Space Plane - Space Plane

GCNRevenger · 2004-03-09 11:52:49

And I think it is fundimentally the best way, provided it can be made to work, because of vast savings in propellant weight and lower peak thrust demands.

And actually, Shuttle does not experience that much horrible heating over the majority of its underside, around 2000 degree which is manageable and only hitting the 3000 region on the leading edges. Some Shuttle tiles in less critical regions have been replaced by metal ones experimentally.

A Scramjet plane will be even better, since most of its surface is parallel to the air flow, and with super-high-temp ceramics being developed and/or active cooling worked on in the 60's should make up the difference just fine. In fact, with active LH2 cooling, the atmospheric friction will actually preheat the fuel.

And as far as aerodynamic control is involved, it need not handle like a F-16, and with intertank pumping (which you can't do well on a high-G acending rocket) or retractable control surfaces... in addition to advanced FBW controls... I think the problem is solveable.

Concept: Simply because the Scramjet vehicle is more complicated does not make it "bad" compared to a DC-X style VTOL-SSTO.

Concept: A TSTO launcher of any sort will inherintly be harder to fly often (an ultimate goal) because of the modes of recovery for the spent booster stages and the need to partially rebuild, not merely reassemble, the vehicle on each flight.

Lars_J · 2004-03-09 12:46:20

Of course SSTO would be preferable to TSTO, and certainly cheaper to operate. No one is arguing that. But does that mean that we should abandon spaceflight until we can do SSTO?

I only suggest TSTO as an interim solution, that clearly is workable with technology that exists *now*. The beauty of the VTOVL approach is that as engine performance, fuels, and structural materials are improved, one can gradually evolve into a SSTO RLV.
1. Build a sub-orbital test vehicle (similar to the DC-X) Gradually fly higher and higher, pushing the envelope.
2. Scale it up, and add a second stage for TSTO orbital access.
3. As performace improves, 1st stage comes closer and closer to orbit. Eventually it will require no 2nd stage and will become SSTO.

Concept: Simply because the Scramjet vehicle is more complicated does not make it "bad" compared to a DC-X style VTOL-SSTO.

Perhaps, but if all other factors are equal, simplicity wins out every time. The more parts you have, the more things can fail.

Concept: A TSTO launcher of any sort will inherintly be harder to fly often (an ultimate goal) because of the modes of recovery for the spent booster stages and the need to partially rebuild, not merely reassemble, the vehicle on each flight.

But TSTO is not the ultimate goal, just a practical intermediate step. (BTW, it is quite possible to design completely reusable TSTO systems, both winged and vertical)

Ian · 2004-03-09 13:11:49

I think that the idea of a space plane is cool. It would go outside the atmosphere into space and back down for a landing somewhere else on earth. People have to make sure that this technology isn't misused.

GCNRevenger · 2004-03-09 13:28:16

You'd be surprised... some of the X-Prize/"Alt Space" folks are so adamant that TSTO is so much cheaper that SSTO is ultimatly less efficent, which is kind of silly.

And i'm not so sure that TSTO VTOL is quite as evolutionary as you'd like... there is a threshold of efficency where SSTO becomes practical, and since this is most likly quite a bit higher efficency than what is needed for a good TSTO, the will to push the technology from TSTO optimum to SSTO minimum may not be there. TSTO may be practical, but i'm not sure i'd label it as an intermediate.

I do like the ol' DC-X and its children, but its still a massive rocket with a relativly tiny payload since it has to lug along so much propellant mass and extra engine power. Plus, unless the rocket can land verticly on a pad, recovery costs and turn-around start getting pretty signifigant.

Ad Astra · 2004-03-09 13:35:08

In response to Lars_J, I first have to say that jet/scramjet/rocket is not the only way for an X-30 type aircraft to fly into orbit. The jet mode could be replaced with a rocket (the same one you'd use for orbital insertion) or some kind of launch catapult.

