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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.
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Well, Skylon is supposed to do this and they are working on it.
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As ravens_cry said that's a description of the Skylon, and if all goes well the answer to how far in the future is 2020, though we will know if the key technology works in the next couple of months.Originally Posted by r4758
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There are also a couple of vehicles in development that fulfill some but not all of the criteria. The Lynx would take off from a runway but is suborbital while the Dreamchaser is orbital but would be launched on an Atlas V.
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And a bikini (two piece) orbital craft can still be cheap, what is important is that reusability, servicing and reliability is like an airplane. (A commercial airplane, not a military jet.)
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You mentioned the shuttle, which is a manned vehicle. Skylon is a concept for an *unmanned* horizontal takeoff and landing space plane. It would not be piloted or crewed like the shuttle.
Ideas for various space planes have existed since the early 20th century. However due to factors which may not be immediately obvious, it is much more difficult reach orbit with a single stage regular rocket, and an air-breathing, horizontal takeoff SSTO is probably the most difficult kind of SSTO to make: http://en.wikipedia.org/wiki/SSTO
The United States spent several billion dollars on the National Aerospace Plane (NASP), or X-30. It was intended to be a manned vehicle which would take off and land horizontally, and fly into orbit. It was deemed not possible at the available levels of funding and technology: http://en.wikipedia.org/wiki/X-30
NASP was technologically very ambitious and developed most of its orbital velocity with airbreathing propulsion. It's possible a different approach might work better.
However all horizontal takeoff/landing approaches share common problems. The main problem is reaching orbit is very weight-critical. That's why rockets drop stages. Single-stage horizontal takeoff means you must have wings, landing gear, airbreathing propulsion, structure and thermal protection for all those. You must haul all that extra mass to orbital velocity, which makes getting there harder.
It's not necessarily impossible, but basic physics and engineering make it more difficult to reach orbit this way than other methods.
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Laser propulsion seems the most likely even far future. Little fuel is left for maneuvering, payload nor re-entry if the winged craft has to take off with that much fuel. Also the environment is harsh to expect to take off on the next flight to low Earth orbit without extensive retesting and repairs. Neil
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I wonder if the DH-1 would have worked. Fictional, yes, but designed to be something actually buildable.
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Well, there are still plenty of problems with a two stage reusable craft. I only know what I read in the wikipedia article about the DH-1, but there are a few things about it that I don't understand. Why does the first stage use jets to land? Rather than carrying the weight of the jets wouldn't it be cheaper and easier to carry a little extra rocket fuel? I also don't understand why it wastes a considerable portion of its 2.3 tonne payload on a biologically based control system. But, anyways, if an orbital craft could be made that only needed a quick check over and refulling before most flights, access to orbit would be relatively cheap.
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How about 40 years ago?How far into the future? An aircraft that launches from a runway and enters low
earth orbit?
The X-15 was designed to mount external fuel tanks and go into orbit.
They stopped them from doing it and shut down the X-15 program to keep
space 'non-military' (despite the fact all the astronauts were military test pilots.)
http://www.astronautix.com/lvs/x15a2.htm
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The X-15 was never designed to fly into orbit, it lacked an adequate heat shield for one thing, that was why the USAF commissioned the X-20 design. The X-15 also could not have taken off from a runway and the page you link to simply describes the stretched drop tank version version of the X-15 that reached a high but still suborbital altitude.
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There was the plan for the X-15B, but it was hardly an SSTO and the craft was ditched at the end of the flight.
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It is *unpiloted*. That doesn't mean it can't carry a passenger module with people in it. Actually REL has released their concept proposal of how that will work.
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With regards to Skylon's 2020 target date, it is also worth noting that this is not the same as a government agency putting something 9 (or more) years in the future. When a politician schedules something to occur beyond his term of office, he is saying he absolutely is not going to deal with that. The people at reaction engines have poured a large portion of their professional lives into developing this concept, so their predictions, even if not correct, are at least sincere.
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There are several problems with this: Skylon isn't man-rated, so it's not certified to fly humans. Assuming this was ever done, the passenger module has no launch escape capability. It's even worse than the shuttle -- there's not even bailout capability.
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That's incorrect. Information about the passenger module is sparse on their corporate website, but if you do a bit more reading you will find that the module is designed to survive breakup of Skylon and land with parachutes.
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My statement was absolutely correct. I said Skylon has no launch escape sytem, which is a fact. There is also no bailout capability.
If Skylon is ever funded and built, IF it's ever man-rated, then IF the passenger module is built, as currently conjectured it will have a parachute. But this is NOT a launch escape system, nor bailout as normally defined. If the vehicle broke up, IF the passenger module was luckily thrown free, IF it maintained integrity, IF the parachute system wasn't damaged by the breakup, and IF the module luckily assumed stable attitude permitting parachute deployment, in theory it could be deployed.
However even purpose-built, rocket-powered cabin ejection systems like on the B-1A and FB-111 have a relatively poor record. And those -- which ARE properly termed escape or ejection systems -- are specifically designed for ejection, post-ejection stabilization, and either water OR land touchdown:
http://www.f-111.net/ejection.htm
It's good the primary design purpose of Skylon is an unmanned, cargo-carrying vehicle, because it appears if a passenger-carrying Skylon ever had to ditch in the ocean it would not be survivable.
