for safety and astrodynamic reasons, launch loops are intended to be installed over an ocean near the equator, well away from habitation.

The published design of a launch loop requires electronic control of the magnetic levitation to minimise power dissipation and to stabilise the otherwise under-damped cable.

This tells me it's going to need 'magic materials'. 'Magic materials' cost money to develop, time to learn to manufacture, machine, assemble, etc.

Did I mention that this launch loop is almost the size of the Great Wall of China?

Re:Space Elevator

[evanbd]

What part needs magic materials? The ribbon is made of soft iron iron or steel, probably woven in a manner not unlike normal cables, or possibly in solid sheets. That's not exactly difficult to make. The sheath is a kevlar or carbon fiber composite with an aluminized mylar liner. The control magnets are copper windings over soft iron. You didn't actually read any of the papers, did you?

What part of "mega-scale engineering project" made you think this would be small?

Re:Space Elevator

[jamstar7]

What part needs magic materials? The ribbon is made of soft iron iron or steel, probably woven in a manner not unlike normal cables, or possibly in solid sheets. That's not exactly difficult to make. The sheath is a kevlar or carbon fiber composite with an aluminized mylar liner. The control magnets are copper windings over soft iron. You didn't actually read any of the papers, did you?

The tethers holding that sucker to the ground. Did you think of doing a back-of-the-napkin calculation on the tensile strength needed to hold this sucker down???? We're talking orders of magnitude beyond the best artificial spider silk to hold this thing down, and I don't think you can quite order that up in industrial quantities yet.

What part of "mega-scale engineering project" made you think this would be small?

What part of 'too goddamned big and expensive to be economically feasible in our lifetimes' do you not understand? Especially since you'd have to build the sucker in order to test its viability. I'd guestimate it'd only cost a couple trillion dollars, so wait a few weeks for the economy to finish pancaking before writing the check; you'll get your money's worth then. I'm supposing this will be a government project, nobody else would have the cash and the desire to pull this off (although there's bound to be a few private sector entities that could concievably get the cash together, I wouldn't count on their stockholders allowing them to spend it on something like this), which means it won't come in anywhere near budget or on schedule. Yes, I've done heavy construction in my younger crazier days; it put me through college.

Oh, and don't count on selling this to Congress unless you can do like Ike did with the interstate highway system that came about in the 60's & 70's.

Contrast this to a laser launching system. For a few million, you can do a real-world feasibility study. Hell, Lightcraft Technologies already did a feasibility study using a 10 kw laser to push a 25 gram weight to 200 feet as a test. The test worked. Show me a comparable feat with your launch loop.

Re:Space Elevator

[evanbd]

The first paper includes cost estimates. There's nothing hard about the cables to hold it down; they can be as thick as they need to be. The original paper has numbers for them using ordinary steel cable -- they're tapered, so they're a little abnormal, but strength certainly isn't a problem. The weight problem is more likely to be keeping the sheath light enough that the ribbon can stay up. Each kg of ribbon can lift a little less than 1 kg of other stuff, including sheath, cables, and payload. Seriously, the materials science is not the hard part, and neither is the physics.

Building a test model is actually a place where the launch loop does well in comparison to the other mega-scale engineering proposals. A small scale launch loop is useful, unlike an elevator. A launch loop that's an arch capable of lofting your payload to 50km and 2km/s is decidedly useful -- that's an excellent starting point for the second stage of a rocket.

I'll have to get back to you on a lab bench scale test. I don't know of any that have been done; I do, however, have some magnets in the mail for exactly that purpose. It's very much a back burner project, though, so don't expect results for a couple months. (Try building a laser launch demonstrator in your garage by yourself on a 3-digit budget...)

Holy shit, it's a proto-Firefly!

[Dr. Spork]

I never thought that the Firefly form factor would ever actually fly, but look at the picture of the Skylon and tell me you don't see the resemblance!

Re:Holy shit, it's a proto-Firefly!

[Timesprout]

I dont see the resemblance. Anything else I can help you with?

Re:Holy shit, it's a proto-Firefly!

[EdIII]

I wish I could see any picture of it. Those sites have been Slashdotted :)

Re:Holy shit, it's a proto-Firefly!

[MadeOuttaNerf]

I see no resemblance other than that they're both pointy on the front end (a wise design choice IMO).

Re:Holy shit, it's a proto-Firefly!

