*=To put it mildly I am 'irked' significantly that in reality EVERYTHING about the SABRE concept has in fact been shown to be practical and hardware, (test if not flight weight) was tested to show this in the late 50s and early 60s but was dropped in the rush to accept that "Liquid Air Cycle," "Hypersonic Cruise" and "SCRamjets" were "required" for any air-breathing orbital concept. Coupled with the more recent, (and seemingly more pervasive) attitude that anything with 'wings' is the "Shuttle and therefor can never work as suggested" it makes it difficult to believe anyone can actually significantly lower the cost of space access when they refuse to actually examine all the possibilities rather than sticking to the 'usual' assumptions.
Quote from: RanulfC on 11/21/2016 08:30 pmNo one can 'break' a circle that in fact does NOT exist. Note that there IS a "demand" and a "market" in existence, the fact that it is not as large or extensive as some would like and that it does not in fact 'service' a market that does not exist but which some want to exist is totally beside the point.But it does exist, which Skylon can service.
No one can 'break' a circle that in fact does NOT exist. Note that there IS a "demand" and a "market" in existence, the fact that it is not as large or extensive as some would like and that it does not in fact 'service' a market that does not exist but which some want to exist is totally beside the point.
QuoteThe fallacy here is "we" need to "make" destinations and markets for reusable SSTO, (and yes that's the main argument FOR SSTO by the way) by building an extensive LEO orbital infrastructure for them to service.And it's one that REL is aware of and does not subscribe. Enable yes, require, no.
The fallacy here is "we" need to "make" destinations and markets for reusable SSTO, (and yes that's the main argument FOR SSTO by the way) by building an extensive LEO orbital infrastructure for them to service.
QuoteNot so obviously does this apply to SSTO vehicles mostly for the fact that MOST SSTO concepts have never managed to reach a comparable operational payload to an ELV or multistage reusable vehicle. Note I wrote "operational payload" rather than just 'payload' because in fact while Skylon is an SSTO it does in fact require a second stage to allow getting the 'payload' to the most in-demand destinations despite that fact. But at least REL was realistic about that and therefore designed the Skylon with more capacity than the average SSTO concept.But note Skylon can support an "all electric" design by starting outside the Van Allan belts.
Not so obviously does this apply to SSTO vehicles mostly for the fact that MOST SSTO concepts have never managed to reach a comparable operational payload to an ELV or multistage reusable vehicle. Note I wrote "operational payload" rather than just 'payload' because in fact while Skylon is an SSTO it does in fact require a second stage to allow getting the 'payload' to the most in-demand destinations despite that fact. But at least REL was realistic about that and therefore designed the Skylon with more capacity than the average SSTO concept.
QuoteAnd lastly on which is the better 'strategy' of builder/operator or builder to owner/operator for the most part the differing sides seem bound and determined to ignore history and reality to make their point The latter ALWAYS takes over from the former once a certain level of traffic is reached as the builders can no longer afford to do both they inevitably form partnerships/consortiums to "buy" the vehicles and then own and operate them while they then concentrate on design and manufacture of new and improved vehicles. REL is simply assuming that the traffic levels will hit the levels that both SpaceX and BO are PLANNING on reaching and planning accordingly while SpaceX and BO are currently not looking to that point. Yet.Careful about "historical inevitability"
And lastly on which is the better 'strategy' of builder/operator or builder to owner/operator for the most part the differing sides seem bound and determined to ignore history and reality to make their point The latter ALWAYS takes over from the former once a certain level of traffic is reached as the builders can no longer afford to do both they inevitably form partnerships/consortiums to "buy" the vehicles and then own and operate them while they then concentrate on design and manufacture of new and improved vehicles. REL is simply assuming that the traffic levels will hit the levels that both SpaceX and BO are PLANNING on reaching and planning accordingly while SpaceX and BO are currently not looking to that point. Yet.
While the market should transition to separate mfg and operators note that US market, where Boeing/TWA was probably broken up before this stage. IOW government intervention accelerated the split.
But any kind of VTO rocket is a potential ICBM so the odds on bet is govt intervention will be negative. I don't see ULA, SX or Blue setting up a Guianna branch any time soon, do you?
Skylon does not look like an ICBM. It does not fly like an ICBM. It's very difficult to modify into an ICBM or an ICBM delivery vehicle and if you have the skills to do so you can probably make an ICBM yourself, so why bother?
