New Space Shuttle

Dook · 2005-01-03 18:31:32

I have this idea about a new space shuttle. Essentially it would look the same as the ones we have only it would be slightly larger, have a high 'T' tail like a C-130 aircraft, and an aft cone that opens for loading and unloading satellites or whatever. There are no cargo bay doors so the fuselage would be stronger.

This shuttle would not take off straight up. Rather it would take flight like an airliner powered by its four F-119 jet engines (2 each side, inboard, above the wing to fuselage joint). The shuttle would gain altitude gently (15 to 20 degrees nose up) and slowly compared to the currect way but when it reaches 40-60,000 ft the pilot would ignite two JATO type solid rocket motors mounted to the bottom center of the wing. At this point the shuttle would nose up and around 90,000 ft the crew would shut down the jet engines. The jet intake and exhaust doors would slowly close tight. As the two solid rocket motors finish the crew would power up the shuttles three liquid rocket engines, one each in the wing root (mounted under the inboard jet engine), and another in the tail under the vertical stabilizer. The crew would then ignite two more solid rocket motors mounted to the belly. By now the shuttle would be vertically accelerating and the pilot would do a 180 degree roll and pull inverted to assume low earth orbit. The shuttle would fly an elongated S shape to orbit but with much less stress on the vehicle.

The wing tanks would hold the liquid fuel for the rocket motors and separate tanks would hold the jet fuel. The solid rocket motors could be jettisoned or not.

In space the aft cone door can be opened and the satellite expelled out the back.

The shuttle could then re-enter the atmosphere but with the help of the jet engines it may be able to slide in rather than plummet. I know it's a delicate maneuver. If they slide too much they skip off the atmosphere and fly away but if they could do it then the re-entry heating would be less. Also the jet engines would make the shuttle able to land almost anywhere. A drogue chute could be housed in the aft cone. Hopefully with the use of carbon composites the weight would be about the same as the current shuttle.

GCNRevenger · 2005-01-03 21:35:49

Mmmmm I think its going to be awfully heavy.

Liquid hydrogen also takes up a huge amount of volume with its low density, a regular airplane shape probobly isn't going to hold enough.

Solid rocket boosters are also pretty heavy, and aren't well suited for easy (as in, just refuel) reuse.

Commodore · 2005-01-03 22:02:22

Aren’t the F-119s used to power either the F-22 or F-35?

Point being, if it takes two to power each of those, its going to take a lot more than 4 to propel this monster.

I honestly can't see a need for "shuttle"-like craft for some time.

In the short term satellites can be launched relatively economically on rockets. In the medium to long term they'll be either be partially or fully assembled and launched from the moon.

Likewise, people in the short term can be cheaply launched via the CEV (assuming its a reusable capsule supporting 6-8 people). There’s also no reason a pair of CEVs can't be launched in tandem if the rocket can support it, and there’s a will at NASA to put all their eggs (and sperm ) in one basket.

In the long term, a passenger shuttle will be needed, but only when we need to send up 30+ people at once. At that point scramjets will probably make that realitively simple.

SpaceNut · 2005-01-04 05:32:26

Why would we want a new ship with more wing surface? Since it is so easy to bring this style ship to a horrible ending on re-entry. If anything you would only want the re-entry portion of the craft to have small wings and nor would we need a large cargo bay for that could be expendable before re-entry. I would go with a lot more heat shield that is replaceable whether it be the TPS system or the boiler plate as well as radiational shielding on just that section.

Dook · 2005-01-04 05:56:31

I'm not sure how much the current shuttle designs uses composites. The structure is mostly made of aluminum so if composites were used for most of the fuselage and wings it's empty weight may actually be less than the current design.

The current space shuttle weighs 230,000 pounds empty. One F119 engine puts out 35,000 pounds of thrust. A C-17 aircraft has four engines that produce 41,000 pounds of thrust each and the C-17 weighs 585,000 maximum. Now my design carries liquid hydrogen, liquid oxygen (both in heavily insulated wing tanks), jet fuel, an aft cone, and 4-6 solid rocket boosters so it would be heavier at launch but not nearly as heavy as the current launch design.

