New Space Shuttle

Martin_Tristar · 2005-02-28 03:58:20

GCNRevenger,

Firstly, you didn't read my statements correctly, I said " that we would build a strap on booster for the NTR Engine " thus allow it to stay in orbit and be used in larger spacecrafts for moon and mars.

I can guarantee that Mars Research Stations on earth are here to trial different technologies, social interaction and other systems both human and mechanical that will be used on Mars and the social factors that could make or break the human spirit on Mars, Also the Moon Society is trying to access them as well for lunar testing.

Secondly, we have increased our technology in the field of nuclear energy and have developed new materials , ceramics and metals. we haven't looked at different methods to expell the hydrogen, also control mechanisms that could keep the reactor functioning above 1950-60's norms.

There are many different reactor designs across the world, and no-one has looked into the reactor design for the NTR or the fuel control systems or secondary coolant systems or radiation shield options including using magentic fields and other methods outlined in different scientific journals worldwide. We need testing, testing, and more testing before we use it in a spaceplane , I am not saying that the drive systems are completely safe ( but human safe ) but if we want long term space colonization we will need drive systems like NTRs and nuclear-thermo-plasma propulsion systems.

I think we need to revisit the development, design, testing and delivery systems to build the best spaceplane transportation system for the future for colonization of space. ( not the tourist space visits that we have right now ) We need newer technologies and systems that can help humanity to get off the earth and expand rapidly into space with large scale human movement into space stations and eventually to the Moon and Mars.

SpaceNut · 2005-02-28 07:03:39

Could the vehicle design be altered to have a verticle take off using drop off srb's and only use the jet engines for landing?

Dook · 2005-02-28 07:12:05

I think GCN would at least prefer the vertical launch, though I don't. What's the point in having an RLV when after it lands you have to go through all the trouble of loading it with new cargo and turning it vertical?

The whole benefit of having the jet engines is to get the vehicle to the top of the atmosphere then use the liquid engines since they produce 100,000 lbs more thrust in a vacuum. Plus the jets would enable the vehicle to be flown to maybe Vandenberg for a launch.

GCNRevenger · 2005-02-28 07:15:23

I read what you said and I commented on it. No RLV must have any expendable componets or that will ruin the usefulness and advantage of such a vehicle. No strap-on unreuseable anything.

And again, for the third time, since you cannot ensure that the hot reactor will reach orbit, no NTR engine for launch will ever be safe enough for everyday operations. I support the use of nuclear fission for space missions, but only in space, and no space reactor should be activated below or in an unstable orbit.

"Secondly, we have increased our technology in the field of nuclear energy and have developed new materials , ceramics and metals. we haven't looked at different methods to expell the hydrogen, also control mechanisms that could keep the reactor functioning above 1950-60's norms."

No we can't. We are reaching the upper limit of what is possible for any solid material to retain its cohesion because there is an upper limit to the strength of the chemical bonds between atoms. If you add more energy then the bond strength (heat), then the bonds break... kaboom. Since the efficency of a nuclear engine is based almost soley on its operating temperature, we therefore cannot build a pure solid core NTR that is much more efficent. Not now, not ever.

"no-one has looked into the reactor design for the NTR or the fuel control systems or secondary coolant systems or radiation shield options including using magentic fields and other methods outlined in different scientific journals worldwide."

Why would they do that? If you add all these things to an NTR engine, it will be so much heavier that you might as well use regular chemical engines instead. Magnetic fields are also only good for stopping charged particle radiation, which won't do you any good at all against the intense gamma and neutron radiation that makes fission reactors so deadly.

Yes we will need nuclear engines to get between the planets and to provide energy, but we neither need nor should employ NTR engines to launch off of Earth's surface.

GCNRevenger · 2005-02-28 07:17:27

I think GCN would at least prefer the vertical launch, though I don't. What's the point in having an RLV when after it lands you have to go through all the trouble of loading it with new cargo and turning it vertical?
The whole benefit of having the jet engines is to get the vehicle to the top of the atmosphere then use the liquid engines since they produce 100,000 lbs more thrust in a vacuum. Plus the jets would enable the vehicle to be flown to maybe Vandenberg for a launch.

Where did you get this idea? Absolutely not, any winged RLV should launch off of a runway.

The other bennefit of jet engines is that they are several times more efficent then rocket engines and are much easier to reuse and don't tend to explode as much.

Martin_Tristar · 2005-02-28 22:03:44

GCNRevenger,

If you are so supportive of nuclear drive, then you should be supportive of renewed development and testing of NTR and hybrid drive systems and new integrated control management systems for space crafts.

In the future we will not, just develop space vessels to launch from earth in a chemical rocket mode and then go nuclear in space. Ion Drive, Plasma Drive and other nuclear type drive systems that use reactors within the engine or provide power are all have the same risks, and we are going that road. We need testing, testing, testing, and development of new casings, reactors, and power sources for the next 50 yrs and we need to start now !!!!!!!!!!!

