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Thread: How far into the future? An aircraft that launches from a runway and enters low

  1. #31
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    Well, Skylon keeps being mentioned. I assume it has wings to give it lift, as it has been said that it will take off from an air strip. Even the X 15 had trouble with those kind of speeds through atmosphere.These expectations may be
    wanting. This I have to see .

  2. #32
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    Quote Originally Posted by danscope View Post
    Well, Skylon keeps being mentioned. I assume it has wings to give it lift, as it has been said that it will take off from an air strip. Even the X 15 had trouble with those kind of speeds through atmosphere.These expectations may be
    wanting. This I have to see .
    You assume Skylon has wing to give it lift !!! Don't you think you could take the time to read about it before writing all these negative posts ?

  3. #33
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    Quote Originally Posted by danscope View Post
    Well, Skylon keeps being mentioned. I assume it has wings to give it lift, as it has been said that it will take off from an air strip. Even the X 15 had trouble with those kind of speeds through atmosphere.These expectations may be
    wanting. This I have to see .
    Skylon won't go above Mach 5.something in the air-breathing mode. The wings are fairly small - just as they need to be for such a spaceplane:




    X-15:

  4. #34
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    Quote Originally Posted by danscope View Post
    Even the X 15 had trouble with those kind of speeds through atmosphere.These expectations may be
    wanting. This I have to see .
    You're comparing Skylon's expectations to a craft that was designed to study those kinds of aerodymic forces that flew between 60 and 40 years ago. I think we learned a few things since then.

    Quote Originally Posted by Winner View Post
    Skylon won't go above Mach 5.something in the air-breathing mode.
    I got my Mach 8 from the spacereview article. So; I went directly to the "horses mouth" to see what the real story is. You're right, 5.4.
    That's directly from Reactionengines site, and probably the same document you got your chart from. (fig.2)

  5. #35
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    My big worry is that, while we have seen some nice CGI and blue prints, we don't even have a rocket engine yet, let alone anything like the massive SSTO seen here. We don't know except theoretically if it will even work. It's extremely daring, and I like that, but we have seen amazing projects proposed like this before and fail for a variety of reasons.
    So I am hopeful, I want them to succeed, but I am still watching with caution.

  6. #36
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    Quote Originally Posted by ravens_cry View Post
    My big worry is that, while we have seen some nice CGI and blue prints, we don't even have a rocket engine yet, let alone anything like the massive SSTO seen here. We don't know except theoretically if it will even work. It's extremely daring, and I like that, but we have seen amazing projects proposed like this before and fail for a variety of reasons.
    So I am hopeful, I want them to succeed, but I am still watching with caution.
    One thing that favours Skylon is, or so I hear, that the engine could potentially have profound military applications, so large aerospace contractors might be interested in funding the development - if only to get their hands on the technologies involved. How true these rumours are I cannot judge.

  7. #37
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    Quote Originally Posted by danscope View Post
    Well, Skylon keeps being mentioned. I assume it has wings to give it lift, as it has been said that it will take off from an air strip. Even the X 15 had trouble with those kind of speeds through atmosphere.These expectations may be
    wanting. This I have to see .
    So you were taliking about Skylon, so could you explain where in the technical data for the Skylon you got this from:

    It sounds interesting on paper, BUT....... just how much velocity do we expect to get out of this vehicle durring it's
    flight in breathable airspace ? Here's a fantastic number.....500 MPH .
    It's designed to fly at Mach 5 in airbreathing mode and it passed an ESA technical review which found no reason to dispute this so please tell us where you get 500mph, or is it a 'fantastic number' in the sense that you just made it up?

  8. #38
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    Quote Originally Posted by ravens_cry View Post
    My big worry is that, while we have seen some nice CGI and blue prints, we don't even have a rocket engine yet, let alone anything like the massive SSTO seen here. We don't know except theoretically if it will even work. It's extremely daring, and I like that, but we have seen amazing projects proposed like this before and fail for a variety of reasons.
    So I am hopeful, I want them to succeed, but I am still watching with caution.
    Which is the sensible thing to do. I want to see it succeed but I also want see SpaceX and Sierra Nevada Corporation making progress. The more people working on improving access to space the better the chance of success.