Only the REL business model (and something like it's architecture) have a chance of getting away, of unifying the market by giving the economies of scale of a large market IE every payload on the planet but giving individual countries (or even corporations) the security of delivery of their payload.
Telecos talk about the "last mile" of cable being the most expensive because there's so much of it to maintain and the individual payoff is so small but in space launch it's the first 100-200Km that's the major PITA. Skylon take that away in a way that no nation based rocket programme (and that includes Blue or SX) can ever do.
Quote from: oddbodd on 11/21/2016 09:44 pmJust to nit-pick one thing. I did specify that the exploding thing was a hindrance to human presence, not cargo. Annual rocket failures seem to be bumping around in the 5% area, so 1 in 20 flights frequently has a fiery, premature end. Go to Heathrow and tell all those business and tourist travelers that every flight has a 1 in 20 chance of catastrophic failure, killing everyone aboard. Excluding the mentally ill, suicidal and people under extreme duress, I'll take a wild stab in the dark that zero people would choose to fly. Even if they were, there'd be no pilots or cabin staff willing to roll that D20-of-death every time they did their job. Hopefully the abort system in the SpaceX Dragon module will at least mean that it's just very expensive, instead of tragic.Closer to 4% really (86 launches/5 failures in 2015, 72/1 this year) but the whole point was that humans ARE treated differently than cargo as in most transportation systems. Transport systems make a specific point to assure travelers that they have little chance of dying even in the worst case and given a "better than even" chance to survive an accident most people will willingly keep travelling. You would also be lying, (and liable ) if you told anyone that was their 'chances' in a launch accident since it's quite obvious that there are systems in place to keep the PEOPLE alive in the case of a failure. (None of the travelers at Heathrow have that option though and it does not seem to effect travel statistics)
Just to nit-pick one thing. I did specify that the exploding thing was a hindrance to human presence, not cargo. Annual rocket failures seem to be bumping around in the 5% area, so 1 in 20 flights frequently has a fiery, premature end. Go to Heathrow and tell all those business and tourist travelers that every flight has a 1 in 20 chance of catastrophic failure, killing everyone aboard. Excluding the mentally ill, suicidal and people under extreme duress, I'll take a wild stab in the dark that zero people would choose to fly. Even if they were, there'd be no pilots or cabin staff willing to roll that D20-of-death every time they did their job. Hopefully the abort system in the SpaceX Dragon module will at least mean that it's just very expensive, instead of tragic.
According to many on this site if given the opportunity they would volunteer to ride a Dragon-1 WITHOUT an abort system come what may so I'd watch out throwing around the accusations of only the "mentally ill, suicidal and people under extreme duress" being willing to take their chances. If you've been over to the SpaceX ITS threads you'll note one discussing the lack of an abort system on the ITS which does in fact 'bother' some people but as noted it is in fact similar to current aircraft in that regard. If you are on an airplane that crashes you have no way of escaping and have to ride the plane to whatever the end point is, similarly if you were a passenger on Skylon you and the airframe are 'wedded' in fates. SSTO tends to assume a higher margin for 'safety' than a multistage design but in fact there is no basis for that assumption other than the "fact" that over their evolution most OTHER transport systems are 'technically' "single-stage" vehicles that have become much safer over time. Note that is OVER TIME during which they continually got safer and more efficient as they evolved.
My point is and was that the "chances" of dying being launched in a current rocket are no worse than most other transportation accidents SPECIFICALLY because passenger transport is currently considered and addressed as a safety issue.
This is only "different" in designs that assume, with no data to back that up, that the vehicle is much 'safer' because it emulates a CURRENTLY "more safe" evolved design of another form of transportation. AKA it's "safer" because it resembles and airplane which is rather silly because what it looks like has almost nothing to do with what it actually DOES over the majority of it's flight and over that flight conditions change radically from anything any "airplane" does except the very beginning and very end.Skylon is still a LAUNCH VEHICLE with all that implies.
Randy, it comes down to money (physics too.. but mostly money) in the end. REL have been working on SABRE for how long now? Decades? ..and exactly what do they have to show their backers apart from a long list of receipts? At the time the Wright Brothers made history, both gliders and petrol engines were tested technologies - but they had to do a lot more than stick the two together to make history.
Examining multiple possibilities (your 'due diligence') costs money also, rushing off down an endless list of rabbit-holes. One reason NACA/NASA was founded in the first place was to allow this 'research' to be carried out without impacting private companies' (Musk's and Bezo's in particular) wallets.. and the aerospace world is a better place for that. ..But REL are not NASA and neither is UKSpace.