[Wandering Wombat]

Uhm... they made this 15 years ago. It was called the Venturestar. They had all the bugs worked out. It was cheap.

Re:Holy shit, it's a proto-Firefly!

[RocketGeek]

Actually not. Venturestar was a pure rocket SSTO, as opposed to an air breathing rocket SSTO. Big difference. Because it was reliant solely on pure rocket propulsion, the structural mass required materials that were very light, and one of the reasons it wasn't continued was problems with the composite non cylindrical liquid hydrogen tank, which was a major show stopper.

Skylon gains significantly by being able to use an engine that air breaths to Mach 5.5 before transitioning to pure rocket propulsion.

Re:Holy shit, it's a proto-Firefly!

[pittance]

The engines-on-the-side configuration is a way to try to deal with engine weight changes. Huge trim issues arise if your engine isn't as light (or heavy) as you think it will be.

Spaceplanes with engines at the back face a real struggle with balance if _anything_ changes in the engines - they tend to be very heavy compared to anything else in the 'dry' structure of the vehicle and a small error either way can leave you with depleted uranium bulkheads to pull your CG back if it's too late in the development programme to change the configuration.

You really can't get away with stuff like that since single-stage-to-orbit is _really_ hard to do.

Couple that with the big aerodynamic centre changes that you tend to get over such a large flight regime and you may end up with a lot of mass budget being taken up by control surfaces.

I understood from a couple of lecturers at Uni and past co-workers that this would have been one of the really big problems that HOTOL would have had to deal with had it not been cancelled... (which project Alan Bond of Reaction Engines was also involved in)

Re:Holy shit, it's a proto-Firefly!

[AJWM]

VentureStar was never anywhere near having all the bugs worked out. It was way over budget.

In addition to the above-mentioned problems with the V-shaped composite tank, the launch/landing profile (vertical takeoff, horizontal landing) meant that the structure was designed for perpendicular load paths, and there was no way to land after a launch abort until it had reached sufficient altitude/airspeed to turn around and return, and it had burned off/dumped enough fuel to be light enough for the landing gear (which unlike Skylon, were only designed to support the empty weight). They hadn't done much in-flight testing of the linear aerospike engine, either, although static ground tests were promising.

SR-710?

[Mateorabi]

Actually I see more of an SR-71 Blackbird with a fat tail. Can really see it here from above.

Re:SR-710?

[S-100]

Looks to me more like the ship in George Pal's "When Worlds Collide": http://www.imdb.com/media/rm3091372032/tt0044207

Re:SR-710?

[hcdejong]

Actually, it looks more like the Avro 730 concept for a high-speed reconnaisance aircraft. Including the four engines at each wingtip.
image

Did anyone else misread the title?

[Amazing Quantum Man]

Reaction Engines is the name of the company. It's using conventional LOX/LH2 engines.

And for those who are calling this Shuttle 2.0, it's unmanned.

Re:Did anyone else misread the title?

[rift321]

They allude to the ability to _shuttle_ persons into space later down the road using the craft, and specifically state that they aim to bring the cost of such an endeavor to the sub-$100k range.

Re:Did anyone else misread the title?

[SoupIsGoodFood_42]

From what I've read, they aren't conventional rocket engines. But if you know better, then please explain.

Re:Did anyone else misread the title?

[Hal_Porter]

Reaction engines do have a design for a manned hypersonic airliner

http://en.wikipedia.org/wiki/Reaction_Engines_A2

The A2 is designed to leave Brussels International Airport, fly quietly and subsonically out into the north Atlantic at Mach 0.9 before reaching Mach 5 across the North Pole and heading over the Pacific to Australia. ...

The developers say it would be able fly from Brussels to Sydney in about 4.6 hours.

Re:Did anyone else misread the title?

[Hal_Porter]

They are anything but conventional. They run as an precooled jet engine upto Mach 5.5 breathing air from the atmosphere and then close an inlet and run as a rocket using onboard liquid oxygen as an oxidizer.

http://en.wikipedia.org/wiki/Reaction_Engines_SABRE

enough propellant?