I couldn't find a weight for the F119 engine but I'd guess it's 1,500 lbs, lets just say they're 2,000 lbs so thats an extra 8,000 pounds on the vehicle. There is also the weight of the aft cone but that wouldn't be significant since it could be almost entirely composite, 1,000 pounds at the most. By using the composites we are talking about a vehicle that is only slightly heavier.

The hope was to get to 60,000 feet powered purely by the F119's then fire off two of the four solid boosters but you could fire off two of the boosters on the runway to assist in takeoff. Maybe this design would need a total of six solid boosters then? The liquid motors are really only needed for flight control after you get above the atmosphere so you wouldn't need a lot of fuel for them.

Don't get me wrong, I still opt for cancelling the current shuttle but if we are going to stick with it then maybe this idea would be more cost efficient? Also it would continue to give us the capability we have with the current shuttle: satellite (Hubble) rescue, supply and people delivery to the ISS, research... No having to move the shuttle around on a 747. No launch facility, just a long runway. You wouldn't have to lift it vertically to set up for launch. No external liquid fuel tank. A newer craft incorporating all modifications and improvements. Maybe it would actually meet it's hoped for launch per cost estimates?

GCNRevenger · 2005-01-04 11:35:02

Getting into space is simply not that easy. Such vehicle will never reach space because it is too heavy... The C-17 doesn't have to fly at Mach-25 or withstand the firey hypersonic plunge of reentry, which requires huge structural strength and insulation to keep the thing from burning up or the wings shearing off.

You have to absolutely keep vehicle weight to a minimum, including fuel, if you are going to get into orbit with a single-stage vehicle. The only airplane-like vehicle concieved that didn't use exotic regenerative scramjets that don't exsist was the Venturestar concept. A flying composit derigible because of the huge volume of liquid hydrogen needed, it never had much of a chance of working without some leap in technology, even with its advanced aerospike engines. The only SSTO that might be viable with today's technology is the DC-I "Clipper," for which the DC-X was a demonstrator. It too would probobly not have been able to carry much cargo because of its weight, and had to perform a pretty scarry reentry maneuver.

I think you should be looking at a two-stage vehicle, with the lower stage being a large carrier airplane powerd by jet engines that are boosted with liquid oxygen and perhaps carry a "sprint" kerosense rocket engine. The upper stage would be a pure rocket lift body powerd by Hydrogen/Oxygen rockets, perhaps fed by slushed hydrogen (spiked with Al powder maybe) and go into space.

Dook · 2005-01-04 13:38:54

I don't disagree with anything you are saying but you are comparing the design to other, failed, attempts. This design should instead be compared to one it most resembles, in fact, it's almost identical to it. The space shuttle!

Why can't jet engines carry a very heavy vehicle to 40-60,000 ft? They do it every day. The C-5 weighs in at a maximum of 850,000 pounds!

Yes, I know it has to go Mach 25 and withstand a firey plunge. This design would have to use the same ceramic tiles the space shuttle uses and accelerate with the exact same three engines the space shuttle uses now. I didn't say "take a C-17 into space".

Todays shuttle costs too much to launch. The total launch weight is about 4.5 million pounds. My design should be under 1 million and would be much more efficient.

It's simply a space shuttle that goes from 60,000 feet to LEO using 2-4 solid rockets. The liquid engines are only for space maneuvering and slowing for re-entry.

GCNRevenger · 2005-01-04 14:03:35

Just getting the vehicle up to 50,000ft isn't good enough, there is no way any vehicle can reach orbit from 15-16km @ Mach ~1.0 with solid rocket engines of practical size. It will weigh far far more then you predict, the jet engines simply don't add enough speed so that low specififc impulse solid rockets can achieve orbit.

For example, look the the Pegasus rocket from Orbital, for all its size and bluster, it can't even put a single ton into orbit, much less bring itself back down. It is carried to high altitude by a cargo jet and goes on to orbit with solid rocket engines too.

You are also neglecting the large volume and weight that rocket engines, even solid rockets, take up: they are pretty big, and adding ones large enough to push the plane into orbit will mean they are pretty huge. So you'll need a bigger plane, but then you will need bigger solid rockets, in which case you need an even bigger plane... and so on. Its a vicious cycle.

Even if you ditched the solid rocket engines and added more efficent Hydrogen fueled SSMEs like Shuttle, you will still be too heavy and you will have nowhere near enough fuel tankage. Its hard to really drive home how big the hydrogen fuel tank is: it is so big, that you could fit the entire space shuttle in it if you cut it into pieces... And you would have to drag this huge tank into orbit and get it back down.

