Over here I posited stealing space flight tech … The SR71 basically got almost into space, realistically how the hell more difficult could it be to actually bump it into space like the space shuttle? Lose the specialty coating, it doesn’t need to be sneaky, the crew are already in pressure suits and breathing bottled air. sigh We were supposed to have L5 space colonies by now, where is my cubical and space suit?
Just off the top of my head: how would you generate lift at higher altitudes?
Blackbird top speed at a little over 2000 mph. Orbital velocity something over 17000. I’d say it would take quite a bit.
And how about generating thrust? The SR-71 had jet engines, which are air-breathing. You can’t just keep going up, because you eventually run out of air. That, also, has the aforementioned detrimental impact on lift generation.
You’re going to have a hell of a time getting back to earth if you do achieve orbit. Those jet engines are going to be useless without oxygen.
The problem with “rocket planes” and space flight isn’t getting them into space, its that orbital velocities are a lot higher then that needed simply to get up that high. The SR-71 only goes some one thirtieth of the speed needed for LEO. There isn’t really any way to get an aircraft that relies on wings for lift up that high with enough fuel to get it up to orbital velocities. The best plane-based lift systems like Spaceshipone can do is go up and come right back down.
Getting into orbit and staying there requires a lot more than just going up. You can fairly easily put a capsule into space (that is, above the atmosphere) but unless it’s going at orbital velocity it’ll just fall right back down. The SR-71 is going at about 1/8 of orbital velocity. Energy requirements scale as to the square of speed, so you’d need about 64 times the energy to get it to orbital velocity. Also, it’s using air-breathing engines, and steers by aerodynamic control surfaces, relies on external airflow for cooling, and doesn’t have the capacity to survive reentry from orbital speed. You’d have to change it so much that you’d end up with something much like the Space Shuttle by the time you were finished.
This is one of the biggest misconceptions I hear about space - it seems that many think that once you’ve left the atmosphere of Earth you are weightless and free to fly whereever you want to go!
The edge of space is usually defined as 50 miles up and the Space Shuttle flew about 200 miles up. If I built a platform 200 miles up which you could climb to using a ladder you’d still feel a strong pull towards the Earth. It would be less than you’d feel at ground level but not significantly so. If you jumped off of it you’d fall straight down.
So why do people that fly to space look weightless even if they aren’t in orbit? In the case of Spaceship 1;or the suborbital flights of the earliest space capsules; once the vehicle reaches altitude they cut engines and just free fall back to Earth. Since the astronaut and vehicle are falling at the same rate the astronaut appears weightless with respect to the capsule around him so he and everything around him appears to float.
Orbit is attained when the capsule or shuttle achieves a horizontal speed so high that the Earth curves away from the vehicle at the same rate that the vehicle is falling towards the Earth. As mentioned above this is about 17000 MPH. Most physiscists don’t like to say the shuttle and astronauts are weightless, they prefer the more accurate term that they are in free fall. Everything in the vehicle is falling at the same speed towards the Earth, they just keep missing it!
The reason orbital vehicles need heat protection is that the atmosphere is the most efficient way to slow down. More accurately they’ll fire small retro rockets to slow their forward motion enough that they fall into the upper part of the atmosphere which then slows them enough to fully reenter. At those speeds the friction is so intense that any unprotected vehicle would melt. Exotic materials are needed that can withstand that heat long enough to slow the vehicle.
Getting into space isn’t the issue. *Staying *in space is complicated and getting back more so.
All wonderfully informative answers =)
I ask because I am not a rocket scientist, nor have I stayed at a holiday inn lately:D
I am just grumpy that we have lost space access 
They’ve known the end was coming for over a decade. Bush started a half-hearted effort; Obama now too. There’s enough blame for both parties.
The shuttle was 1970’s tech. The computers were dumber than your iPhone (dumber than a COmmodore 64!) and the code to run the shuttle equipment was a million lines of custom-written code. You don’t just drop in a bigger faster processor… The other tech while not so outdated (i.e. metallurgy tech probably does not age as fast as computers) is equally old. A system refresh was needed.
Everyone knew it was coming but like the deficit battle, nobody wants to stick their nec out and make a decision. Capsule technology is not rocket science (oh, wait, it is…) They’ve built them for 50 years, they know what works and what doesn’t in space. It’s just a matter of settling on a technology and doing the full design and construction. Considering Boeing just spent how many years building a new jetliner, it does take a while to fully design and complete a piece of high tech.
Simple would be to build a generic capsule and generic rocket so that no matter what rocket, you just attach the payload; no matter what rocket, the capsule will work with it. That requires even more money, and nobody wants to shell out today.