But Lars_J's ideas for true TSTO systems are very sound. I was a very sad camper when DC-X died. In hindsight, I don't think the nose-first re-entry was a good idea. Yet plug-nozzles / aerospikes are untested in the area of re-entry. But Chrysler came up with a solution when they designed their SERV SSTO: put the engines inside the rocket and have them fire through hatches on the edges of the heat shield.

My support for ballistic SSTO designs does not diminish my desire to see winged space planes; the ballistic ships might be better suited for cargo while the space planes would tend towards carring passengers. The Lockheed Starclipper is a good starting point for a spaceplane. They were foolish not to have resurrected it for the X-33 (and NASA was foolish enough to think they could get a winged spacecraft to achieve SSTO.)

Lars_J · 2004-03-09 13:39:55

GCNRevenger,
Well, TSTO would certainly be cheaper *right now* - since it is more realistic with current technology, and development costs for an SSTO would be ... well huge and development times long. I guess we really need to separate out development and operational costs to discuss it further.
So I can agree with them in that aspect. Eventually SSTO will be the way to go, of course. As for there not being much of an incentive to move to SSTO from TSTO - if the economics really are there for SSTO's, someone will take that step.

A VTOVL craft will certainly be composed of mostly fuel with a relatively small payload, yes. But fuel is cheap. And having a vertical landing on a pad would certainly be the way to go.

RobertDyck · 2004-03-09 14:05:40

I would have liked to see X-33 fly, but it didn't. I would have liked the original space shuttle to be TSTO, but it wasn't. I would have liked to see DC-X developed further to seriously assess its virtues, but it wasn't. I would also have liked to see OSP built as a reusable lifting body atop Atlas V 401, but it will never be. I would have liked America to focus on OSP and a manned spacecraft for Mars; leave the expendable capsule and HLLV for the Russians to build (they already have Soyuz and Energia), but that will never be. George W. Bush's decision has been to send humans to the Moon with American built equipment and sacrifice everything else. That directive has even been interpreted as sacrificing Hubble; a mistake I hope will be corrected. So where do we go from here?

Future spacecraft will be expendable capsules on expandable rockets, at least until we return to the Moon. That means we don't have a need for an intermediate shuttle. We have the time to do it right, so let's focus on the ultimate goal: a Single Stage To Orbit fully reusable launch vehicle. X-43 is the way there.

For the short term we'll need a HLLV to get to the Moon (and as W. said, eventually Mars). We could argue whether a SDV or bulked-up EELV is better, but let's leave that for another thread.

RobS · 2004-03-09 23:19:43

Relevant to this discussion is the novel *The Rocket Company* which advocates a two-stage shuttle. The first stage has methane fuel to keep it compact and simple and is launched straight up, so that after burnout it comes straight back down to the spaceport, simplifying flyback. It lands vertically on rocket power after use of parachutes, making it VTOVL. The second stage is hydrogen-oxygen and separates from the first stage after it escapes the bulk of the atmosphere (40-60 miles, I think). The delta-v of the first stage is such that the second stage will coast up to orbital altitude, then fall straight back down. The delta-v of the second stage is 17,500 mph, in other words, exactly enough to achieve orbital velocity without having to do any lifting against gravity. I think the delta-v of the first stage is 5,000 mph. These numbers are roughly the same as the Saturv V 1st and 2nd stages, or the shuttle solids and the fuel tank. The second stage uses active liquid cooling of a heat shield and enters the atmosphere vertically, then deploys a parawing and lands on wheels on a runway. It's a fascinating model for a cheap, reusable shuttle.

-- RobS

GCNRevenger · 2004-03-10 08:29:44

Ballistic re-entry from orbital velocity? Pardon, but that doesn't sound all that cheap, especially with active cooling. I also wonder if the first stage can impart enough momentum to keep the 2nd stage from re-entering before it can reach orbital speeds. The parawing flyback thingie sounds kind of risky too.

dicktice · 2004-03-10 09:58:50

Ballistic re-entry from orbital velocity? Pardon, but that doesn't sound all that cheap, especially with active cooling. I also wonder if the first stage can impart enough momentum to keep the 2nd stage from re-entering before it can reach orbital speeds. The parawing flyback thingie sounds kind of risky too.

