You are not logged in.
As long as people claim Kyoto is just an underhand economical attack on some countries the idea behind it will not progress any further.
Just as you can say that with an every increasing population you can not keep down CO2 emissions, you could look at it from another angle and say that with more people the effectiveness of CO2 controls could be improved.
It's too easy to keep passing the buck, eventually it has to stop somewhere, if every country keeps going "you start".... "no, you start" we'll be able to see which model on global warming is correct.
You could have every country that releases CO2 contribute funds in proportion to the amount of CO2 that they release. This money would then go to fund climate research and the development of renewable sources of energy.
Apply the example to Kyoto. China is exempt, today. But if we were to comply with Kyoto by going to effiicent technologies and hydrogen (which we can do with our superior technology) then in future years - - maybe ten years out or fifteen years - - we ally with the European greenies and bash the heck out of China for carbon dioxide emissions.
Like the big gas stations we can comply and we can use that as a hammer, after we comply.
Now, all we do is piss off the Europeans and lose our moral leverage for allies to compel others to do anything.
Lets look at the goals for Kyoto: National targets range from 8% reductions for the European Union and some others to 7% for the US, 6% for Japan, 0% for Russia, and permitted increases of 8% for Australia and 10% for Iceland." The EU, Japan, and Russia all have stagnant economies and declining populations. Why should the US have to reduce emissions by the same amount when it has an increasing population and relatively robust economy?
If we really wanted to reduce CO2 emissions, the most cost-effective way would be to start with China. Since China does not have as much fossil fuel dependent infrastructure, it would be much easier for the Chinese to start building renewable energy infrastructure. Of coarse the Chinese would not agree to limit their emissions without getting anything in return, but if the rich countries agreed to subsidize the development and construction of renewable infrastructure, I think that the Chinese would go along with the deal.
After reading Dennis Wingo's book, a move to a hydrogen fuel cell economy will create substantial new demand for platinum for making fuel cells. It's only a piece of the puzzle for the hydrogen economy but it's a very real incentive for lunar resource exploitation.
But, if the US government has it's interests attached to business as usual - - military dominance of the Persian Gulf and higher miles per gallon is a purely private virtue that government has no business being involved with, where will the money come from to mine lunar platinum?
Hydrogen powered cars would actually increase CO2 emissions unless we stop getting our electrical power from fossil fuels. Fuel cells are also very expensive, fuel cell cars would have a limited range, and the conversion from petroleum to fuel cells would take a very large amount of investment. I am far from convinced that fuel cells are the answer.
Once the land based ice melts watch out. Without the ozone at the poles I am sure the arctic oceans will warm up more.
You are sure of a lot of things that are wrong. The polar ice may melt as part of global warming, but that has nothing to do with the depletion of the ozone layer; if anything, the hole in the ozone layer should actually cool the polar regions.
It's got nothing to do with the polar ice caps - there isn't enough water in them to make any noticeable difference, even in Tuvalu. However, as the ocean water warms, it exchanges heat with its lower layers over the course of several centuries. The warmed water - eventually the bulk of the ocean - will expand, changing the sea level.
The last time I did much research on global warming, the "experts" were saying that the effects of ice melting and ocean water expanding should be about the same magnitude.
Stearns says the calving brings the Ross Ice Shelf to the about the size it was in 1911, when members of Robert Falcon Scott's British expedition first mapped it.
Neither the breakup of the Larsen B Ice Shelf nor the melting of icebergs that break off Antarctic ice shelves causes sea levels to rise because the ice is already floating.
The breakup of Antartic ice shelves is not related to the holes in the ozone layer, and it will not affect sea levels until the breakup reaches ice that is not already floating.
If the "scientists" from Greenpeace and the "scientists" from Exxon shout each other into a draw, then the "do nothing" agenda wins by default.
Which is why articles like the one linked to by Cobra are a particularly noxious form of propaganda.
The article basically says that global warming could be a more serious and more complex problem than previously thought, and that it needs to be investigated. How does that support a do nothing agenda?
If there is a shortage in plutonium, then this might be a good time to try out the new RTGs that project Prometheus is developing. By using more efficient Stirling heat engines instead of the less efficient thermocouples, the new RTGs will reduce the amount of plutonium that is needed by at least 2/3.
