11 ms·

Reagan’s Impossible Dream: The X-30 National Aerospace Plane

83 points by high_frontier 11y ago

DanielBMarkham 11y ago
Interesting. So Wiki says a fully-loaded B-52 can carry 35 tons of bombs. Everybody knows 1) re-entry after achieving orbital speeds is non-trivial, and 2) doing a stationary drop from orbital heights is possible. There is even some talk of "skydiving from orbit" So you take a B-52 out over the ocean. At 50,000 MSL, you extend two rocket pods, point the nose straight up, and take yourself out of the atmosphere post-haste. Somewhere around 200-400,000 MSL, you roll over into a standard orbit configuration. Burn about half your fuel. Once you get to where you want to go, burn the other half, reach a dead stop, then parachute into the lower atmosphere, do an engine re-start, and be on your way. I'm not saying it wouldn't be a helluva ride, but I'm failing to see the part where we couldn't have done this 20 or 30 years ago. Perhaps the problem was that folks tried to imagine some sort of new propulsion system -- and the numbers just don't work out. Instead of solving SCRAMJET, maybe that money would have been better spent on truly reusable rockets and high-performance, plane-rated parachutes? ADD: This comment was meant to address the problem of sub-orbital flight from point A to point B, not getting completely to orbit. Both SSTO and suborbital flight were mentioned in the article. My point was that suborbital flight doesn't have as many problems as we might think it does.
- TeMPOraL 11y ago
  > Once you get to where you want to go, burn the other half, reach a dead stop, then parachute into the lower atmosphere, do an engine re-start, and be on your way. I think that would require a shit ton of fuel. If you want to actually achieve orbit, that's at least 7.8 km/s of Δv to do it, and that much again to reach "dead stop". Your B-52 would have to be carried on a booster rocket, as opposed to carrying one. A suborbital trajectory would make more sense, but that's generally what the US has ICBMs for.
  - deleted 11y ago
    [deleted]
- mnw21cam 11y ago
  The amount of energy required to lift an object to 50,000 feet altitude under mach 1 is insignificant compared to the amount of energy required to achieve orbit. You're basically talking about making a rocket, but saving a very small amount of fuel by starting a little higher in the atmosphere. Then you double the delta-v required by having a dead stop in orbit. That much delta-v would require a very large multi-stage rocket indeed, which defeats the object of your exercise.
  - DanielBMarkham 11y ago
    Yes. Apologies. I will make an addition to my comment. I was only addressing sub-orbital flight, not orbital flight. The initial article was about the old NY-to-Tokyo in 2 hours thing we've been reading about for ages. You cannot make orbit, but you should be able to go a long ways ballistically. Add: A great way to learn about the energies involved is to create your own simulator in your programming language of choice. The ballstic/orbital math isn't that hard, and you don't run into a huge number of problems just modeling how to get to orbit. I did this many years ago, and concluded that for non-biological items, mass drivers win hands-down. Unless the magic of field propulsion finally happens, taking your own fuel along with you sucks.
- rayiner 11y ago
  In your hypothetical, the initial flight is doing almost none of the real work and you might as well just launch that booster from the ground. Look at the rocket equation. You have to achieve a given delta-v to get into orbit. That drives the required mass ratio of the rocket. Getting up to 500 mph or whatever a B-52 can do basically has negligible impact on the required delta-v, so the require rocket size is no smaller. SCRAMJETS are interesting because they can get up to a significant fraction of the required delta-v while in air-breathing mode. They can do that because unlike a traditional jet engine, they don't have to slow air down to subsonic speeds for combustion. That's what drives the maximum speed of traditional jet engines. Edit: saw your other response. Delta-v is still an issue for suborbital trajectories. Hitting 100 km altitude requires a speed of about 3,200 mph. If you've got a subsonic air breathing stage, you're still not getting much benefit. The big benefit of SCRAMJETS for suborbital flight is that they can hit the required speeds in air-breathing mode the whole way. No need to carry around heavy oxidizer.
- ashark 11y ago
  It takes way more fuel to reach a dead stop in orbit than it does to just nudge yourself down into the atmosphere and let friction do the work for you. Waaaay more. And you have to lift all that extra fuel into orbit with you, which means even more fuel.
- jessriedel 11y ago
