A Shuttle Designed And Built Today

Dayton Kitchens · 2006-12-21 10:11:48

Lets say that within five years or so, someone made the decision that the U.S. needed a new space shuttle system.

The criteria for it would be:

1) completely reusable
2) two stage to orbit
3) Standard crew of 6, 10 in an emergency.
4) crew escape capability including Zero-Zero (that is an escape means that will work at zero altitude, zero velocity-that is sitting on the ground).
5) Two week turnaround time from landing to relaunch.
6) Maximum to LEO payload of 50,000 lbs.
7) Standard duration of 10 days in orbit, ability to be extended to 30 days.
8) Use existing Kennedy Space Center facilities.
9) Ability to fit modular payloads in the payload bay. Including a personnel module that could carry up to 50 people .

How would such a craft be built and launched? What would it look like?

Assume use of 21rst century technology and materials.

GCNRevenger · 2006-12-21 14:32:13

The upper stage should come in three varieties sharing similar mold lines, a manned version with seating for up to 14 (including 2 crew), unmanned "dense" cargo ~20MT, and an unmanned tanker version for maximum Hydrogen carriage. Since we're talking reuseable vehicles, it is absolutely critical to maximize efficiency. Computers weigh much less and take up less room than a pressurized crew cabin, and would make all the difference.

The thing would be air launched, probably like the old Shuttle LSA or Sanger-II, from a turbine/rocket or augmented turbo-ramjet carrier plane, so there would be no need for an escape pod or something perhaps just ejection seats. The rocket engines of the upper stage will be fourth-generation liquid Hydrogen fueled and will be sufficiently reliable to disregard the possibility of a CATO.

Air launch also permits injection into any orbital inclination you like, radically reduces the problem of weather delays, and to some extent relaxes launch windows.

cIclops · 2006-12-21 15:18:34

Air launch 50klbs to LEO? The company with that very name have just set a record for an airlaunched vehicle, total weight .. 72klbs. It would need a gigantic carrier aircraft to lift a RLV with that capacity. The development cost for the carrier alone would be billions and billions and billions

Grypd · 2006-12-21 16:08:18

It would need a gigantic carrier aircraft to lift a RLV with that capacity. The development cost for the carrier alone would be billions and billions and billions

Not really. The lower stage of the TSTO spaceplane will be just that aeroplane based. It will benefit from all the advantages that an aeroplane has and though yes it would cost billions to develop. That is standard for any project in development. It would though make this cost back in total reusability and rapid turnaround.

The engine needed for such a craft would be jet based to get height and it is then that either we will have that engine have the capacity to throttle up and if we then also add water or O2 to the airflow to compress the air get the craft up to mach 4 to 6 before seperation. Another possibility is to use standard jet engines to gain height but to have a rocket to accelerate the craft to seperation speed and height. Again we could develop even more powerful ramjet/scramjet hybrid engines but they are not really needed though if we want an SSTO spaceplane for the future these will have to be developed.

The size of the lower stage aircraft will depend on which of the engine options are used and also what else we will use the plane for. The Sanger the German advanced TSTO spaceplane design had a proposed wingspan of 46 metres and its design would make the total wing area of about 880 m2. The orbiter would have a wingspan of 18 metres.

dicktice · 2006-12-21 18:54:27

The Airbus 380 airframe, with the fuselage suitably redesigned might fit the bill.

Austin Stanley · 2006-12-21 20:42:32

The Airbus 380 has more than enough payload capacity, but couldn't carry a usefull payload to a usefull hight or (more importantly) speed. It's could never withstand the high mach number necessary for a usefull launch speed.

Something like the B-1 lancer would probably be ideal. The B-1 itself is to slow and probably doesn't have the necessary payload capacity, but its somewhat like the kind of design and size we might expect. A big supersonic lifting body, possibly with variable wings like the B-1, you're going to need a lot of lift to get something as big as a shuttle off the ground.

