Concorde, the Channel Tunnel
Quote from: adrianwyard on 11/26/2015 12:44 amNow that semi-reuse has been demonstratedSemi-reuse has been demonstrated 35 years ago.New Shepard is designed for suborbital tourism, that's a market that could potentially support a very high flight rate. No such market will exist for orbital spaceflight anytime soon (i.e. decades), and whether Skylon could create that market is very uncertain at best.Why does REL not design an engine for suborbital tourism? I don't understand REL's obsession with SSTO, it sometimes makes me question whether their technology is ready for reality.
Now that semi-reuse has been demonstrated
QuoteConcorde, the Channel TunnelExcuse me, but those are not very good examples. We all know that Concorde was a money pit, but the Shunnel economic case was a major boondoggle. The Eurotunnel company lost tons and tons of money, to the great pleasure of the poor guys who had bought shares in it. Never, ever buy any share in Eurotunnel. I don't know what the situation is today, but in the 90's the shunnel was losing money pretty horribly. As for the ISS, in 1984 it was to cost $8 billion, but it ended at $100 billion, twelve times more !
Quote from: Oli on 11/26/2015 02:04 amWhy does REL not design an engine for suborbital tourism? I don't understand REL's obsession with SSTO, it sometimes makes me question whether their technology is ready for reality.Because there is no need for a complex new engine class for suborbital flightyou can easily achieve this using legacy rocket technology
Why does REL not design an engine for suborbital tourism? I don't understand REL's obsession with SSTO, it sometimes makes me question whether their technology is ready for reality.
On which data do you assume there such a high market for suborbital flights and there is not for orbital ones?
Quote from: lkm on 11/25/2015 08:42 pmQuote from: adrianwyard on 11/25/2015 03:39 pmIn a different universe where there were no other credible projects that could potentially reduce launch costs through re-use, Skylon would surely attract attention from investors.If there were no other credible projects that could potentially reduce launch costs through re-use why would anyone need to invest in it? If SpaceX or Blue Origin lowers launch costs through reuse is Boeing going to just exit the launch market or are they going to invest in reuse? Is Airbus just going to exit the launch market or are they going to invest in reuse? The only launch provider that can launch Falcon is SpaceX, the only launch provider that can launch New Shephard is Blue Origin for everybody else there's what? Well if they care to invest there's Skylon, which every launch provider can buy. There's 14 active launch service providers globally, only one of which is SpaceX. In a potential age of reusable launch they all have to be launching something competitive or go out of business.I think you've succeeded in laying out a hopeful and plausible scenario for Skylon. It just involves waiting a number years. IIUC the story goes something like:1] By ~2020, REL have a working development engine, AND SpaceX are undercutting the competition by reaping the rewards of their reusable first stage. 2] Faced with either paying high prices for expendable launchers, or ceding the launch market to SpaceX (and Blue?) interested parties band together and form a consortium which cumulatively has the financial clout and risk capacity to complete a next generation vehicle that can compete with SpaceX. Now that semi-reuse has been demonstrated there is a desire to skip a generation ahead of the competition, and Skylon fits the bill as a fully reusable SSTO. Hopefully Franscesco's timeline of orbital testing in 2028 could still be kept.Such a scenario is dependent as much on geopolitical/financial realities as the rocket equation, but who knows - perhaps such as consortium could be assembled. There are precedents: Concorde, the Channel Tunnel, and of course the ISS come to mind. Even Ariane. Viewing the problem this way does prompt some interesting new questions: For example, the Russians and Chinese have not put much energy into re-use thus far. Their indigenous expendable programs are surely expensive, and there must be some pressure internally to find more cost-effective ways to launch commercial/civilian payloads.Such a consortium would need to be truly multinational - so no one put RAF roundels on the wings .And we'd likely see parts of development farmed out to member countries Ariane-style.Or perhaps if we stretch the timeline out to where ESA is looking beyond Ariane 6, it could just be Ariane 7.
Quote from: adrianwyard on 11/25/2015 03:39 pmIn a different universe where there were no other credible projects that could potentially reduce launch costs through re-use, Skylon would surely attract attention from investors.If there were no other credible projects that could potentially reduce launch costs through re-use why would anyone need to invest in it? If SpaceX or Blue Origin lowers launch costs through reuse is Boeing going to just exit the launch market or are they going to invest in reuse? Is Airbus just going to exit the launch market or are they going to invest in reuse? The only launch provider that can launch Falcon is SpaceX, the only launch provider that can launch New Shephard is Blue Origin for everybody else there's what? Well if they care to invest there's Skylon, which every launch provider can buy. There's 14 active launch service providers globally, only one of which is SpaceX. In a potential age of reusable launch they all have to be launching something competitive or go out of business.