  "Suborbital" refers to a ballistic trajectory that is "close" to an orbital trajectory, so that the projectile follows an unpowered arc, but one that is not wide enough to achieve orbit. The energy required for suborbital trajectories is still in the same neighborhood as orbital flight. The reason your proposal doesn't work is that during the portion of the trajectory outside the atmosphere, you either need to be ballistic (and therefore suborbital if you're traveling intercontinental) or you need to be constantly directing a portion of your rockets thrust downward. The latter is fantastically inefficient, which is why planes operate in the atmosphere (where they can use air to convert efficient horizontal thrust to lift) and why suborbital rockets are ballastic for the large majority of their flight.
  - mikeash 11y ago
    Suborbital just means you went to space but didn't achieve orbit. There's no requirement to be "close" to an orbital trajectory. Blue Origin's New Shepard and Virgin Galactic's SpaceShipOne are classic examples of suborbital spacecraft, and neither of those came anywhere near orbital speed.
  - vpribish 11y ago
    Appreciate that you are trying to help here, but there is a lot that is simply wrong or confused in your comment. Suborbital does not imply "close to orbital", and does not require an amount of energy in the neighborhood of that for orbital flight, and ballistic/intercontinental/efficient-horizontal-thrust is just a very muddled way to think about this.
- mikeash 11y ago
  An empty B-52 is about 83 tons. Add in 35 tons of rocket propellant (assuming liquid hydrogen, others will be worse) with no additional tankage or engine weight and you get about 3.7km/s of delta-v. Expend half of that on a suborbital trajectory, and you get about an 85km trip. Not terribly useful.
- Merad 11y ago
  Your hypothetical is missing the part where the rocket pods tear the B-52 apart and a flaming ball of debris falls to earth. You see, to accelerate straight up (or nearly so) your thrust must be greater than your weight. To get enough acceleration to be useful, you usually need an amount of thrust that's more like 1.2x your mass. For example, the fully loaded Saturn V weighed about 6,500,000 lbs and the first stage had 7,650,000 lbs of thrust. So your fully loaded B-52 (~265,000 lbs) needs around 320,000 lbs of thrust from the rockets. This is more than double the amount of thrust produced by the jet engines. By the time you've accounted for your rocket engines, strengthened the airframe to survive the rocket thrust, and added a reaction control system (to turn around for deceleration), you've lost a good chunk of your 35 tons of rocket fuel. It's about this time you realize that even 35 tons of rocket fuel is a laughably small amount. A single space shuttle main engine is a bit more powerful than what you'd need (~420,000 lbs of thrust), but it's good enough for ballpark numbers. It will consume 35 tons of fuel in about a minute... meaning your mission profile is probably something like 30 seconds of vertical acceleration, 15 second horizontal acceleration, 15 seconds horizontal deceleration. Not enough to take you very high or very far. It's not that we can't do it, it's that it's woefully inefficient.
walkingolof 11y ago
Great article! For the latest developments: https://en.wikipedia.org/wiki/Skylon_(spacecraft) https://en.wikipedia.org/wiki/Skylon_(spacecraft)
- irremediable 11y ago
  How much of a future do you think the Skylon project has? A couple of friends in the aerospace industry have told me they think SpaceX will effectively "win" now that they can land the Falcon. Are they too optimistic about SpaceX?
  - deleted 11y ago
    [deleted]
  - creshal 11y ago
    All SpaceX did was building a normal rocket that can land again. Which, as it turned out, was anything but trivial and took 14 years. Their main competitors – ULA and Arianespace – already announced they won't be able to manage similar capabilities this decade; and their plans for the next decade are still not as sophisticated as SpaceX's approach (they only want to recover the engines and build a wholly new stage around them). Skylon is a massively more ambitious undertaking compared to that – if it works, it'll be the first practical SSTO, the first horizontal takeoff spaceplane, the first vehicle to use multi-mode engines, the first practical space plane to use a novel heat shield technology, … That's an awful lot of challenges to tackle. If it turns out to work, and if it then turns out to be as re-usable as hoped (something that did never panned out for the Shuttle, and which SpaceX will only learn over the next years for their Falcon), then it could beat SpaceX… in a decade or two.
    - mikeash 11y ago