I would think what is meant is: braking to geostationary orbital velocity before atmospheric re-entry, not so, robS?

SpaceNut · 2015-08-15 22:17:10

Was searching for topics on Space Plane and found this one and a few more so did the shifting text fix to the topic which continues in this next.... Military Spaceplane outline - By Northrop Grumman

Antius · 2015-08-17 07:45:35

A standard ramjet is workable up to airspeeds of 2km/s. This suggests that it may be useful as part of the lower stage of a TSTO, which can then glide back to its landing site. At these more modest speeds, the requirement for a heat shield is greatly relaxed, along with its associated weight penalty.

Terraformer · 2015-08-17 09:23:14

Antius,

That sounds very, very familiar... that seems to be the architecture of the "NewMars Space Launch System"...

GW Johnson · 2015-08-17 10:47:41

Ramjet works very, very well from M2 to M4 in the stratosphere, with real supersonic external-compression inlet features. (Designs capable of thrusting subsonic with simple pitot inlets generally cannot reach Mach 2, while supersonic inlet designs cannot thrust much below Mach 2.)

Up to about Mach 4 in the stratosphere (Mach 3 at sea level), captured air temperatures are generally under 1000 F, and bare metal uncooled structures are feasible for the external inlet and skin surfaces, and the internal inlet surfaces. But there ain't no such thing as cooling air: any air you capture for whatever purpose is that hot. You have to line your combustor with ablatives.

Plain subsonic-combustion ramjet does work to about Mach 6 OK (ASALM accidentally flew that fast briefly in flight test about 1980), but for steady-state flight, all the skins, and all the inlet external and internal surfaces must be insulated or cooled in some way. The air in the subsonic duct is flame hot at 3000 F at Mach 6, even in the cold stratosphere. It's beginning to ionize, too.

Ionization instead of heating is fundamentally what limits the subsonic combustion ramjet to about Mach 6. Nozzles do not convert ionization to velocity, only temperature.

The stagnation zones and leading edges are almost as "bad" at Mach 5+ as during reentry from orbit. I would never make the claim that heat protection needs at Mach 5 or 6 are "less demanding than for entry", simply because they are not. The sensible heat transfer is as bad or worse, because the air is a lot thicker in the stratosphere than it is at entry altitudes.

But you cannot fly ramjet much over 100,000 feet, because the air is too thin to make useful thrust. Thrust and drag scale with ambient pressure, but weight does not. All designs have a service ceiling because of this effect: somewhere between 60,000 and 120,000 feet, usually.

Just something to think twice about.

GW

Last edited by GW Johnson (2015-08-17 10:52:20)

Antius · 2015-08-17 11:09:01

GW Johnson wrote:

Ramjet works very, very well from M2 to M4 in the stratosphere, with real supersonic external-compression inlet features. (Designs capable of thrusting subsonic with simple pitot inlets generally cannot reach Mach 2, while supersonic inlet designs cannot thrust much below Mach 2.)
Up to about Mach 4 in the stratosphere (Mach 3 at sea level), captured air temperatures are generally under 1000 F, and bare metal uncooled structures are feasible for the external inlet and skin surfaces, and the internal inlet surfaces. But there ain't no such thing as cooling air: any air you capture for whatever purpose is that hot. You have to line your combustor with ablatives.
Plain subsonic-combustion ramjet does work to about Mach 6 OK (ASALM accidentally flew that fast briefly in flight test about 1980), but for steady-state flight, all the skins, and all the inlet external and internal surfaces must be insulated or cooled in some way. The air in the subsonic duct is flame hot at 3000 F at Mach 6, even in the cold stratosphere. It's beginning to ionize, too.
Ionization instead of heating is fundamentally what limits the subsonic combustion ramjet to about Mach 6. Nozzles do not convert ionization to velocity, only temperature.
The stagnation zones and leading edges are almost as "bad" at Mach 5+ as during reentry from orbit. I would never make the claim that heat protection needs at Mach 5 or 6 are "less demanding than for entry", simply because they are not. The sensible heat transfer is as bad or worse, because the air is a lot thicker in the stratosphere than it is at entry altitudes.
But you cannot fly ramjet much over 100,000 feet, because the air is too thin to make useful thrust. Thrust and drag scale with ambient pressure, but weight does not. All designs have a service ceiling because of this effect: somewhere between 60,000 and 120,000 feet, usually.
Just something to think twice about.
GW

