Enough with the unsupported words. - Time for a reality check.... Once the railgun vehicle is sent up at speed, only small 'sustainer rockets' will suffice to get that vehicle to whatever speed is required for orbit or extra-orbit (to moon) trajectory/velocity. ...
Enough with the unsupported words. - Time for a reality check....
....develop some required technology and do some scientific exploration - not nearly as useful or cheap as deep ocean...
RealityCheck
Railguns could be used to put raw materials in orbit, but the linear accelerator in an evacuated tube going up the slope of a tall mountain would be more effective and utilize much lower accelerations. Put a laser pumped ramjet on the back of the capsule and no propellant at all would be required for LEO and acceleration would be man friendly(2-3 G max).
Going to the moon for anything but research or raw materials is a huge waste. We should put robots at the poles to mine and lauch(Linear accelerators are nearly perfectly efficient in vacuum)water and other minerals to the Lagrange points and stay in freefall to build our habitats and vessels. Mars should be a one way destination for older scientists until infrastructure has been built for permanent settlement, then build a Beanstalk.
Gravity Wells suck!
Grumpy
Enough with the unsupported words. - Time for a reality check.
(1) What is this speed (as it leaves the end of the rail gun)?
(2) What is the velocity direction as it leaves the rail gun? (Degrees from zero, the Earth radial direction or "straight up")?
(3) What is the length of the rail gun? (This and terminal speed fixes the required acceleration, a. Then the mass of the vehicle, m, fixes the force, F, (F=ma) that must be steadily applied to vehicle on the rails, presumably by many adjacent, large, high ampere-turn coils that do not tear each other from their mounts on the rail gun sides.)
(4) What is the weight of the iron in the vehicle that this magnetic force acts on, Or do you envision a massive copper plate and eddy current interaction force F achieved in it? Note iron or copper are much heavier elements than the hydrogen fuel a more convention vehicle has to get up to speed.)
(5) How far from the center of the Earth is the terminal end of the rail gun? (This determines the "gravitational hill" the vehicle must climb with reduction of its rail gun terminal velocity.
(6) What is the atmosphere density and resulting friction force, ff, on vehicle as it leaves the end of rail gun? (It surely is super sonic, so is producing a shock wave. That is an energy drain, E per meter of travel. So there is also a force retarding the vehicle to do that work / create the shock wave energy of fsD (force times distance but as E is for one meter, D =1 and fs=E. Thus the total retarding force Fr = ff + fs, but it decreases as vehicle gets further form the center of the earth (less dense air).
As a quick guess, these considerations very likely make it impossible to put even very small weight vehicles (say 100 pounds) into even low earth orbit, much less to climb out of earth´s gravity to point close to the moon where moon´s gravity is equally strong. Fact that no one even tries, is proof enough for most reasonable people. Rail guns are not even attractive for less than low earth orbit trajectories, such as Iran throwing explosives at nearby Israel etc.
SUMMARY Reality comes only from quantative analysis after these questions are answered, not from a bunch of hand waving words. Do you not suppose that rail guns have been considered, REALISTICALLY, (quantatively) by many well qualified rocket scientists, and rejected as they are less attractive for making vehicles leave the Earth than liquid fuels, especially light-weight, high-specific-impulse, hydrogen?
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Now to answer the thread´s question:
US suffered a great psychological blow when the USSR put Sputnik into orbit. Going to the moon was done to restore self confidence (and as minor consideration, develop some required technology and do some scientific exploration - not nearly as useful or cheap as deep ocean research would have been, but the "science" was low priority compared to showing world US was still the most advanced country.)
Currently the US is again under stress, in danger of having lost its status of the world´s only reserve currency and the petrodollar convention with oil exporters - that allows the US to import nearly everything it needs and pay for these imports with printed green paper. As the large and growing debt with annual deficits of about 1.5 trillion dollars is the foundation of these global doubts about the fiscal soundness of the dollar, spending on a new manned trip to the moon would not help with the US´s current financial credit problems. It might even make SDRs, the increasing gobally used RMB, gold or some mix of these the "least ugly" currency (main reason dollar has not already collapsed is the lack of more attractive alternatives)
“…Two years after BAE Systems was awarded a US$21 million contract from the Office of Naval Research (ONR) to develop an advanced Electromagnetic (EM) Railgun for the U.S. Navy, the company has delivered the first industry-built prototype demonstrator to the Naval Surface Warfare Center (NSWC) Dahlgren. …Hi Billy T.