      The trouble with Skylon is that all of these things you mention make it more ambitious, but they don't really make it more useful. The main advantage Skylon would have over the Falcon 9 is the fact that the Falcon 9 is not fully reusable because they don't and can't recover the second stage, while the entire Skylon is recovered. That's significant, of course. The second stage makes up about 25% the cost of the rocket, so that places a ceiling of about 75% on how much Falcon 9 reusability can save.. But then, starting from where the Falcon 9 is now, building a new rocket that can also recover the second stage doesn't seem too difficult. It's a big challenge, to be sure, but relative to Skylon it's not too bad. Skylon is certainly much more ambitious in terms of how it works, but it doesn't seem to be very ambitious in terms of what it can do, which is not a promising combination.
ck2 11y ago
And just think today we can't even get Congress to fund repair crumbling infrastructure - why do today what you can wait for a national crisis tomorrow?
- Shivetya 11y ago
  while the numbers are large when measured in percentages it isn't that bad. Most of the deficient bridges are locally owned, this means at levels lower than state level. No one also ever seems to mention that at is peak in the 90s there were nearly 150,000 bridges found to be deficient and that number is down to near 60,000. In other words, the Federal government isn't responsible for most of what is out there and many state and local governments refuse to fully fund their own obligations.
  - randallsquared 11y ago
    > No one also ever seems to mention that at is peak in the 90s there were nearly 150,000 bridges found to be deficient and that number is down to near 60,000. Wow. No kidding that "no one also ever seems to mention"! That puts things in perspective a bit, doesn't it?
    - twoodfin 11y ago
      Believe you me, "crumbling infrastructure" has been a constant talking point of those who want greater federal spending for decades. Not to say it's all crying wolf, but if it had been true the whole time it was being complained about, by now things would be more obviously crumbled. State governments in particular love federal infrastructure spending, since it is more or less a direct cash transfer to a) their own budgets, where local infrastructure spending can crowd out other priorities and b) the politically potent building and construction trades.
Shivetya 11y ago
So how does the new SABRE engine factor into this? Originally a lot of skepticism was there but BAE did invest in it so it might pan out
Gravityloss 11y ago
"DuPont’s configuration devised under COPPER CANYON had included no landing gear, orbital manoeuvring system or fuel reserves." I've long held the opinion that the real lesson to take from NASP is that the higher the level of decision making, the more detached it is from physics or business. Air breathing works for cruise (limited speed and altitude range, long duration, low thrust requirements). Rockets work for acceleration (wide speed and altitude range, short duration, high thrust requirements). Orbital missions are only about acceleration. Bringing very heavy air breathing engines to orbit doesn't make sense at all. The lowest dry mass (=lowest cost) single stage to orbit vehicle designs tend to be dense propellant pure rockets. In Finnish there's a saying "ajaa käärmettä pyssyyn": make the snake go into a gun barrel. An organization trying to achieve a needlessly hard thing because of political reasons. Closely related to Not Invented Here.
- high_frontier 11y ago
  I agree with your thoughts on the decision making behind NASP. Even while it was still COPPER CANYON, doubts were being raised. Most of the big decisions to proceed seem to have been made after relatively brief presentations with limited technical detail or discussion. NASP was a case of selling a big picture without stopping to ask how possible it really was. Personally, I find the X-33 more frustrating as this got far closer to flight and although it may never have led to VentureStar it would have been a great hypersonic testbed
  - Gravityloss 11y ago
    Nowadays we do get critical articles about programs like the Joint Strike Fighter, but often they seem a little bit besides the point, for example comparing it to seventies design paradigms. The lightweight fighter mafia is emphasizing dogfighting, visual identification and gun kills, from an era when missiles were very unreliable and there was no stealth. I guess it would require a lot of expertise and access to rare information, to be able to evaluate the JSF on its own merits. Stillion and Sweetman have been the most interesting reads. I think the problem with X-33 was that it was too big and risky for an experimental-only platform. If you want to develop things like aerospike engines or composite multilobe tanks, you should first have ground tests and then relatively small demonstrators using a lot of off the shelf technology. It makes no sense to bet so much stuff on a multi-faceted big expensive program that can fail when any of it components doesn't deliver. Or if you want to build something big, either use proven technology or retire risk in smaller programs first. I guess people were emulating Apollo and the Space Shuttle. They had high performance but were not flexible or low cost, for a reason.