But that is beside the point, that if whatever rocket is put together cannot reach the payload threshold, then it isn't going to fly.
Why must it meet this arbitrary threshold of 100MT or not fly at all? 70MT is still a lot bigger than an EELV, and there shoud be plenty of missions that the vehicle can perform in this configuration.
In order for a huge SSTO rocket powerd by RS-68's to do this, it would start getting truely monsterous. You would need about eight engines to do this versus Shuttle-C's four, and the Hydrogen tank could not be built on exsisting Shuttle ET lines.
Even an 8 RS-68 SSTO would still be smaller than a shuttle ET sized core with 2 big SRBs. However, it would not need 8 engines. If you are putting upgraded SRBs on your rocket, it is only fair that the SSTO should be able to use upgraded RS-68. With some relatively small improvements in thrust and Isp, the SSTO can get into the same payload range as the vehicle with SRBs.
One of the problems with all-cryogenic arrangements is that they have poor thrust/weight ratios that forces them to burn inefficient amounts of fuel to get off the ground and up to an altitude where their superior Isp really kicks in unless you use a huge number of engines (which will weigh you down too late in acent). The Delta-IV HLV you list takes a full fifteen seconds to clear the launch pad. Boeing's own growth-path shows that payload could be increased ~25% simply by adding a quartet of tiny SRM motors to the stack. The low specific impulse at sea level for Hydrogen engines doesn't help either.
Cryogenic rockets can get better T/W ratios than other liquid rockets because their fuels are much lighter. However, I was still worried about gravitational losses, which is why I gave my model vehicle a T/W ratio greater than a Delta IV rather than making the fuel tank as large as possible.
The combination of heavy SRMs or RP1 boosters and a cryogenic core is the superior arrangement, where you get high thrust when you need it but not the extra engine/tankage weight when you don't.
Using SRMs in combination with a cryogenic core does have some advantages. However, when your base vehicle is already more solid than cryogenic then the efficiency of the arrangement starts decreasing as you try to add more SRBs.
For a superheavy launcher, there really isn't any practical way to make it all-cryogenic and small enough to build or move, and a 100MT launcher it would be too powerful for a superheavy. I also believe that the superior reliability of a pair of SRBs versus a quartet of RS-68s is no worse then the extra staging event.
If Saturn 5 was small enough to build and move, then the SSTO will also be small enough to build and move. It's dimensions will be similar to the Saturn V, and it will be lighter. Also, it does not have to be moved a long way since the launch pad will be close to the factory.
100 MT too powerful for a superheavy? I though you were considering rockets in the 200MT range to be superheavies.
When you add the SRBs, you add 2 new dangers: there is the chance of something going wrong in the staging event, and the chance of an SRB failing(like Challenger). The SRBs also can't be turned off, which takes away most of your abort options. However, when you the extra RS-68 engines you add engine out capability, so that the 6 engine vehicle would likely be even more reliable than a single engine vehicle.
Yes, a medium core + Delta-IV CCB will not be quite as efficent as a larger core stage alone, but I do not think that it will be greatly inferior either, and it will be well worth the improved flexibility and use of only exsisting tooling.
Using only existing tooling is an advantage for the small core, but it is the larger core that has better flexibility. By making the core capable of launching itself, you add a new ability and increase the number of possible launch vehicle configurations.
A rocket of similar proportion to Shuttle using only a pair of RS-68s and a pair of SRBs could hit the 100MT goal that six of the big 68s' cannot is more efficent.
A shuttle with only 2 RS-68 and 2 SRBs should not be able be able to get 100MT into orbit on it's own; Shuttle C could only get 77MT into orbit and it was powered by 3 SSME. You also have to factor in that four RS-68 are probably cheaper than 2 SRBs, so it might still be a better deal to use the big cryogenic core. In addition, the SSTO gets bonuses for reliability, and it will get bigger performance bonuses when you start adding boosters than the vehicle that already has boosters. The version with 1 big core + 4 SRB would definitely have more capacity than the version with 1 medium core + 4 SRB + 2 delta IV CBCs.
Or compare it to Delta IV. 2 Delta IV heavies can deliver 50MT of cargo using 6 RS-68, 6 CBC, and 2 upper stages. If you can deliver 70 MT to orbit with 6 RS-68 and only 1 big tank, that will be a much better deal.