GCNRevenger · 2005-03-01 06:53:47

And what is wrong with using chemical engines for launch from Earth into orbit and nuclear engines from there on? Chemical engines for a spaceplane aren't that much less efficent due to their weight & shielding, they are far cheaper, and don't have that little radiation problem.

"all have the same risks"

But thats not true, not true at all. Ground launch with a large and poorly shielded reactor is far more dangerous then using small NTRs or reactors only in space. You will need a large reactor for your nuclear spaceplane, and if something goes wrong then that reactor is going to come back down while it is still intensely radioactive. At least in orbit, the reactor would have months or years for the really bad radioisotope daughter particles to decay safely.

Again I state, that given the huge risks involved, where a failure of the launch vehicle could kill thousands or tens of thousands, offers no performance advantages over chemical engines with requisit shielding/larger tanks/cooling systems, and is far more expensive then chemical... ultimatly makes no sense. In fact, if regenerative Scramjets were invented, they would be 150-200% more efficent per-pound of fuel then nuclear engines.

Martin_Tristar · 2005-03-01 07:32:49

GCNRevenger,

You have made assumptions for Large NTR Reactors and Engine Assemblies. We don't know what size and configuration for the particular spaceplane design. We haven't even looked into the drive designs to see if any changes in design could provide an advantage to lessen radiation, weight, increase fuel consumption or combination of factors.

I find your statements, illogical because we haven't experimented with NTRs from the 1950's-early 1960's. We need to test, examine existing designs and create in new technologies and if necessary develop newer technologies to improve the engine design and performance.

RobertDyck · 2005-03-01 08:24:02

We've had this debate before. I've seen a presentation by anti-military conspiracy theorists who point out that plutonium is extremely chemically poisonous, even a tiny amount in our environment from a single RTG aboard a failed satellite will kill thousands. Their claims are obviously exaggerated, but plutonium is poisonous. They immediately assume all nuclear must be plutonium, ignoring the fact that uranium oxide is not chemically toxic at all. They also mention depleted uranium caused Gulf War Syndrome. That's not true either, the US military knows the symptoms from depleted uranium and GWS is not it. GWS was caused by release of several nerve gasses when the US Air Force bombed the chemical weapons factory/storage depot. Iraq never used chemical weapons, but one US general thought you can destroy anything by dropping a bomb on it. Stop and think for a moment, what happens when you drop a bomb on gas? French troops were down wind and their chemical weapon sensors did go off; American troops were down wind of them. Hysteria about anything "Nookyoular" is irrational and the reason the US doesn't have a reprocessing facility to convert nuclear power plant waste into materials that aren't radioactive. However, there is a chance they will gain political muscle again once George W. is out of office. In 4 years someone else will be president.

Try calculating it. GCNRevenger does have some valid points. The Nerva design is way too heavy. I tried to calculate it and found a launch vehicle with chemical rockets can lift about as much cargo for a given size rocket, and nuclear engines will cost more. Timberwind is more efficient, but an air breathing launch vehicle doesn't have to carry most of it's propellant. Think about it; the atomic weight of oxygen is 16 and hydrogen is 1, so the molecular weight of H2O is 18. Actually they're 15.9994 and 1.00794 so water is 18.01528, but in combustion the H:O ratio isn't perfectly 2:1 anyway, there are partially combusted products. So an air breathing vehicle only carries 2/18 of its fuel, or simplifying fractions that's 1/9th. Even a nuclear thermal rocket can't compete with that.

But we'll never get anywhere if we sit on our ass and do nothing.

GCNRevenger · 2005-03-01 15:17:52

You have made assumptions for Large NTR Reactors and Engine Assemblies. We don't know what size and configuration for the particular spaceplane design. We haven't even looked into the drive designs to see if any changes in design could provide an advantage to lessen radiation, weight, increase fuel consumption or combination of factors.
I find your statements, illogical because we haven't experimented with NTRs from the 1950's-early 1960's. We need to test, examine existing designs and create in new technologies and if necessary develop newer technologies to improve the engine design and performance.

Thats correct, I am assuming that you need a large reactor, because that is the only way.

You need a rocket engine with considerable thrust, much bigger then the J-2, probobly with the same thrust as the SSME engines on Shuttle aproximatly. Such an NTR engine with that much thrust must have a large reactor, there is just no way around it.

Why? In order for the efficency of a nuclear engine to be superior to that of a chemical rocket, it must reach a very high operating temperature, in the region of 3000C aproximatly. In order to heat a large enough mass of ultracold hydrogen to this temperature quickly so that you have enough thrust, your reactor must therefore produce a large amount of energy.

The output of energy is limited by the temperature, which cannot be radically improved because no solid resists temperatures much higher, and the mass of the nuclear fuel that is at that temperature in practical reactors. But say you want to accelerate the reaction of a smaller amount of fuel?

NTR engines like Timberwind, the lightest and hottest reactor ever concieved, would use up most of its fuel in a single firing. So, if you include even less fuel to save on mass but try and accelerate the reaction, you will run out of Uranium before you even reach orbit.