sandworm101 11y ago
If the super-rich are in that much of a hurry to get from london to newyork that they will pay the ticket prices needed to sustain such an aircraft, I have a better idea. Build some mercury capsules. Stick them and a solid upper stage atop a one-engine version of a SpaceX booster. For what, 40K worth of fuel and upper stage (?) billionaires can now fly solo to NY in minutes, experiencing all the majesty of vomiting in zero G. Think of what suborbital, zero-G, would be like in a plane with 100 passengers. Given the forces involved I cannot see suborbital transport ever replacing first class seats on BA.
- api 11y ago
  A more luxury version of this is what I've long suspected the Virgin Galactic project to be: suborbital flights around the world. I've long thought it to be a stealth suborbital spaceplane effort that would add a very expensive but extremely rapid long range flight option to Virgin's lineup.
  - sandworm101 11y ago
    Virgin Galactic is suborbital, but the scheme has nowhere near the velocities necessary to cover any distance. It's just a rollercoaster. There is little point in launching a transport from a plane. Getting to 10,000m is nothing compared to the speed needed for london-NY.
quattrofan 11y ago
Likely this dream will be achieved but perhaps not by the US: https://en.wikipedia.org/wiki/HOTOL https://en.wikipedia.org/wiki/HOTOL http://www.reactionengines.co.uk/ http://www.reactionengines.co.uk/
Balgair 11y ago
Hm, maybe add in fuel rods in place of the fuel to generate the heat? I mean, sure, an open and unshielded just sub-critical reactor is going to have 'environmental effects'. But if the point, from the black budget perspective, is to have an under the radar bomber, the environment is going to shit anyways. Project Pluto is a good, and completely insane, starting point into nuclear scramjets. https://en.wikipedia.org/wiki/Project_Pluto https://en.wikipedia.org/wiki/Project_Pluto Choice Quote edit:"After delivering all its warheads, the missile could then spend weeks flying over populated areas at low altitudes, causing tremendous ground damage with its shock wave. When it finally lost enough power to fly, and crash-landed, the engine would have a good chance of spewing deadly radiation for months to come"
Animats 11y ago
Ben Rich, while he was head of Lockheed's Skunk Works, looked at the proposal, and decided they would not bid. He'd worked on the SR-71, which was the highest performance aircraft ever built. His comment: "We used titanium. You know something stronger?" Getting rid of the heat was the biggest problem. Rockets which launch vertically don't spend much time in the atmosphere. Aircraft which accelerate horizontally do. Hypersonic in-atmosphere travel means having to get rid of huge amounts of heat with no place to dump it. Running liquid hydrogen fuel over the vehicle exterior for cooling was considered and rejected for the SR-71. (Many rocket engines run the cryogenic fuel and oxidizer through cooling channels in the engine bell before using it as propellant. That's not a totally unreasonable idea.) The X-30 was supposed to have a big cabin, which would have to be kept cool. Only a small part of the SR-71 is kept cool; the pilot is in a space suit. Even cooling the pilot was hard. Remember, at hypersonic speeds in atmosphere, there's no place to dump the heat; you have to bring your cold with you. The only real advantage of this approach over rockets which get out of the atmosphere as soon as possible is that you don't have to carry oxidizer. That improves the mass fraction (rockets to orbit are > 90% fuel). Not enough to be a win, though.
- high_frontier 11y ago
  It's interesting to note though that although Ben Rich explains that they decided they wouldn't bid, Lockheed WERE one of the airframe contractors in Phase 2 and it's difficult to imagine that the Skunk Works weren't a part of that effort especially given the work they did towards the scramjet powered X-24c in the seventies. Also, they went on to the X-33 in the mid 90's so clearly felt confident in a suitable "something stronger" thermal protection system by then
trhway 11y ago
btw, the BrahMos 2 Indian-Russian cruise missile coming in 2017 (well, of course there is always a big "if") is scramjet powered and expected to fly at Mach 7. https://en.wikipedia.org/wiki/BrahMos-II_%28missile%29 https://en.wikipedia.org/wiki/BrahMos-II_%28missile%29

