Iskierka

Well, if we ever get one operational, most likely it'll be fitted to a ring ship (so that debris is capable of passing through) and be driven through small targets to test. Simplest way to find out.

Not especially - the reason nuclear tests stopped was more than "people are scared of the N-word", and a running NTR is looking at levels of radiation comparable to the grounds around Chernobyl mid-meltdown. It's not exactly insignificant.

If you look at the screenshot again, you can see Planetside 2 in the background, a notoriously CPU-heavy game. Granted, it's not light on GPU either, so the GPU limit may be hiding CPU issues that will crop up when the restriction is removed. Definitely want a GPU upgrade, CPU is a maybe.

The multi-passenger module would most likely not be ejectable, just as airliners are not ejectable, as there is no need for the functionality above a certain level of reliability. The only point the vehicle is likely to fail such that you would like to be away from it is re-entry, in which case you do not want to eject - lower down, anything bar total control failure (which is liable to prevent escape systems from working anyway) is fail-safe as the vehicle can re-land easily due to high glide ratio. For initial human rating a smaller 5-man crew module would be used, which would not feature full module ejection, but individual crew ejection with blasting holes through the cargo bay doors. Experience proves that aerospace projects ALWAYS end up at least slightly overweight, slight underpowered, and hugely overbudget. The truth is that nobody has the faintest idea how Skylon will perform exactly, what its margins will be, and what its operating costs are going to be. Except for that the paper estimates do everything reasonable to under-estimate, using heavier fuel tank alloys despite better being known and proven, engine performance as absolutely certain and ignoring numerous improvements being investigated, and with comfortable over-estimations on the heat shielding. The supposed guarantees of it never flying are based on other projects that have had to push as hard as possible to sell themselves and say "I'm going to be the best, I'll take over!", Skylon can make performance with less, and so one of the very things it is selling itself on is the fact that they are very, very, VERY sure of the performance. Quoted numbers should be considered probable minimums, not hopes. Almost every single aspect of Skylon would have to go wrong for it to not be at least competitive. And what market exactly does the military serve? The one it makes itself that would not exist without its own funding? Hmm, perhaps if NASA had a chance ...

May -have- stood a chance? It's still in development, and the company proposing it does not intend to be the manufacturer, they are in discussions with other companies that have the resources. REL simply solved the key limiting problem in the way of the hybrid rocket engine it uses.

No nature whatsoever, nothing lives there, hence the lines remaining undisturbed for as long as they had. Not fair to trade culture to promote environment, but they aren't the literal opposite of their goals such as PETA.

The major differences with rotational gravity is that if you drop from a significant fraction of the radius, you will have a lower velocity and the ground will appear to accelerate below you, and in a very small structure the human ear can detect the rotation when turning around. However, the Halo structures are very large, so neither of these would be noticeable effects - the only things that would affect aircraft at all is that flying higher would reduce gravity at a slightly faster rate, and if you flew at very high speed against the rotation gravity would appear to increase. But, at any low speeds, it would be imperceptible.

The issue with this is that mating/reassembly is still expensive, and the flight path constraints on making each part returnable significantly reduces payload capability - plus, far more engines to maintain. SSTO is massively beneficial if it can provide significant payload as it cuts out many maintenance and reassembly steps allowing faster and cheaper turnaround, removes a point of failure, and gives greater operational simplicity overall. The shuttle is kind-of useless as a cost reference point as there were so many bad design and operational considerations, drastically increasing its cost with things that either weren't or shouldn't have been necessary. Reusability, in any number of stages, won't look like the shuttle ever again.

Many of you are overlooking an obvious space drone, the Pegasus, currently operational with a payload of 450 kg to LEO. The X-37b isn't much of a drone launch considering it is launched atop a rocket, and thus far isn't known to have deployed a payload, it is the payload.

There is genuinely no sound in space - sound is generated by being able to pulse waves of pressure from a source, but at the low densities of orbit, there is genuinely so little material that air-air collisions are so rare they could not propagate a sound's pressure wave. Something exploding would generate its own gasses and thus pressure, which would hit you with a thud-like sound, but it would sound very different to a conventional explosion, as it would simply be particles hitting you in one burst and bouncing away immediately. As for the "bass boost", I believe that's more due to the inter-particle dynamics of water absorbing higher velocity differences, which is due to the particle of water itself, rather than the density. I don't believe higher or lower pressure air would significantly affect the dominant frequencies that air can carry, beyond some very high extremes (likely hundreds of atmospheres). A plane's engine certainly sounds basically identical at surface and less than 1/3rd pressure, excepting rpm changes.

You couldn't program this in any way that would give LaGrangian-esque behaviour, or get it to work on-rails with the patched conics system as it assumes very particular equations for gravity.