The only other inspiration I could add is the carrier plane should act as a fuel carrier, much like shuttles tank does. Let it carry the shuttle up to the performance limits of it's engines and airframe, then let it carry the fuel for the shuttles engines as the boost it nearly to escape velocity. Then the carrier aircraft seperates and desends while the shuttles internal tanks or SRB give the final push.

SpaceNut · 2006-12-21 21:01:03

I guess the question I have is are the ramjet/scramjet hybrid engines under developement more powerful that shuttles SSME?
If so shift the engines from the shuttle to the carrier making them ramjet/scramjet hybrid engines leaving the OMS for orbit entry.

Austin Stanley · 2006-12-21 21:21:29

No scramjet has reached the development point where it could be deployed in a vehcile the size of the one we are talking about. We are still quite some time away from a scramjet that could be used in a missle, much less a something of this size. As for ramjets, the SR-71's Pratt & Whitney J58 are very much like the sort of engine we would like to use, but a more modern version would probably be signifigantly more powerful and fuel efficent.

As for a comparision of power, air-breathing engines in general are about an order of magnitude less powerful than rocket engines like the SSME. We talking like ~1500kN for the SSME and ~150kN for the most powerful turbojets. But thats okay, since unlike the SSME the turbojets do not have to push their payload straight up against earths gravity (they can use lift for assistance), and since they don't have to carry there (heavy) oxidiser, they are much more fuel efficent (ISP ~2000) so you can afford to take longer.

GCNRevenger · 2006-12-21 22:30:35

Yes the carrier airplane will be quite large, but it won't be outrageously large: because the faster you can go at separation the smaller the upper stage becomes, and the size of the upper stage determines the carriers' size, if you can make your carrier plane fast then it doesn't need to be as large.

The "favorite" propulsion type for the carrier plane would be a large, modern decedent of the famous J-58 turboramjet that powered the SR-71 spyplane, optimized for sprinting at high altitude instead of cruising. Perhaps boosted with oxygen/kept from melting with water late in the sprint phase. These types of engines work well at both low speed (takeoff from runway, cruise back for landing) and moderately high speeds/altitudes (~Mach 5, 100,000ft), which is where the size of the upper stage really begins to shrink.

If high-power advanced jet engines aren't an option and we're stuck with subsonic engines, then one of three things happens:

1-The upper stage is much bigger, which requires the lower stage airplane to be huge, bigger than any present commercial airliner. However, this makes the lower stage simple since it need not go supersonic. This option might be more attractive if materials would improve, but as it stands now the upper stage would have problems with its big empty fuel tanks on reentry.
2-The lower stage is powered by both subsonic jets and its own set of rocket engines. This lets you use the best rocket for the best purpose, high thrust kerosene fuel with nozzles built for lower atmosphere use for the lower stage and high efficiency near-vacuum hydrogen engines for the upper stage. However, this multiplies the number of engines, increasing weight and complicating the design. The lower stage must also resist high supersonic speeds, making it much more expensive.
3-The lower stage is powered by jet engines but carries fuel for the upper stage engines to fire while still mated together. This keeps the upper stage small and reduces the number of engines, but loses efficiency since the upper stage engines must also work both vacuum and atmosphere, while working well in neither one. The thrust required for the upper stage engines is also much greater, so you may not save much engine mass versus (2). Also potentially very large fuel tanks due to high thrust required. Lower stage must again be capable of withstanding hypersonic velocities.

GCNRevenger · 2006-12-21 23:02:37

Oh, and a side note, no SRBs of any kind are ever going to be on such a rocket. Their efficiency is awful and their empty mass extreme, which can be lived with if you are launching off the ground to low Mach numbers, but too heavy to lug into the air (or space).

RobertDyck · 2006-12-22 11:29:18

I question the guidelines. Why would a new shuttle have to be the same as the old? The original 1968 requirements called for a fully reusable TSTO. It was intended to re-supply a space station so had to lift 11,340kg to a station at 400km altitude and 50° inclination. It was also required to carry up to 12 crew, but that would sacrifice cargo capacity. This was for re-supply only; construction would involve lifting large modules with a Saturn 1B or Saturn V rocket. Expendable rocket for bulk cargo, reusable for crew taxi; a sane design that was abandoned for short-sighted budget reasons.