IF REL can't make SABRE work, then who can? What it tells me is that getting the SABRE concept to actually, practically, work is far more difficult than REL are prepared to publically admit.
Actually the money has always been the problem and it wasn't until REL began getting more that they managed to do more than component testing. And lets be honest they have a LOT to show investors as they DID test and prove those components which was the whole point. Much in the same way that in order to succeed the Wright's had to build their on engine, which many experts said was not possible mind you, in order to get the needed thrust. REL has to build it's engine to 'prove' what many say can't be done. Note that there is no physical (or physics) reason it should not in fact work as REL says it should it is simply that people don't believe it should work.
Musk and Bezos started with a certain premise and went forward in that direction. I'm not blaming them or saying that's wrong but it would be nice for people to understand they had no intention of every looking beyond what they had in mind which is very often the case. People think that IF they knew and considered SABRE and then went ahead with their designs anyway that MUST mean that SABRE doesn't work which is clearly false from the outset. As they never considered it or even knew of it assuming they somehow 'rejected' it due to technological or "physics" reasons is totally false, but that's an 'assumption' that's made because they 'obviously' considered every possible method for getting to orbit. They didn't, they didn't even try. I would very much like that to be clear which was my point.
What I find really funny is in fact both NACA and NASA were aware of the general concept behind the SABRE cycle and specifically noted that the ONLY issue at the time it was studied was the lack of a viable heat-exchanger system AND the fact that their work required using "Liquid Air" as it was not clear that a rocket engine could be run on 'deep-cooled' air even though a subcontractor had indicated that it WAS possible. So if you want to think of it this way NASA in fact DOES know that SABRE is not only NOT a "rabbit hole" but that their own public records show they are well aware that no matter what else REL has solved the ONE problem they did have with the technology in the first place!
Expensive does not equal difficult though to be honest the fact that REL is in a corner due to the requirements of the design is annoying. But NASA had issues with working with and exploiting liquid hydrogen which took billions of dollars and years of effort to get operational so it would only make sense with REL having a fraction of the budget and manpower available to NASA, (let alone NACA before it) it may take them longer to achieve.I very much suspect I understand why REL hasn't made the connection to NASA's earlier work more clear but the fact that I among others have pointed out that connection and the relevant background but been ignored because NASA clearly isn't 'interested now' in the technology is annoying to say the least.
Money and access to it is the ONLY real problem facing REL, much as it has been from the beginning.
Given their bias and obvious intent, (with some obvious issues both political and practical granted for a non-US company) neither Musk or Bezos would have invested in REL but the fact that have not should in no way reflect on the viability of the SABRE engine since they did not WANT to even consider that type of propulsion.
OK, so 4%. I wasn't that far out, and you are using a very small sample size to argue the figure. I think the "1 in 20" is pretty widely accepted as a rule-of-thumb.The reason Heathrow travel statistics aren't affected is because when people (often subconsciously) assess the risk of stepping onto a plane they conclude the risk is negligible. The US NTSB's preliminary stats for 2015 show no fatalities in all of their flights, and from the report http://www.usatoday.com/story/news/2016/02/15/2015-another-safe-year-airliners/80398194/ the worldwide equivalent is 1 in 3.1 million flights are lost.
SSTO tends to assume a higher margin for 'safety' than a multistage design but in fact there is no basis for that assumption other than the "fact" that over their evolution most OTHER transport systems are 'technically' "single-stage" vehicles that have become much safer over time. Note that is OVER TIME during which they continually got safer and more efficient as they evolved.
You are comparing two very different groups of people there at different stages in the industries evolution. The group at Heathrow are not at the vanguard of the industry, pushing the boundaries. These people are just getting from A to B to do a job, or get some sun, or visit family. The journey is expected to be routine and boring, at least in the sense of surviving it. The people in the forums are space fans (nuts?), who you could liken more to the Emilia Earhart's of the early aviation industry, and willing to take that extra risk to be the first, push further, helping make the remarkable routine. I'd also point out that people sitting behind a keyboard safe at home will say a lot of things they won't back up in real life. Stick them in a flight suit in the elevator up to the crew capsule with that 1 in 20 hanging over them, and I wonder how many would still actually go through with it.