  9. #39
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    With the size of those wings and the total weight of the fueled craft, it is unlikely that this will get off the ground,
    in my opinion. I simply don't see a lift configuration compatible with the job of carrying enough fuel to fly part way to orbit. Looks more like a rocket sled which will meet with a fiery end once the tires melt and fall off. Consider the B-36, and how much it weighed. And that was a mighty take off roll indeed. Maybe this thing will defy logic and history.
    I wish them joy of such an endeavour. It makes for thrilling science fiction. We shall see if it makes flying fact.
    Then there is the problem of taking these engines back through atmosphere at 18,000 MPH . Or is there a provision for separation of the skylon air breathing engines to separate and return by parachute?
    History shows a design favouring vertical takeoff with modest velocity up and through the area of maximum
    dynamic effort , above which more efficient, higher velocities are obtained , boosting less mass and shedding
    what can be jettisoned.
    So.... we will see. And if we think landing an F-104 is tricky at elevated velocities, just wait untill they try to come in " Hot " as Robert Stack used to say . And he actually flew aircraft . Has anyone noted the landing speed of this design? Curious .

  10. #40
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    Quote Originally Posted by danscope View Post
    With the size of those wings and the total weight of the fueled craft, it is unlikely that this will get off the ground,
    in my opinion. I simply don't see a lift configuration compatible with the job of carrying enough fuel to fly part way to orbit. Looks more like a rocket sled which will meet with a fiery end once the tires melt and fall off. Consider the B-36, and how much it weighed. And that was a mighty take off roll indeed. Maybe this thing will defy logic and history.
    I wish them joy of such an endeavour. It makes for thrilling science fiction. We shall see if it makes flying fact.
    Then there is the problem of taking these engines back through atmosphere at 18,000 MPH . Or is there a provision for separation of the skylon air breathing engines to separate and return by parachute?
    Well that last question seems to confirm my suspicion, you are making comments on the Skylon while knowing nothing about it. But you could prove me wrong by quoting the technical references you have used to draw your conclusions, and bear in mind that as has been mentioned previously, and ignored by you, ESA conducted an independent technical review of the Skylon and concluded there were no 'showstoppers'; that is its airframe and operational mode were entirely feasible with the proviso that the precooler technology passes its tests this summer.
    You've made one extraordinary statement after another in this thread, are you going to show any substance to back them up?

  11. #41
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    Quote Originally Posted by Garrison View Post
    Which is the sensible thing to do. I want to see it succeed but I also want see SpaceX and Sierra Nevada Corporation making progress. The more people working on improving access to space the better the chance of success.
    Oh yes. In space, the more the merrier I say. :-)

  12. #42
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    Quote Originally Posted by ravens_cry View Post
    Wow, that must have been pretty terrifying, even for trained cosmonauts. Those 20 seconds must have been some of the longest of their lives, both for the cosmonauts and the people on the ground.
    Great article:

    ...Titov claimed that the crew's first action after the escape rocket fired was to deactivate the spacecraft's cockpit voice recorder because, as he put it, "We were swearing."
    Really?

    14 to 17g even for 5s is not fun! Not to mention knowing that you are on top of a potential (and burning) bomb as powerful as a small nuke!

  13. #43
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    Quote Originally Posted by danscope View Post
    Consider the B-36, and how much it weighed. And that was a mighty take off roll indeed. Maybe this thing will defy logic and history.
    Again; an apples to pianos comparison.
    By the same logic, a 747 can't take off either since it has twice the max takeoff weight.

    The B-36 was piston powered. The aerodynamics were tailored for piston power. We're talking about almost the entire Jet age and its related advances occuring since then.

  14. #44
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    We need look at the size and airfoil section of the 747 and variants as well as the B-52 or 36 to note that their wing is
    long enough to do the lifting job , and at modest speeds. We are talking about some considerable weight , much of it in fuel to orbit, in addition to what skylon engines will consume level to 140,000 feet. It is a tall order with not much of a wingspan.
    Any other opinions welcomed.

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    Quote Originally Posted by danscope View Post
    We need look at the size and airfoil section of the 747 and variants as well as the B-52 or 36 to note that their wing is
    long enough to do the lifting job , and at modest speeds. We are talking about some considerable weight , much of it in fuel to orbit, in addition to what skylon engines will consume level to 140,000 feet. It is a tall order with not much of a wingspan.
    Any other opinions welcomed.
    You've been told several times now that the Skylon has passed a technical review by ESA and there is a fair amount of information freely available about the Skylon, which has been linked by other posters. You've responded with posts such as this:

    Then there is the problem of taking these engines back through atmosphere at 18,000 MPH . Or is there a provision for separation of the skylon air breathing engines to separate and return by parachute?
    That show you have failed to do any research on the subject. Are you planning to offer any relevant data or analysis to support your position or just more empty rhetoric?