Today I would question whether you need a reusable shuttle even that big. The Russian MAKS-OS was a proposal for an air-launched shuttle with expendable external tank and no booster rockets. A mid-size shuttle with a cockpit for 2 crew and cargo bay capable of lifting 7.0 tonnes to ISS, or 9.3 tonnes to a science orbit at 28° inclination. A passenger module could carry 4 more astronauts, but that module plus an airlock filled the cargo bay. It had some variations. It was designed to be air launched from an existing aircraft, the AN-225 Mria. I'm sure the United States could come up with something similar.
Multipurpose Aerospace System (MAKS) by the manufacturer, Molniya

Actually MAKS had a problem: it wasn't able to dock with the station unless it carried the external airlock in its cargo bay. The cargo bay was so small the airlock took half of it. A new design should include a docking hatch and the ability to decompress the cockpit. Apollo did that. It keeps the vehicle small.

SCRAM jet or RBCC is the ultimate; it could enable an SSTO RLV. The engines will require some research though.

Dayton Kitchens · 2006-12-22 11:38:39

I supposed it would be reasonable to cut the crew size and payload bay.

Cut the bay down to 20,000 lbs. perhaps.

And wasn't the original shuttle sized for 65000 lbs. because the Air Force wanted it capable of lifting a next generation of spy satellites that were projected to be that big?

cIclops · 2006-12-22 13:03:44

I supposed it would be reasonable to cut the crew size and payload bay.
Cut the bay down to 20,000 lbs. perhaps.
And wasn't the original shuttle sized for 65000 lbs. because the Air Force wanted it capable of lifting a next generation of spy satellites that were projected to be that big?

Cutting it down to 1000 lbs might work. This RLV has to carry its engines, tanks, TPS, wings/lifting body etc etc all to orbit.

Let's say that can be built using a 25 mT RLV (note that the Orbiter weighs 100mT). Give it 900 km/hr velocity from the carrier, and power it with 470 Isp engines (exhaust velocity 4794m/s).

Then using the full 152 mT capacity of a A-380F cargo plane (as yet unbuilt)

approx final mass = 152*e^(-8550/4794) = 25.5 mT

So the payload is approx 25.5 - 25 = 0.5 mT ( 1000 lb)

Of course every ton less than 25 increases the payload by the same amount.

GCNRevenger · 2006-12-22 15:12:19

No no! No! The RLV must be able to carry real serious cargo, that is just as important if not moreso than being a simple people mover. And that means serious tonnage, not 10,000lbs, not 20,000lbs, but 44,000lbs should be the target payload. Its not a taxi!

Huge rockets like Ares-V are nice, but rockets of that scale are never going to be within the realm of reason for private enterprise (Lunar mining, orbital tourism) or any sort of exploration besides small-scale trips to the inner planets, and this is the sort of thing the RLV will enable. Thus, the RLV should at the very least be able to carry Atlas/Proton scale payloads, and not a gram less.

Because huge expendable rockets aren't going to be affordable for these purposes, which are "the next big thing" beyond VSE, there won't be any place to fly a taxi to. The cargo RLV must come first, if later on or concurrently we want a smaller cheaper-to-fly taxi fine, but 44,000lbs and not an ounce less.

This is not an unreasonable mass, we can do this, for an RLV its high time we started using some of these advanced technologies that have always been so much promise and stop "oh we'll make do" with updated antiques (eg A380 launch aircraft, MAKS mini-shuttle). One of the great sins of the past 30 years is that so many things are done half-way, but this just won't do. Twenty metric tonnes.

First of all we get rid of the crew, we are good enough at making automated/remote aircraft that we don't need people flying it anymore. Just deleting this requirement from, say, the Space Shuttle would nearly cut its mass in half and let you get away with one less SSME. While the mass savings aren't as great with a cabin for 2-4, they are still too significant to pass up. This also means that you can devote all the mass and volume you want to crew/light cargo "taxi" version, and make it very robust.