Huh? I really cannot understand you here. Unless you're referring to a current transport system that has already gotten in an accident, and you're only talking about the survivability of the accident. But when we decide whether to get on board a rocket or plane (or train, or boat, or car, or motorbike) we have to account for the risk that that act bording will result in being in a catastrophic accident.1 in 20vs.1 in 3,100,000Sure, if you're on the one that does have the accident, chances of surviving either type are low.I don't think I said in this that Skylon specifically would be automatically safer. Simply that significant human presence would require better than what we have now. Current rockets don't have a lot of scope for craft survival of a big failure. They tend to explode, tumble and disintegrate, slam back down on the pad and explode, and so on. In the event of a problem, there is one option for the passengers to survive, which is to get the hell out of there with a Launch Escape System. One crew has been saved by these in the past.
I think it would probably still have to have an LES itself for anything that resembled the proposed SPLM carrying people.
The Space Shuttle is possibly a closer analogue to the Skylon design than a rocket. They did 25 to 39 missions each for those that weren't lost, with a total of 139. The two that were lost were:1) Columbia, where foam insulation fell off the disposable tank and damaged the wing, causing disintegration during reentry. Skylon design is SSTO, so no external tanks to shed bits.2) Challenger, where a known design flaw was not yet fixed, and the temperatures increased the risk from that flaw, resulting in an SRB failing. Again Skylon design is SSTO, so no SRB's.Of course, the Skylon design will have it's own problems, but 400 unmanned test flights should find and fix many of these. I imagine that way in the future, if Skylon is ever realised, a unit would get built, have a number of non-passenger flights, then provide the option to carry people, up till some limit. Then it would go back to non-passenger till retirement or loss.
Don't forget that in the late 60's Rolls Royce did a development LH2/LO2 engine called the RZ20. This was a GG cycle with a LH2 turbopump, so the UK was not without LH2 experience.]Don't forget that in the late 60's Rolls Royce did a development LH2/LO2 engine called the RZ20. This was a GG cycle with a LH2 turbopump, so the UK was not without LH2 experience.
Quote from: t43562 on 11/22/2016 06:49 amQuote from: Coastal Ron on 11/21/2016 11:46 pmQuoteI think you might be under the illusion that state support is bad...No. I just like to keep the lines clear on what is state aid and what is payment for services rendered.I think you mean keeping the line unclear. However you weasel around it, the state is helping an industrial sector to compete against foreigners - for whatever reasons and with whatever justification. Whether or not they have a right to is completely beside the point - I don't care about that and I can't see anyone else here who does. It only matters in as much as it seems improbable at this time that one might survive without such arrangements.No, Ron is right, there's a very clear line between payment for goods and services and payment that is not in exchange for goods and services, or above the price the government would have to pay for those goods and services from another source. There's no weaselling involved. It's the distinction that makes the most sense to make.It's the difference between business and charity.
Quote from: Coastal Ron on 11/21/2016 11:46 pmQuoteI think you might be under the illusion that state support is bad...No. I just like to keep the lines clear on what is state aid and what is payment for services rendered.I think you mean keeping the line unclear. However you weasel around it, the state is helping an industrial sector to compete against foreigners - for whatever reasons and with whatever justification. Whether or not they have a right to is completely beside the point - I don't care about that and I can't see anyone else here who does. It only matters in as much as it seems improbable at this time that one might survive without such arrangements.
QuoteI think you might be under the illusion that state support is bad...No. I just like to keep the lines clear on what is state aid and what is payment for services rendered.
I think you might be under the illusion that state support is bad...
Quote from: ChrisWilson68 on 11/22/2016 07:48 amQuote from: t43562 on 11/22/2016 06:49 amQuote from: Coastal Ron on 11/21/2016 11:46 pmQuoteI think you might be under the illusion that state support is bad...No. I just like to keep the lines clear on what is state aid and what is payment for services rendered.I think you mean keeping the line unclear. However you weasel around it, the state is helping an industrial sector to compete against foreigners - for whatever reasons and with whatever justification. Whether or not they have a right to is completely beside the point - I don't care about that and I can't see anyone else here who does. It only matters in as much as it seems improbable at this time that one might survive without such arrangements.No, Ron is right, there's a very clear line between payment for goods and services and payment that is not in exchange for goods and services, or above the price the government would have to pay for those goods and services from another source. There's no weaselling involved. It's the distinction that makes the most sense to make.It's the difference between business and charity.All you have to do is invent some reasons for the business and you're away, you can also choose a mechanism for doing it that spreads more money or less money around. The whole set of reasons around it may be "nice-to-have" rather than critical to national survival which is true of some big infrastructure projects too. Then you limit the competition to your own companies and hey presto - competitive advantage through state funding. Without this kind of thing, SpaceX would be far behind at best or on powerpoint at worst and probably a lot of other industries in other countries too.