There is a very good reason why NASA didn't simply put jet engines on the Shuttle Orbiter and strapped solid rocket boosters to the wings: because there would be no place for the Hydrogen/Oxygen fuel.

To recap, the Shuttle solid rocket boosters do much more for the Shuttle then simply getting it up to 15km at 4% of orbital velocity, they add a large amount of speed and altitude beyond that, which Shuttle needs to reach orbit.

Also, solid rocket engines aren't efficent enough to push any practical vehicle to orbit on their own, they would be too heavy, which also makes the whole plane bigger and heavier that defeats simply using bigger engines.

el scorcho · 2005-01-05 09:58:46

I had been thinking of essentially the same kind of shuttle replacement vehicle that is made of composites, takes off horizontally and flies to a certain altitude using jet engines, where it then attempts to go to space. However, instead of a chemical rocket, it fires a VASIMR plasma rocket (Isp of about 300 seconds or so) to get to space. Anyone know the weight of the VASIMR engine or the small nuclear fission reactor you'd need to bring along? ???

Martian Republic · 2005-01-05 11:21:37

I had been thinking of essentially the same kind of shuttle replacement vehicle that is made of composites, takes off horizontally and flies to a certain altitude using jet engines, where it then attempts to go to space. However, instead of a chemical rocket, it fires a VASIMR plasma rocket (Isp of about 300 seconds or so) to get to space. Anyone know the weight of the VASIMR engine or the small nuclear fission reactor you'd need to bring along? ???

The current shuttle was OK, but if we are going to buy new shuttle or try and redesign the current shuttle, we should consider going with a clean slate. Although the current shuttle were designed and built in the mid 70 to mid 80 and so were not designed with composites in mind. But, adding composites now would only add a little bit of benefit to the new shuttle and wouldn't worth the development cost to build them. If we going with a new shuttle with composites or a carbon fiber construction which will reduce the weight of our space craft, we need to also rev up the engines too with scram jets. But, even the we would still have to have a two piece shuttle to escape the earth gravity and to reduce the cost of going into space with any efficiency. Supposedly it would be 1/10 price of the current shuttle to send the same mass into space. The lower part of this two part shuttle would have the scram jet which can excellerate to mach 7 to 10 which would be about 1/3 the speed need for escape velocity. But, it would be flying like an air plane and it may even be able to fly suborbital too. So it would probably be flying little higher than a jet can and a whole lot fast. The lower part of the space shuttle configuration would also have most of the mass that would penalize us when we try to get into space. At about the highest point and as about as fast as that scram jet can go, it will release our new space shuttle orbiter with it rockets to push it the rest of the way into space.

This or something like this, is currently our best options if we are going to build more shuttle with the technology that we currently have on hand.

Larry,

GCNRevenger · 2005-01-05 12:14:00

VASIMR engines don't have anywhere near the thrust required to get into space. The reactor you would need would also be too heavy, especially with the radiation shield... Don't forget that a nuclear reactor is still ultra-dangerous even several months after shutting it off because of decay particles, which also means you will need big cooling radiators when you reach space.

There is a better and easier way I think of getting into orbit MR, and that is to use regular jet engines and bring along a supply of liquid oxygen and perhaps a kerosene rocket on the lower stage. If you inject LOX into the jet engines, they will get you up to Mach 5 and operate at a higher altitude, perhaps all the way to U-2 like heights. Carry along a rocket for a short burn if needed otherwise. The upper stage then won't need aerospike engines, and with slushed Hydrogen fuel can be built to handle more of the work in getting to orbit then regular liquid hydrogen.

Grypd · 2005-01-05 14:57:45

There is a better and easier way I think of getting into orbit MR, and that is to use regular jet engines and bring along a supply of liquid oxygen and perhaps a kerosene rocket on the lower stage. If you inject LOX into the jet engines, they will get you up to Mach 5 and operate at a higher altitude, perhaps all the way to U-2 like heights. Carry along a rocket for a short burn if needed otherwise. The upper stage then won't need aerospike engines, and with slushed Hydrogen fuel can be built to handle more of the work in getting to orbit then regular liquid hydrogen.