Technological improvements and increases in size increase the competativeness of a SSTO vehicle like this with respect to all other types of expendable vehicle. If it made sense for a medium sized 80s vehicle, it should certainly make sense for a large 21st century vehicle.
If you assume that the fuel tanks of the core have the rame weight/surface area ratio as the Shuttle ET, a 1.4*10^6 kg core would have about 40 tons of tankage and 6 RS-68 would be about another 40 tons. The payload should be about 75 tons to LEO, mabey only 70 after deducting the payload fairing. That is still pretty good for a vehicle that is as simple, reliable, and relatively cheap as this. Presumably with upgraded RS-68 engines it could do even better.
Using multiple types of boosters I don't think is a big problem because these boosters will already be available and tested in that role, albeit on smaller vehicles. The decreased tankage efficency would be partially compensated for by the extra staging event perhaps too.
Using Delta IV core CBCs as boosters in the superheavy vehicle might actually decrease staging efficientcy. The CBCs would have a lower T/W ratio than the small core with 4 SRBs, meaning they would actually be dragged along by the vehicle rather than boosting it in the early stages of flight.
The entire Chinese economy is centerd around supplying foreign demand with cheap labor and unrestricted industry, which is a percarious situation to have in the long run. There is indeed a "China Bubble" of sorts, and as the demand for quality of life in China increases, then so will labor costs... as democracy increases, so will calls for environmental restrictions... and then there is the cost of socialist-style welfare states... and to top it off, the point of Chinese pride and political stature, its huge military will need updating to face the challenges ahead.
I don't think that we will see a "China Bubble". Nearly all of the profits made from China's recent economic growth are being reinvested into infrastructure and education. Graduation rates for Chinese colleges have doubled in the last four years and are expected to double again in the next four. While there is a limit to how much China can grow while being the world's center for cheap labor, a well educated high-tech China is the future and it can still grow a lot more before it stops.
Don't let the "communist" designation fool you, China right now is as capitalist as the US, and even more so in some respects. They also spend proportionately much less than the US on the military; While 0.5% of people in the US are part of it's 1.5 million person military, only 0.18% of China's population is part of China's 2.3 million person military.
Meanwhile, no one is watching India! It's population is approaching China's and will surpass it in the next few decades. China's one-child policy will produce a huge social security problem in about thirty or forty years. India doesn't have that problem. It is a democracy and has a huge English-speaking population. It has rule of law (more or less). And it now has pro-growth economic policies. In 100 or 150 years, India may be number one, China and the US vying for number two. Who knows.
India has the potential to be very powerful, but they are a bit behind China. If all goes well, in ten years India could be where China is now economically, but by that time China will have advanced considerably further. While India could be an economic superpower in the long term, China will be one in the short term.
China's economic numbers for 2004 are in, and it's another year of impressive growth. Some links:
http://biz.thestar.com.my/news/story.as … siness]Tax revenue up 25.7%
Chinas]http://www.thestar.com/NASApp/cs/ContentServer?pagename=thestar/Layout/Article_Type1&c=Article&cid=1105397411490&call_pageid=968256290204&col=968350116795]China's bright future
http://quote.bloomberg.com/apps/news?pi … ome]Record trade, record surplus
I don't have the December 2004 trade numbers for the US or Germany, but China's trade growth might have been sufficient to make China the world's #2 trader overall and the #1 exporter in December.
http://news.xinhuanet.com/english/2005- … .htm]China is also getting interested in astronomy. Lets hope they go ahead and build a 100m OWL type telescope.
Small Engine Propane or LNG Conversion
This is how many people are proposing to run a mars rover - using an internal combustion engine just like a typical terrestrial off-road vehicle. LNG and propane have been proposed as fuels for such a vehicle, since they’re something we can make using in situ resources. What’s really involved and how easy is it to do?
I am pretty sure that the major auto manufacturers make some engines that are designed to run on natural gas or propane. I think that the real question is what happens when you try to run them off stored oxygen rather than having air.
I would kill to have assignments like 300 page essays,
What are you, a masochist? I have enough trouble with the 20 page essays that some of my classes assign.
