It's that kind of exaggeration that makes people so sceptical of the continual claims that Skylon has no "showstoppers".
Quote from: Paul451 on 07/30/2016 01:13 amIt's that kind of exaggeration that makes people so sceptical of the continual claims that Skylon has no "showstoppers".For that matter, it's why I detest the constant use of the phrase "no showstoppers" in aerospace. As if "theoretically within the laws of physics, as far as we can tell, having never done anything remotely like it before" is the sole criteria for the practicality of a design.
Quote from: john smith 19 on 07/29/2016 11:18 pmQuote from: high road on 07/29/2016 11:24 am'detachable' carbo bay that can be preloaded and quickly swapped upon landing... Much like how most passenger luggage is shipped in fact. No aircraft uses a detachable cargo section that must function as an integrated part of the vehicle. ULD's are not even remotely analogous.It's that kind of exaggeration that makes people so sceptical of the continual claims that Skylon has no "showstoppers".[The only aircraft I've seen with detachable cargo-pod was the failed Fairchild XC-120 "Packplane".]
Quote from: high road on 07/29/2016 11:24 am'detachable' carbo bay that can be preloaded and quickly swapped upon landing... Much like how most passenger luggage is shipped in fact.
'detachable' carbo bay that can be preloaded and quickly swapped upon landing...
Quote from: Paul451 on 07/30/2016 01:13 amQuote from: john smith 19 on 07/29/2016 11:18 pmQuote from: high road on 07/29/2016 11:24 am'detachable' carbo bay that can be preloaded and quickly swapped upon landing... Much like how most passenger luggage is shipped in fact. No aircraft uses a detachable cargo section that must function as an integrated part of the vehicle. ULD's are not even remotely analogous.I used the phrase "passenger luggage" very specifically to denote the sort of boxes used to speed up passenger luggage handling at airports https://en.wikipedia.org/wiki/Unit_load_device
Quote from: john smith 19 on 07/29/2016 11:18 pmQuote from: high road on 07/29/2016 11:24 am'detachable' carbo bay that can be preloaded and quickly swapped upon landing... Much like how most passenger luggage is shipped in fact. No aircraft uses a detachable cargo section that must function as an integrated part of the vehicle. ULD's are not even remotely analogous.
As for "no showstoppers" that paraphrases the professional opinion of the ESA technical centre, with full access to the SABRE technology and the Skylon development plan.
SABRESkylon is a high risk/high cost/high reward programme
Quote from: Paul451 on 07/30/2016 10:30 amQuote from: john smith 19 on 07/30/2016 07:01 amQuote from: Paul451 on 07/30/2016 01:13 amQuote from: john smith 19 on 07/29/2016 11:18 pmQuote from: high road on 07/29/2016 11:24 am'detachable' carbo bay that can be preloaded and quickly swapped upon landing... Much like how most passenger luggage is shipped in fact. No aircraft uses a detachable cargo section that must function as an integrated part of the vehicle. ULD's are not even remotely analogous.I used the phrase "passenger luggage" very specifically to denote the sort of boxes used to speed up passenger luggage handling at airports https://en.wikipedia.org/wiki/Unit_load_device I'm curious what you believed the highlighted part of my comment was referring to?Quote from: john smith 19 on 07/30/2016 07:01 amAs for "no showstoppers" that paraphrases the professional opinion of the ESA technical centre, with full access to the SABRE technology and the Skylon development plan.Rolls-Royce and British Aerospace thought the same thing about the inherently flawed HOTOL design. As did the UK government for 6 years.Similar "no showstoppers" claims were made about similarly flawed designs, from NASP to X-33. Likewise JWST, as is slips multiples overbudget. Likewise there are "no showstoppers" with SLS today nor were there with Ares before it. And "no showstoppers" with the launch of Orion on a modified SRB launcher and now on an SRB-boosted launcher.You wonder why whenever I hear that phrase, I expect the best-case scenario is that the project will merely go several times over-budget and deliver a fraction of what was promised, but more likely fail completely.