You will also not decrease the amount of radiation produced, since the radiation output of the reactor is related to how much Uranium would be used up, so you won't save much on shielding mass. Yes the reactor will be smaller, but it would produce more radiation per-area, requiring a thicker and heavier shield.

So, to put it simply, there are no changes you can make to improve this situation. You need to produce a certain amount of energy to reach orbit, and the amount of radiation produced is directly linked to this amount of energy, so there really isn't any way to produce far less radiation.

We don't need to experiment anymore, we already know the answer.
-------------------------------------------------------------
I would like to think that USAF generals wern't that block-headed Robert...:
1: Maybe they thought that destroying the weapons was worth the risk to the troops, especially since sunlight might probobly weaken the vapors from the UV and desert heat.
2: Saddam was known to use binary weapons, so there wouldn't be any of the actual nerve agent sitting in munitions or tanks, but rather only the componet chemicals. Spreading them around would limit the nerve agent formation since they would need to be in intimate contact. The toxticity of the componets might have been sorely underestimated however.

Anyway, even comparing NERVA style NTR engine to chemical rockets for a reuseable spaceplane, the NTR engine doesn't have a solid edge. The extra size of the vehicle due to the bigger H2 tanks would add drag as well as mass, plus it would increase the vehicles' area more then its mass, which will make reentry harder. The shielding is obviously going to be a big problem, and might easily weigh tons for the large reactors needed for a spaceplane. Thats not counting crash/reentry armor nor 360deg shielding for safer handling if it were reuseable... you might also have to worry about assured cooling to remove decay heat.

And of course the radiation, which I think a large NTR engine(s) will produce such a large amount of daughter particles that they pose a real danger, and not an imagined "we're goonnnna diiie!" one like Cassini's plutonium.

Martin_Tristar · 2005-03-03 21:22:09

The only time, NTR engine may an issue with public safety is crashing not re-entry because it stays in orbit and used for other space vessels from earth to moon or mars expeditions.

Get your facts correct !!!!!!!!!

GCNRevenger · 2005-03-03 22:17:50

It would really help if you learned how to read I think Tristar...

Throwing away an NTR engine for every flight of a reuseable vehicle is fiscal suicide, you shouldn't even need to read that, as it is obviously a terrible idea. Hence why I haven't really given it much time in the above posts... I'm not even going to quantify how bad an idea that is.

Martin_Tristar · 2005-03-04 19:26:48

GCNRevenger,

I am not throwing it away, The NTR Engine would move from the spaceplane onto a space-based vessel. We can then clip and install the drive component directly on the space frame without any modifications.

Example

Spaceplane once per month launches into space carrying 25+ personnel and cargo for a space station / factory platform, once in orbit the NTR is shutdown, removed from spaceplane by robotic arm, either stored in orbit storage depot or attached to a new space vessel frame under construction for a lunar or mars mission. These engine assemblies are designed on earth with all the appropriate safeguards, monitoring systems and control systems pre-built before space vessel assembly in orbit.

12 spaceplanes per year : 2 engine assemblies per space frame = 6 space vessels for space exploration, cargo transports, lunar missions, or mars missions. Provides a reduced lead time to development of large space vessels in orbit.

But before this can happen we need a world class test, and development center for nuclear research and development as well the nuclear rated engineers and other qualified personnel for earth based facilities and space based facilities and vessels. Thus these engines that use nuclear energy as propellant or as power must be tested first. I don't believe the saying - it won't work. I need to see the data relating to the design, aerodynamic data and the nuclear research data before i can say it does't work and then we find another way or new technology and make it work.

GCNRevenger · 2005-03-04 21:38:09

I don't think that you are really understanding the reasons we should build a true RLV spaceplane, Tristar.

There is never going to be a spaceplane or other RLV powerd by any kind of practical engine that will have a huge heavy-lift payload, if for no other reason that it would be unreasonably large. This is not a consequence of any technological limitation, but rather the sizes of things that are convienant to operate, the unchanging force of gravity, and the limited energy density of practical fuels.

Since spaceplanes or other RLVs cannot deliver much payload, then the only good reason to pay their extreme development and construction costs is to fly them very often. Really often. Like weekly, not monthly... If you can't fly often, you might as well use an expendable rocket.

If you can't fly except monthly, then your spaceplane isn't worth much. If you have to buy a brand new NTR engine for every flight, its REALLY not worth much... Why not? First off is the cost, that if your nuclear engine/rad-shield/tank costs even a few tens of millions, then each spaceplane flight will be far too expensive and you'll never save any money that way.

But most of all, the idea of donating the engine from your spaceplane to new ships in orbit is bad for a simple reason... You need to launch fuel for those engines, and you will always be launching more engines then you will ever need.

And again, I remind you about the radiation problem...

-A large reactor will never, ever be safe enough to use for getting into orbit on a regular basis. Ever. The risk of catastrophy and the deaths of thousands from exploding or suborbital reentry from a technical "glitch" is unacceptable. Period... This is not like a nuclear power reactor, there is no containment dome, no exclusion zone, and no warning.