The core stage would use either two or three RS-68R engines, which would be surrounded by two or four Shuttle SRBs of either four or five segments each. For superheavy payloads, the core would also be flanked by a pair of "EELV+" updated Delta-IV core stages, perhaps stretched to hold more fuel. The upper stage would be either the small kick stage for orbital circulization, or a heavy-duty cryogenic upper stage with a single RS-68 tailored for vacuum performance and maximum Isp.
If you need light payloads to Earth orbit, use only the core with a pair of SRBs of either size. Medium or Earth-escape payloads would include the heavy upper stage. Heavy payloads would use all four SRBs and the heavy upper... And finally, for superheavy loads you would add the Delta-IV boosters on the sides.
Rather than ending up with the heavier versions of this vehicle using huge numbers of multiple types of large boosters, I would start out with a much larger core. It would be similar the http://astronautix.com/lvfam/alsnls.htm]ALS/NLS family of rockets that were proposed to launch Star Wars, but using upgraded RS-68 engines in place of the "STME" engines. It would also be a bit bigger than the ALS/NLS cores, with a larger diameter than the shuttle ET.
The base vehicle would just be the core by itself as an expendable SSTO with a payload a little larger than the payload provided by a Delta IV heavy. Since the vehicle would have engine out capability and zero staging, it should be extremely reliable. To make heavier versions, just add SRBs. Since the core is bigger, the superheavy version of this vehicle would only need as many boosters an the heavy version of your rocket. This system would get the benefits of simplicity, reliability, and tankage efficiency without losing any flexibility.
Raising the retirement age seems like the most logical solution to keeping social security solvent. Americans are now living longer healthier lives than ever before. They spend more time getting educated, wait longer before getting married, wait longer before having children, and live longer before dieing. I see no reason why they should not be expected to work longer before they retire. You would not have to raise the retirement age so high that most Americans would not live that long either; if the age was increased to about 70, benefits could be substantially increased while still saving money, and the vast majority of Americans would live long enough to see their benefits.
Then the knee-jerk response is to nationalize healthcare, making the whole mess even worse
Hopefully that will happen. The current US healthcare system is incredibly inefficient, to the point where even a government program should be able to do better. With government funded health care it would be necessary to raise taxes, but it should still result in a net savings for most people.
I doubt that it will ever be economical to beam solar power from the moon to the Earth, and it would make even less sense to try and beam power from the moon to Mars.
The military has a lot more resources than NASA, so if the military increase it's interest in space that could greatly increase the rate of space-related technological advancement. China is also starting to take an interest in space, so we might end up with a Space Race 2.0.
Obviously, that would be very good for space enthusiasts.
No one is trying to privatize Social Security, Bush has proposed aloowing those paying in to invest a small percentage of their money in private stocks. It remains a big, bloated government program. One that remains likely to implode regardless of the accounting voodoo used to make it appear solvent.
The problem is that the money that people are paying into Social Security is not "thier" money, it goes to pay the people who are already retired. Social Security is basically a pyramid scheme, so it will only work if there are a lot more workers paying into it than there are retired people. If people instead save there own money, then the government will have to borrow trillions of dollars to make up for the shortfall.
Zubrin did an interesting http://www.risacher.org/bh/analog.html]study on using a rocketplane with aerial refueling. I don't agree with all of the assumptions that he made or the conclusions that he reached(for instance, his estimates for the Isp of the lox/methane and the H2O2/kerosene propellants are too high), but he has some interesting ideas. I do not think that the "Black Horse" SSTO is practical with our current level of technology, though a "Black Colt" type vehicle should not be too hard to implement. The vehicle that we are considering would be much larger than Black Colt. A KC-10 tanker can carry a maximum fuel load of 160,000 kg, so the rocketplane could be scaled up to about 7 times larger than Black Colt before multiple tankers are required.
Oh, and for those Kerry fanatics... did you know that he refused to release all his military reccord? He still hasn't to this day... probobly because he was dishonorably discharged for consorting with the enemy (Vietcong) in Paris and in the VVAW (funded/directed by Vietcong) while he was still a member of the military.
Now you are starting to sound as crazy as MR. Both of you are believing whatever extremist propaganda you want to believe without making any effort to figure out if it corresponds to reality or not.
