How far into the future? An aircraft that launches from a runway and enters low

[dicktice]

By routinely I mean up to an including daily, once LEO becomes like another "ocean" of Earth, needing to be supplied and serviced continuously, for mission-assembly and space-only vehicle refurbishment as well as tourist passenger transport.

[Antice]

Daily spaceflight will happen if there ever is a market that needs that many flights. it's the launch market that decides how many flights there are in a given year. and not the vehicles that perform said flights.
RLV's enable cheaper access and the hope is that cheaper will entice more investment into space related activities. thus bootstrapping a higher launch rate.

It's a classic chicken and egg problem. prices for launches are so high that only high end applications like earth observation, long range communications and science is conducted in space. only when prices drops down to something affordable by potential tourist and industrial markets does the market really start to grow with new customers. ironically this growth is exactly what is needed to get launch prices down in the first place.

[dicktice]

I think there's little to choose between regarding horizontal flyback booster runways at sea level or near-vertical mountain top single-stage-to-orbit launches, just as long as expendable booster stages are eliminated. They represent the "egg," which would have to appear first in the chicken-and-egg analogy. Any manner of payloads could be launched without further development, using existing passenger parachute return capsules and unoccupied "empties" which are simply allowed to burn up in the atmosphere. So...what to do about the still to be developed spaceplanes? Once they're in orbit they'll have transition back through atmosphere and land on wheels. Isn't that the "chicken" which will create the market for daily flights to and from LEO?

[danscope]

There remains the question of engine survival at these high temperatures on re-entry. Talk is cheap, but will those engines work again or be disposable?

[Antice]

I think there's little to choose between regarding horizontal flyback booster runways at sea level or near-vertical mountain top single-stage-to-orbit launches, just as long as expendable booster stages are eliminated. They represent the "egg," which would have to appear first in the chicken-and-egg analogy. Any manner of payloads could be launched without further development, using existing passenger parachute return capsules and unoccupied "empties" which are simply allowed to burn up in the atmosphere. So...what to do about the still to be developed spaceplanes? Once they're in orbit they'll have transition back through atmosphere and land on wheels. Isn't that the "chicken" which will create the market for daily flights to and from LEO?

that was confusing. the chicken and egg problem refers more to the economics of spaceflight rather than the hardware.
consider the following formula for a second:

launch cost = (facility fixed costs/number of launches total) + recurring launch costs.

there are more factors involved but these are the major categories of costs.
facility fixed costs are what it costs to maintain the full supply line from raw materials to finished rocket's ready for integration on the pad. as well as the fixed costs of owning and maintaining the pad. all of these costs that are essentially fixed regardless of launch rate.
number of launches is rater self explanatory. this would have to be the number for the same period of time that the fixed costs span.
recurring costs is the costs of all the materials and fuel that goes into the vehicle. essentially this is the true cost of the vehicle. it may or may not include labor. it depends on what kind of contract laborers work under. if they are only hired for the one mission then it's a recurring cost. if they are hired full time they have to be paid for regardless of launch rate, and hence belong under fixed costs.

when considering that formula it becomes apparent that there are 2 ways to cut costs per launch. one is to put fixed costs on a strict diet. this is what SpaceX has been doing. by designing their facilities and vehicles as cheaply as possible they have cut down on the fixed costs and can offer launches more cheaply than the competition. being cheaper means getting more business and hence launch rates go up. this has the synergistic effect of bringing launch costs closer to the level of the recurring costs.

the second way to decrease launch costs is the RLV path.
in this path we put recurring costs on a strict diet. in fact we build a much more expensive vehicle that is reused instead. thus effectively putting as much of the previous recurring costs into the fixed costs category as possible. this is then countered by being able to do many launches with very low recurring costs.

in both scenarios launch rates has a profound effect on launcgh costs. for each doubling of the launch rate there is a corresponding halving of the fraction of the fixed costs each launch has to carry.