To answer the OP, as pointed out orbit speed requires 17,000mph. As you “fall” around the earth, you are going fast enough that the arc of your “fall” curves around the earth instead of hitting it. Alan Shepard was the first American in space, Mercury-Redstone 3 - Wikipedia but he just went up 116 miles and across 300 miles to splashdown. And… 3 weeks after Gargarin orbited the earth. (This is what Virgin is planning doing - which is why their rocket is not mostly fuel tank…)
The X15 was a rocket rather than a jet, and reached about 4500mph and 60 miles high with a head start being dropped off a big bomber at altitude. This is still short of orbit. Wikipedia mentions that the Air FOrce was planning launching one on a Navajo missile which might hav reached orbit.
Note the big problem - speed, aka energy. To go twice as fast requires twice as much energy (ignoring air friction). But, you need to carry the fuel for the second half as “twice as fast”, meaning you need even more fuel for the first half, and so on. It’s a vicious cycle. to reach orbit, most rockets need to be about 90% fuel by weight. To get around this, most systems use stages, so you throw away heavy but empty tanks and the bigger engines once that part of the fuel is gone. If you want a fancy toy with wings, rather that a minimalistic disposable capsule, the fuel requirements go up accordingly.
There’s a reason why it’s not just a matter of building from off-the-shelf right now. The private companies doing this (like the Falcon) generally are building smaller rockets that will launch your smaller satellites into space in low orbit. The real money is in launching stuff that is the size of a small bus and has an extra stage to launch beyond low orbit; up at 22,300 miles an orbit takes 24 hours and a satellite stands “stationary” above a point on the equator. That tech is still a national endeavour by NASA contractors, ESA, Russia or China.
Twice as fast is four times as much energy.
At least it’s been well tested. Can you imagine it otherwise?
Captain: “Calculate the burn to Mars and configure the engines for the trip.”
Navigator: “Captain! The nav computer is saying that BurnData GetBurnDataToPlanetaryObject(SpaceLocation currentLocation, Trajectory currentTrajectory, EngineConfiguration shipEngineConfiguration, Planet planet) is throwing a DivideByZeroException on line 24!”
Captain: “This was written by drunk CS students on a summer internship, right?”
Max altitude was 67 miles - over 100km - which qualifies as spaceflight.
The X-15 was certainly a lot closer to what the OP seems to be seeking: flew much higher and faster than the SR-71, did not rely on air-breathing engines (useless in space), and had a reaction control system to take over when aerodynamic controls became ineffective. But it would have required much more development to make it or its derivatives capable of reaching orbit and returning safely.
I’ll just mention the single-state-to-orbit spaceplane called the Skylon. It hasn’t been built yet, but is using several innovative features: it breathes air as a jet until it hits Mach 5.4, at which point it switches to rocket propulsion; the engines are designed (as I intimated) to work both ways, and have an intercooler to solve the issue of overheating the engine parts at speed; and it’s very fuel efficient. It thus should be able to carry enough fuel to get it into orbit without the weight of said fuel being too prohibitively heavy.
One aspect about the Shuttle software: it never crashed, never hung, rebooted, nor even acted “buggy” during any of the Shuttle flights. Not once.
To be fair, it’s not a fair comparison to make with Windows or other software goodies we buy online. The Space Shuttle platform was pretty much fixed in 1980, unlike, for example the PC evolving from Intel 8086 verses whatever the hell Intel or AMD are putting out today.
And FWIW, the Shuttle was originally designed to help ferry supplies to a space station. This was to be used in conjunction with the long-term goal of putting a permanent base on the moon. When the space station was cancelled, the Shuttle was a solution in search of a problem. That was Nixon’s call at the time, and I don’t recall anybody being outraged about the decision–we’d beat the Russians and bigger problems had developed (Vietnam, inflation, etc.).
The Karman line actually starts at 100 km (62 miles). While the definition of “the edge of space” is somewhat arbitrary, this is the most widely recognized boundary to space.
Pedantic nitpick; most of the heating does not come from any kind of friction, i.e. direct interaction between particles of the air and the tenuous atmosphere, but rather compression heating of the air forward of the vehicle (called ram pressure). This rapid acceleration of air from a quasi-static condition to the speed of the vehicle results in extreme heating, which causes the air to radiate heat onto the nearby surfaces as it flows around the vehicle. This is intensified in complex and sharp-featured geometries by shock-shock interactions between compression boundaries, which results in thermal amplification; in layman’s terms, the hot air at one boundary transfers energy to the hot air at another boundary where those boundaries cross, resulting in very high heating. This is why the Space Transportation System (STS) Orbiter Vehicle had a slightly melted look, and why all other manned space capsules have a blund-arsed shape, which has no sharp boundaries and creates a protective sheath of compressed air that forces heated air away from the capsule, requiring only a relatively simple thermal barrier on the aft end instead of the complex and delicate system of thermal tiles, blankets, and reinforced carbon-carbon leading edges that were critically damaged on the doomed Columbia.