83 points by high_frontier 11y ago

Interesting. So Wiki says a fully-loaded B-52 can carry 35 tons of bombs. Everybody knows 1) re-entry after achieving orbital speeds is non-trivial, and 2) doing a stationary drop from orbital heights is possible. There is even some talk of "skydiving from orbit" So you take a B-52 out over the ocean. At 50,000 MSL, you extend two rocket pods, point the nose straight up, and take yourself out of the atmosphere post-haste. Somewhere around 200-400,000 MSL, you roll over into a standard orbit configuration. Burn about half your fuel. Once you get to where you want to go, burn the other half, reach a dead stop, then parachute into the lower atmosphere, do an engine re-start, and be on your way. I'm not saying it wouldn't be a helluva ride, but I'm failing to see the part where we couldn't have done this 20 or 30 years ago. Perhaps the problem was that folks tried to imagine some sort of new propulsion system -- and the numbers just don't work out. Instead of solving SCRAMJET, maybe that money would have been better spent on truly reusable rockets and high-performance, plane-rated parachutes? ADD: This comment was meant to address the problem of sub-orbital flight from point A to point B, not getting completely to orbit. Both SSTO and suborbital flight were mentioned in the article. My point was that suborbital flight doesn't have as many problems as we might think it does.

TeMPOraL 11y ago
> Once you get to where you want to go, burn the other half, reach a dead stop, then parachute into the lower atmosphere, do an engine re-start, and be on your way. I think that would require a shit ton of fuel. If you want to actually achieve orbit, that's at least 7.8 km/s of Δv to do it, and that much again to reach "dead stop". Your B-52 would have to be carried on a booster rocket, as opposed to carrying one. A suborbital trajectory would make more sense, but that's generally what the US has ICBMs for.
- deleted 11y ago
  [deleted]
mnw21cam 11y ago
The amount of energy required to lift an object to 50,000 feet altitude under mach 1 is insignificant compared to the amount of energy required to achieve orbit. You're basically talking about making a rocket, but saving a very small amount of fuel by starting a little higher in the atmosphere. Then you double the delta-v required by having a dead stop in orbit. That much delta-v would require a very large multi-stage rocket indeed, which defeats the object of your exercise.
- DanielBMarkham 11y ago
  Yes. Apologies. I will make an addition to my comment. I was only addressing sub-orbital flight, not orbital flight. The initial article was about the old NY-to-Tokyo in 2 hours thing we've been reading about for ages. You cannot make orbit, but you should be able to go a long ways ballistically. Add: A great way to learn about the energies involved is to create your own simulator in your programming language of choice. The ballstic/orbital math isn't that hard, and you don't run into a huge number of problems just modeling how to get to orbit. I did this many years ago, and concluded that for non-biological items, mass drivers win hands-down. Unless the magic of field propulsion finally happens, taking your own fuel along with you sucks.
rayiner 11y ago
In your hypothetical, the initial flight is doing almost none of the real work and you might as well just launch that booster from the ground. Look at the rocket equation. You have to achieve a given delta-v to get into orbit. That drives the required mass ratio of the rocket. Getting up to 500 mph or whatever a B-52 can do basically has negligible impact on the required delta-v, so the require rocket size is no smaller. SCRAMJETS are interesting because they can get up to a significant fraction of the required delta-v while in air-breathing mode. They can do that because unlike a traditional jet engine, they don't have to slow air down to subsonic speeds for combustion. That's what drives the maximum speed of traditional jet engines. Edit: saw your other response. Delta-v is still an issue for suborbital trajectories. Hitting 100 km altitude requires a speed of about 3,200 mph. If you've got a subsonic air breathing stage, you're still not getting much benefit. The big benefit of SCRAMJETS for suborbital flight is that they can hit the required speeds in air-breathing mode the whole way. No need to carry around heavy oxidizer.
ashark 11y ago
It takes way more fuel to reach a dead stop in orbit than it does to just nudge yourself down into the atmosphere and let friction do the work for you. Waaaay more. And you have to lift all that extra fuel into orbit with you, which means even more fuel.
jessriedel 11y ago
"Suborbital" refers to a ballistic trajectory that is "close" to an orbital trajectory, so that the projectile follows an unpowered arc, but one that is not wide enough to achieve orbit. The energy required for suborbital trajectories is still in the same neighborhood as orbital flight. The reason your proposal doesn't work is that during the portion of the trajectory outside the atmosphere, you either need to be ballistic (and therefore suborbital if you're traveling intercontinental) or you need to be constantly directing a portion of your rockets thrust downward. The latter is fantastically inefficient, which is why planes operate in the atmosphere (where they can use air to convert efficient horizontal thrust to lift) and why suborbital rockets are ballastic for the large majority of their flight.