the chicken and egg problem here refers to the fact that without customers you do not have any launches. it does not help if you can launch a vehicle per hour if you do not have any payload for said launches. thus vehicles like skylon face the chicken and egg problem. they can cut launch costs to a level far below what SpaceX will ever be able to deliver, but only if there is enough customers to get to the point in the launch rates where RLV's becomes cheaper than ELV's

Reactionengines ltd have adressed this issue btw. by only selling vehicles they make a dividing line between the development costs and the operator costs. thus the development cost risks belongs to the manufacturer. they can only charge what the market (read:launcher operators) are willing to pay per vehicle. this makes the fixed costs more predictable, and this is something that investors like a lot.
Their business model also suggests moving fixed pad/spaceport costs over to a third party as well. namely the spaceport owner.
this model is the same as airliners operate under. airline companies does not own airports. they pay a fee for using them. thus airliners have minimal fixed costs, but pay for everything trough their operational costs. thus allowing for the economy of scale to work across multiple providers instead of a single entity.

This cost sharing does not stop with the vehicle operators however. consider all the secondary and tertiary businesses that also thrive in airports. spaceports need not be any different in that regard. in fact. With skylon the spaceport will probably double as an airport in any case. those payloads will have to be shipped in to the port one way or another after all. (this is called externalizing costs. sometimes it is referred to as a hidden subsidy as well. depending on what/who one is talking about/with.)

Combining these fixed cost reduction methods helps make skylong a bit cheaper from the get go. even before the economy of scale starts to kick in properly. it's also a cost reductions scheme that ELV's cannot use due to needing specialized pad's unique to each end every type of vehicle. and no ability to share facilities with other industries.
wither they can break the chicken and egg barrier is something we cannot truly know before it happens however. we do not know exactly where in the price range market plasticity starts to do it's magic. and there is only one way to find out. namely to build it and see.

[Hal37214]

There remains the question of engine survival atthese high temperatures on re-entry. Talk is cheap, but will those engines work again or be disposable?

If the vehicle is recoverable, why couldn't the engines be as well? According to Pratt & Whitney, 115 shuttle missions were powered by a total of 42 SSMEs: SSME Flight Experience

[danscope]

Hi Hal, Yes, the vehicle is recoverable. But I was talking about the effects of severe heat durring re-entry to
the engines which are supposed to be re-used.....over and over and over and over..... There's the rub.
That's a tall order. I'm thinking that anything which sticks out of a vehicle that isn't firebrick is toast.

[Garrison]

Hi Hal, Yes, the vehicle is recoverable. But I was talking about the effects of severe heat durring re-entry to
the engines which are supposed to be re-used.....over and over and over and over..... There's the rub.
That's a tall order. I'm thinking that anything which sticks out of a vehicle that isn't firebrick is toast.

And again neither REL nor the ESA appear to regard this is as a major issue, what technical information or expertise do you base your opinion on?

[ravens_cry]

Well, there is a lot of new engineering involved here. I wish them the best, but just because it is theoretically possible does not mean it is feasible. We will have to see once they start test firing the actual motor. This is supposed to be pretty soon I here.

[Paul Wally]

Hi Hal, Yes, the vehicle is recoverable. But I was talking about the effects of severe heat durring re-entry to
the engines which are supposed to be re-used.....over and over and over and over..... There's the rub.
That's a tall order. I'm thinking that anything which sticks out of a vehicle that isn't firebrick is toast.

Can't the engines be closed by some kind of hatch during re-entry? I'm sure they won't be needed during re-entry. Excuse me if this sounds silly, I haven't read the specs.

[Hal37214]

Can't the engines be closed by some kind of hatch during re-entry? I'm sure they won't be needed during re-entry. Excuse me if this sounds silly, I haven't read the specs.

Again, they did manage to protect the SSMEs well enough to allow their re-use. Other boosters may employ "re-usable" engines as well, but the economics of vehicle recovery mean it's cheaper to treat them as disposable. The same decisions go into every launch vehicle design. But if the question is, "can we recover and re-use engine hardware from orbit," the answer for the past 30 years has been "Yes."

[Garrison]

Well, there is a lot of new engineering involved here. I wish them the best, but just because it is theoretically possible does not mean it is feasible. We will have to see once they start test firing the actual motor. This is supposed to be pretty soon I here.