-The shielding required to make the reactor safe enough to not fry the crew or orbital handling technitions, combined with the extra drag and mass due to the bulkier Hydrogen tanks on the spaceplane, will largely eliminate any performance advantages versus chemical engines. By making the engine reuseable, you also require that it be of the much heavier NERVA type and not the light weight Timberwind type.

"I don't believe the saying - it won't work. I need to see the data relating to the design, aerodynamic data and the nuclear research data before i can say it does't work and then we find another way or new technology and make it work."

Here is where you take a detour from reality; the way things actually work is that you don't do anything, not one single thing... no experimental data, no technology development searches, no offical design studies... nothing until all of the conceptual, fundimental, roadblocks are cleared and the concept is validated.

If there is a conceptual problem with your idea, then no other investigation is warrented to deciseivly state that your idea will not work... Plenty of ideas simply are not good ideas, and blind faith in technology that doesn't yet exsist to fix fundimental physical problems is irrational... and irrationality does not a spaceship make.

Martin_Tristar · 2005-03-04 22:55:22

GCNRevenger,

Crash Course in Space Economies

The strap-on booster would be cargo for the space vessel development projects every time it is carried onboard with the spaceplane thus can be charged as cargo by weight of assembly without fuel. The fuel would be an expense on each launch and the spaceplane would be an asset to be maintained and depreciated against for the life of the plane similar to an airline. The return large cargo and personnel would be a paying flight similar to airlines ( cargo from space based factories, and passengers from staff of other businesses, and our own personnel in orbit. again profitable)

GCNRevenger, you enjoy the rocket concept and I don't have any issues with your opinion on one use delivery methods except when over a period of time it is extremely expensive particular when talking about movement of 300 personnel per year in earth space rotations, lunar surface rotations and eventually going to mars missions and crew rotation for it as well.

Earth Space Objective

Our Earth - to - orbit goal is to create a viable RLV that can be used for large cargo and volume personnel to meet the view of 1000+ personnel in crew rotations from orbit, moon, mars and human exploration missions. We have the aerodynamic design for the spaceplane, but the engines and other control and management systems are still on the concept stage. After conceptual development over then prototype the concept in separate stages before full mockup vessel for testing.

For now we can still use re-entry capsules or one way spacecrafts for earth space until we can complete our objective, after that point a RLV would be the only way we should go into space and I would be looking to marketing that spaceline service to all countries for a lower fee then launching their own spacecrafts.

GCNRevenger · 2005-03-04 23:03:32

"The fuel would be an expense on current launch and the use depreciation would be a paper loss for other businesses to absorb. "

"Abosrb" means "adds to the cost of" here in reality unlike Dilbert execuspeak land. And if you add the cost of a whole second flight and its expensive NTR engine just to launch fuel for previously launched NTR engines, that kind of doubles your payload costs. And that is to say nothing about wasting an entire NTR engine just for a crew flight.

You cannot build a spaceplane of practical size with heavy cargo capabilities. It cannot be done. You really have no idea the scale of the vehicles involved here... Since you can't build a heavy-lift spaceplane, you must therefore build a smaller one that can fly much more often. Weekly lets say.

The only way a spaceplane makes sense is if it has modest payloads and is flown often. Very often. And each flight cheaply... in order to do this, it must 100% come back down to the ground. No "strap on" anything. Period.

Martin_Tristar · 2005-03-05 01:05:48

GCNRevenger,

Yes i do , understand the size, the spaceplane is an aircraft upto 40,000+ ft and then space drive takes over and launches the spacplane into orbit. The booster is an attachment to the spaceplane design, once the booster is detached the spaceplane will re-enter earth atomsphere the same way the current space shuttle does and returns to spaceport.

The difference with this spaceplane and previous spaceplanes / space shuttles is that this vehicle is designed primarily for passengers and airline cargo containers for personal effects and small cargo supplies, not an all purpose bulk haul spaceplane like the American Space Shuttle. The passenger spaceplane could be as large physical as the current space shuttle but redesigned for HTOL with not large vacant cargo area.

Other types of horizontial take off vehicles will supply large cargo components that don't fit nicely into a small diameter rocket into earth orbit thus developing a total / systematic transportation system for earth space.

Utlimately we need to start looking at the different methods to launch a large scale population of humans into space and rotate and supply them continously from earth for the near future until we have growth in our permanent human space based population. That is why these spaceplanes are going to be useful in the long term exploration, colonization of space from earth.

Grypd · 2005-03-05 05:44:04

The strap-on booster would be cargo for the space vessel development projects every time it is carried onboard with the spaceplane thus can be charged as cargo by weight of assembly without fuel. The fuel would be an expense on each launch and the spaceplane would be an asset to be maintained and depreciated against for the life of the plane similar to an airline. The return large cargo and personnel would be a paying flight similar to airlines ( cargo from space based factories, and passengers from staff of other businesses, and our own personnel in orbit. again profitable)

Having read the last few postings I have to say. That this sounds suspiciously like the space shuttle that we have now where the majority of it is expended each flight. It takes months to get each flight ready but it was claimed on creation it could be done in weeks. Oh and it is one of the most expensive designs for spaceflight ever created. It was supposed to be truly reusable, but the dream was dropped and now it is a fundamentaly expensive millstone for spaceflight.