There are no jet engines in production that are capable of getting a lower stage to the speed of mach 7. It could be possible to adapt a jet engine to do this maybe by injecting LOX into the engine stream but more likely by use of water to be injected instead to cool the air as it hits the engine so allowing greater compression.

But fundamentally it will be easier to have a rocket on the plane to push a lower stage high enough and fast enough to allow the seperation of the smaller and space capable upper stage which can ignite its pure rocket engine to enter space and be able to return. Seperation was allways the most dodgiest part of using two stage space planes and Saanger had real problems with it. But if you go high enough and air pressure is severely reduced then you get a lot easier seperation.

GCNRevenger · 2005-01-05 15:32:42

Oxygen to accelerate combustion and provide oxidizer, and water to keep the engine cool. Sounds good to me.

If that doesn't get high enough, nose up and fire a kerosene rocket engine (RS-86 perhaps, not to be confused with the 68) to get above as much of the atmosphere as possible.

With no air, the spaceplane could use conventional fixed bell nozzles on its engines, avoiding the need for aerospike engines, and it should burn slushed or superchilled Hydrogen to save on density.

Grypd · 2005-01-05 16:08:56

If possible we should avoid the use of hydrogen as it really needs good storage and causes cryogenic problems. If we can get away with using Kerosene that would be better. Obviously the isp will be much reduced but the ease in handling and storage should increse flight rate capacity.

Of course another option is hydrogen peroxide/kerosene mix this with an improved isp of 271 should allow the required thrust with a decent safety level and quick refueling of the lower stages.

Still it is the upper stage that the problem occurs as we can get a much increased flight rate but still need to have an upper stage that can survive safely constant reuse. More to the point im thinking of a safely reusable heat shield.

GCNRevenger · 2005-01-05 16:47:57

No, there is no way you can make the upper stage light enough without a high Isp fuel, and Hydrogen is the only game in town. If you used kerosene or liquid methane it would still be too heavy. Peroxide/Hydrocarbon or solid rockets are definatly out too. The Russians, who have avoided cryogenic rockets like the plauge for decades, even broke down and called for Hydrogen/Kerosene hybrid engine for their MAKS spaceplane. Since the lower stage will be doing more of the work to get to orbit then in MAKS, it does the work that the Kerosene would do, which permits an all-Hydrogen upper stage.

Composit tanks can probobly be built, but not the honeycomb ones used on X-33/Venturestar that failed but solid composit.

Slushed hydrogen is about 25-30% more dense then regular liquid hydrogen, which will make a big difference in the size and empty weight of the vehicle.

Dook · 2005-01-05 17:17:08

After giving it more thought I would change the design to give it a more aerodynamic shape. Make it an elongated triangle with a flat bottom, rounded top, and a high split V tail like the F-119 stealth fighter. Keep the aft loading and unloading of cargo/satellites but instead of a cone have split doors that open like a C-141.

One thing I wanted to accomplish was to lessen the forces applied to the vehicle during launch as well as make it more efficient. Holding back the ship while all the engines are firing then accelerating to mach 7 through the atmosphere places tremendous stress on the airframe, equipment, cargo, and crew. This ship would accelerate more gently.

Also, it's not a single stage to orbit, it's 5 stages:
1) 4 jet engines from ground level to 100,000 feet, gentle 15 degrees nose up.
2) 2 solid rockets fired at 50,000 feet, gently nose up to a vertical climb.
3) 2 more solid rockets fired at 80,000 feet.
4) 2 more solid rockets fired at 110,000 feet, roll to inverted.
5) 3 liquid engines fired at 130,000 feet.

By using composites for the structure the weight of the four F119 jet engines (8,000 lbs total) shouldn't increase the weight of the vehicle more than the current 230,000 lbs. I think we could do it for about the same weight as the current shuttle. Make each solid rocket 1/8th the size and thrust of the current solid rockets and mount them all to a plate that attaches to the belly of the ship. This plate could be ejected when the ship reaches orbit. If a 777 can fly to 50,000 ft at 700 mph on four jet engines then so can this shuttle design.

Kerosene rocket engines sound better to use than shuttle hyd/oxy ones since the fuel tanks are the wings. As I've said the liquid engines are only for orbit maneuvering and slowing for re-entry, not to assist in making it to LEO.