Sorry but my point is that Danscope is claiming that this is an issue without offering an reasoning or evidence, and apparently without having read the specifications for Skylon despite having been offered links to do so. What is actually being tested is the precooler, which is really the only radically new technology in the Skylon.

[TrAI]

Can't the engines be closed by some kind of hatch during re-entry? I'm sure they won't be needed during re-entry. Excuse me if this sounds silly, I haven't read the specs.

The 2-shock intake assembly on the SABRE is designed to be able to close completely, something that would be done when the engine transitions to rocket mode. The engines would keep this configuration during the rest of the mission, so they are not open during reentry.

[dicktice]

ANTICE wrote, in part:
"the chicken and egg problem here refers to the fact that without customers you do not have any launches. it does not help if you can launch a vehicle per hour if you do not have any payload for said launches. thus vehicles like skylon face the chicken and egg problem. they can cut launch costs to a level far below what SpaceX will ever be able to deliver, but only if there is enough customers to get to the point in the launch rates where RLV's becomes cheaper than ELV's"
That was not MY chicken and egg: I erred in failing to specify passenger carrying spaceplanes of the future, not the unmanned kind. In any case, without a proven vehicle (the egg) the economics "chicken" is just so much blather....

[Antice]

ANTICE wrote, in part:
"the chicken and egg problem here refers to the fact that without customers you do not have any launches. it does not help if you can launch a vehicle per hour if you do not have any payload for said launches. thus vehicles like skylon face the chicken and egg problem. they can cut launch costs to a level far below what SpaceX will ever be able to deliver, but only if there is enough customers to get to the point in the launch rates where RLV's becomes cheaper than ELV's"
That was not MY chicken and egg: I erred in failing to specify passenger carrying spaceplanes of the future, not the unmanned kind. In any case, without a proven vehicle (the egg) the economics "chicken" is just so much blather....

passengers is an unproven and highly speculative market possibility. No concept should ever be based on passengers as a primary customer source.
This is exactly why the skylon concept is so much more likely to actually get realized. the business case is built upon the proven satellite market of today and not a speculative tourist market of tomorrow.
Skylon is a likely winner because it's going to be able to compete with ELV's even before you add in any growth in the launch market.
A skylon vehicle is tentatively priced at 600 million or so. this is the only fixed cost the launch operator needs to worry about. with each vehicle being able to do 200 flights, that puts the vehicle amortization cost per flight down to a very competitive 3 mill.
No ELV is ever going to be able to get the vehicle cost per launch to go that low.

REL is assuming that the manufacturer will make a profit if as many as 70 vehicles is sold during the operational lifetime of the skylon mk1 model. the production lifetime of skylon can be set to a fairly long time period. skylon's will never be rolling off the assembly lines en mass. rather a few will be built each annum. with a rush of construction during the early years then only replacement vehicles and spare parts for at least the next 20 to 40 years.

Assuming that skylon operators more or less corner the market for 15 tonnes or less launches to LEO then that means that skylons will be launching payloads around 40 times per annum.
with 4 operators owning 2 skylons each that translates to around 5 launches per annum per vehicle.
at this rate each skylon will reach it's end of life after 40 years. this is actually not an unreasonable timeframe for such a vehicle. consider how old the shuttles are. or many still in service airliners are.

this is probably the worst case scenario for the manufacturer however. with only 8 vehicles built they will face the inevitable result of never being able to pay back the initial development costs. The construction facilities may be profitable however. so ironically. even tho skylon may never repay it's R&D it can still end up being a huge long term success.

[cjl]

I don't think that low earth orbit will ever be accessed routinely by us from level runways, at least between sea level and 10,000 feet above sea level, at supersonic velocities through the lower 40% of the atmosphere. China might try it on the Tibeten plateau, of course, since they have the political clout to commandeer the necessary acreage....