But this can't be a half measure! Especially given how much money will go into making a true RLV, with no drop tanks or any expendable component.[/i]

cIclops · 2006-12-22 15:19:15

If you want say 25 mT of payload that makes the takeoff weight of the RLV 300 mT - assuming that it can be built weighting only 25 mT which is probably impossible. If it weighs a more realistic 50 mT then the wet weight is about 450 mT ... and that will need a carrier with 3 times the capacity of an A-380F.

GCNRevenger · 2006-12-22 15:23:40

Of course, if you launch at subsonic velocities and low altitudes it would be much too big and heavy. Try a separation velocity of 7,600km/hr (Mach 6) and knock off a little of the total Delta-V for increased altitude.

Edit: Oh, and I want a total payload of 20MT, not 25MT.

RobertDyck · 2006-12-22 15:55:35

Its not a taxi!

Yes it is. This will sound like a Monty Python skit soon.

I want an argument. No you don't. Yes I do. You just had one. No I didn't. Yes you did. ...

A reusable spacecraft is affordable only because it's reusable. The heatshield, wings, aerodynamic control surfaces, wheels, are completely useless for spaceflight so it's only economical for access to LEO. Any mission beyond Earth orbit requires a heavy lifter without all that atmospheric stuff. This results in a few conclusions:

a space station must be in low orbit, medium orbit where the orbit won't decay is out of reach for a shuttle with atmospheric capability
a shuttle can be used to service a LEO station, deliver satellites into low orbit, or service telescopes or other equipment in low orbit only
communication satellites require geostationary orbit, or at least medium orbit for satellite phones. These orbits are out of reach for a shuttle.
a shuttle is useless for Lunar or Mars unmanned probes
the only way a shuttle could be useful for a Lunar or Mars manned mission is Earth orbit assembly

The real problem is expendable rockets have become prohibitively expensive. Cost must come down, but that can only occur through mass production. Currently rockets are hand made by large numbers of guys with Ph.D.s, resulting in high salary expense. Once a design is complete and manufacturing procedures are established it should be possible to manufacture using power tools that need fewer people, factory operations will not require engineers to oversee work or do the work themselves, and established tools and jigs make work quicker and cheaper and more reliable. The Russian R-7 line of rockets is dirt cheap by comparison, but that's because they launched more than 1700 of them, not including ICBMs.

This is quite a turn-around. I thought I was the one arguing to continue the shuttle, and you wanted big-dumb-rockets. Now I'm saying any new shuttle should be fully reusable or don't bother, and keep it small to keep cost down.

cIclops · 2006-12-22 16:03:31

Well 7600 kms/hr saves 2.1 kms/sec of Delta V to orbit leaving "only" 6.7.

If you can build this incredible machine weighing no more than 25 mT you can have 17 mT of payload and fly with an A-380F class carrier (152 mT). The problem has moved of course to flying at Mach 6 carying 152 mT. Now we should really add many more billions to solve the problems of separating the vehicles at hypersonic velocity.

For 20 mT payload, make the fueled RLV weigh around 180 mT.

All these numbers are approximate and not to be used as a basis for funding proposals

publiusr · 2006-12-22 16:13:45

I would have a pressure-fed Energiya Buran type system myself.

Grypd · 2006-12-22 16:25:49

The problem is that if we deliberatly limit the payload capacity of the upper stage to reduce the lower stage aircraft it limits the potential expansion of the system. Unlike a rocket the lower stage is an aircraft and increasing its size to deliver more cargo is not a practical proposition. And no SRBs will help.

The lower stage will have to be larger than a 747. But the actual size is not really too much a problem considering that it is mostly engine and fuel tanks. There is also advantages for the lower stage to use kerosene fuel and as the lower stage aircraft is to be large it can fit a rocket engine in to get acceleration. The higher the seperation the better the whole operation and especially if the pair are traveling in the high mach numbers. Less wind resistance increases safety especially for the upper rocket powered stage.