  16. #46
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    Quote Originally Posted by danscope View Post
    With the size of those wings and the total weight of the fueled craft, it is unlikely that this will get off the ground,
    in my opinion. I simply don't see a lift configuration compatible with the job of carrying enough fuel to fly part way to orbit. Looks more like a rocket sled which will meet with a fiery end once the tires melt and fall off. Consider the B-36, and how much it weighed. And that was a mighty take off roll indeed. Maybe this thing will defy logic and history.
    Well, it wouldn't be a short takeoff plane, it is expected to need a specially reinforced runway 4 km long to get up to the optimal takeoff speed of .5 mach, there would also be a further stretch of runway at least 1,6 km long for breaking in case of takeoff abort(but this does not need the same level of strength as the main runway). Still, the engines produce a lot of thrust, so the Skylon would have a thrust to weight ratio of around 0.77(with payload, full fuel tanks and engines in air breathing mode). It is interesting to note that if the takeoff must be aborted, the mass of the craft means that the emergency breaks will have to be water cooled, so that the Skylon carries a few tonnes of water(this is dumped shortly after takeoff). When the craft is airborne, aborts would involve dumping the fuel, as there is no way the craft can do a regular landing with full tanks.

    Quote Originally Posted by danscope View Post
    I wish them joy of such an endeavour. It makes for thrilling science fiction. We shall see if it makes flying fact.
    Then there is the problem of taking these engines back through atmosphere at 18,000 MPH . Or is there a provision for separation of the skylon air breathing engines to separate and return by parachute?
    The design of the Skylon is intended to limit the heating during reentry to a more manageable level than traditional reentry vehicles, the maximum temperatures being around 800-900 Celsius, though I did see something about there being some potential hot spots in the design that might require a redesign or active cooling. However, REL does not seem to expect that it will be necessary to separate the engines.

    Quote Originally Posted by danscope View Post
    History shows a design favouring vertical takeoff with modest velocity up and through the area of maximum
    dynamic effort , above which more efficient, higher velocities are obtained , boosting less mass and shedding
    what can be jettisoned.
    I would think that the reason for choosing the approach that REL is attempting is that it it has the potential for having a competitive mass fraction compared to traditional rockets with a much shorter time between launches, and at lower price since the whole craft does not have to be rebuilt for each launch.

    Quote Originally Posted by danscope View Post
    So.... we will see. And if we think landing an F-104 is tricky at elevated velocities, just wait untill they try to come in " Hot " as Robert Stack used to say . And he actually flew aircraft . Has anyone noted the landing speed of this design? Curious .
    The landing speed would be around 250 km/h.

    Really, it seems fairly obvious to me that if we are to have any larger scale exploration and exploitation of space we have to look into less traditional designs than what we are currently using, and something like the Skylon would be useful.

  17. #47
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    Quote Originally Posted by danscope View Post
    We need look at the size and airfoil section of the 747 and variants as well as the B-52 or 36 to note that their wing is
    long enough to do the lifting job , and at modest speeds. We are talking about some considerable weight , much of it in fuel to orbit, in addition to what skylon engines will consume level to 140,000 feet. It is a tall order with not much of a wingspan.
    Any other opinions welcomed.
    I suppose, much of the lift comes from propulsion rather than wingspan, like conventional rockets. Even very fast cars need something to keep them from going airborne, and they don't even have wings. This is probably why the Skylon needs a longer runway so that it can take off at much higher speed than conventional planes.

  18. #48
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    These are hopefull responses to some casual observations. Still, it's very far in the future. They have never built a mock-up or flown an unloaded prototype or built and tested a full sized "real" skylon engine , so we have much to look forward to ....in 20 years maybe.

  19. #49
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    Quote Originally Posted by danscope View Post
    These are hopefull responses to some casual observations. Still, it's very far in the future. They have never built a mock-up or flown an unloaded prototype or built and tested a full sized "real" skylon engine , so we have much to look forward to ....in 20 years maybe.
    Sigh. Why don't you read something about Skylon?

    REL plans to

    1) test the heat-exchanger on an existing jet engine to prove that it works (i.e. that the problem with frost build-up has been solved, that the performance is as good as the models have predicted, etc.). Since the heat exchanges is the key part of the Sabre engine, this must succeed.
    2) If the tests are successful, REL claims it will receive about $350 million from private investors to fund the next stage of development, which will be to build the whole SABRE engine and a nacelle test vehicle. This will be done by a consortium that will be set up to build SKYLON, something like Airbus.
    3) After that, the consortium will proceed to build the vehicle itself.