Spaceplanes will be devloped starting with a TSTO design where the lower stage is completely reused but for actually getting anything heavy to space we will still need a Heavy lift option. This is the problem that the shuttle faced and failed to actully implement. If we want to put more than 5 tons into orbit we need to have to use a rocket as spaceplanes mass fractions are perfect for quick reusable light cargos like people but not for heavy loads and trying to mix both options in one craft makes it an undesirable launch option.

GCNRevenger, you enjoy the rocket concept and I don't have any issues with your opinion on one use delivery methods except when over a period of time it is extremely expensive particular when talking about movement of 300 personnel per year in earth space rotations, lunar surface rotations and eventually going to mars missions and crew rotation for it as well.

Then you can use a basic TSTO design where it docks with something in orbit and crew transfer is done. Having a single craft that can go from the ground and go anywhere in the solar system is truly a science fiction plan. Even to have a single stage RLV is frankly too far ahead for us and though it could be made its cargo capacity would be so small as to make it fundamentally useless. We do not have the engine (this includes nuclear) and material knowledge to do this yet and for the forseeable future. T

GCNRevenger · 2005-03-05 09:13:01

Let me get this straight...

You want to build a two-stage horizontal takeoff spaceplane that is exclusively for large crews and light/pressureized cargo that has a reuseable low/mid temperature solid-core nuclear thermal rocket... where this spaceplane must fly often and cheaply to effect efficent crew rotation (which would demand 100% reuseability) yet the half-spent NTR engine is removed from the spaceplane and stored in orbit to build future cargo ships...

No provision for heavy payloads, no provision to return the NTR engine to Earth, no provision that carries enough excess fuel for that engine and its future payload to go from LEO to anywhere.

And for all that fuel you'll need, tons and tons of it, you are going to get that where? "Other types of horizontial take off vehicles will supply large cargo..."

Passing the buck aren't we? Relying on a seperate vehicle to lift payloads to make your spaceplane make sense doesn't seem like a good idea to me, given you would have to develop TWO spaceplanes instead of one...
---------------------------------------------------------------------
Your spaceplane is a textbook study of the "worst of all worlds" and is a horrible idea... But besides that, you are willfully ignoring the two fundimental and unchangeable reasons why your spaceplane is a terrible idea:

1)...You are again completly failing to address the issue that no spaceplane makes any sense unless it can be flown often and inexpensively. That is the whole reason why an RLV spaceplane is superior to regular rockets despite their inferior payloads... your vehicle clearly does not meet these statutes, because it can't fly very often (only monthly?) and because it cannot ever fly as cheaply as it must (expends an NTR engine on every flight).

The major strength of a spaceplane to effect the large-scale and very regular manned travel from Earth to LEO and back is that you get the entire vehicle back, which radically reduces costs. You are never going to need as many NTR engines as you need flights to orbit, that is never ever going to happen, especially if your engines are reuseable multiple times, so a "strap on" engine is just out of the question reguardless of its technical feasability. 100% of the entire vehicle must return, everything except the explosive bolts, or its not worth the trouble.

2)...Radiation. It should be possible to build a shield for the reactor that is safe enough to protect the crew from being fried. But even if it is possible, it is still a bad idea from a purely performance standpoint. Why? Because the shield will weigh many many tonnes, and will actually weigh about as much as your payload. The reactor itself, being of NERVA type must also be by nessesity pretty heavy given the thrust required, and will easily exceed the mass of a comperable chemical engine... Since NTR engines are roughly twice as efficent as regular chemical ones you will get no performance bennefit at all, because the extra weight of the shield & core will be about as big as the mass you save by using NTR in the first place. That is not counting the extra fuel tank mass for the less dense hydrogen nor the extra drag from the low-altitude (40,000ft) ignition altitude... Chemical engines will actually lift more cargo probobly!

Then there is that teensy problem of what happens if there is an "incident" before you reach a stable orbit, which you have time and time again refused to acknowledge even though I have clearly illustrated the problem. This is not the same kind of risk as the "Stop Cassini!" whimps or the threat posed by a power reactor on the ground. This is much different because of the HUGE amount of radiation produced, which is easily thousands or millions of times more intense then if Cassini blew up. There is a such thing as level of radiation that will fatally wound you just by being in the area... and your reactor would generate this radiation.

Come to think of it, this would also radically increase the radiation shield mass for the crew module... But anyway, it is really quite simple, that you can never protect the reactor sufficently to make it worth the risk of killing tens of thousands of people if there were a crash or an explosion. I personally don't think that it would ever be worth the risk, and I would abandon spaceplanes entirely if it were required... but thankfully it is not, since chemical engines can do the job. If you try and wrap the reactor in armor, it would still kill everyone within a mile of impact, and no armor could ever ensure a safe reentry, and trying to add it would make the reactor so heavy that a chemical engine would be FAR superior.