[khallow]

It doesn't seem to have enough propellant mass for the task. To get to LEO, it needs something like 7.5 km/s or more in delta v (ignoring very substantial gravity and air resistance losses). If it were purely a rocket, that would be roughly 7.2 km/s (rocket equation is delta v = -4420 m/s*log(53 tons/273 tons), where 4420 m/s is perfect exhaust velocity in vacuum for LOX/LH2 burning rockets). Even if we assume we can get to Mach 5 for free (which is 1.5 km/s roughly), that leaves no more than 1.2 km/s margin. A regular rocket picks up 1.5-2 km/s or so in gravity and air resistance losses. While gravity losses might be somewhat lower (due to lift), air resistance is definitely going to be higher than the 100-200 m/s a rocket of similar size would have. So we have gravity and air resistance losses. We also have probably an inefficient nozzle design with a tradeoff between greater bell size (and efficiency in vacuum) and lower air drag. Something like drop tanks would help a little, but there doesn't seem to be the space for a lot of extra mass there. Another possibility is to use denser fuel in place of LH2 for the early parts of the flight, but that weakens the isp a little.

Re:enough propellant?

[evanbd]

You can get slightly better Isp than that, actually. For example, I get 4664 m/s vacuum Isp for O:F of 6:1 and 3000 psi expanded to 1 psi. I don't know what pressure they run at, but for a wide altitude range I would imagine it's high. Furthermore, I believe they plan to still be using some outside air even at Mach 5 -- and at that altitude, they've also got some delta-v in the altitude itself, not just the velocity. Small effects, but they help... Anyway, I don't know the details of their flight plan, but I do know that the engineers behind it are decidedly competent, and do have a detailed trajectory plan that includes good estimates of air drag and such. If you can find trajectory details, though, I'd love to see them...

(Oh, to pick a few nits about your dv budget... 7.2 km/s is orbital velocity; don't forget nearly 500 m/s of Earth rotational velocity. So if you ignore air and gravity drag, it's actually slightly under 7 km/s total delta-v, though air and gravity drag will usually add more than 2 km/s to that.)

Re:enough propellant?

[khallow]

(Oh, to pick a few nits about your dv budget... 7.2 km/s is orbital velocity; don't forget nearly 500 m/s of Earth rotational velocity. So if you ignore air and gravity drag, it's actually slightly under 7 km/s total delta-v, though air and gravity drag will usually add more than 2 km/s to that.)

7.5 km/s is orbital roughly. Still leaves up to 1.7 km/s which is pretty tight. OTOH, the payload could be a second stage, which gets you neatly around the problem.

Re:enough propellant?

[MichaelSmith]

(Oh, to pick a few nits about your dv budget... 7.2 km/s is orbital velocity; don't forget nearly 500 m/s of Earth rotational velocity. So if you ignore air and gravity drag, it's actually slightly under 7 km/s total delta-v, though air and gravity drag will usually add more than 2 km/s to that.)

7.5 km/s is orbital roughly. Still leaves up to 1.7 km/s which is pretty tight. OTOH, the payload could be a second stage, which gets you neatly around the problem.

Yeah I think a spaceplane should never go into orbit. Instead it should make suborbital hops. Non-aerodynamic payloads could be exchanged during the ballistic part of the flight.

Re:enough propellant?

[MarkRose]

You can get slightly better Isp than that, actually. For example, I get 4664 m/s vacuum Isp

DUDE!!! You must have a ton of warez!! Where can I sign up for Vacuum Isp?? My ISP suck0rs!! Im lucky if I get 3 Mb/s, but ur getting 4664!! NO FAIR!!!!1!

Re:enough propellant?

[khallow]

My ISP suck0rs!!

Be careful what you ask for. No matter how bad your ISP is, it can't suck0rs as much as *vacuum* ISP.

Re:enough propellant?

[dkf]

Be careful what you ask for. No matter how bad your ISP is, it can't suck0rs as much as *vacuum* ISP.

Don't forget black-hole ISPs. They suck nearly as much as... hmm, what a choice...

Re:enough propellant?

[StevePole]

A friend of mine works on the heat exchange system for the SABRE engines that will power Skylon. The SABRE engines are air breathing i.e. they use air they pick up on the way as fuel, hence they need less fuel at launch.

From their website: "The Sabre engine is essentially a closed cycle rocket engine with an additional precooled turbo-compressor to provide a high pressure air supply to the combustion chamber. This allows operation from zero forward speed on the runway and up to Mach 5.5 in air breathing mode during ascent. As the air density falls with altitude the engine eventually switches to a pure rocket propelling Skylon to orbital velocity (around Mach 25)."