GCNRevenger · 2005-01-05 17:47:10

Its not the altitude Dook, its the velocity. Your rocket plane probobly could reach the edge of the atmosphere, but there is no way that solid rocket engines would be light enough to give you much ground speed. You have to reach Mach-25 ground speed to enter orbit.

Solid rocket engines just don't offer enough push per pound to do the job. It isn't going to happen... you have to reach high speeds and not just altitudes, if you reach 200km straight up but are stationary versus the ground, you are going to fall right back down. The heavy casings for the solid rocket engines alone will prevent you from reaching orbit... LOX/Kerosene engines offer much more efficency, but the amount of fuel you need will prevent you from building a very streamlined rocket either.

The Space Shuttle needs such huge fuel tanks because it has to do most of the work in building this speed.

Dook · 2005-01-05 18:21:36

Hmm. Okay then each SRB has to automatically eject after burning out. The shuttle would have to maintain a gentle climb the whole way so they come away clean, maybe 55 degrees maximum. Also this relaxed climb would swap altitude for ground speed and give you more time with the jet engines online, still it wouldn't be enough. It needs something, 2 more solid SRB's for a total of 8? A scramjet? But you need serious speed to begin with (mach 3+?) to get a scramjet going. I don't know. Maybe someone has a solution.

Anyway some numbers on the SRB's for this design:
75' long each
4' wide
Each should burn for 1.25 seconds per foot length which comes out to 93.75 seconds of burn time each. Total thrust from each SRB is 375,000 pounds.

GCNRevenger · 2005-01-05 18:42:48

You can't simply add more solid rockets, because then your rocket plane will be heavier, which requires more solid rockets... See, the weight of the vehicle grows exponentially in order to reach higher speeds. Unless your plane uses a very efficent fuel, much more efficent then solid propellants, then it would have to be absurdly big. Fuel efficency and vehicle dry weight are absolutely critical for a more-or-less "one piece" spaceplane, and the heavy duty casings combined with low efficency from the solid rocket engines makes them unsuitable for anything except takeoff.

If you camp out in the atmosphere to run your jet engines, the air drag will keep you from reaching orbit easily either. You have to be able to pick up signifigant speed using the jet engines to make this worthwhile. Its also a question if turbine jet engines can survive speeds higher then Mach 5-6 or so without getting pretty hot.

Scramjets, in their current form, are good somewhere between Mach 3-4 up to Mach 15, which would be great for the carrier plane, but these are still pretty exotic and would require you to make the carrier plane very aerodynamic and stable to handle the stress of high-hypersonic flight. Advanced regenerative scramjets have the potential to reach Mach 20+, but those are still just an engineering concept.

Currently, LOX/H2O augmented turbine engines or ramjets are as good as it gets, which gives you speeds up to about Mach-5 and altitudes likly similar or a bit better then the SR-71 Blackbird.

Dook · 2005-01-05 21:22:32

Yeah, the SRB's weigh too much. 187,800 lbs each. Available power would only be 140,000 from the jet engines. No way you could get airborne.

You could fire 2 SRB's on the runway to assist with takeoff, they would put out 750,000 pounds of thrust for a total of 890,000 pounds. The total vehicle weight would be 1.5 million pounds.

Weights:
6 SRB's- 1,126,800 lbs
Empty Shuttle- 230,000 lbs
Kerosene- 100,000 lbs
Cargo- 63,500 lbs
Jet Fuel- 20,000 lbs
Total Weight- 1,550,300 lbs

It may just be possible. Have to be some very stout wings.

Edited: Jan 6th-SRB weight correction

Dook · 2005-01-07 15:35:05

After putting some more thought into the idea the only real purpose the shuttle serves is as a transportation system. Retrieving satellites is a neat little option to have but we've never used it and really it would only be used for the hubble.

So what if this new shuttle was half the size? Maybe 70' long instead of 122? It's cargo bay would be 20' long by a circular 15' wide and would mostly be used for carrying supplies to the ISS but also you could perform satellite (hubble) maintenance from it. With an elongated triangle shape it would have a lot of room in the wings for fuel tanks (kerosene and jet fuel). It would probably weigh about 130,000 lbs, slightly more than half the current shuttle's weight.

Weights:
Shuttle 130,000 lbs
kerosene 80,000 lbs
jet fuel 20,000 lbs
2 small SRB's 20,000 lbs
TOTAL 250,000 lbs

Thrust:
F119's 140,000 lbs
2 SRB's 41,772 lbs
Liquid (kerosene) engines ?