In a different universe where there were no other credible projects that could potentially reduce launch costs through re-use, Skylon would surely attract attention from investors.
Quote from: tl6973 on 11/26/2015 08:35 amQuote from: Oli on 11/26/2015 02:04 amWhy does REL not design an engine for suborbital tourism? I don't understand REL's obsession with SSTO, it sometimes makes me question whether their technology is ready for reality.Because there is no need for a complex new engine class for suborbital flightyou can easily achieve this using legacy rocket technologyHow's that even an argument?New Shepard does staging, because an engine failure would be fatal otherwise. Its engine is also high-thrust, despite using hydrogen.SpaceShipTwo uses a carrier aircraft.The XCOR Lynx is the only runway takeoff/landing single stage vehicle, but it doesn't exactly win a trophy when it comes to payload delivered (passengers, cabin size).So I think in principle an air-breathing rocket engine would very attractive for suborbital flight. Whether REL's technology would be useful/cost-effective is another question of course, but have they actually considered it?Quote from: francesco nicoli on 11/26/2015 11:54 amOn which data do you assume there such a high market for suborbital flights and there is not for orbital ones?700 individuals have signed up for a ride on SS2. The Futron space tourism study sees a potential demand of 1'298 passengers per year at a $100k price, and 15'712 passengers at $50k. That's a lot flights.The same study sees demand for orbital tourism as well, but we're absolutely nowhere near the price point where it would have a significant impact on todays flight rates. In fact the study expects 60 passengers per year at $5m, but that's at least an order of magnitude less expensive than commercial crew, and even then it would only lead to maybe 10 more flights.Other than that I don't see any potential market. Even a constellation like OneWeb can easily be deployed with "a few" expendable launchers.P.S. Of course the Futron study could be total bull****, but I haven't come across anything better.
Skylon's biggest market potential is point-to-point transport. I know that's not how it's designed, but it dwarfs the orbital launch market (which they're probably going to lose to the likes of SpaceX and Blue Origin anyway).
VTVL systems take substantial hits for being SSTO. Multi stage VTVL reusable takes substantial hits for reintegration and Musk has said reuse of a 2nd stage in F9 sized payloads is dead, although he won't say why.
Travelling 18 000 km using P2P would take as much energy as Earth escape, or beyond.
Any all-rocket system takes a huge hit for being SSTO; winged HTO is probably counterproductive on something with engines that light. And Musk did in fact say why F9 won't be fully reusable; it's because it's too hard to get the upper stage back from a GTO mission.
He also applied it specifically to the kerosene systems, citing Isp issues. Do you have a reference where he says that any F9-sized upper stage reuse is off the table?QuoteI'll need to review the MIT presentation he gave. IIRC he said "F9 and F9 derived." Obviously an interesting question would would an F9 sized Methalox system be viable?Quote from: lkm on 11/27/2015 12:04 pm So in the long run it really can't make sense.What can't make sense, or do you mean his statements form a logical paradox where something has to be true and false at the same time?
I'll need to review the MIT presentation he gave. IIRC he said "F9 and F9 derived." Obviously an interesting question would would an F9 sized Methalox system be viable?Quote from: lkm on 11/27/2015 12:04 pm So in the long run it really can't make sense.What can't make sense, or do you mean his statements form a logical paradox where something has to be true and false at the same time?
So in the long run it really can't make sense.
Quote from: lkm on 11/27/2015 12:04 pm So in the long run it really can't make sense.What can't make sense, or do you mean his statements form a logical paradox where something has to be true and false at the same time?
It could be true if Falcon ends up cheaper at a moderately high flight rate than Skylon does at a very high flight rate. That doesn't seem especially likely to me, but we don't actually know yet...
Do not forget the potential market for point to point delivery of 200lb warheads. While it might be nice to imagine investors looking towards space, I'm sure investors BAE is looking at Skylon and thinking 'mach 5 cruise missile' or '150,000ft bomber'. If the engine works, and can be made to work on something a little more practical, like methane (which it supposedly can) then that is something they can sell to a lot of customers, whether the space business works out or not.