More info here: http://www.reactionengines.co.uk/sabre.html

The engine saves weight by using the same combustion chamber during both modes of operation and in air breathing mode it only cools the oxygen to it's vapour point (as opposed to full liquidization) which greatly simplifies the engine design.

At least that's my understanding, IANARS.

Re:enough propellant?

[RocketGeek]

Your understanding is spot on.

Re:enough propellant?

[khallow]

Yes, that's pretty much what I gathered from looking at the design, especially the odd-shaped, untapered outlets for the Sabre engines and the fact no other nozzles appear anywhere on the ship.

The engine saves weight by using the same combustion chamber during both modes of operation and in air breathing mode it only cools the oxygen to it's vapour point (as opposed to full liquidization) which greatly simplifies the engine design.

This sounds like quite an effort. Would like to see if it works out. Recently, I was discussing a scramjet design with the internet:

tnphysics: The key to a gas-and-go SSTO RLV IMO is airbreathing engines-somewhat like the Forerunner V business jet proposed somewhere on the forum (afterburning ultra-high-bypass turbofan to Mach 8, then LNG scramjet to Mach 15, then switch to LH2 to Mach 20), with a small rocket added for EOI. A metallic TPS should be used.

At the time, I recommended reducing the complexity of the vehicle by eliminating the air-breathing turbofan at the start and using the rocket instead to get the vehicle up to scramjet speeds. The Sabre engine sounds like a more effective way to do that. It could boost the vehicle up to Mach 8 with a combination of air breathing and rocket modes, switch over to the scramjet for that phase of the acceleration, and then switch back to the sabres for the final acceleration to orbit in vacuum. Still overly complex, but the Sabre is a good fit for the launch profile.

Re:enough propellant?

[RocketGeek]

We also have probably an inefficient nozzle design with a tradeoff between greater bell size (and efficiency in vacuum) and lower air drag.

That's why we are developing the ED nozzle :-)

The ED nozzle is a very efficient nozzle design and provides altitude compensation across the thrust operation range. Part of the engine development at the moment is concerned with development of the ED nozzle for this purpose.

Re:enough propellant?

[Plekto]

It doesn't necessarily have to make it to orbit, though. If its goal is to merely drop a payload into space and then come back down, there's a small window for it to unload the object before it starts to drop back down. The question is whether we're talking about an hour or so or minutes.

I suspect that they plan to have the payload have its own small engine to do the final positioning and get up to orbital speeds. 5% change it actually works. It looks fancy, but seems to me to be yet another company that's trolling for rich investors. Loads of good intentions but little likelihood that it will actually work. (see SpaceX for a perfect example)

As for the space elevator, it does need to be built. If we can get items to orbit for a cost of even a thousand dollars per pound, it's suddenly possible to make space actually viable for living and exploration. Once it's built, it'll require very little day to day cost to run. The reason nobody bothers with space isn't that they don't want to get up there. It's the horrendous cost and less than 100% success rate.

Imagine if they could make a satellite as one giant piece of pre-assembled kit down on earth and then lift it up this way. There would be no need to spend millions on making it fit into a shuttle bay, have retractable solar panels, using exotic weight saving materials, or other costly idiocy. Most satellites today could be built for under $1 Million if you were to make it in a typical workshop and use commodity parts.(ie - ignore space and weight concerns entirely)

Re:enough propellant?

[khallow]

Quite true about the RLV. It should also be good for suborbital flights.

Loads of good intentions but little likelihood that it will actually work. (see SpaceX for a perfect example)

SpaceX is perfect example of what? 1) They don't troll for rich investors, 2) they actually work (I know, 1 out of 4 sucks, but it's a lot better than 0 out of 0), 3) they're getting some serious contracts.

Re:enough propellant?

[khallow]

Hmmm, the problem I was thinking of was in pure vacuum. Does the pintle (adjustable central obstruction in the nozzle) improve performance in vacuum? Seems to me that if you wanted almost perfect ISP, you still need a high expansion bell on your nozzle.

Re:enough propellant?

[RocketGeek]

Hmmm, the problem I was thinking of was in pure vacuum. Does the pintle (adjustable central obstruction in the nozzle)

Yes, you'll be pleased to know, I know what the pintle is, I have had to extract it from the motor several times :-) Not straight after testing you'll understand :-)

improve performance in vacuum?