GCNRevenger · 2005-01-07 16:35:10

NASA is only going to have enough money to make one "Shuttle-II" most likly for a long time. We can set up and maintain small bases on Moon/Mars using expendable rockets, but there is no way we can do more then this without a truely, honestly, 100% reuseable cargo launch vehicle. I think a lift capacity similar to Proton, in the region of 20MT with a minimum of aproximatly 5m X 15m cylinder, perferably longer. A manned version would have a target capacity of 12 people with limited cargo or 16 people with "carry on" bags. We shouldn't even bother with a smaller spaceplane, since there isn't going to BE an ISS when this thing is finished.

Still not good enough, it must be powerd by Hydrogen rocket engines, thats all there is to it. There is no way you can get a one-piece spaceplane to orbit with Kerosene rockets, the stuff is simply too heavy. The SRBs will likewise be even worse, and drag you down even more. Even with jet acent and Hydrogen rocket sprint to orbit, I don't think you can do it, it will still be too heavy even without a payload.

Mad Grad Student · 2005-01-07 23:28:40

Unfortunately, the problem with your idea, Dook, is that even if the new shuttle were powered entirely by LOX/LH2 engines it would need to keep its structure weight down to 9-10% of its GTOW in order to allow for any reasonalbe payload and design margins. That leaves you with a shuttle that weighs at least 2,300,000 pounds on the ramp at best if it has an empty weight of 230,000 pounds. That wouldn't get very far with four 35,000 lb-thrust engines.

I don't buy into the whole VTVL SSTO concept. I'm all in favor of SSTO, but using a VTVL setup leads to a scary flight plan and probably won't save much mass over winged vehicles. During the X-23/X-24 program, NASA did a fair amount of research into lifting body aircraft, perhaps a concept that can be applied here. By creating a lifting body fuselauge filled almost entirely with fuel, there would probably only be a small mass penalty over a vertical takeoff setup.

This shuttle would takeoff like an airplane with four F-119s modified for LOX injection, and get up to about mach 5 and 120,000 feet under jet power. From there, LOX and either hydrogen or methane stored in the fuselauge would be used to propel it the remaining distance into orbit. Assuming a GTOW of 600,000 pounds, if the plane could be designed with an empty weight 50,000 pounds it could take 10,000 pounds of payload with it into orbit. The HTHL flight profile is inherently safer than anything involving vertical flight, as it allows fuel dump and glide to landing at any point in flight.

So can an orbital rocketplane be designed to fly with a little more than ten times its empty mass? With composite construction, aerospike engines (this was one of the few areas that actually saw a good deal of progress during the X-33 program), clever engineering... hmm... you never know.

Euler · 2005-01-08 01:46:41

This shuttle would takeoff like an airplane with four F-119s modified for LOX injection, and get up to about mach 5 and 120,000 feet under jet power. From there, LOX and either hydrogen or methane stored in the fuselauge would be used to propel it the remaining distance into orbit. Assuming a GTOW of 600,000 pounds, if the plane could be designed with an empty weight 50,000 pounds it could take 10,000 pounds of payload with it into orbit. The HTHL flight profile is inherently safer than anything involving vertical flight, as it allows fuel dump and glide to landing at any point in flight.

The problem with using jet engines is that they add a lot of weight and complexity, while only being useful for a very shout portion of the flight. I don't think that it makes much sense to use them on a SSTO.

I don't think you could keep the dry mass down to 50,000 lbs. The F-22, for example, has a dry mass of 31,670 lbs and it is many times smaller than this proposed vehicle.

I don't buy into the whole VTVL SSTO concept. I'm all in favor of SSTO, but using a VTVL setup leads to a scary flight plan and probably won't save much mass over winged vehicles. During the X-23/X-24 program, NASA did a fair amount of research into lifting body aircraft, perhaps a concept that can be applied here. By creating a lifting body fuselauge filled almost entirely with fuel, there would probably only be a small mass penalty over a vertical takeoff setup.

