Skylon may fly this year, first SSTO spaceplane?

[Red Iron Crown]

There's no customers because there's no SSTO precedent. There was no demand for 4 hour transatlantic flights before the first passenger plane was built.

And yet when 4 hour transatlantic flight became available, there weren't enough customers to support it because 8 hour was good enough and cost much less.

Customers putting things in orbit don't care if it's SSTO or multistage, they care about the costs of getting there. If Skylon can get payloads to orbit for cheaper than the alternatives, customers will beat a path to their door. If they can't, it'll be another Concorde. Cool and technically interesting, but not economically viable.

[Rakaydos]

And yet when 4 hour transatlantic flight became available, there weren't enough customers to support it because 8 hour was good enough and cost much less.

Customers putting things in orbit don't care if it's SSTO or multistage, they care about the costs of getting there. If Skylon can get payloads to orbit for cheaper than the alternatives, customers will beat a path to their door. If they can't, it'll be another Concorde. Cool and technically interesting, but not economically viable.

Which means it comes down to how much money SpaceX can shave off launch costs by recovering stages.

Both Skylon and the Falcon R are trying to cut launch costs with reusability- SpaceX claims they will eventally be able to get the cost per pound to orbit to a fraction of NASA's cost. The question is if Skylon's flight and recertification can get their price that low.

[Red Iron Crown]

Which means it comes down to how much money SpaceX can shave off launch costs by recovering stages.

Both Skylon and the Falcon R are trying to cut launch costs with reusability- SpaceX claims they will eventally be able to get the cost per pound to orbit to a fraction of NASA's cost. The question is if Skylon's flight and recertification can get their price that low.

Exactly. I think we're in the most interesting times of spacecraft development since the space race fizzled.

[Nibb31]

If SpaceX brings launch costs down to $50 million as they claim, that is not going to bring spaceflight to the masses. Even at $25 million per launch, people won't be queueing up to launch stuff into orbit because there simply isn't much to do in orbit.

[Winter Man]

If SpaceX brings launch costs down to $50 million as they claim, that is not going to bring spaceflight to the masses. Even at $25 million per launch, people won't be queueing up to launch stuff into orbit because there simply isn't much to do in orbit.

Yes there is. There's profit to be had. Private companies could put up their own GPS network that's more accurate than the one offered by the US military (and not subject to said military's whim) and license the tech.

[Azimech]

Eventually there will be enough satellites. To avoid the Kessler syndrome it would be nice to have some ship to scoop up debris, compress it into small blocks and return with those (precious) metals which otherwise would be atomized across the surface when the orbits decay. Important work but far from glamourous. And very costly but it's our own fault.

There isn't much to do in orbit for humans other than scientific experiments and marketing. Maybe someday we'll need to build factories in LEO for something and we'll send a bunch of highly educated blue-collars up there.

[LordOfTheOrbits]

To avoid the Kessler syndrome it would be nice to have some ship to scoop up debris, compress it into small blocks and return with those (precious) metals which otherwise would be atomized across the surface when the orbits decay.

I don't think you understand how much ship like that would cost. It would need to have quite some dV to rendevous with the debris and have a huge compressor, which weights a lot. I didn't do the math on this, but I would bet that even if all debris was made out of pure gold, it would be cheaper to mine it on earth.

[Azimech]

If the Kessler syndrome becomes reality, debris orbiting Earth could have the price of gold-pressed latinum if it means we won't be able to launch anything useful for decades. Then again, returning it would be the least problem so an SSTO wouldn't be needed. Just firing it retrograde.

Edited March 18, 2014 by Azimech

[Rakaydos]

Note that you dont need to enter orbit to deorbit debris. A missile with an aerosol payload can be fired balistically, with an apogee directly in front of the debris you want to deorbit, and explode in a dense cloud of gas, which the debris is slowed by before the gas disperses. Once slowed, the debris quickly decays, and the wreckage of he missile you used simply falls back down.

[Winter Man]

On that note you could stick a hunter-killer satellite up. I mean, with SSTO planes it's pretty much a given we're going to stick a fuel depot up there that it can refuel from to match all those different orbits.

[KerbMav]

http://www.theregister.co.uk/2012/02/16/swiss_junk_grabber_satellite/

How do they plan to deal with reentry heat - using the same ceramics as the Space Shuttle?

[Winter Man]

http://www.theregister.co.uk/2012/02/16/swiss_junk_grabber_satellite/

How do they plan to deal with reentry heat - using the same ceramics as the Space Shuttle?

Yeah, it's a ceramic composite. Basically like carbon fibre you normally see, but instead of a polymer bonding it together and giving it its rigidity you use a ceramic like zirconium carbide or something.

[Seret]

Eventually there will be enough satellites.

Even if the number of satellites in use stays constant we'd still need to be launching new ones on a regular basis. They don't last forever. Satellite launch is the one part of the space industry that you can rely on to stay profitable in the future.

[sgt_flyer]

The spacecleaner bot won't survive reentry - it's disposable, and designed to be launched basically like cubesats (due to it's small form factor of 10x10x30cm). I doubt it would be used for any debris of size over 1m anyway

If you were asking for the skylon's Thermal Protection System, they will have a much more lighter and cheaper system than what was installed on the space shuttle. (Because skylon has a much less agressive reentry profile - skylon's bigger than the space shuttle, but weight less than it once it's fuel tanks are almost empty, so they can start to have a meaningful drag slowdown at higher altitudes. They'll also use active cooling for the leading edges with the lh2, (in order to not need the same heavy and fragile advanced leading edges ceramic tiles they used on the space shuttle.)