Compared to a bell nozzle, yes, since it is operating at optimum efficiency throughout the thrust regime.

Seems to me that if you wanted almost perfect ISP, you still need a high expansion bell on your nozzle.

Absolutely, you're spot on :-) And in fact, the ED nozzle does have a very large area ratio. Even with the large area ratio, the performance gains compared to a bell nozzle should be greater than any mass hits you take by having a large area ratio nozzle in the ED. In terms of how great, that's what the ED rocket test programme that Reaction Engines is carrying out is designed to find out.

Re:enough propellant?

[Plekto]

They don't troll as such, but they are still basically sucking investors for loads of money. Why? Because like this spaceplane concept, it won't actually do the one thing that it really needs to do, which is to make it to orbit. Not because of technical reasons. But because both designs are several times too small a fuel supply to actually make it to a stable orbit. This means a complete re-design with a far larger vehicle would be required.

They obviously know this, so why they are making this "spaceplane" like this... It makes you wonder.

Re:enough propellant?

[khallow]

You must be talking about someone else, perhaps Scaled Composites or XCOR, both who have unproven "spaceplanes" that are incapable of reaching orbit. SpaceX's Falcon 1 rocket made it successfully to orbit last year. Payload to low Earth orbit is about two thirds of a metric ton. They are currently readying the bigger Falcon 9 for a flight out of the JFK Space Center and have seven flights planned this year of the Falcon 1 and 9 rockets.

Sky-Lon?

[pcgabe]

Sounds like a Skynet-Cylon joint venture. Please don't be sinister-looking....

*Opens link*

Ah, crap.

does this add up ?

[freddy_dreddy]

from this presentation:
- air intake in the order of hundreds of kg per second (400 kg/s to quote) ...
- passes through thousands of small tubes (resistance at that speed ?!?) ...
- in a few milliseconds ...
- cooled from + 1000degreesC to -150degreesC

Forgive me my ignorance, but are these materials physically possible ?

Re:does this add up ?

[Anonymous Coward]

Yes

Re:does this add up ?

[freddy_dreddy]

Thanks

Re:does this add up ?

[Thing 1]

Thanks again for the sig quote! Randomly yours,

Re:does this add up ?

[Anonymous Coward]

- passes through thousands of small tubes (resistance at that speed ?!?) ...

would you say it's a series of tubes?

Re:does this add up ?

[freddy_dreddy]

Hey dude, you're welcome :)

Re:does this add up ?

[freddy_dreddy]

it's holes drilled in the body of the compressor chamber

Re:does this add up ?

[Thing 1]

By the way, it's a space not an underscore. Of course, since it's underlined it's easy to miss that, unless you cut-and-paste. Well, that is, copy-and-paste, as you can't really remove text from a web page. :)

comments?

[Anonymous Coward]

where the crap are all the worthwhile comments from our /. readers/commentators?
I'm disappointed

George Lucas copyright?

[VincenzoRomano]

Hmmm ... I would suggest GL to sue that company for (R) infringement!
And later (from a galaxy far far away) the Empire will sue GL!

Re:George Lucas copyright?

[Anonymous Coward]

Why would the Green Lantern sue them?

Still going?

[jeroen94704]

Reaction Engines Ltd have been working on this for well over 10 years now (maybe closer to 20) with not a lot of actual hardware to show for it. I first heard about Skylon when I was still in uni, around 1996 or so, and not much has happened since. So while the Skylon design is inordinately cool, with some very nifty and innovative features, I'm afraid it's never going to actually fly.

Sad, really, as it's one of Europe's few contenders in the non-gov space race, and probably the most promising one, in terms of design maturity.

Re:Still going?

[Stoutlimb]

It might fly, but will it stand the heat of re-entry? There doesn't seem to be any heat shielding at all. I'm wondering how it's not going to disintegrate?

Re:Still going?

[Dr Bip]

The concept predates 1996 by a good bit. (disclaimer: I used to work on Interim HoToL) HoToL, a British air-breathing SSTO, would also have used a similar engine cycle to that of the Skylon engines (aye, there are differences aplenty), and HoToL flourished as a project in the mid 1980s.

The Internet

[mcrbids]

How many "2.0" Internet businesses exist only because of the unexpected consequences of humanity building the largest peer based computer network in existence?