- mikeash 11y ago
  Suborbital just means you went to space but didn't achieve orbit. There's no requirement to be "close" to an orbital trajectory. Blue Origin's New Shepard and Virgin Galactic's SpaceShipOne are classic examples of suborbital spacecraft, and neither of those came anywhere near orbital speed.
- vpribish 11y ago
  Appreciate that you are trying to help here, but there is a lot that is simply wrong or confused in your comment. Suborbital does not imply "close to orbital", and does not require an amount of energy in the neighborhood of that for orbital flight, and ballistic/intercontinental/efficient-horizontal-thrust is just a very muddled way to think about this.
mikeash 11y ago
An empty B-52 is about 83 tons. Add in 35 tons of rocket propellant (assuming liquid hydrogen, others will be worse) with no additional tankage or engine weight and you get about 3.7km/s of delta-v. Expend half of that on a suborbital trajectory, and you get about an 85km trip. Not terribly useful.
Merad 11y ago
Your hypothetical is missing the part where the rocket pods tear the B-52 apart and a flaming ball of debris falls to earth. You see, to accelerate straight up (or nearly so) your thrust must be greater than your weight. To get enough acceleration to be useful, you usually need an amount of thrust that's more like 1.2x your mass. For example, the fully loaded Saturn V weighed about 6,500,000 lbs and the first stage had 7,650,000 lbs of thrust. So your fully loaded B-52 (~265,000 lbs) needs around 320,000 lbs of thrust from the rockets. This is more than double the amount of thrust produced by the jet engines. By the time you've accounted for your rocket engines, strengthened the airframe to survive the rocket thrust, and added a reaction control system (to turn around for deceleration), you've lost a good chunk of your 35 tons of rocket fuel. It's about this time you realize that even 35 tons of rocket fuel is a laughably small amount. A single space shuttle main engine is a bit more powerful than what you'd need (~420,000 lbs of thrust), but it's good enough for ballpark numbers. It will consume 35 tons of fuel in about a minute... meaning your mission profile is probably something like 30 seconds of vertical acceleration, 15 second horizontal acceleration, 15 seconds horizontal deceleration. Not enough to take you very high or very far. It's not that we can't do it, it's that it's woefully inefficient.

walkingolof 11y ago

Great article! For the latest developments: https://en.wikipedia.org/wiki/Skylon_(spacecraft) https://en.wikipedia.org/wiki/Skylon_(spacecraft)

irremediable 11y ago
How much of a future do you think the Skylon project has? A couple of friends in the aerospace industry have told me they think SpaceX will effectively "win" now that they can land the Falcon. Are they too optimistic about SpaceX?
- deleted 11y ago
  [deleted]
- creshal 11y ago
  All SpaceX did was building a normal rocket that can land again. Which, as it turned out, was anything but trivial and took 14 years. Their main competitors – ULA and Arianespace – already announced they won't be able to manage similar capabilities this decade; and their plans for the next decade are still not as sophisticated as SpaceX's approach (they only want to recover the engines and build a wholly new stage around them). Skylon is a massively more ambitious undertaking compared to that – if it works, it'll be the first practical SSTO, the first horizontal takeoff spaceplane, the first vehicle to use multi-mode engines, the first practical space plane to use a novel heat shield technology, … That's an awful lot of challenges to tackle. If it turns out to work, and if it then turns out to be as re-usable as hoped (something that did never panned out for the Shuttle, and which SpaceX will only learn over the next years for their Falcon), then it could beat SpaceX… in a decade or two.
  - mikeash 11y ago
    The trouble with Skylon is that all of these things you mention make it more ambitious, but they don't really make it more useful. The main advantage Skylon would have over the Falcon 9 is the fact that the Falcon 9 is not fully reusable because they don't and can't recover the second stage, while the entire Skylon is recovered. That's significant, of course. The second stage makes up about 25% the cost of the rocket, so that places a ceiling of about 75% on how much Falcon 9 reusability can save.. But then, starting from where the Falcon 9 is now, building a new rocket that can also recover the second stage doesn't seem too difficult. It's a big challenge, to be sure, but relative to Skylon it's not too bad. Skylon is certainly much more ambitious in terms of how it works, but it doesn't seem to be very ambitious in terms of what it can do, which is not a promising combination.