Quote from: john smith 19 on 07/30/2016 07:01 amQuote from: Paul451 on 07/30/2016 01:13 amQuote from: john smith 19 on 07/29/2016 11:18 pmQuote from: high road on 07/29/2016 11:24 am'detachable' carbo bay that can be preloaded and quickly swapped upon landing... Much like how most passenger luggage is shipped in fact. No aircraft uses a detachable cargo section that must function as an integrated part of the vehicle. ULD's are not even remotely analogous.I used the phrase "passenger luggage" very specifically to denote the sort of boxes used to speed up passenger luggage handling at airports https://en.wikipedia.org/wiki/Unit_load_device I'm curious what you believed the highlighted part of my comment was referring to?Quote from: john smith 19 on 07/30/2016 07:01 amAs for "no showstoppers" that paraphrases the professional opinion of the ESA technical centre, with full access to the SABRE technology and the Skylon development plan.Rolls-Royce and British Aerospace thought the same thing about the inherently flawed HOTOL design. As did the UK government for 6 years.Similar "no showstoppers" claims were made about similarly flawed designs, from NASP to X-33. Likewise JWST, as is slips multiples overbudget. Likewise there are "no showstoppers" with SLS today nor were there with Ares before it. And "no showstoppers" with the launch of Orion on a modified SRB launcher and now on an SRB-boosted launcher.You wonder why whenever I hear that phrase, I expect the best-case scenario is that the project will merely go several times over-budget and deliver a fraction of what was promised, but more likely fail completely.
Rolls-Royce and British Aerospace thought the same thing about the inherently flawed HOTOL design. As did the UK government for 6 years.
Similar "no showstoppers" claims were made about similarly flawed designs, from NASP to X-33. Likewise JWST, as is slips multiples overbudget. Likewise there are "no showstoppers" with SLS today nor were there with Ares before it. And "no showstoppers" with the launch of Orion on a modified SRB launcher and now on an SRB-boosted launcher.
You wonder why whenever I hear that phrase, I expect the best-case scenario is that the project will merely go several times over-budget and deliver a fraction of what was promised, but more likely fail completely.
But if anyone but a True Believer says that, we get lectured at.
Quote from: Paul451 on 07/30/2016 10:30 amRolls-Royce and British Aerospace thought the same thing about the inherently flawed HOTOL design. As did the UK government for 6 years.With the benefit of 20/20 hindsight of course. HOTOL taught the REL design teams lessons which others still seem either unwilling or unable to recognize.
In particular I'm still looking forward to seeing how SX will make their BFR a fully reusable TSTO when they said they could with F9, but in fact can't.
fully reusable TSTO when they said they could with F9, but in fact can't.
Big risk, big gains. Anyone who tells you different is either rigging the game or about to take you for a bag of cash.
SABRESkylon has had that assessment and there are no holes.
...In particular I'm still looking forward to seeing how SX will make their BFR a fully reusable TSTO when they said they could with F9, but in fact can't. ...
Quote from: john smith 19 on 07/30/2016 05:15 pmQuote from: Paul451 on 07/30/2016 10:30 amRolls-Royce and British Aerospace thought the same thing about the inherently flawed HOTOL design. As did the UK government for 6 years.With the benefit of 20/20 hindsight of course. HOTOL taught the REL design teams lessons which others still seem either unwilling or unable to recognize....then you immediately say...Quote from: john smith 19 on 07/30/2016 05:15 pmIn particular I'm still looking forward to seeing how SX will make their BFR a fully reusable TSTO when they said they could with F9, but in fact can't. You don't see the double-standard here?One failed project gives REL innovation superpowers, but SpaceX deciding not to pursue US-reusability for F9 somehow means the opposite.A group that has never delivered a completed launcher, or aircraft, or analogous project, working on a design that has never been built, of a type (SSTO) that is a graveyard of failed designs, is seen as beyond criticism. Because they have Experience! Meanwhile a company that has successfully built and operated two launchers in a decade, recovered both the first stage and cargo-capsule, is assumed to be incompetent when it comes to scaling up because they decided the numbers on a single sub-project didn't work, before they'd spent a dime on itsdevelopment.[Personally, I'd be shocked if SpaceX can pull off the BFR booster alone within a decade, forget the rest of MCT, not to mention the rest of Mars-side infrastructure. They seem to be skipping over too many steps between here-and-there. (IMO, taking too big a leap caused some of the early issues with F9.) But using the F9-US as a reason for scepticism is nuts.]Quote from: john smith 19 on 07/30/2016 05:15 pmfully reusable TSTO when they said they could with F9, but in fact can't. ...and speaking of poorly researched.Quote from: john smith 19 on 07/30/2016 05:15 pmBig risk, big gains. Anyone who tells you different is either rigging the game or about to take you for a bag of cash.QuoteSABRESkylon has had that assessment and there are no holes. You go from "Big Risk" to "There are no holes!" within even a single post.Which was my point. When a non-believer points out the risk (and the cost), they get lectured. The ESA has done an assessment! The ESA! REL has eliminated every risk! Every remaining part is off-the-shelf, low-risk, industry standard! Who are you to dare suggest Skylon is a high-risk concept?! Vested interests!