Sounds like something that would end up costing a fortune in development costs and would then have a rubbish utilisation factor because of all the maintenance you would have to pour into it after every single flight. The same sort of disease that ended up ruining the space shuttle.

The only plus side I can see is that the high velocity part of flight would be very short - about 90 seconds between takeoff and second stage deployment. Maybe some sort of sacrificial fluid could be used for cooling high temperature components without having a disasterous effect on mass ratio over such a short period. But that means building complexity and cost into something that needs to be simple...

Again, I am left wondering is a simple, pressure fed kerosene/LOX big dumb booster might not be a better choice for a lower stage. The thing could be ablatively lined, non-throttleable (the decline in chamber pressure would do that for you anyway) and as you are flying a winged vehicle within the atmosphere, the nozzles would not need any gimbling.

GW Johnson · 2015-08-17 11:42:57

I actually do think ramjet is appropriate for certain kinds of launch. The frontal thrust density of the airbreather is far lower, so it fills the body of the lower winged stage. The thermal protection issues are severe at M5 to 6, yes, but such can be done. I have been investigating ceramic composite refractories for the combustor and inlet duct. Skins should respond to radiative cooling with a little backside liquid cooling with the fuel. The nose tips, inlet compression surfaces, and leading edges should respond to either massive backside liquid cooling or ablatives, or both together.

The real trick is carrying the second stage. Any parallel configurations will be subject to shockwave impingement from the adjacent bodies. Above about M3-or4-ish that's not very survivable. Internal carriage may be required. If so, then supersonic store separation becomes the next head on the hydra that must be addressed. Otherwise, a tandem arrangement must be used with side-mounted inlets. Those generally limit by drag to about M3 or 4.

Any such craft rigged as a horizontal landing aircraft will need some amount of on-board rocket power to take off, and then accelerate to ramjet takeover speed, which is between about Mach 1.8 to 2-ish. The rocket and the ramjet can use the same kerosene fuel. The LOX that the rockets need could largely be carried in drop tanks that you drop after ramjet takeover. I'd keep a little LOX on board to have go-around capability for landing, using the rockets.

Most of the paper studies I have run with a ramjet airplane used in this way indicate basic feasibility, although the second stage payload that flies to orbit does better as a two-stage rocket than as a single stage.

An alternative is to take the weight and volume penalties of carrying a lot more kerosene and LOX, and go back on rocket at Mach 6, climbing fast out of the atmosphere, to release the payload in vacuo at around 10,000 fps (3 km/s). You can even do parallel-burn rocket and ramjet, during the M2 to 6 interval where ramjet works. Thermally protecting the internal flow path structures above M6 is the bugaboo waiting for you in that approach.

I have never run the studies to see if ramjet assist might be useful to a vertical launch rocket. If it is, the range of operation is subsonic to about M2, when the vehicle leaves the sensible air near 100,000 feet. That's a simple pitot inlet design, which could be a lot lighter, especially with little needed in the way of thermal protection. You would add these to a core vehicle as strap-on pods, and stage them off for recovery at about M2 100 kft. I'm not sure there's enough frontal thrust density to make this very useful during vertical ascent, though.