These two problems are inherint, conceptual problems with your spaceplane concept Tristar. You must either overcome them, or abandon your design... thats all there is to it.
---------------------------------------------------------------------
"Yes i do , understand the size,"

No, you don't. Since you will be using only liquid hydrogen, your fuel tanks will have to be VERY large, as Hydrogen has such a low density. Chemical engines have superior density, and would yeild a spaceplane of sane size. Yours will not.

"40,000+"

Is also much too low. 100,000ft should be the target seperation altitude.

And if you want to somehow increase the efficency of your nuclear engine, or reudce its mass, you are out of luck. Since the NTR engine must be able to fire more then once, you cannot use the carbon/ceramic Timberwind-type cores, since they quite literally melt after just one firing. In fact, you are limited to a low maximum core temperature because no material can withstand temperatures high enough to improve on the ~900-950sec Isp that NERVA can provide. Temperatures much higher then this exceed the maximum theoretical bond strength of any combination of atoms, so no solid that can withstand radically higher temperatures is even possible.

Let me reiterate again, that the main strength of a spaceplane that makes it worthwhile is its ability to fly often and fly cheaply. The only way to do this is to make a smaller spaceplane, while still holding a reasonable payload (Proton-sized unmanned, or 12-16 crew manned in an escape cabin like F-111 medium bomber), and returning 100% of the vehicle back to the launch site for quick turn-around. If you can do neither of these things, then your idea will never get off the ground... literally.

Martin_Tristar · 2005-03-05 23:56:46

GCNRevenger,

Regarding your comments

Firstly, the spaceplane is a single stage development with a strapon booster that only comes off after orbit is achieved. The first few years we will only require a minimum number of flights per year ( approximately one per month ) to slowly increase the personnel in space and rotate them until we move to second scale developments on the lunar surface and mars planning.

Heavy lift payloads are sent via other single use vehicles into orbit and disassembled in orbit and recycled. Again reducing the overall cost to frieghting components into space, we are currently designing space vehicles with cargo volumes that exceed the space shuttle cargo haul.

We don't believe in a one ship does all and everything going into space needs to fit that vessel shell. We work on the method that what do we need ( component ) to get into orbit and design a system around it from a modular designed space vehicle system that would conform to those requirements.

However we need a permanent human centric reusable space vehicle that can accommodate a larger volume of personnel then current space vehicles and also accommodate their personal effects and cargo that can be packed into space designed cargo containers similar to airline containers for the aircraft hauls.

About the Nuclear Engines and our Drive Principles

We don't know of any privately owned and operated spacecraft design and evaluation center for nuclear drive systems, Well not yet !!!!. So, we are working on old data from tests on nuclear research from the 1950-60's. That is why we need to design and test for a new nuclear type engine system.

Some of the new features that we are looking for in the engine design are :

1. Reusable engine from earth launch on the spaceplane to use in space for extended mission vessels from earth to moon, mars and beyond.

2. Appropriate safeguards for earth environment and personnel in the use of this engine system both on earth and in space including any personnel close to the system while on the spaceplane.

3. The Thrust ratio to engine weight is better than chemical engines of the same size and weight.

4. Designed to be Recycled for space based vessels for future missions and can be maintained and upgraded easily for future developments.

We have looked at the data from the 1950-60's and didn't hold to these principles above, that is why we need to do more research in the materials used, methods of propellant used, methods of propulsions, control mechanisms, and radiation issues , just to name a few issues that we have with these drive systems and we are confident to overcome these issues in the timeframe we have set.

But before we design an engine system to meet the above principles for the future in HTOL Spaceplane development. It always comes down to infrastructure - the design, and conceptual development of the new engine assembly could be down from anywhere but the testing will require a location for nuclear testing and that is harder to find within the country or anywhere else across the world.

At the beginning of this discussion I said that we need to test, test, and research new nuclear type drive systems for future spaceplane development. I haven't stopped saying that and I don't see coming out , opposed to the development from a fear background when we don't have the data to know either way, but we need better nuclear drive systems for the future of space based missions to mars and beyond and the movement of large scale population to other space locations ( moon, mars and beyond)

RobS · 2005-03-06 06:36:23

In other words, you've ignored almost everything GCN said.

GCNRevenger · 2005-03-06 09:45:49

Yeah pretty much Rob...

Okay Tristar,

If you want to support a manned space program that has need of flying three hundred crew per year, I think that it is very safe to say that we could never afford enough expendable rockets to fly cargo to keep them in productive business. If they were doing anything valuble on Earth that needed down-mass, like returning Lunar fuel cell catalyst metals or Helium-3 or supercrystalline silicon ingots or whatnot then expendable rockets won't do. Furthermore, recycling of spent rocket stages and mating to your reuseable nuclear engines doesn't make alot of sense, because if they are reuseble, then they won't need many of them since the vehicles would be reuseable.

The solution? Build a cargo-carrying spaceplane.