In the past, there were many proposals for two part shuttle or rocket launch systems using a conventional high speed, high altitude aircraft as the first stage as a carrier for a rocket-propelled second stage. This can be found in many of the early phase proposals for the STS, as well as the Soviet Spiral 50/50, and other proposals in the 'Eighties. However, while it allows for horizontal take-off and return of an almost immediately reusable lower stage this approach has a number of problems. For one, the size of upper stage than can be reasonably carried is fairly limited and/or the amount of impulse that the carrier stage can impart is small. You either end up with a subsonic jumbo jet carrier aircraft, or a high supersonic carrier like the A-12 or SR-71 that can only carry a small payload.
Second, there are a lot of problems with separations at high supersonic speeds that can result in recontact between the carrier stage and the upper stage, which is usually catastrophic as discovered in efforts to allow the SR-71 to carry a deployable UAV. The cost savings turns out to be not that impressive, either; the Orbital Sciences Pegasus air-launch vehicle is not especially cheaper than other ground-based launch vehicles, although the ability to launch from essentially any azimuth does allow greater flexibility in orbit parameters. The SpaceShipOne and SpaceShipTwo vehicles use this same mode with their respective White Knight carrier aircraft, but of course they barely reach the Karman line and do not get anywhere close to orbital speed, nor could they survive return from orbit.
Efforts have been and continue to be made to develope a single stage spaceplane-like system that takes off vertically, uses rocket propulsion to achieve orbital speeds, and then returns via unpowered gliding (VTHL), such as the Lockheed Martin X-33/VentureStar but this requires the vehicle to carry both oxidizer and fuel, where an air-breathing aircraft stage need only carry oxygen. The techical hurdles in making the vehicle light enough to achieve orbit with onboard propellant seem to be unattainable with existing materials. There are also some efforts to develop a horizontal takeoff/horizontal landing (HTHL) vehicle, the most notable of which are the HOTOL and follow-ont Reaction Engiens Skylon, which uses the SABRE dual model (air breathing and internal oxidizer) engine; however the SABRE is at a very immature stage of development (technology readiness level 2, where TRL 7 is the threshold for full scale flight testing and TRL 9 would be required for operational flight) and may have some fundamental problems that make it unsuited to a manned vehicle.
An even more fundamental problem is that spaceplane type systems are inherently delicate due to the complex reentry heating modes referenced above. You either end up with a blunt shape like the OV that is poorly suited to hypersonic speed to orbit, thus requiring more oxidizer carried to achieve orbital speeds above the atmosphere, or a sharp-featured aircraft that results in heating problems that cannot be resolved with conventional materials without active cooling systems. And all of this is to support a particular feature of the vehicle that is only used for a few minutes of the total operation. The blunt arsed capsule shape, on the other hand, provides more internal volume per “dead” (non-payload or propellant) mass and is easier to design for safe reentry. In fact, the Gemini and Apollo heat shields were so robust that the vehicles could have been reused with minimal refurbishment. The McDonnell-Douglas DC-X ‘Delta Clipper’ vertical takeoff/vertical landing (VTVL)demonstrator used a blunt arse, although it was intended for pitch down flight to attain high cross range; the descendant Blue Origin New Shepherd and Kawasaki Kankõ Maru use a straight arse-down reentry approach, as did the innovative Chysler Aerospace SERV proposal for the STS. This is, in my estimation, the most practical approach for a truly resuable single-stage to orbit vehicle using conventional materials, albeit one with payload size and mass limitations.
Stranger
Is there a reason SABRE or other airbreathing to mach 5 / hybrid solutions aren’t being chased by other commercial companies or NASA? It would seem to have a lot of advantages, whats the downsides that prevent it being adopted?
IIRC - At least one launch was scrubbed in the early days because the software crashed, or rather detected an error condition that required an abort. One article at the time marvelled at how they could isolate and fix the bugs within a week in a million lines of assembler code.
I vaguely recall the article discussing the tech, which by the time of the launches in the 80’s was considered primitive. There were 3 computers or 5 or something, and a majority had to agree for the system to work (in case the fault was a computer glitch or communication error by one of them to one of the sensors). On at least one occasion, one computer did not agree but the launch proceeded. I assume within a dozen flights they had worked out most of the problems.
Cost? When it’s hundreds of millions for an aircraft, and the market for people affording $8,000+ tickets (Concorde, anyone?) is relatively limited… and the airline industry has been close to bankruptcy for over a decade… who’s going to shell out? Without volume sales, the development costs would be too high per unit.
The US had a major lead in commercial aircraft because the military funded initial development of the tech, and even the designs. The 747 was the loser to the Galxy C5-A; who came out ahead in that competition, after the military funded both designs and then Lockheed was too busy with the contract to take on Boeing in the civilain market? Only a massive cash infusion by several European states has broken that monopoly.
The commercial market lets the military work out the kinks. Based on what the military found with the Osprey, I bet it will be a while before you see that going in and out of airports.