Building a SSTO rocket is easy. In fact, I think that an expendable SSTO HLLV is likely the cheapest way to launch payloads with current technology. The hard part comes when you try to get the vehicle back down in one piece. You are right that the VTVL method is dangerous and it also means that you have to carry extra fuel. However, wings are also dangerous and the extra weight of the wings takes away most or all of the payload mass. Even having a lifting body would significantly increase the dry weight and cost of the vehicle. That I why I don't think our technology is advanced enough for a practical SSTO spaceplane right now.

With composite construction, aerospike engines (this was one of the few areas that actually saw a good deal of progress during the X-33 program), clever engineering... hmm... you never know.

I don't think that aerospike engines are the answer. The X-33 engine had a lower Isp than traditional engines both at sea level(which was supposed to be its strong point) and in a vacuum. They don't seem to have sufficient advantages to justify their use.

Still not good enough, it must be powerd by Hydrogen rocket engines, thats all there is to it. There is no way you can get a one-piece spaceplane to orbit with Kerosene rockets, the stuff is simply too heavy. The SRBs will likewise be even worse, and drag you down even more. Even with jet acent and Hydrogen rocket sprint to orbit, I don't think you can do it, it will still be too heavy even without a payload.

Getting a one piece spaceplane into orbit with kerosene engines should be easier than making a spaceplane with only Lh2/lox engines. The dry weight of an SSTO spaceplane, especially a relatively small one, is dominated by its fuel tanks and the structures that it uses to land its fuel tanks. If you assume that the weight of the tanks is mainly dependent on volume, then you want a propellant that can get a lot of mass into orbit while only taking up a relatively small volume. I made some mathematical models to test the relative competitiveness of Lh2 and RP-1, and the RP-1 comes out ahead in most of them.

There are also some other fuels that can be considered. http://www.dunnspace.com/alternate_ssto … s.htm]Here are the results that someone else got when studying various other propellants. Hydrazine and MMH also come into consideration, since they are both denser and have a higher Isp than kerosene or UMDH. Unfortunately, both have some toxicity concerns. If you are really pressed for performance, you could even add in some fluorine when you get into the upper atmosphere, though that does have some severe handling issues.

The best option is probably to use a tripropellant engine that launches using a dense fuel and switches to Lh2 as if gets closer to orbit. That would add cost and complexity, but in a vehicle like this you need to maximize performance as much as possible just to make it work at all.

Dook · 2005-01-08 07:46:09

Total launch weight of this vehicle is 250,000 lbs with a thrust of 140,000 lbs. Compare that to a C-17 aircraft that can weigh 585,000 lbs and fly 500 mph at 40-45,000 feet with a thrust of 164,000 lbs. I'm sure we could get this smaller shuttle up to 60,000 feet and 450 mph on the F119's alone but the next mach 24.5 and 340,000 feet is the problem.

The shuttle could reach 60k altitude and level off to gain speed then fire the SRB's to accelerate to mach 3 where two scramjet engines would kick in. The crew would then shut down the F119's, intake and exhaust doors would close, and accelerate to mach 20 and 120,000 feet. From here on up it's liquid engines, kerosene or some other mixture.

The cargo bay is quite small, 20' by 15' circular. Mostly it would just carry supplies for the ISS but it could be used for other things. Maybe extra seats for future passengers? Maybe it could open it's bay doors for robotic arms to go out and grab a satellite to conduct in space repairs?

Just guessing, it would cost $10 billion to build but it would be much more cost efficient in the long run over the current shuttle.

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#12 2005-01-05 14:57:45

Re: New Space Shuttle

#13 2005-01-05 15:32:42

Re: New Space Shuttle

#14 2005-01-05 16:08:56

Re: New Space Shuttle

#15 2005-01-05 16:47:57

Re: New Space Shuttle

#16 2005-01-05 17:17:08

Re: New Space Shuttle

#17 2005-01-05 17:47:10

Re: New Space Shuttle

#18 2005-01-05 18:21:36

Re: New Space Shuttle

#19 2005-01-05 18:42:48

Re: New Space Shuttle

#20 2005-01-05 21:22:32

Re: New Space Shuttle

#21 2005-01-07 15:35:05

Re: New Space Shuttle

#22 2005-01-07 16:35:10

Re: New Space Shuttle

#23 2005-01-07 23:28:40

Re: New Space Shuttle

#24 2005-01-08 01:46:41

Re: New Space Shuttle

#25 2005-01-08 07:46:09

Re: New Space Shuttle

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