If anything, having a runway at sea level would be desirable, not bad. The extra air density will allow for more thrust from the airbreathing engines, as well as a lower takeoff speed. Therefore, it will take substantially less runway, and the tire speed won't be as high either. Since the vehicle would accelerate after climbing to a higher altitude to prevent excessive drag anyways, your concern about supersonic flight in the lower atmosphere is really unfounded.

[danscope]

The SSMES are in the back, not exposed to the direct atmospheric stream of re-entry heat. Those are rockets,see?
This skylon has the engines mounted on the side, like an F-104 . Going up, fine . Comming in...toast .
Maybe they expect to solve that problem later. Remember: this is only a concept at this point.

[joema]

The SSMES are in the back, not exposed to the direct atmospheric stream of re-entry heat. Those are rockets,see? This skylon has the engines mounted on the side, like an F-104 . Going up, fine . Comming in...toast...

The SABRE intake cone simply moves forward and totally seals the inlet during reentry. The intake cone has thermal protection (either passive or active).

This is conceptually no different from the J-58 engine on the SR-71, where an inlet cone moves considerably fore and aft to control inlet shock wave. Only in Skylon's case the interior inlet circumference is shaped to fully mate with the cone in the full forward position, similar to how a valve mates with the valve seat in an internal combustion engine.

http://en.wikipedia.org/wiki/File:SR...w_Patterns.svg

[NEOWatcher]

The SSMES are in the back, not exposed to the direct atmospheric stream of re-entry heat. Those are rockets,see?
This skylon has the engines mounted on the side, like an F-104 . Going up, fine . Comming in...toast .
Maybe they expect to solve that problem later. Remember: this is only a concept at this point.

I thought this was answered in post #63. Is there something you still disagree with on that concept?

[Antice]

The SSMES are in the back, not exposed to the direct atmospheric stream of re-entry heat. Those are rockets,see?
This skylon has the engines mounted on the side, like an F-104 . Going up, fine . Comming in...toast .
Maybe they expect to solve that problem later. Remember: this is only a concept at this point.

and why exactly should engine pods differ from any other engine placement? you know. those pod's are going to be made from advanced ceramic composites. the same stuff they plan to make the outer fuselage out of. and fyi. the SABRE's are rocket engines. they are not jet engines altho they have a superficial resemblance when viewed from the front. the closest match would be an air turborocket. altho that is not an exact match either. the SABRE's are unique in what they do and how they do it.

[aquitaine]

There's also the differences in the materials used in the first place, the shock cones on the engines are an integral part of the heat shield.

[kamaz]

Thread resurrection alert.

REL starts testing the precooler: http://www.bbc.co.uk/news/science-environment-17864782

Reaction Engines Limited (REL) believes the test campaign will prove the readiness of Sabre's key elements.

This being so, the firm would then approach investors to raise the £250m needed to take the project into the final design phase.

"We intend to go to the Farnborough International Air Show in July with a clear message," explained REL managing director Alan Bond.

"The message is that Britain has the next step beyond the jet engine; that we can reduce the world to four hours - the maximum time it would take to go anywhere. And that it also gives us aircraft that can go into space, replacing all the expendable rockets we use today."

To have a chance of delivering this message, REL's engineers will need a flawless performance in the experiments now being run on a rig at their headquarters in Culham, Oxfordshire.

The test stand will not validate the full Sabre propulsion system, but simply its enabling technology - a special type of pre-cooler heat exchanger.

[ravens_cry]

You know, I was wondering about these guys.
They are certainly ambitious, but I like that in engineering.

[Garrison]

Thread resurrection alert.

REL starts testing the precooler: http://www.bbc.co.uk/news/science-environment-17864782

I posted that a little while ago in the 'Rocketplane by 2020' thread, it is good news, and its the key to whole concept. If it works the rest is 'just' money and engineering.

[danscope]

Thread resurrection alert.

REL starts testing the precooler: http://www.bbc.co.uk/news/science-environment-17864782

Hi, I think they need to test their engine at super velocity as per placing it on something like the
X-15 . Now, maybe they can impress someone enough to build some.

[Garrison]

Hi, I think they need to test their engine at super velocity as per placing it on something like the
X-15 . Now, maybe they can impress someone enough to build some.