RobertDyck · 2006-12-22 20:26:59

MAKS used an AN-225 which gave it altitude and permitted launch from any runway, but not much speed. Spiral was to be a small, single seat shuttle with expendable rocket launched from the back of an aircraft. The aircraft was to have air breathing jet engines, flying hypersonic and designed similar to an Concord. It's interesting they started the project in 1965, before Concord. The original specification called for an aircraft fueled by liquid hydrogen, launching the rocket from its back at mach 6. The two-stage expendable rocket booster would use liquid fluorine and liquid hydrogen ([tex:52a7a1b8b9]LF_2 + LH_2[/tex:52a7a1b8b9]), and the little orbiter itself would use liquid fluorine and ammonia ([tex:52a7a1b8b9]LF_2 + NH_3[/tex:52a7a1b8b9]). A later version was more modest, it carried no cargo, strictly a reconnaissance spacecraft, which permitted less toxic fuel. The aircraft used kerosine separating the rocket at mach 4, rocket boosters used [tex:52a7a1b8b9]LO_2 + LH_2[/tex:52a7a1b8b9], and the orbiter used "AT fuel + dimethylhydrazone". I'm yet to find what that is, but I suspect "AT fuel" is N2O4 and dimethylhydrazone is a hydrazine compound. NASA today uses N2O4 + MMH for the Space Shuttle.

One X-Prize contestant wanted to build a TSTO with hypersonic carrier aircraft. Bristol Spaceplanes.

Grypd · 2006-12-23 06:19:39

Spiral was designed for a combat spaceplane. Its capacity for cargo was at best minimal and it had little if any worthwhile ability to put paasengers into orbit.

MAKS requires the craft to be three stage as the Antanov will not have the speed or height to allow any other option. The advantage is that the Antanov can fly from any airport, the disadvantage is that to deploy the actual MAKS second and third stage onto the top is a complicated and time consuming procedure.

Other costs involved is that the second stage is designed to not be reusable and since the Antanov is not designed for the seperation the actual operation of the second and third stage could pose risk as the air density at seperation would be high.

Still we already have engines powerful enough and with a little modification that on a craft specifically designed and built could easily provide quick and easy access to space.

The only problem is that for this to happen there has to be a reason for such a development of cheap access and currently with the launch industry as it is there is not this reason.

RobertDyck · 2006-12-23 11:07:05

The MAKS-OS used a single orbiter with expendable fuel tank launched from the back of an existing aircraft. The reason it works is they used the largest aircraft in the world; the AN-225 Mria is larger than an A380 Airbus. It didn't use multiple stages, rather you could think of the aircraft as the first stage, and the orbiter with external tank as the second stage. Traditional thinking says you need high density fuel for the first stage, then high fuel efficiency for the upper stage. Saturn V used LOX + kerosene for the first stage, LOX + LH2 for the second & third stages. The spacecraft itself used storable propellants so they wouldn't boil off on the way to the Moon. The Apollo service module used N2O4 + UDMH. MAKS uses a "tri-propellant" engine. That uses LOX + kerosene + a trickle of LH2 during initial ascent, then switches to LOX + LH2 for the final push into orbit. This means a single reusable engine on the orbiter does both jobs. The expendable external tank has 3 chambers: kerosene, LOX, LH2. An ingenious design, you have to give them credit. However, it isn't fully reusable.

The MAKS-M was a fully reusable though unmanned version. It could lift 3.5 tonnes to ISS. MAKS-OS could lift 7.0 tonnes plus 2 crew, or 8.2 tonnes and no crew. If the difference is 1.2 tonnes, then a manned MAKS-M should lift 2.3 tonnes of cargo plus 2 crew. That's pitiful; a useful mid-size shuttle will have to carry more than that.