But it does seem Space X gets a free pass from criticism on here by some yet REL gets told that will never happen, perhaps some tire of the double standards expressed.
Quote from: Star One on 07/31/2016 08:30 amBut it does seem Space X gets a free pass from criticism on here by some yet REL gets told that will never happen, perhaps some tire of the double standards expressed.As much as I hate a lot of the idiotic SpaceX amazing peopleism on here, which is why i don't post very often anymore, at least SpaceX are flying stuff...
One failed project gives REL innovation superpowers, but SpaceX deciding not to pursue US-reusability for F9 somehow means the opposite.
A group that has never delivered a completed launcher, or aircraft, or analogous project, working on a design that has never been built, of a type (SSTO) that is a graveyard of failed designs, is seen as beyond criticism.
Because they have Experience! Meanwhile a company that has successfully built and operated two launchers in a decade, recovered both the first stage and cargo-capsule, is assumed to be incompetent when it comes to scaling up because they decided the numbers on a single sub-project didn't work, before they'd spent a dime on itsdevelopment.
I'd say SX's failure to make F9 upper stage reuse work
As for confidence. We know 3 vehicles have demonstrated winged reentry from full LEO velocity. There is no track record of any conventionally shaped upper stage coming in from full LEO velocity.
Quote from: john smith 19 on 07/31/2016 09:48 pmAs for confidence. We know 3 vehicles have demonstrated winged reentry from full LEO velocity. There is no track record of any conventionally shaped upper stage coming in from full LEO velocity.None of your 3 winged vehicles have been real upper stages with full-size tanks. 1 was only a payload that was lifted all the way up to orbit with a rocket, 1 was payload with just very small apogee engines, and had the main engines of the upper stage but lacked the fuel tank.And there are also much greater amount of wingless capsules that have demonstrated re-entry from full LEO velocity, at least two also from much higher velocities.
Quote from: RanulfC on 07/28/2016 05:53 pm...... There are details that they would have trouble understanding at first because of their knowledge base, but in general they'd see the 747 layout as very 'conventional', requiring advanced materials and propulsion far in advance of what they had available certainly but recognizable from their own knowledge.Mebbe add 'controls' to that list. The Wright brothers didn't invent the joystick/rudder pedals (that came later over in Europe) so they wouldn't recognise anything in the cockpit either.
...... There are details that they would have trouble understanding at first because of their knowledge base, but in general they'd see the 747 layout as very 'conventional', requiring advanced materials and propulsion far in advance of what they had available certainly but recognizable from their own knowledge.
Really "epic" patent fight "Wright vs Curtis", folks should google it...
I can look at the shuttle and Skylon, and see that the underlying principle is the same. Heat shield on a winged vehicle, correct angle of attack, with relatively small mass to large surface area, vehicle slows, then glides in to land. Purely on the reentry heating DLR in Germany have anaylsed the reentry of a Skylon and say that the heating is less than that of the Shuttle because... science! math! CFD! Germans!
And costly as well. "Birdmen" (https://www.amazon.com/Birdmen-Wright-Brothers-Curtiss-Control/dp/0345538056/ref=sr_1_1?s=books&ie=UTF8&qid=1470066111&sr=1-1&keywords=birdmen) makes a good case that the feud managed to set American aviation back a huge amount as well as the Wright's insistence on a complete monopoly on "aircraft" (world wide no less) for at least a decade.