Slashdot itself, and other newcomers like Netflix "on demand" only exist because of the Internet. Did we build the Internet so that we could stream "Superman" in real time, or argue politics with people from around the world?

No. but they all happened because we built the Internet!

So build it! Society will profit in ways we can't today imagine today any more than Bob Metcalfe imagined Slashdot when he co-invented Ethernet!

Re:The Internet

[khallow]

OTOH, we (or rather DARPA) built the Internet because there was at the begining a a demand for the internet. Namely a test stand for protocols and equipment that would maintain communications in time of nuclear war. Shortly thereafter, one of the most important applications to ever grace the internet was introduced, email. If we threw up a space elevator today, what would we use it for? How would we pay the upkeep and operations for the elevator? What is the equivalent of "email", of the "web", etc and how long would it be before they manifest?

My take is that it'd be a long time. We don't have much in space that requires products from Earth. Even though a space elevator has good economies of scale, there's no scale to exploit.

Re:The Internet

[mcrbids]

My take is that it'd be a long time. We don't have much in space that requires products from Earth. Even though a space elevator has good economies of scale, there's no scale to exploit.

You think this this because you don't know what the benefits are, any more than anybody could have predicted email. There are distinct advantages to a space elevator. For example, carbon nanofiber in the 5,5 "armchair" configuration is highly conductive, making it possible to build a solar power station in space and send the electricity home over the elevator cable!

What other advantages are there when the cost of going into space drops from $10,000 per pound down to $25?

Re:The Internet

[khallow]

You think this this because you don't know what the benefits are, any more than anybody could have predicted email. There are distinct advantages to a space elevator. For example, carbon nanofiber in the 5,5 "armchair" configuration is highly conductive, making it possible to build a solar power station in space and send the electricity home over the elevator cable!

I'd have to say that based on almost a century of prior work, that yes, I have a pretty good idea of what we can do. Space solar power via an elevator cable isn't that sexy unless the cable is near isolated electricity customers. A lot of the places where a cable would be anchored (mountain top, middle of Pacific Ocean) don't have customers.

What other advantages are there when the cost of going into space drops from $10,000 per pound down to $25?

You need demand for that price drop to occur. Otherwise it is an unrealistic assumption just like the cost per pound for the Space Shuttle. The designers expected that the Shuttle would be launching as many times in three years (40 times a year) as it has in reality ever launched. An underutilized space tether just isn't going to deliver the prices you want.

I'm impressed.

[jcr]

I checked out their video gallery. These people know what they're talking about.

-jcr

àOENewton's

[bobbagum]

AM I the only one who reads the headline as 'Reactionless Engine' otherwise reaction engines sounds like another name or description of rockets to me, not a name of an unheard of company

Re:àOENewton's

[rts008]

No, you're not the only one.
I had to read it three times before I could parse it correctly.
I blamed it on not enough coffee yet. :-)

a 21st Century DC-3

[alizard]

From what I saw at the company website, it looks like they're building the orbital equivalent of the first commercial airliner, the DC-3.

If they can get the cost to orbit even remotely close to the $200/kg number the Space Power Satellite program proposed by NASA was based on, we could either build a full system or a large proof of concept orbital power array. We're a bit more desperate for power than we were when Bush defunded the SPS project. The launch capability is the hard part of SPS, the rest is just engineering we know how to do.

That could take up enough launches to provide the company a reasonable chance at profit.

Re:a 21st Century DC-3

[YourExperiment]

From what I saw at the company website, it looks like they're building the orbital equivalent of the first commercial airliner, the DC-3.

Cool. Now if we can just scale up to build space DC-8s, we can take all the scientologists to another planet and drop them in a volcano.

Re:a 21st Century DC-3

[rarel]

From what I saw at the company website, it looks like they're building the orbital equivalent of the first commercial airliner, the DC-3.

Bit of a nitpick here, but that would be the first tremendously successful commercial airliner.

The DC-3 was an evolution of the DC-2, which was designed to compete with Boeing's 247. The 247 itself was preceded by a bunch earlier designs by various constructors, like the Ford Tri-Motor.

Re:a 21st Century DC-3

[Anonymous Coward]

Do we really want to cause Olympus Mons to erupt?

HOTOL?