ck2 11y ago

And just think today we can't even get Congress to fund repair crumbling infrastructure - why do today what you can wait for a national crisis tomorrow?

Shivetya 11y ago
while the numbers are large when measured in percentages it isn't that bad. Most of the deficient bridges are locally owned, this means at levels lower than state level. No one also ever seems to mention that at is peak in the 90s there were nearly 150,000 bridges found to be deficient and that number is down to near 60,000. In other words, the Federal government isn't responsible for most of what is out there and many state and local governments refuse to fully fund their own obligations.
- randallsquared 11y ago
  > No one also ever seems to mention that at is peak in the 90s there were nearly 150,000 bridges found to be deficient and that number is down to near 60,000. Wow. No kidding that "no one also ever seems to mention"! That puts things in perspective a bit, doesn't it?
  - twoodfin 11y ago
    Believe you me, "crumbling infrastructure" has been a constant talking point of those who want greater federal spending for decades. Not to say it's all crying wolf, but if it had been true the whole time it was being complained about, by now things would be more obviously crumbled. State governments in particular love federal infrastructure spending, since it is more or less a direct cash transfer to a) their own budgets, where local infrastructure spending can crowd out other priorities and b) the politically potent building and construction trades.

Shivetya 11y ago

So how does the new SABRE engine factor into this? Originally a lot of skepticism was there but BAE did invest in it so it might pan out

Gravityloss 11y ago

"DuPont’s configuration devised under COPPER CANYON had included no landing gear, orbital manoeuvring system or fuel reserves." I've long held the opinion that the real lesson to take from NASP is that the higher the level of decision making, the more detached it is from physics or business. Air breathing works for cruise (limited speed and altitude range, long duration, low thrust requirements). Rockets work for acceleration (wide speed and altitude range, short duration, high thrust requirements). Orbital missions are only about acceleration. Bringing very heavy air breathing engines to orbit doesn't make sense at all. The lowest dry mass (=lowest cost) single stage to orbit vehicle designs tend to be dense propellant pure rockets. In Finnish there's a saying "ajaa käärmettä pyssyyn": make the snake go into a gun barrel. An organization trying to achieve a needlessly hard thing because of political reasons. Closely related to Not Invented Here.

high_frontier 11y ago
I agree with your thoughts on the decision making behind NASP. Even while it was still COPPER CANYON, doubts were being raised. Most of the big decisions to proceed seem to have been made after relatively brief presentations with limited technical detail or discussion. NASP was a case of selling a big picture without stopping to ask how possible it really was. Personally, I find the X-33 more frustrating as this got far closer to flight and although it may never have led to VentureStar it would have been a great hypersonic testbed
- Gravityloss 11y ago
  Nowadays we do get critical articles about programs like the Joint Strike Fighter, but often they seem a little bit besides the point, for example comparing it to seventies design paradigms. The lightweight fighter mafia is emphasizing dogfighting, visual identification and gun kills, from an era when missiles were very unreliable and there was no stealth. I guess it would require a lot of expertise and access to rare information, to be able to evaluate the JSF on its own merits. Stillion and Sweetman have been the most interesting reads. I think the problem with X-33 was that it was too big and risky for an experimental-only platform. If you want to develop things like aerospike engines or composite multilobe tanks, you should first have ground tests and then relatively small demonstrators using a lot of off the shelf technology. It makes no sense to bet so much stuff on a multi-faceted big expensive program that can fail when any of it components doesn't deliver. Or if you want to build something big, either use proven technology or retire risk in smaller programs first. I guess people were emulating Apollo and the Space Shuttle. They had high performance but were not flexible or low cost, for a reason.