Quote from: Lars-J on 11/22/2016 06:39 pmQuote from: john smith 19 on 11/22/2016 08:31 amSomething I'd like people to keep in mind. Let's just repeat that for people who think either of them looked at Skylon:neither Musk or Beezos did much 'due-diligence' work on anything OTHER than the concepts they went forward with. ::) Repeating such an assertion does not make it any more true.Repeating the truth no matter how much some people may not like it does not make the statement false either :)Both projects started with clear bias which were stated and quite visible up-front.
Quote from: john smith 19 on 11/22/2016 08:31 amSomething I'd like people to keep in mind. Let's just repeat that for people who think either of them looked at Skylon:neither Musk or Beezos did much 'due-diligence' work on anything OTHER than the concepts they went forward with. ::) Repeating such an assertion does not make it any more true.
Something I'd like people to keep in mind. Let's just repeat that for people who think either of them looked at Skylon:neither Musk or Beezos did much 'due-diligence' work on anything OTHER than the concepts they went forward with.
No concepts beyond those already in mind were considered or 'traded' and this has been stated by both SX and BO.
Neither considers Skylon as a viable concept,
more to the point neither has any consideration that an air-breathing rocket engine capable of operation from zero-to-Mach 20 has any 'use' in their plans.
Both Musk and Beezos started with an idea of what they wanted in the end to have, it is no surprise that they ended up with pretty much what they wanted in the first place.
There is no evidence that they seriously considered any concepts or ideas that did not fit their already pre-conceived ideas on what they would end up with, (which oddly enough is something REL is accused of doing as if it were a "bad" thing) and there IS evidence that the only 'trades' done were within the already defined parameters rather than anything more general and inclusive.
I think you mean keeping the line unclear.
However you weasel around it, the state is helping an industrial sector to compete against foreigners - for whatever reasons and with whatever justification.
Whether or not they have a right to is completely beside the point - I don't care about that and I can't see anyone else here who does. It only matters in as much as it seems improbable at this time that one might survive without such arrangements.
Quote from: t43562 on 11/22/2016 06:49 amI think you mean keeping the line unclear....Because it makes no sense to the taxpayer to NOT make it available to domestic industry to increase the overall GDP. Right? So this is not just a NASA issue, but what many government do. Otherwise you're just wasting taxpayer money, and that would not be in the best interests of anyone...
Coupled with the more recent, (and seemingly more pervasive) attitude that anything with 'wings' is the "Shuttle and therefor can never work as suggested" it makes it difficult to believe anyone can actually significantly lower the cost of space access when they refuse to actually examine all the possibilities rather than sticking to the 'usual' assumptions.
Quote from: john smith 19 on 11/22/2016 08:31 amSomething I'd like people to keep in mind. Let's just repeat that for people who think either of them looked at Skylon:neither Musk or Beezos did much 'due-diligence' work on anything OTHER than the concepts they went forward with. Repeating such an assertion does not make it any more true.
Quote from: t43562 on 11/22/2016 06:49 amI think you mean keeping the line unclear.No, I meant what I said, and I like to use clearly defined and accepted definitions for words.QuoteHowever you weasel around it, the state is helping an industrial sector to compete against foreigners - for whatever reasons and with whatever justification.Regarding the Falcon 9, if you look into the contracts that SpaceX has won from NASA, no money was designated for building the Falcon 9. The only contracts SpaceX has won are related to ensuring that their Dragon spacecraft is able to carry and deliver cargo to the ISS (i.e. COTS & CRS), and that they can safely carry and deliver humans to the ISS (i.e. CCDev 1&2, CCiCap, & CCtCap), and for all the contracts SpaceX has had to deliver or accomplish specific goals in order to be compensated.In contrast, a subsidy would be a payment to a company with no expectation of a product or service in return. That is typically what "state aid" is, but as I've described, that is not the case with SpaceX and NASA.QuoteWhether or not they have a right to is completely beside the point - I don't care about that and I can't see anyone else here who does. It only matters in as much as it seems improbable at this time that one might survive without such arrangements.This regards U.S. companies having access to taxpayer funded NASA research. I don't know, but I would imagine this happens in every democracy, and likely in the UK. Have you researched it?Because it makes no sense to the taxpayer to NOT make it available to domestic industry to increase the overall GDP. Right? So this is not just a NASA issue, but what many government do. Otherwise you're just wasting taxpayer money, and that would not be in the best interests of anyone...