    The development is set to take about 10 years from start to finish, and cost about $12-15 billion.

  20. #50
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    Quote Originally Posted by Garrison View Post
    As ravens_cry said that's a description of the Skylon...
    It's also a description of the USAF "Aero Space Plane" concept from the very late 1950's/early 1960's. Every American aerospace company worth its salt pitched SSTO or sorta-SSTO "airplanes." Lockheed and Douglas both liked spaceplanes that would meet up with tankers planes in flight... at something like Mach 4 to Mach 6. Martin liked a nuclear powered orbital aircraft. Republic wanted a scramjet powered vehicle. Boeing, in contrast, wanted a relatively simple all-rocket vehicle that used a Dyna Soar as both the cockpoit and the pitch-controlling canards (at least, at one stage of the program that's what Boeing wanted... at other stages, they wanted other things).

  21. #51
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    You know..... if you planned to take off from a very large frozen lake...on skis , you could get up to some pretty high speeds. 4 mile take off run... no problem. But you lose some equatorial velocity. Nothing's easy.

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    Quote Originally Posted by danscope View Post
    You know..... if you planned to take off from a very large frozen lake...on skis , you could get up to some pretty high speeds. 4 mile take off run... no problem. But you lose some equatorial velocity. Nothing's easy.
    You don't believe Skylon will work but you think a 250-300 tonne launcher with jets/rockets can launch from a layer of ice a few meters thick?

  23. #53
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    Quote Originally Posted by danscope View Post
    You know..... if you planned to take off from a very large frozen lake...on skis , you could get up to some pretty high speeds. 4 mile take off run... no problem. But you lose some equatorial velocity. Nothing's easy.
    Maybe this will work on Europa. Oops, no atmosphere.

  24. #54
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    I was just wondering what take-off velocity is for such a craft? V-1 must be around 4 miles. Emergency stop/abort
    by a really big parachute and emergency separation to section craft for survival of pilots/crew .

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    Dan,

    Your questions are answered in the Skylon FAQ.
    http://www.reactionengines.co.uk/faq.html

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    Most impressive,.... but have they ever built one ? Does a full sized engine exist? When ?

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    Quote Originally Posted by danscope View Post
    Most impressive,.... but have they ever built one ? Does a full sized engine exist? When ?
    short answer: No, No, and sometime during the early 2020's.

    long one: The skylon fuselage is based on space frames. like those used on zepelins and early aircraft. it's a well understood construction method altho somewhat unorthodox for a faster than sound vehicle. (most aircraft are based on a monocoque hull nowadays).
    A full sized engine will be built if investors are happy with the scaled testing being done this summer. there are 350 mill worth of funding hanging on these tests working out ok. so we'l just have to wait for a while longer on that. at least it's being worked on seriously. unlike most other concepts we hear about.

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    Quote Originally Posted by danscope View Post
    ....emergency separation to section craft for survival of pilots/crew .
    Skylon is an unmanned, robotic vehicle. There is no crew. IF the vehicle is ever funded, fully designed, built, and operationally flown, it will initially be an unmanned cargo carrier only. If that is ever acheved, there are ideas for later adding a human-carrying cargo module in the payload bay. It would still not be piloted in the normal sense. So there would be no pilots or crew, even when carrying human cargo.

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    Quote Originally Posted by r4758 View Post
    earth orbit?

    The end of the space shuttle era causes me to speculate that there is something a whole lot better just around the corner.

    Perhaps an aircraft that can lauch from a runway, enter low earth orbit, dock at the ISS (or future space station), return to earth, and be used again and again.
    I don't think that low earth orbit will ever be accessed routinely by us from level runways, at least between sea level and 10,000 feet above sea level, at supersonic velocities through the lower 40% of the atmosphere. China might try it on the Tibeten plateau, of course, since they have the political clout to commandeer the necessary acreage....
    Last edited by dicktice; 2011-Aug-14 at 10:48 PM. Reason: Spelling

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    Quote Originally Posted by dicktice View Post
    I don't think that low earth orbit will ever be accessed routinely by us from level runways, at least between sea level and 10,000 feet above sea level, at supersonic velocities through the lower 40% of the atmosphere. China might try it on the Tibeten plateau, of course, since they have the political clout to commandeer the necessary acreage....
    Again neither REL nor ESA seem to have issues with this operational mode, so what exactly is it that you feel makes this so problematic?

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