sandworm101 11y ago

If the super-rich are in that much of a hurry to get from london to newyork that they will pay the ticket prices needed to sustain such an aircraft, I have a better idea. Build some mercury capsules. Stick them and a solid upper stage atop a one-engine version of a SpaceX booster. For what, 40K worth of fuel and upper stage (?) billionaires can now fly solo to NY in minutes, experiencing all the majesty of vomiting in zero G. Think of what suborbital, zero-G, would be like in a plane with 100 passengers. Given the forces involved I cannot see suborbital transport ever replacing first class seats on BA.

api 11y ago
A more luxury version of this is what I've long suspected the Virgin Galactic project to be: suborbital flights around the world. I've long thought it to be a stealth suborbital spaceplane effort that would add a very expensive but extremely rapid long range flight option to Virgin's lineup.
- sandworm101 11y ago
  Virgin Galactic is suborbital, but the scheme has nowhere near the velocities necessary to cover any distance. It's just a rollercoaster. There is little point in launching a transport from a plane. Getting to 10,000m is nothing compared to the speed needed for london-NY.

quattrofan 11y ago

Likely this dream will be achieved but perhaps not by the US: https://en.wikipedia.org/wiki/HOTOL https://en.wikipedia.org/wiki/HOTOL http://www.reactionengines.co.uk/ http://www.reactionengines.co.uk/

Balgair 11y ago

Hm, maybe add in fuel rods in place of the fuel to generate the heat? I mean, sure, an open and unshielded just sub-critical reactor is going to have 'environmental effects'. But if the point, from the black budget perspective, is to have an under the radar bomber, the environment is going to shit anyways. Project Pluto is a good, and completely insane, starting point into nuclear scramjets. https://en.wikipedia.org/wiki/Project_Pluto https://en.wikipedia.org/wiki/Project_Pluto Choice Quote edit:"After delivering all its warheads, the missile could then spend weeks flying over populated areas at low altitudes, causing tremendous ground damage with its shock wave. When it finally lost enough power to fly, and crash-landed, the engine would have a good chance of spewing deadly radiation for months to come"

Animats 11y ago

Ben Rich, while he was head of Lockheed's Skunk Works, looked at the proposal, and decided they would not bid. He'd worked on the SR-71, which was the highest performance aircraft ever built. His comment: "We used titanium. You know something stronger?" Getting rid of the heat was the biggest problem. Rockets which launch vertically don't spend much time in the atmosphere. Aircraft which accelerate horizontally do. Hypersonic in-atmosphere travel means having to get rid of huge amounts of heat with no place to dump it. Running liquid hydrogen fuel over the vehicle exterior for cooling was considered and rejected for the SR-71. (Many rocket engines run the cryogenic fuel and oxidizer through cooling channels in the engine bell before using it as propellant. That's not a totally unreasonable idea.) The X-30 was supposed to have a big cabin, which would have to be kept cool. Only a small part of the SR-71 is kept cool; the pilot is in a space suit. Even cooling the pilot was hard. Remember, at hypersonic speeds in atmosphere, there's no place to dump the heat; you have to bring your cold with you. The only real advantage of this approach over rockets which get out of the atmosphere as soon as possible is that you don't have to carry oxidizer. That improves the mass fraction (rockets to orbit are > 90% fuel). Not enough to be a win, though.

high_frontier 11y ago
It's interesting to note though that although Ben Rich explains that they decided they wouldn't bid, Lockheed WERE one of the airframe contractors in Phase 2 and it's difficult to imagine that the Skunk Works weren't a part of that effort especially given the work they did towards the scramjet powered X-24c in the seventies. Also, they went on to the X-33 in the mid 90's so clearly felt confident in a suitable "something stronger" thermal protection system by then

trhway 11y ago

btw, the BrahMos 2 Indian-Russian cruise missile coming in 2017 (well, of course there is always a big "if") is scramjet powered and expected to fly at Mach 7. https://en.wikipedia.org/wiki/BrahMos-II_%28missile%29 https://en.wikipedia.org/wiki/BrahMos-II_%28missile%29