Actually the next step is a sub scale prototype engine, and has been pointed out to you before REL have stated they already have potential backers to carry on to that phase.

[swampyankee]

Single-stage-to-orbit (SSTO) is a very difficult target, with required propellant fractions something like 97% of the takeoff weight. Two-stage-to-orbit systems are much more practicable, which is essentially what OSC's Pegasus is: SSTO with a recoverable booster. I'd guesstimate that a 2STO system, with a reusable, man-rated lander could be developed for something in the neighborhood of $45 billion, or about 3 times the cost of developing the A380.

[Antice]

Single-stage-to-orbit (SSTO) is a very difficult target, with required propellant fractions something like 97% of the takeoff weight. Two-stage-to-orbit systems are much more practicable, which is essentially what OSC's Pegasus is: SSTO with a recoverable booster. I'd guesstimate that a 2STO system, with a reusable, man-rated lander could be developed for something in the neighborhood of $45 billion, or about 3 times the cost of developing the A380.

That is much more expensive than what skylon is going to be. air-breathing up to mach 5.5 changes the propellant fractions a LOT skylon C1 revision had a calculated payload ratio that was on par with a falcon 9. according to rumor this could very well improve with the higher fidelity calculations we will get alongside the D1 revision with the much improved performance numbers from the Sabre 4 cycle.

[swampyankee]

That is much more expensive than what skylon is going to be. air-breathing up to mach 5.5 changes the propellant fractions a LOT skylon C1 revision had a calculated payload ratio that was on par with a falcon 9. according to rumor this could very well improve with the higher fidelity calculations we will get alongside the D1 revision with the much improved performance numbers from the Sabre 4 cycle.

No, that's much more expensive than they claim Skylon is supposed to be. If they manage to get a flight-worthy, man-rated vehicle for that, I'll be shocked. If they claim it costs less, I'd want to see an audit report, because I'd bet they were lying.

[Antice]

No, that's much more expensive than they claim Skylon is supposed to be. If they manage to get a flight-worthy, man-rated vehicle for that, I'll be shocked. If they claim it costs less, I'd want to see an audit report, because I'd bet they were lying.

They do not claim that skylon will be man rated at first. the business case for skylon is not based on passenger traffic at all.
They had a review of their business case, and it was judged as good even with only the current satellite market.
Secondly. Skylon is going to be the first ever 100% reusable SSTO capable vehicle in history. there are NO standard, rules, nor even guidelines to follow in regards to man rating it.
Either skylon is capable of reliably performing it's stated 200 flights, and will thus have set a new de-facto gold standard for reliability in regard to launchers, or it fails.
There is no middle ground when we talk about re-usable launchers. Failed launches is not acceptable as part of the routine operations of RLV's, therefore the margins for safety have to be really high. prohibitively high compared to those we typically find on ELV's.
The technology going into skylon, while a bit more advanced in regards to materials and engine tech, is not all that different than that of the Airbus. both vehicles exist in the same universe, and are designed with the same reliable re-usability criteria. Their dev programs both should, and will be approximately on par with each other costs wise.

It is TSTO's that do not make sense on a planet where SSTO is feasible. the added cost and complexity of staging makes that solution much more expensive, not just to develop,(two vehicles instead of one). But also more failure prone due to the increased number of possible failure modes such a system has.

As for the cost numbers floating about. they are fairly old, and should be taken with a pinch of salt. however. it should be noted that REL has not been pushing things to the right a lot unlike some other companies i am not going to argue about in a skylon thread. skylon is more or less on schedule believe it or not, but that is not unusual at this stage of development. They are still mostly working on the engines after all, and a lot of stuff can happen once they start working on making a vehicle proper. It seems to me that most dev programs hit some nasty snags once they start trying to integrate multiple technologies into a integrated whole rather than during the technology development itself. it's hard to predict interactions between the various aspects of the vehicle until you actually have the hardware you need to start building it. unfortunately, that is the point in the cycle where people start having serious expectations about delivery dates as well. hence shifting the schedule to the right becomes a somewhat bigger issue than it should be imho.