The MAKS page has a bunch of downloadable documents. One titled "Analysis of Various Concepts of the Reusable Space Transportat Systems" by Dr. Dudar E.N. talks about cargo capacity being dependant on launch energy. So the faster the aircraft the more cargo the orbiter can carry. That's rather obvious, but it is nice to have it confirmed numerically. His chart shows dramatic cargo increase with a supersonic carrier instead of the current subsonic cargo plane.

Spiral was a combat vehicle, it's only cargo was space-to-space missiles. However, launch from a supersonic carrier aircraft was very interesting. The aircraft design can be utilized for a future shuttle. Bristol Spaceplane was based on a similar carrier aircraft. The ability to fly mach 6 using air breathing engines, even fuelled by LH2, was a very ambitious goal for 1965. Normal jet fuel is based on kerosene, so the kerosene variant was more normal; it was expected to launch the spacecraft at mach 4. Between mach 1 and 5 is supersonic, mach 5 and higher is hypersonic. So this means the aircraft using jet fuel is supersonic, not hypersonic. That's still impressive for 1965. The US air force is funding research into new turbine engines that should propel an aircraft with jet fuel to mach 6. Kerosene is much more dense than LH2, permitting smaller fuel tanks. Can we get access to those?

Have I pulled from enough sources go get a sense of a new vehicle? Here are a few more: the X-38 had a docking hatch on its back (dorsal side). It didn't have an airlock, just a hatch. Let's use that.

The X-38 also initially was going to use inconel metallic heat shield to avoid the tile loss problems of the current shuttle, but they were heavy and didn't handle as much heat. That could be handled by shallower atmospheric entry, but you don't want your flight profile too tight when it's used as a life boat. An emergency on the station that requires its use means they won't have time for finesse. They used an autopilot with one "go" button, but still. Anyway, the problem is the combination of an ET that looses foam together with fragile tiles. The tiles alone are fine if they don't have to endure chunks of foam hitting them. The black tiles are silica foam with a densified side where they bond to the shuttle, and a black glaze to radiate heat. They're only about 1 inch thick and feel about as heavy as so much Styrofoam. White tiles have already been replaced by thermal blankets. AFRSI blankets are silica fibre cloth on the outside, normal fibreglass cloth where the press against orbiter's aluminum skin, and filled with silica fibre batting. They're a quilt, and the threads to "quilt" it together are also silica. The silica used is the same as the foam tiles. A new heat shield is DurAFRSI, using Saffil batting, Nextel 440 cloth, and covered in inconel foil. It handles higher temperatures than AFRSI blankets, but not as high as black tiles. Blankets, whether AFRSI or DurAFRSI, are soft so immune to foam strikes. Fine, use what's appropriate where appropriate. The grey RCC leading edge and nose cap can handle higher temperatures than black tiles, and are strong enough for the leading edge. The only time it failed on the Shuttle was a foam strike at hypersonic speed. This new vehicle won't use an external tank so there won't be foam loss.

To reduce maintenance cost between flights, replace the windshield with a durable material. Currently Shuttle windshield is hand ground before every flight to get the pits out. Micrometeors cause pitting in space. The US army developed a strong, light-weight material for tank windows. AlON is spelled with a lower case L, everything else upper case because the name is the chemical formula: Aluminum, Oxygen, Nitrogen. It's a transparent metallic ceramic. Actually, the material for tank windows was a triple layer sandwich: AlON outside, spinel core, and polycarbonate inside. Polycarbonate was really a spall shield. Spinel is aluminum, magnesium, oxygen, nitrogen. This sandwich can be 1/4 the thickness and consequently 1/4 the weight of a multilayer armoured glass window. AlON may have slightly lower tensile and compressile strength than synthetic sapphire, but it has greater impact strength. Since the application was stopping bullets, impact strength was everything. On a shuttle, the goal will be stopping micrometeors; again impact strength is important. For maximum protection, used the full triple-layer laminate. Polycarbonate is the same material as spacesuit helmets, so it's quite established for use in space. NASA developed an anti-scratch coating for micrometeor protection, apply that same coating to the inside of the windshield. All this together should mean no need to service the windshield between flights.