[footnmouth]

Hmm... as I'm getting old I thought I remember this concept as HOTOL, and sure enough: wikipedia Reaction engines was started by one of the HOTOL designers. Still, it's had probably 30 years of intellectual development and it looks believable to me. Go Reaction Engines.

I see...

[argStyopa]

... 5 million pounds spent in developing an engine.
I see tests that have demonstrated only the precooler - not the thrust, not the reliability, ie none of the things critical to it actually working.

I see no prototype having been tested.

I see something that's a hairsbreadth from the 'I've pulled this kewl idea out of my butt!'.

Re:I see...

[RocketGeek]

Then you may need to work on your reading :-)

The precooler tests were run separate to the thrust tests. The thrust tests were related to the ED nozzle work.

As for the reliability, well when I wrote the test plan for the ED nozzle test engine, I can assure you, that reliability was very much part of the plan.

As for you not seeing any prototype being tested, note the photograph of a rocket shaped object with hot flame coming out of it in the News section?

I'm sorry the photograph isn't any better, but none of us were prepared to step outside the bunker during the hot firings. I'm working on improving the photos taken during test runs.

Re:

[Kaetemi]

It looks like a flying ballpoint pen.

This will never work, because.

[Anonymous Coward]

we'll never let it.

For godssake, this is NOT developed in AMERICA! It will be like the Concorde. Clever idea, could have been developed, we starved it of cash and put all the barriers we could think of in its way.

I predict that, if this goes to prototype and works:

1) we will step in and buy it up, then claim the we have invented it and transfer all the production facilities to Utah
2) we will step in, buy it up and then close it down because of political pressure from our current technology production facilities
3) we will ignore it and refuse to certify any vehicle developed from it for any US launch purpose
4) we will pull what strings we can to prevent other countries from signing up to it as well

That should be enough to kill it off right now. We don't need any technical considerations. Besides, as a politician, they hurt my head....

Re:This will never work, because.

[turgid]

we'll never let it.

+5, insightful.

Actually, it might be more like the UK's original space rocket programme. Just as they get something built that looks like it might work, some bureaucrat will try to terminate the project. There will be begging and pleading to let it fly just once, which it will, and do so perfectly much to the admiration of the world.

Then it will be canceled properly and everyone will have a nice cuppa tea, a slice of cake and a sit-down.

Still, mustn't grumble.

Re:What to do in orbit?

[Migraineman]

Honestly, I'm not being pedantic here, but exactly what are the "new" commercial applications that'll magically appear in LEO? Earth imaging? Yep, we do that already. Communications relays? Yep, from both LEO and GEO. Tourism? That implies a destination that doesn't exist yet, and obviates the "cargo" bias of the launcher. Note: "scientific research" isn't a commercial application nor is it a business model. It may be a necessary component, but the research phase is usually an expensive precursor to the commercial application.

I toss this out there because I've built satellite hardware, and it really is difficult to answer the question "what are you going to do in LEO?" I understand the Catch-22 that exists - nobody considers orbital apps because you can't get there; consequently, no demand for orbital transport develops because there are no on-orbit applications. However, just creating a transport mechanism won't magically make applications fall out of the sky (so to speak.) And unless several industries are planning applications in lock-step with your launch service, there will be a sever over-capacity that will drive the launch provider into bankruptcy.

Further, if there isn't standardization for the payload-to-vehicle interface, there won't be any competition in the market. You'll choose a launch provider at the beginning of the program, and you'll be locked-in to their infrastructure for the duration. Changing providers would essentially be a "do over" from a programmatic view. This isn't a taxi where you can get out of one and into another, receiving comparable service out of either.

Whilst

[necro81]

Skylon will be able to repay its development costs, meet its servicing and operating costs and make profits for its operators whilst being an order of magnitude cheaper to customers than current space transportation systems.

Can I trust my payload and/or investment dollars to a company that uses "whilst" on their site?

Re:Whilst

[tripmine]

Absolutely not. As everyone on Slashdot knows, your engineering prowess is directly proportional to the correct usage of the English language.

Re:Whilst

[hierophanta]

i have a hard time trusting a company who has a $10billion budget but uses CG images that are worse than i can do in less than a weekend (including rendering time [no seriously]).

for the record - i dont work as a graphic artist

Re:Whilst

[RocketGeek]

1) The graphics were produced a fair while ago. I daresay they could be improved nowadays. Much of the design work is in Solid Works, so I imagine that could be skinned and modeled accordingly.