Now, since your vehicle relies almost entirely on its NTR engine for acent, it is going to be HUGE because of the very large Hydrogen tanks. This will make having a large crew cabin difficult since you must keep your size as low as possible. If it is much bigger then a modern airliner, it will be too large to operate economically. Too many engines, too many landing gear wheels, too many heat shield seams, too many rivets, too many fuel lines, too many of everything.

The solution? Build a smaller spaceplane. In order to do this but maintain the number of people flown per year, you must resign to carrying a smaller crew but flying more often, say 14 people (2 crew + 12 passengers) would fit snugly with sufficent escape hardware. This will go a long way to getting your vehicles' size under control.

So why not kill two birds with one stone... If the spaceplane is capable of flying more often, as you want to ramp up flight rate beyond monthly, why not have the same vehicle (or varients thereof) carry both the cargo and the crew? If it is capable of flying weekly, then you have a full 25 flights a year worth of capacity going to waste. Just like an airliner, the less time your plane is in the air, the more it costs to operate.

But now we run into another problem... since a nuclear rocket booster is an expensive item, easily costing eight digits for a quality reuseable one, then you will need alot of them. Since they are reuseable, then the orbital space-freight people won't need a large number of them. If you intend to have an open-ended number of crew/cargo flights for future expansion of operations, then you would have even more unessesarry extra engines.

The cost of all these nuclear engines will bankrupt your space-line, because the inherint inferior efficency of spaceplanes will actually make conventional rockets like Zenit, Angara, or Atlas-V with a HL-20/X-38/Klipper style crew taxi cheaper then flying your spaceplane given the cost of developing it.

So the solution? The expendable nuclear booster has to go, no ifs/ands/buts. This also solves alot of other problems which I will detail below.

Since you have to abandon the nuclear engine idea because you can't afford to fly a new one each time and you can't bring it back to Earth because of the radiation, you can now no longer reach orbit in a single stage. You must therefore adopt a two-stage aproach, using a conventional jet/ramjet or jet/rocket powerd carrier airplane and putting your rocket spaceplane on top. This way is ideal since you get maximum bennefit from each engine type and keeps the size of your spaceplane small, which will reduce costs substantially.

...Which brings you back to the spaceplane that NASA wanted almost fifty years ago, the plane that should have been the Space Shuttle, and the one I am advocating.
---------------------------------------------------------------------
Now, back to the conceptual physical reasons that you continue to blythely ignore in the hope that some future technology will magically heal...

There is no justification to spend any effort investigating nuclear engines for this application, not a workday, not a single dollar, nothing because it is inherintly unacceptable for a host of reasons. No further research is needed, we already know that a solid-core nuclear engine, because of its basic and unchanging physical (not technological) principles, will not work here. Not in the 1960's, not now, not ever.

1: It is seriously doubtful that your spaceplane could reach orbit in a single stage because of the poor thrust/weight ratio of your engine, the weight of your lift body, and radiation shield. A nuclear engine has trouble just getting off the ground without boosters because of its low thrust/weight ratio, and that is not counting wings/wheels, radiation shields, or reentry armor.

You cannot improve the efficency because of very simple reasons: that in order to produce more thrust, you must have a bigger reactor to generate more thrust because there is a limit to how hot you reactor can be. If you increase its temperature, it will melt, just like the Timberwind single-use cores. It wouldn't be reuseable then... We have basically reached the limits of possible heat-resistant materials, the chemical bonds themselves have limited strength.

The air drag presented by your very large hydrogen tanks will also be a huge problem, and would make this problem even worse. Furthermore, during reentry your vehicle will be very light, especially without its booster, but it will be very large. This means you will have high G-forces during reentry, and could crush your spaceplane like a tin-can. Adding structural stiffiners will make your spaceplane even heavier and need even more thrust.

2: The "incident" problem if you fail to reach orbit or reenter intact: "Appropriate safeguards for earth environment"... You will never be able to convince people that any small bennefit of NTR engines over chemical engines are worth the risk. You are talking about millions of times the radiation of a little RTG, except that it could fail and explode at any time during acent/decent and fall anywhere without warning. You are deluding yourself if you think the public will accept this. I wouldn't accept it, and I am a pro-nuclear a person as you will find, even if that were to mean spaceplanes were impossible.

No vain attempts to fix this problem are the least bit acceptable. Wrapping the thing with armor will make it so heavy that you might as well use a regular chemical engine instead. There is just no way you can ensure that nobody on the ground will die if your spaceplane crashes. Even if the reactor falls intact, it will still emit VAST quantities of radiation over a small area and kill everyone and everything in it or perminantly cripple anyone a little further away. Even if the reactor is shut down!

You can never, ever make a fission NTR engine safe enough to fire in our atmosphere, or for that matter return it to Earth either. This is a simple but unavoidable consequence of the fact that you must use alot of Uranium to reach space, and in doing so you will produce lots of very intensely radioactive waste, combined with the fact that no nuclear spaceplane will ever launch or reenter reliably enough.

If you don't believe the phrase "it won't work" then I am going to have a hard time taking you the least bit seriously Tristar. There is no way your spaceplane will be worth the expense and risk of building and flying it... it won't work.