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Its still an escape system, don't split hairs.
No escape system from a spacecraft is going to be perfect. You don't *want* to have to use any of them.However even purpose-built, rocket-powered cabin ejection systems like on the B-1A and FB-111 have a relatively poor record. And those -- which ARE properly termed escape or ejection systems -- are specifically designed for ejection, post-ejection stabilization, and either water OR land touchdown:
http://www.f-111.net/ejection.htm
It's good the primary design purpose of Skylon is an unmanned, cargo-carrying vehicle, because it appears if a passenger-carrying Skylon ever had to ditch in the ocean it would not be survivable.
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But if you do, you really, really, don't want it to fail.
I believe a Soyuz capsule actually had to use its launch escape system at least one point in a real incident. Thankfully, it all went without a hitch.
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By why would it need launch escape capability? It is not a rocket. It takes off horizontally, like an airplane. Which means that if it has an engine failure or something like that, it becomes a glider. Not a very efficient glider, but having wings at all, it should be able to fly controllably for at least several seconds -- long enough to assume correct attitude and eject the passenger module...
Besides, we do not expect passengers to survive breakup of an airliner; we expect the airliner not to break up.
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With a hitch, but in the end it worked: http://en.wikipedia.org/wiki/Soyuz_T-10-1
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It is NOT an escape system as normally defined, and it's NOT splitting hairs to state that fact. The purpose of words is to accurately convey meaning. If those words give most recipients the wrong meaning, that's misleading.
You can query on aircraft or spacecraft escape system and see how it's almost always used. Virtually nobody would consider the vehicle breaking apart and luckily deploying a parachute as an escape system.
Even if you split hairs and definite it as such, that's just a word game. It has almost no utility. You can't escape off the runway, or during powered flight, or during gliding flight, or during an emergency landing on land or sea. The passengers are sealed within the module, which in turn is sealed within the cargo bay. They have less ability to escape than passengers on a commercial airliner.
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Skylon mostly doesn't need launch escape, since it's mostly an unpiloted, unmanned cargo carrier.
However if it ever carried humans, the reality is it's a cryogenically-powered rocket in the shape of an airplane. The appearance is misleading. The energies, stresses and risks are on scale of a rocket not an aircraft.
To give one example, each turbopump on the space shuttle produces 50,000 shaft horsepower in the volume of a trash can, and there are six of them. Skylon's engines are nearly as highly stressed as the shuttle from a chamber pressure standpoint.
Commercial aircraft almost never explode in mid flight. Rockets do. They are so lightweight and highly stressed, they tend to fail catastrophically or not at all.
If you fly humans without an escape system, then ensuring reliability becomes even MORE expensive and time consuming. There's no escape realistically possible, so this further ratchets up the stringency of needed checks. In turn this make development and servicing for re-flight slower and more expensive.
Becoming a glider is useful for an airplane, that's why you have a safety lecture about evacuating. Even if Skylon never failed catastrophically during ascent, gliding is a moot point. It can only land on a few runways, ocean ditching isn't survivable, and there's no way for the passengers to quickly disembark. They are sealed inside. In most cases gliding would simply prolong the crew's inevitable fate.
There is NO ability to eject the passenger module on command. The passengers are sealed within the passenger module, which in turn is sealed within the cargo bay. It would be similar to the shuttle carrying passengers within the SpaceLab module during ascent and reentry (which was never done): http://en.wikipedia.org/wiki/Spacelab
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"Man rating" is largely a NASA bureaucratic process. Skylon as proposed now is supposed to be at least a hundred times safer than any rocket that's currently being used. If the US authorities don't certify it, well, who cares? And saying that, if the suborbital vehicles are certified, there is no reason Skylon shouldn't be.
Actually, REL wants the passenger module to remain inside Skylon in case an accident occurs. Since the passenger module is a self contained unit, it can provide a degree of protection to the crew - Skylon is very large, so the body should work as a deformation zone when it crashes.Assuming this was ever done, the passenger module has no launch escape capability. It's even worse than the shuttle -- there's not even bailout capability.
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And that's the point For the bulk of it's flight profile the Skylon is in effect an aircraft, it makes sense that you take the same approach you would to airliner safety, which means in most survivable crash scenarios the passengers are better off in the plane. A LAS equivalent doesn't seem to offer much in the way of extra safety for a HOTOL configuration.
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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.
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May be you will find this interesting : http://www.thespacereview.com/article/1894/1
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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 . Considering the crossection /frontal area of such a craft, it will be surprising to see how it flies and in what attitude. And what kind of full-up weight are they talking about ? And orbital velocity,.....17,000 MPH + ???? Really ? We haven't even talked about wings or lift yet.
Maybe some drag going on here,no?
Order of Kilopi
Try mach 8.
With a separate turbojet engine for runway takeoff and landing and flight to Mach 2.5, a ram-scramjet engine thereafter to Mach 8, and a rocket engine for ascent thereafter to orbit
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It would help if you told us which vehicle you are talking about because the article mentions several different programs, assuming you are referencing the link in Galacsi's post.
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