For spacecraft inspection, use a free flying inspection camera rather than an arm. The AERCam Sprit was tested in space on the Shuttle; flight STS-87 on December 3, 1997. Mini-AERCam is an updated design that's smaller: 7.5 inches diameter, 10 pounds.
Mini-AERCam

GCNRevenger · 2006-12-23 22:56:46

so it's only economical for access to LEO

Why thank you for pointing that out, Professor Obvious

The real problem is expendable rockets have become prohibitively expensive. Cost must come down

The reason why an RLV needs some serious payload is that expendable rockets of any size or degree of simplicity will never be cheap enough despite mass production or use of lesser skilled/lesser size labor forces. The minimum materials cost, labor, and so on will always be too high simply because of the extreme physics that these vehicles will be subjected to.

The Russians rockets are bad analogies, they are not cheaper than our rockets because they are that much less labor intensive or less complicated, they are cheap because their builders are cheap, literally willing to work for nearly US "fast food" wages. Our rockets would be about the same price if we did that.

And by cheap I mean cheap enough for true space mining, near "everyman-scale" orbital tourism, colonization, or probably affordable outer-planet manned missions and all the other things. We will never be able to do any of these things, the things which will follow the "VSE era," with expendable rockets. Barring a space elevator, that leaves only one option, an RLV with substantial payload capacity (circa 20MT or 12+ seats). A smaller (<10MT) space plane would require too many flights to get anything done, and one with expendable drop tanks comes too close to defeating the purpose.

I still believe that a Sanger-II style TSTO spaceplane is probably the way to go, why is there this fixation about determining upper stage mass based on the capacity of long-range fuel-efficient low-noise 10,000-flight many-runway cargo jets? The TSTO carrier plane is not restricted to any of these, it doesn't have to fly ten thousand miles, nor do so efficiently, and could be based off its own purpose-built runway much longer than regular ones to permit higher take-off speeds. Being hypersonic, the carrier plane shouldn't want for thrust either!

Lets make a nice round figure for the upper stage, say 250MT? That would about hit the 20MT mark and leave 40-50MT for the upper stage.

For instance, the big A380 cargo jet has a payload of 150MT, but fully fueled its also carrying about 130MT of jet fuel. Since the carrier doesn't need to fly 15000km, lets cut that by a third. Now thats ~200MT of payload. Surely, if we aren't terribly worried about fuel efficiency we can increase the lift of the wing a little bit, or maybe we can just get away with a higher takeoff speed to make up some of the remaining 20% without being too much bigger. A little more wear-and-tear for higher payloads is just fine too since the thing will probably never fly even 1/10th of an A380.

Even 300MT shouldn't be out of reach.

I have no illusions that it will be cheap to develop such a vehicle, it will easily run into the low-to-mid tens of billions of dollars, but I think that it can be done. Our technology is almost up to that point, and should be ready by the time the VSE era ends. The payoff, finally escaping the economic noose of throw-away rockets, will be well worth the price.

RobertDyck · 2006-12-24 01:24:39

expendable rockets of any size or degree of simplicity will never be cheap enough ...
Russians rockets are bad analogies ... they are cheap because their builders are cheap, literally willing to work for nearly US "fast food" wages.

Once a design is established, why would production work pay more than an automobile factory worker? When you travel 75mph on a twisting road on the side of a mountain, your life is just as much dependant on that vehicle working.

And by cheap I mean cheap enough for true space mining, near "everyman-scale" orbital tourism, colonization, or probably affordable outer-planet manned missions and all the other things.