Finally, you said something that is true. But you've apparently misunderstood it.To consider Skylon not to be a viable concept is to have a judgement about it. To have a judgement about it means it was considered.
Of course they don't have it in their plans -- they considered it and rejected it early on. That's not evidence of a bias.
Both Musk and Beezos started with an idea of what they wanted in the end to have, it is no surprise that they ended up with pretty much what they wanted in the first place.QuoteNonsense. What they started with was a dissatisfaction with the current state of the launch industry and a desire to find some way to revolutionize it to lower costs and expand access. They looked into how to revolutionize the launch industry and both independently came to the same conclusion: vertical launch and landing of chemical two-stage reusable rockets.
Nonsense. What they started with was a dissatisfaction with the current state of the launch industry and a desire to find some way to revolutionize it to lower costs and expand access. They looked into how to revolutionize the launch industry and both independently came to the same conclusion: vertical launch and landing of chemical two-stage reusable rockets.
Neither one of them had any background in rockets. The idea that they would start out with vertical take-off and landing reusable rockets as a preconceived idea makes no sense whatsoever.
If you're going to claim there is evidence, present that evidence.
Quote from: Lars-J on 11/22/2016 06:39 pmQuote from: john smith 19 on 11/22/2016 08:31 amSomething I'd like people to keep in mind. Let's just repeat that for people who think either of them looked at Skylon:neither Musk or Beezos did much 'due-diligence' work on anything OTHER than the concepts they went forward with. Repeating such an assertion does not make it any more true.OK then where have they mentioned when either of them said they looked at HTOL and concluded it was unworkable?Given Musk's goal has always been Mars I doubt he spent a second on the idea. As anyone with a cursory knowledge of spaceflight and general engineering would expect. REL don't want to build a Skylon that can land on Mars. They'd be happy to enable a greatly cheaper Mars mission based on Skylon flights to LEO however. So where did Bezos mention this? Interview? Media event? Tweets?
You seem so very sure he's wrong. Do you have facts or just your simple faith to guide you?
Quote from: john smith 19 on 11/23/2016 04:09 pmQuote from: Lars-J on 11/22/2016 06:39 pmQuote from: john smith 19 on 11/22/2016 08:31 amSomething I'd like people to keep in mind. Let's just repeat that for people who think either of them looked at Skylon:neither Musk or Beezos did much 'due-diligence' work on anything OTHER than the concepts they went forward with. Repeating such an assertion does not make it any more true.OK then where have they mentioned when either of them said they looked at HTOL and concluded it was unworkable?Given Musk's goal has always been Mars I doubt he spent a second on the idea. As anyone with a cursory knowledge of spaceflight and general engineering would expect. REL don't want to build a Skylon that can land on Mars. They'd be happy to enable a greatly cheaper Mars mission based on Skylon flights to LEO however. So where did Bezos mention this? Interview? Media event? Tweets? I don't think you understand how this works. YOU made the claim, with no evidence to back it up. I challenged it. But since you asked, here is what Musk has said about air breathing launch vehicles: http://shitelonsays.com/transcript/elon-musk-lecture-at-the-royal-aeronautical-society-2012-11-16 (search in page for 'reaction engines')Quote from: john smith 19 on 11/23/2016 04:09 pmYou seem so very sure he's wrong. Do you have facts or just your simple faith to guide you?Pot, kettle, black? You are so convinced that Skylon is the way forward, that anyone who did 'due diligence' on it must have selected it, and the only way one could explain them not selecting that path is by not doing 'due diligence'. I know we are in a post-facts society, but at least TRY to step out of your bubble.
[Question about Reaction Engines.] This is using an air breathing engine? When I looked at the numbers it didn't seem too compelling compared to having a slight increase in the size of the first stage. So if you're going to add a whole bunch of complexity, it needs to really pay off and, at least using the numbers I've seen, I have a hard time seeing how it does pay off - but I could be wrong about that. If there is really a big advantage then it would be worth investigating, but it would have to be a big advantage. I would be reluctant to add essentially some sort of jet engine on top of the rocket engine problem.
So in other words he hasn't seriously investigated it.