2) Reaction Engines is focused on trying to develop an SSTO spaceplane, not a Hollywood movie. If the money was available, yes, I'm sure the graphics could be souped up, but when the budget choice is graphics or components for a rocket engine say, guess what wins in a rocket related company that is focused on developing the hardware?

Personally, I would rather trust a company that bring real hardware that has been tested to the table than a company that just has a bunch of gorgeous CG images and PowerPoint slides.

Re:Whilst

[cheesybagel]

The whole thing looks cool, especially the engines. The problem is I don't expect it to fly. Ever. Much like any of the other nice spaceplane projects (HOTOL, Black Horse, X-34, etc). They are too expensive and none will fund it. The risk is high, it takes long to produce results, it discourages investment. I've heard it can take 5 years to design a rocket engine alone, but these engines are way more complex. Still, my hat's off to you for even trying such a beast. They originally said jet engines weren't possible either, and some British guy tinkered enough to get one working, even if the government made little note of it at the time, so I guess it isn't impossible.

Re:Whilst

[RocketGeek]

I can understand where you are coming from completely. The task is certainly not easy, but we do believe it is achievable, and as has happened until now at Reaction Engines, the key is incremental steps towards the eventual capability.

Rocket engines do take a while to develop yes, but a deeply cooled air breathing rocket engine is in some regards less of a big deal than designs where they use a jet engine, a ramjet, a scramjet and a rocket to get into orbit. Yes, there are some elements of it that are fairly complex, but other elements of it that are more straightforward too.

Although the website lists the main projects, there are a lot of intermediate sub projects along the way that have been achieved or are in process at the moment, and as these come together, the more of that capability will be realised. We will do this, because we genuinely believe it is achieveable, we are too stubborn not to, and we owe it to those on HOTOL, Black Arrow and Blue Streak who blazed the trail. Besides which, I'll be out of a job if there isn't something shiny flying in a while ;-)

Re:Whilst

[hierophanta]

it is generally considered uncouth to comment about your own company at /.
especially if you are not openly saying it.

regardless, i and most others here are definitely applauding your efforts

Re:Whilst

[RocketGeek]

I'm sorry for any offence caused. I am just very enthusiastic about the cause!

Reaction Engines To Fly Reusable Spaceplane

[John Hasler]

There's another kind? Tell me more!

Mod parent rocket scientist up.

[Civil_Disobedient]

Thanks for replying... I think some people forget just how complicated (and time-consuming) it is to design a vehicle for space travel when you don't have billions of dollars in your budget.

Re:Mod parent rocket scientist up.

[RocketGeek]

Thanks for replying... I think some people forget just how complicated (and time-consuming) it is to design a vehicle for space travel when you don't have billions of dollars in your budget.

My pleasure. I'm sat here working on calculations connected with the ED nozzle this afternoon (the rocket side of the engine is the part I am lucky enough to work on), and thought it made sense to reply to some of the comments where I could.

As you can imagine, there is a lot more going on behind the scenes than is indicated on the website. The problem is, we are rocket people, not PR people, so getting the word out doesn't come naturally, and we spend the vast majority of our time working on the technical aspects :-)

Oh I forgot

[khallow]

Space elevators and sky hooks have an additional advantage over RLVs. All three can economically drop mass from orbit, but the tether systems can harvest the energy and momentum of orbital mass going to Earth's surface. This removes the last big restriction to cost to orbit. If there's some large quantity of sufficiently valuable mass in orbit to return to Earth, it might actually yield a negative cost to orbit for material coming from Earth. Eg, if putting a kilogram in space meant a kilogram of gold or other PGMs (with an expenditure of say a few dollars per kg for tether operations and upkeep) was returned to Earth, then that would create a massive economic engine for putting stuff in space from Earth.

"Star Wars-looking"

[GPS Pilot]

The resemblance to Queen Amidala's "Naboo Cruiser" is remarkable.

http://www.galacticempiredatabank.com/NabooCruiser1.jpg

Coincidence?

Re:"Star Wars-looking"

[IHateEverybody]

I was thinking more in terms of the offspring of an SR-71 that got knocked up by a Cylon Raider.

Oh, not bad! Not bad, huh? A Nubian, huh?

[slyborg]

Watto like!

http://starwars.wikia.com/wiki/J-type_327_Nubian_royal_starship