Martin_Tristar · 2005-03-06 19:02:34

GCNRevenger,

I can outline the use of a serious transportation system for earth space but I don't need to, because you know we need one, or should I explain in detail, hmmmm.

Where we got the approx. 300 personnel per year - Orbiting Space Station (30 personnel and 30 for crew rotation ) - Orbiting Space Factories ( 30 personnel and 30 for crew rotation ) - Orbiting Space Construction ( 10 personnel and 10 for crew rotation - specialist work) - Lunar Base : main processing base ( 30 personnel and 30 for crew rotation ) - Lunar Mining Station ( 10 personnel and 10 for crew rotation - 3 station personnel + 7 mining personnel that control robotic/ droid mining teams of 7/1 ratio ) per station - Lunar Transit (10 personnel and 10 for crew rotation ) - Mars Station and Transit ( 50 personnel and 50 for crew rotation in every 2-3 year blocks split in progressive journeys ) per station and other space based specialists ( 10 personnel and 10 for crew rotation )

I am looking at the spaceplane as part of a large transportation system integrating earth - to orbit - lunar transit - lunar landing - to mars transit - to mars landing and how we can deliver a large volume of personnel for all locations without huge costs involved. I have the total transportation system concept drawn out but the fine detail needs research and testing to bring the right mix of engines and movement of components for the benefits of the space transportation structure.

On the subject of profitability about the spaceplanes - as the Nuclear type engine assemblies are charged as cargo and thus are charged based on their weight been taking into orbit ( ex fuel ) against other projects plus the costs of pasengers and other cargo onboard both ways the spaceplanes are quite profitable.

GCNRevenger, Have you experimented with the Nuclear Type Engine designs to create new drive systems ? Have you looked into spacecraft designs and have model data ( virtually or physically) for G-Force Stress on different designs of single stage HTOL Spaceplanes ? If you have then sent me the website that the information has been published on and I will retrieve and study it, If not, then I would suggest detailed statements that you have been making have not basis in fact without any data, that is what research is for !!!!!!!!!.

Martian Republic · 2005-03-06 19:56:58

Martin_Tristar, even I know when to give up an argument that non workable. GCNRevenger, has pretty much stated the case why it not feasible to build a nuclear powered fission rocket. He has a valid argument and your plan is a dead issue on at least two or three fronts and the matters not going to change just, because you want it to.

Baring discovery of new physical laws or development of new technologies that we don't currently know about, what your taking about is just not going happen.

Larry,

Martin_Tristar · 2005-03-06 20:30:27

Martian Republic,

Then I agree with your assessment of the issue it is dead to most you, that we can not find a proper transportation system for large scale movement of personnel and cargo into orbit. If we use the current modes of transport to orbit then we are just WE ARE TOURISTS AND HAVE NO RIGHT TO DICTATE SOLAR SYSTEM POLICIES.

Our organization hasn't got the huge resources yet, to bring us into the space transportation sector yet, but at least we are working towards goals that have better success for long term space research, training, and infrastructure for the future in private enterprise large scale space activities.

Infrastructure means - space vessel construction, communications, navigation, life sciences, colonizations techniques, social interactions, and more.

New Mars Forums

Announcement

#101 2005-02-28 03:58:20

Re: New Space Shuttle

#102 2005-02-28 07:03:39

Re: New Space Shuttle

#103 2005-02-28 07:12:05

Re: New Space Shuttle

#104 2005-02-28 07:15:23

Re: New Space Shuttle

#105 2005-02-28 07:17:27

Re: New Space Shuttle

#106 2005-02-28 22:03:44

Re: New Space Shuttle

#107 2005-03-01 06:53:47

Re: New Space Shuttle

#108 2005-03-01 07:32:49

Re: New Space Shuttle

#109 2005-03-01 08:24:02

Re: New Space Shuttle

#110 2005-03-01 15:17:52

Re: New Space Shuttle

#111 2005-03-03 21:22:09

Re: New Space Shuttle

#112 2005-03-03 22:17:50

Re: New Space Shuttle

#113 2005-03-04 19:26:48

Re: New Space Shuttle

#114 2005-03-04 21:38:09

Re: New Space Shuttle

#115 2005-03-04 22:55:22

Re: New Space Shuttle

#116 2005-03-04 23:03:32

Re: New Space Shuttle

#117 2005-03-05 01:05:48

Re: New Space Shuttle

#118 2005-03-05 05:44:04

Re: New Space Shuttle

#119 2005-03-05 09:13:01

Re: New Space Shuttle

#120 2005-03-05 23:56:46

Re: New Space Shuttle

#121 2005-03-06 06:36:23

Re: New Space Shuttle

#122 2005-03-06 09:45:49

Re: New Space Shuttle

#123 2005-03-06 19:02:34

Re: New Space Shuttle

#124 2005-03-06 19:56:58

Re: New Space Shuttle

#125 2005-03-06 20:30:27

Re: New Space Shuttle

Board footer