This should be fixable if you make use of FAR's AoA% setting on control surfaces - the real Skylon's canards are supposed to track airflow to remain in full control. To do this set AoA% to -100%, IIRC, and it should fly a lot more stable, and be a lot more stall-resistant and controllable at high AoA. Visual reference for the behaviour: They're not perfectly aligned, but the slight raise is a bit of trim to hold against the pitch load, they're still moved well beyond a normal control range and have additional range to handle anything extra required. Unfortunately I've not had chance to play with this yet, I might try get things running on my desktop this week, hopefully it'll work nicely once I do.

That would only be for local FTL travel - all believable FTL techniques involve cheating by not locally travelling faster than light, but either generating a shortcut, or physically moving the space they exist in (which, not being inherently matter or energy, is not limited to c) at a speed greater than that of light. That said, wormholes and alcubierre drives together could allow limited time travel. If you move a wormhole, it experiences time dilation, and thus ends up at a different point in time to its other end point. You couldn't use this to travel to before the wormhole, but in theory you could create it, move one end, then an alcubierre ship could travel through and then back through space to return to before its launch point. One issue with time dilated wormholes however is they would become unstable - when their field radiation propogates far enough to be able to travel through both, energy cycling through repeatedly would drain the wormhole's energy and cause it to collapse, so this would also be a very time-limited technique. Main issue preventing time travel isn't directly physical inability to travel back, but simply that if you could, you would violate conservation of mass and energy - whatever was sent back would be removed from its current timeline and added where it already existed concurrently. The wormholes get a delay because the conservation would only cause the decay once energy can cycle, the space is physically connected so they are technically the same time, even if one has had more local time pass, thus energy is conserved until it starts infinitely cycling. The alcubierre drive further cheats by moving the existence of the additional energy while technically holding within causality. It's weird stuff, but fundamentally, outside a quirky and very limited cheat, time travel is impossible.

Current industries would change in response, but how is unpredictable. Cheaper and more reliable launches, that don't have multi-year-long queues mean many companies may take more risks and develop cheaper satellites that are less-than-perfect, and be willing to replace them, or start using swarms with higher data bandwidth or observational capability and redundancy rather than very precise high reliability. Quite what change will occur is unknown, but even current industries will become elastic, even if only by a small factor to exploit the updated costs. Interferometry is becoming interesting for getting very good pictures, with the ability to launch multiple sats I could see ground observation being replaced by a few smaller units orbiting in formation. Might finally be able to improve on the current resolution limits. (IIRC around 0.5m/pixel)

Where is their own income a concern? The concerns are making back overall development cost, regardless of who footed the bill. And with bigger companies to foot the initial costs and get things going, as well as set up markets, that only improves chances of making back development cost. While they do want to make money from it, REL's goal is revolutionising space access, not to become sole billionaires, so it's perfectly acceptable to sacrifice a majority of the manufacturing to get it done.

It's questioned whether even indefinitely long nanotubes will be strong enough, and how to anchor and repair them is a major problem.

REL have no intention to be manufacturer for anything but heat exchangers. Rest of engine and airframe are being left to bigger companies, and bigger companies are taking interest, so apparently they know more than you.

Space elevators will never exist because they interfere with normal space operations too much. The vast majority of satellites are in low and medium earth orbits, and in ones that do not perfectly resonate with geosynchronous. And a majority of those -need- to be there, either for observation resolution, ping times on communication, or various other reasons. If you built a big elevator going up through their orbits, you'd have to write off tens of billions of hardware offering hundreds of billions in terms of business, with no way to replace them as the elevator cannot provide the same functionality. And that's before considering the cost of protecting or repairing the elevator from damage from these satellites, and before even considering HOW you'd build one of these things. I recently came across an interesting concept where three orbital elevators were linked by a low/medium-orbit ring that they forced ferromagnetic fluid through at high velocity, similar to a launch loop, reducing the structural load on the towers by supporting them partway, but it still offers no solution to lost orbits, construction methods (it may have less static load but you still need to put it together), and it creates different structural requirements at the antipodes to the towers. If you want to put something in orbit with cables and electrical power, launch loops are the way to go. Non-interfering with orbits, possible with current materials technology, access all orbits unlike a space elevator. The idea of a vertical object you simply climb isn't going to happen.

So ... we're agreed there? Skylon gets to skip all the human costs? Cool. And I just said they don't even need that much business to break even in 10, the 200 flights is ten times the break-even. Reading comprehension, much? The satellites, like I said where you precisely quoted. It kind-of is. ESA needs a launch vehicle for Europe - Ariane 6 is definitely going to work. Skylon is a very interesting proposal, but even if they believe it will work, it's not going to be as certain as Ariane, so, funding remains for Ariane, and if Skylon gets to a point that it is comparable certainty, or worthwhile risk, they can still go fund it, assuming the US hasn't taken it. If they haven't, it'll be companies like Airbus that take airframe manufacturing, so funding will remain in the same distribution. And it doesn't need to. Even at current launch rates they can break even, and so long as it provides the same functionality or more (it does) every customer will want to fly with them for the price - so yes, build it and they will come. Also, demand is driven by need, but demand is limited by price, so dropping the price will increase space utilisation, even if not by a predictable amount. The only certainty is more universities launching cheap projects.