That is for air-breathing engines only however Euler, and not for LOX/H2O augmented ones. In such a case, a Turbojet/Ramjet combo engine could probobly reach quite high altitudes and speeds before its engines lost effectiveness, where the somewhat larger tanks on the upper stage for slush Hydrogen are even less troublesome. Tripropellant rockets only really make sense if you are seperating at "conventional subsonic freight plane" conditions, and their inferior efficency in either mode compared to dedicated engines would be a hinderance.
Increasing the speed that the plane can achieve increases the relative competitiveness of a kerosene upper stage rather than decreasing it. That seems paradoxical at first, but it is still true since the rocket equation is not really applicable to the first stage. The higher your velocity gets, the worse the drag will be from a big fuel tank, and the drag increase from increased speed should be larger than the drag decrease from increased altitude. A kerosene rocket would also benefit more from having an assist than a lh2 rocket would.
"Plan B" would be to include a modest sized RP1 rocket engine(s) on the lower stage, where the plane would nose up and rocket up to a better seperation position, which would also seperate the specialties of high density/low-weight too.
This is probably a better idea. While air breathing engines are much cheaper, more reliable, and more efficient, they still have trouble getting the second stage up to high enough speeds and altitudes to make a very large difference. In this case a lh2 upper stage is defiantly better.
Anyway, barring a major advance in Scramjet technology, I support building a TSTO spaceplane with an intermediate/high performance carrier plane which would make Hydrogen the obvious choice for the upper stage.
It is important that the vehicle is light enough to carry, but even using a carrier aircraft there are still arguments for using a denser fuel or a tripropellant engine. A high performance carrier aircraft would travel through the atmosphere at much higher speeds than a traditional vertically launched rocket. The drag of a large fuel tank could become a major problem that prevents you from getting up to high speeds.
The carrier plane should also not be powered by F-119 engines. The F-119 is very expensive and it has stealth and thrust vectoring features that you really don't need for this vehicle. The best option for an existing engine would probably be using NK-321 engines developed for the Tu-160 blackjack supersonic bomber. At 55,150 lbs thrust, they are the most powerful engines ever used on a combat aircraft. However, developing a new engine would probably be necessary. While a low-bypass afterburning turbofan like the NK-321 can achieve speeds around Mach 2.5, if you want speeds close to Mach 3 or higher a turbojet is a better option. Much above Mach 3 and you need to integrate a ramjet onto the turbojet like on the SR-71. An ideal engine would also be very large because if you want much payload the carrier aircraft would have to be the largest supersonic aircraft ever built.
Using slush hydrogen increases the density of the hydrogen from .071 g/cc to .085 g/cc. This is useful, but still not enough to catch up with kerosene in a simple model. However, hydrogen has a few other advantages:
*It generally has a higher combustion efficiency than kerosene, so it's Isp might be a little higher than the model expects.
*Most proposals for SSTOs using Lh2 vary the mix ratio throughout the flight so that more oxygen is used near the ground and less is used when the vehicle approaches orbit. This would have the similar effect as using a tripropellant engine, but to a lesser extent.
*An Lh2 spaceplane should cost less than a kerosene spaceplane of the same volume.
I would have to do more research before I could factor in the changing mix ratio, so I am not sure if that would be enough of an improvement to make Hydrogen a better choice. Hydrogen also gains more from using drop tanks or having a lower stage, so if you did not need it to be a 1 piece spaceplane that would give hydrogen a decisive advantage.
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.
The scientists don't seem to realize that one of the main reasons why people want to learn about space is that so people can eventually live there. If someone could just make them figure that out, then they might begin to support manned space exploration, and that would be good for both the scientists and the engineers.
Even hubble-hugger apraisals of the technology estimate that ground based telescopes will reach optical parity with Hubble by aproximatly 2015. Infrared imaging, which is easier then optical with AO, is already aproximatly equal or superior to HST. Ground based telescopes would operate in much more "noisy" environment being under an atmosphere, but I bet that the much larger practical aperature will help offset this problem.
I think that assessment seriously underestimates the progress that has been made since Hubble was launched. The most advanced ground based telescopes have capabilities far beyond those of Hubble. I remember reading an article about VLTI directly measuring the shape of a star 7,500 light years away. Hubble just doesn't come close to having that sort of resolving power.