[KerbMav]

So it will be only 90% reusable and spend considerable time on ground for inspection and repairs after each trip.

Edit: Oups, forgot to click post and only now saw your post, sgt_flyer.

The spacecleaner bot won't survive reentry - it's disposable, and designed to be launched basically like cubesats (due to it's small form factor of 10x10x30cm). I doubt it would be used for any debris of size over 1m anyway

Not sure, a different article described a bot that would slow down the debris enough to enter atmosphere and then decouple and reestablish its own orbit again for another round.

Edited March 19, 2014 by KerbMav

[Nibb31]

Not sure, a different article described a bot that would slow down the debris enough to enter atmosphere and then decouple and reestablish its own orbit again for another round.

That would require thousands of m/s of dV, which means it would have to be pretty big.

[Nibb31]

Even if the number of satellites in use stays constant we'd still need to be launching new ones on a regular basis. They don't last forever. Satellite launch is the one part of the space industry that you can rely on to stay profitable in the future.

Yes, but a sector needs growth to remain profitable. A few years ago, experts predicted that constellations of LEO sats would be the next big thing, so everyone started designing cheap LEO rockets. But that market failed to emerge and all the plans were shelved.

Large GEO comsats are still profitable, but they suffer from high latency, which only makes them useful for niche markets (like aircraft tracking...) and broadcast applications. Satellite TV is replaced more and more by DSL, cable, and soon by 4G/LTE, so the comsat market is bound to dwindle and become an expensive low-volume niche.

[Seret]

Yes, but a sector needs growth to remain profitable.

Ideally yes. If the market stagnated or contracted some players would go to the wall, some would stay in business. C'est la vie. There will still be a market for sat launch in the future. There's definitely value in Earth observation and satellite comms.

[sgt_flyer]

@Kerbmav skylon's TPS will be much more lighter and durable than the space shuttle TPS - mainly because the Skylon would only experience temperatures up to 1100 K during reentry - (the few part which would be exposed to more would be actively cooled with the Skylon's LH2) the space shuttle experience near 2000 K during reentry. which is why the Space shuttle TPS is both heavy and fragile - there's not many materials which can withstand such temperatures for the duration of the reentry. a TPS rated for 1100 K therefore can use a much wider range of materials, which will have better mechanical properties in the end (i think they plan to use a ceramic skin - much lighter than the space shuttle silicate based TPS)

[softweir]

They describe it as a "carbon-reinforced ceramic", mention that it is "0.5mm thick" and is "corrugated" for stiffness. Also, unlike the shuttle TPS, it isn't rigidly mounted to the airframe but is attached via flexible clips that allow it to expand and contract independently of the underlying structure. The mechanical mismatch between the shuttle TPS and the materials was part of the problem in keeping the tiles on! (REL also describe mounting the cryogenic tanks using a similar system.) They plan to use layers of aluminium foil insulation between the TPS and the underlying structure.

[Nibb31]

Again, this all sounds nice on paper, but the fact is that such a TPS has never been tested. Nobody knows how well it will work, how durable it is, how much maintenance it will need, how much it will weigh, how easy that maintenance will be, or how much it will cost to produce... For all we know, their new TPS might not be workable at all. It might flake off after two flights, needing complete replacement. It might end up being too expensive or too fragile to handle. Or it might not even work at all for large surfaces.

The same goes for just about every bit of Skylon. Their engines of course, but also the airframe, the tank materials, the LH2 spraying thing, the flight profile, the RCS, the avionics, the logistics and the economics.

It's one of the dozens of totally new ideas in Skylon that nobody has any experience with, yet it doesn't stop REL from quoting wildly optimistic figures for cost, turnaround times, and performance. I see so many red flags everywhere on this project that it looks like a 1970's Red Square parade.

Edited March 20, 2014 by Nibb31

[Seret]

Indeed. I'm constantly amused by the wildly optimistic opinions many folks on this forum have of new and untested technologies. A lot of people seem to think that new stuff just flops effortlessly off the drawing board onto the production line.

[Winter Man]

I'm constantly amused by the wildly pessimistic views certain people have regarding the efficiency of a properly managed team. Goes both ways.

[softweir]

Again, this all sounds nice on paper, but the fact is that such a TPS has never been tested.

I couldn't agree more. They are breaking a continent's worth of new ground over this, and it all depends on every single new technology working WELL (not merely "working") for the whole thing to work.

I suppose, however, that REL will be around for quite a while: that precooler tech is a valuable IP to own and could be used for more than just engines. For instance, liquefaction plants that produce liquid oxygen etc have lots of inefficient large-scale stuff to dry the incoming air and pre-cool it before they can start liquefying it, and the REL precooler might be a useful simplifying and optimising early stage in that part of the process. "Might". Not "will"!

[Nibb31]

The way technological innovation usually works is to have new idea, test it, then integrate it into a conventional design.

Attempting to implement so many new ideas in a single project that relies on each one of them working flawlessly only multiplies the chances of that project to fail. Especially when you are a small organization with limited resources.