A C-F load bearing frame is much easier than what most airliners using C-F are aiming for, which is a full C-F airframe in all components including skin. Skylon simply needs a series of girders to mount its other components from, much simpler than an actual full body as with the 787. From immediate reading, RC/C has few strength problems, it only suffers under impact conditions. F1 cars use it for their brakes that sustain absurd loads, and while they could afford to replace parts after each race, they don't because they don't want 10-place grid penalties. Further, Skylon uses C/SiC, which is developed from original RC/C materials, performs much better, and deals well with impacts from studies I find after just a few minute's googling. Care to explain why every man-rated space vehicle has cost so much more then? There's definite savings in that area from not having to support people. And the Buran has flown totally automatically - and how exactly would a single-stage vehicle that simply has two engine modes be more complex than a vehicle that needs to manage five engine units that aren't even part of itself, stage twice, handle the changes in behaviour of each staging, and then perform the same task in the end? Just because it's not been done before doesn't mean we haven't done far more difficult. Why do they have to perform all 200 launches in 10 years? As has been pointed out, they can cover development cost in 10 years with far less, and the typical airliner has a lifespan of at least 25 - why should these be worked so hard that their entire lifespan is gone so quickly? You're the first to mention space tourism. REL say that's a possibility once the vehicle is operating, but have absolutely zero intention of using that market to generate interest. The satellite constellations are what will generate interest, and at so little for the same payload to LEO, or more to GTO, people will be interested in more than just a couple. The customers will queue up for these launches when the launches are actually being offered and the vehicle is beyond quiet discussions that they'd rather not publicise too much so early in development. Or, if you don't snip a quote out of context, REL and ESA together asked some other independent companies to do assessments, so that both REL and ESA could get a better, more certain idea of their business case. Ariane 6 is getting funded because it's simple, certain, and quick - doesn't mean they won't be happy to throw it out if Skylon comes along, just means they don't want to risk waiting around for it. Or maybe because they can earn plenty themselves on simple expensive rockets that they charge stupid amounts for. Maybe because rockets -work-, and space is valuable enough that people will pay those absurd prices, so to bother actually trying to change that and make space for everyone (or as many people as feasible), takes more of a visionary approach fuelled more by determination than big company budget. The need will never naturally arise for an SSTO spaceplane until we need to abandon the planet due to an extinction event - but if you offer one, the market will leap aboard as fast as it can adapt its payload interfaces.

Or so you assume, with precisely zero knowledge of current negotiations REL may be in. Cost estimate is based on them using much more conventional materials than the 787. (only the TPS uses a material new to airframes, but it's not new to high-temperature structural applications. It's already used in F1 engines and exhaust systems.) $12 bn was the development cost of the A380, and the Skylon does not require man-rating in its initial development. Aside from the engines, Skylon is more conventional than most modern airliners - it's certainly a LOT simpler, even if its task is more complex. Also, where on Earth are you getting $100 mn? The quoted unit price for Skylon is £190 mn, or $320 mn at the time that estimate was published. Into $12 bn, that means only 37.5 units are required - market estimates performed expect at least 30 units demand, more likely 60+. $1100/kg is the maximum all-inclusive price for LEO insertion of about 15+ tonnes, so make that $16.5 million. (This is initial launch costs while amortising purchase.) That means each vehicle has to absorb 20 launches individually to pay for itself, when the launcher is expected to last at least 200 launches, likely expandable to 500 after the first vehicles are retired and can be destructively examined for lifetime estimate. With a mere 40 vehicles, that's only 800 launches - so even if this was only over the next ten years, they would only have to take 80/yr, less than current launch rates at less than half the cost of the cheapest launch vehicle we have, the Pegasus, capable of a mere 450 kg to LEO. Try using real numbers and you find they have a hell of a good business case.

Basically this. They don't yet have a facility for it, but their intention is to build one while performing individual mode tests at the separate facilities, then move onto testing transition once the new facility is ready.

Comparative to the billions for the Skylon itself and the engine the upper stage requires, yes, that's pretty minimal dev cost.

Except my laptop is two years older than the consoles, and pretty much exactly equal performance. It cost £600, or about £200 more than the console's launch prices. For that it came with a very nice 900p screen, good sound (for a laptop) and a 600 GB HDD, as well as far more functionality. Again, two years before the consoles existed. EDIT: on the subject of the original topic, the Wii U is the best console by far for interesting and lasting games - just ask plenty of youtube personalities who own all three, barely touch PS4/XBone, but play Wii U plenty.

Skylon is fully intended to have a second stage that can put up to 6.39 tonnes into GTO and return for reuse. Its development cost will be near-nil as it uses the same OMS engines as Skylon and simply needs a couple fuel tanks and some light structure attached. If allowed to reenter destructively (estimated every ten launches, as it's quoted that it will have 10x reusability) it can carry up to 8.08 tonnes. Is that competitive enough?