Bold. You'll never get any of that with anything less than a SSTO RLV. A fully reusable vehicle that doesn't drop off any parts, and can be turned around and flown in less than 2 weeks. Ideal is several times a day, like an airliner. A nice vision, but I only see two ways to do it.
1) hydrocarbon fuels:
Turbine jet for take-off and landing. Forget catapult launch, make the thing able to launch from a commercial airport. Yup, able to launch itself from a runway built for a 747. That's still a substantial runway. Fly to high speed where the SCRAM jet can ignite, then accelerate to near orbital insertion speed. Build the SCRAM jet as a Rocket Based Combined Cycle engine: SCRAM, then smoothly transition to air augmented rocket, then transition to LOX/LH2 rocket. Use kerosene jet fuel for the turbine engine, LH2 for SCRAM, and LOX/LH2 rocket for the final push to orbit. Use N2O4/MMH for manoeuvring thrusters; storable propellants keep without boil-off. After atmospheric entry and slowing to subsonic speed, air-start the turbine engine for powered landing.
2) nuclear:
Use a nuclear jet engine for take-off and landing. A nuclear RAM jet was already developed under project Pluto. A nuclear turbojet should also work, you would just need an electric motor to start it like any other turbojet. It would require uranium instead of plutonium for safety, embedding uranium in ceramic to crash harden fuel capsules, placing engines on wing tips to keep radiation away from passengers, and neutron reflector along the inside of the jet housing. Oxygen and nitrogen exposed to neutron radiation doesn't become radioactive. Hydrogen from humidity in the air becomes deuterium. The tiny amount of deuterium in natural humidity will become tritium. Some will, most neutron radiation will miss deuterium atoms. Tritium decays quickly, and produces beta radiation; it beta decays to 3He. Beta radiation is a high speed electron, which can't even penetrate the outer layer of skin. Exhaust from a shielded nuclear jet would be less toxic than exhaust from a standard jet engine. I could work out nuclear decay paths again. For the final push into orbit, operate the engine as a LH2 fuelled nuclear thermal rocket.

Why wasn't there progress on nuclear rockets while President George W. Bush was in power. Now he's a lame-duck president. Even the reactor for JIMO was stalled. One could argue for a lot of reasons he should be, but he was the pro-nuclear guy.

Saenger II, cool idea. Ok. And the carrier aircraft should not be limited by noise restrictions? Ok, I agree to that. A custom vehicle that's really big? Yup, will need to be. Forget noise concerns of the Concorde, a spacecraft should announce itself with one hell of a noise.

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#1 2006-12-21 10:11:48

Re: A Shuttle Designed And Built Today

#2 2006-12-21 14:32:13

Re: A Shuttle Designed And Built Today

#3 2006-12-21 15:18:34

Re: A Shuttle Designed And Built Today

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Re: A Shuttle Designed And Built Today

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Re: A Shuttle Designed And Built Today

#6 2006-12-21 20:42:32

Re: A Shuttle Designed And Built Today

#7 2006-12-21 21:01:03

Re: A Shuttle Designed And Built Today

#8 2006-12-21 21:21:29

Re: A Shuttle Designed And Built Today

#9 2006-12-21 22:30:35

Re: A Shuttle Designed And Built Today

#10 2006-12-21 23:02:37

Re: A Shuttle Designed And Built Today

#11 2006-12-22 11:29:18

Re: A Shuttle Designed And Built Today

#12 2006-12-22 11:38:39

Re: A Shuttle Designed And Built Today

#13 2006-12-22 13:03:44

Re: A Shuttle Designed And Built Today

#14 2006-12-22 15:12:19

Re: A Shuttle Designed And Built Today

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Re: A Shuttle Designed And Built Today

#16 2006-12-22 15:23:40

Re: A Shuttle Designed And Built Today

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Re: A Shuttle Designed And Built Today

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Re: A Shuttle Designed And Built Today

#19 2006-12-22 16:13:45

Re: A Shuttle Designed And Built Today

#20 2006-12-22 16:25:49

Re: A Shuttle Designed And Built Today

#21 2006-12-22 20:26:59

Re: A Shuttle Designed And Built Today

#22 2006-12-23 06:19:39

Re: A Shuttle Designed And Built Today

#23 2006-12-23 11:07:05

Re: A Shuttle Designed And Built Today

#24 2006-12-23 22:56:46

Re: A Shuttle Designed And Built Today

#25 2006-12-24 01:24:39

Re: A Shuttle Designed And Built Today

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