GW

Antius · 2015-08-17 14:24:35

Mach 2 and 100,000ft is rather poor. It works out as just a 6% of total delta-v needed to reach orbit. Surely the whole point of a lower stage is to reduce the required mass ratio of the upper stage?

Antius · 2015-08-17 14:42:00

GW Johnson wrote:

I actually do think ramjet is appropriate for certain kinds of launch. The frontal thrust density of the airbreather is far lower, so it fills the body of the lower winged stage. The thermal protection issues are severe at M5 to 6, yes, but such can be done. I have been investigating ceramic composite refractories for the combustor and inlet duct. Skins should respond to radiative cooling with a little backside liquid cooling with the fuel. The nose tips, inlet compression surfaces, and leading edges should respond to either massive backside liquid cooling or ablatives, or both together.
The real trick is carrying the second stage. Any parallel configurations will be subject to shockwave impingement from the adjacent bodies. Above about M3-or4-ish that's not very survivable. Internal carriage may be required. If so, then supersonic store separation becomes the next head on the hydra that must be addressed. Otherwise, a tandem arrangement must be used with side-mounted inlets. Those generally limit by drag to about M3 or 4.
Any such craft rigged as a horizontal landing aircraft will need some amount of on-board rocket power to take off, and then accelerate to ramjet takeover speed, which is between about Mach 1.8 to 2-ish. The rocket and the ramjet can use the same kerosene fuel. The LOX that the rockets need could largely be carried in drop tanks that you drop after ramjet takeover. I'd keep a little LOX on board to have go-around capability for landing, using the rockets.
Most of the paper studies I have run with a ramjet airplane used in this way indicate basic feasibility, although the second stage payload that flies to orbit does better as a two-stage rocket than as a single stage.
An alternative is to take the weight and volume penalties of carrying a lot more kerosene and LOX, and go back on rocket at Mach 6, climbing fast out of the atmosphere, to release the payload in vacuo at around 10,000 fps (3 km/s). You can even do parallel-burn rocket and ramjet, during the M2 to 6 interval where ramjet works. Thermally protecting the internal flow path structures above M6 is the bugaboo waiting for you in that approach.
I have never run the studies to see if ramjet assist might be useful to a vertical launch rocket. If it is, the range of operation is subsonic to about M2, when the vehicle leaves the sensible air near 100,000 feet. That's a simple pitot inlet design, which could be a lot lighter, especially with little needed in the way of thermal protection. You would add these to a core vehicle as strap-on pods, and stage them off for recovery at about M2 100 kft. I'm not sure there's enough frontal thrust density to make this very useful during vertical ascent, though.
GW

Interesting post. At mach 6, the ramjets have provided about 20% of orbital DV. I wonder if it would be possible to produce an SSTO burning LOX/LNG that takes off from a normal airport using your rocket assisted ramjet?

GW Johnson · 2015-08-17 15:58:23

You can't use M6 as a % of orbital speed. You have to boost the ramjet to around M1.8 to M2 before it can even function at all (about Mach 1.8 min, really). Then, it can take you to around M6, but not at super-high altitudes. So the delta-Mach is about M4 (maybe M4.2). Out of about M25 equivalent for orbit speed.

When this delta comes out of your lower stage, where masses are so much higher, it is significant enough to consider.

Scramjet has a min takeover Mach near M4. It might function on kerosene to Mach 8, maybe 10. But I doubt it. They demo'd M5 on X-51 with kerosene. So call it Mach 7 or 8-ish. That's a delta-Mach of about 3 or 4 out of 25, same or less than as plain ramjet, and with a technology so very apparently not yet ready for "prime time".

You're better off with ramjet, which has been flying since WW2. Since about 1975 in its current form.

Turbine doesn't save you, although it does generate standing start thrust (just nowhere near as much as rocket). Its max speed is turbine inlet temperature-limited to under Mach 3.5, probably closer to Mach 3.3. That's a delta-Mach of near 3.3 to 3.5. You're quite literally better off with ramjet plus a rocket booster.

Rocket will take you faster than ramjet, but at a lot lower Isp. That's why I keep thinking a ramjet lower stage is a good idea for horizontal takeoff schemes.

As I said above, I'm not so very sure about the utility of ramjet assist for a vertical launch rocket. Most of those are leaving the sensible atmosphere at around M2-ish, 100 kft-ish. A very lightweight ramjet pod could be devised for that regime, which could develop usable thrust as low as M0.7-ish. But the specific impulse capability is lower for that type of ramjet. And the delta-Mach is at best about 1.3.

GW

Antius · 2015-08-19 11:27:09

GW Johnson wrote:

You can't use M6 as a % of orbital speed. You have to boost the ramjet to around M1.8 to M2 before it can even function at all (about Mach 1.8 min, really). Then, it can take you to around M6, but not at super-high altitudes. So the delta-Mach is about M4 (maybe M4.2). Out of about M25 equivalent for orbit speed.
When this delta comes out of your lower stage, where masses are so much higher, it is significant enough to consider.
Scramjet has a min takeover Mach near M4. It might function on kerosene to Mach 8, maybe 10. But I doubt it. They demo'd M5 on X-51 with kerosene. So call it Mach 7 or 8-ish. That's a delta-Mach of about 3 or 4 out of 25, same or less than as plain ramjet, and with a technology so very apparently not yet ready for "prime time".
You're better off with ramjet, which has been flying since WW2. Since about 1975 in its current form.
Turbine doesn't save you, although it does generate standing start thrust (just nowhere near as much as rocket). Its max speed is turbine inlet temperature-limited to under Mach 3.5, probably closer to Mach 3.3. That's a delta-Mach of near 3.3 to 3.5. You're quite literally better off with ramjet plus a rocket booster.
Rocket will take you faster than ramjet, but at a lot lower Isp. That's why I keep thinking a ramjet lower stage is a good idea for horizontal takeoff schemes.
As I said above, I'm not so very sure about the utility of ramjet assist for a vertical launch rocket. Most of those are leaving the sensible atmosphere at around M2-ish, 100 kft-ish. A very lightweight ramjet pod could be devised for that regime, which could develop usable thrust as low as M0.7-ish. But the specific impulse capability is lower for that type of ramjet. And the delta-Mach is at best about 1.3.
GW

Very interesting. I wonder if the ramjet could be fed with stored compressed air until it reached M1.8? This is still only about 0.3% of total dV to orbit in terms of energy needed to reach orbit, so the mass burden would be tolerable if the acceleration to M1.8 was high. It would avoid the need to carry the upper stage piggy back and operate its rocket engines at low speed, where propulsive efficiency is awful.

The most elegant way to deal with the shock heating problem would appear be some form of regenerative cooling. I wonder how much that would add to the complexity and development cost of the engine? Would a replacable ablative liner or sacrificial cooling method make more sense in terms of the balance between development and operating costs? Would thermal fatigue put a limit on the effective life of the cooling tubes in any case?

To reduce the shockwave impingement problem, could the second stage be mounted in series, rather than parralel?

SpaceNut · 2015-08-19 17:50:51

so we have been talking about Air launch to orbit simular to Pegasus only with more capability.....

Mars_B4_Moon · 2024-03-29 13:11:03

Stratolaunch flew its Talon-A hypersonic vehicle for the first time after dropping it out of the belly of Roc
https://gizmodo.com/worlds-largest-plan … 1851339594

Burt Rutan legacy? TA-1 or Talon-A the Hyper-A, Stratolaunch is developing a reusable, rocket-powered the company and development project backed by Microsoft co-founder Paul Allen and Scaled Composites founder Burt Rutan, who had previously collaborated on the creation of SpaceShipOne, it might link to military or some defense contracting but is possibly related to some of the Airplane on Mars threads and Mars flight discussion.

another topic

Space planes -Sierra Nevada and ESA
https://newmars.com/forums/viewtopic.php?id=7196

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