I am not personally attached to any particular launch system, merely musing on the possibilities, mate. As for the technical aspects you mentioned, I suppose I am musing on the possibilities of:
- siting the railgun infrastructure in any one of the many extremely deep mine shafts around the world, and extending the vertical run of the structure above grund to as convenient an altitude as possible with the steel and concrete girder/tube construction techniques available;
- providing for a cradle which would have all the actual electro-magnetic boost components which would interact with the rails, so that the vehicle itself just sits in the cradle and when the vehicle & cradle exit the 'muzzle', they would separate and the cradle (robust) would be recovered using integral parachutes and re-used;
- muzzle velocity is a function of the power and the rail-length used, which would be 'tuned' to the actual installation (I haven't any hard figures, as I am only musing on the possibilities);
- trans-atmosphere vertically reduces the in-atmosphere dwell-time consisiderably, so the drag is over a lesser time than in conventional rocket trajectories (conventional rockets also go supersonic very early in atmosphere and suffer from the greater surface area of the much greater bulk of stage one and two rockets motors and tanks etc);
- given high muzzle velocity, the dwell time for railgun-type launcher vehicles (much less bulky and heavy and fragile than the conventionally launched vehicles etc) is relatively short and the carbon-carbon nose protection is enough to cut through the atmosphere with least drag profile/area, and the rest of the vehicle can be made of relatively cheap steel because the dwell-time in the atmospheric heating regime is so short that the heat transfer between the shock 'stagnation' boundary layers to vehicle surfaces has little time to take place before the vehicle is in space and radiating. ...
Anyhow, mate, I am not in the field of railgun technology nor do I know of the very latest technical/military developments in the efficiencies/feasibilities for various railgun applications at various scales/power....
I leave it to you and others to explore this area if you're interested. I have made my musings and suggestions on the topic and will lave it at that, mate! ...
“…Two years after BAE Systems was awarded a US$21 million contract from the Office of Naval Research (ONR) to develop an advanced Electromagnetic (EM) Railgun for the U.S. Navy, the company has delivered the first industry-built prototype demonstrator to the Naval Surface Warfare Center (NSWC) Dahlgren. …
While the muzzle velocity of gunpowder-propelled projectiles is generally limited to around 4,000 ft per second (2,727 mph/4,389 km/h), the U.S. Navy says its railgun will be capable of launching projectiles at velocities of 4,500 to 5,600 mph (7,242 - 9,012 km/h). This kind of speed translates to greatly extended range. Navy planners are initially targeting a 50 to 100-nautical mile (57 to 115 mile/92 to 185 km) range, …”
From the very latest (7 Feb 2012) not yet tested most advanced rail gun. More at: http://www.gizmag.com/first-industry-railgun-prototype-launcher/21377/
They do not tell the projectile weight, but I think it is less than 100 pound and must be 100% conductive metal.
Just to give you some slight understanding of how nonsensical your suggestion of rail gun launch to moon etc. is, note that the escape velocity required to climb out of earth´s gravity field is 25,038.72 mph, falsely assuming that there is no friction with the air of energy loss producing the shock waves in the air. Actual terminal speed required off the end of the rail gun is much, much, higher and sort of a losing game as the higher the initial speed, the more energy is lost to the shock wave and air friction.
Thus this state of the art, rail gun falls short of speed needed at end of the rail gun by much more than 25,038.72 / 5,600 or at least by a factor of ten (or 100 times to weak in terms of energy).
This $21 million dollar gun does not even have enough range to let Iran throw even a copper slug at Israel, much less any HE. In fact it would very likely cause the HE to explode before it left the end of the rails – the heating of the “bullet” and the entire system is extreme. Read about that in the article.
Again, only hand waving words, with no quantative analysis, are self delusion in this case.
My point is that words / speculation, etc with zero analysis is next to useless. In post 84 I asked you to answer 6 or 7 specific questions with numbers (and even told part of how these numbers would be used in evaluation of your ideas.) but that would just be a start - need especially to know how much energy goes into the shock wave - quite possilby more than in the fuel tank o a Saturn liquid fuel rocket
Little time, mate. So briefly in answer....
1. Note the "Naval Warfare". So the kind/scale of would be compact for naval mounting platformetc, not in the 'long rail' versions I am speculating about. So your counter-arguments there are not that relevant.
2. The railgun launch system 'straight up' on shortest trans-atmosphere trajectory for orbit/moon would be appropriately designed with the necessary heat shielding/streamlining etc and would not be in the atmosphere long enough for the drag/heating to be a limiting factor. I covered this aspect before.
3. Any military shots/warheads are DESIGNED AS warheads, and not as space vehicles. So again, your arguments there are not that relevant. Apples and oranges. Because the space vehicles would have sustainer rockets for maintaining muzzle velocity and ensuring quick passage through the short vertical crossection of the atmosphere. Whereas the ground-to-ground weapons projectiles you speak of must be readily deployed and fired frequently and on a trajectory that would take them through the atmosphere for LONGER PERIOD in its upwards trajectory and its downwards trajectory, hence the drag/heating etc profiles to be allowed for would be entirely different.
I hope that clarifies the difference between what you are thinking of and what I am speculating about, mate! ...
Hi Billy T. - siting the railgun infrastructure in any one of the many extremely deep mine shafts around the world, and extending the vertical run of the structure above grund to as convenient an altitude as possible with the steel and concrete girder/tube construction techniques available
- given high muzzle velocity, the dwell time for railgun-type launcher vehicles (much less bulky and heavy and fragile than the conventionally launched vehicles etc) is relatively short and the carbon-carbon nose protection is enough to cut through the atmosphere
with least drag profile/area, and the rest of the vehicle can be made of relatively cheap steel because the dwell-time in the atmospheric heating regime is so short that the heat transfer between the shock 'stagnation' boundary layers to vehicle surfaces has little time to take place before the vehicle is in space and radiating.
As for why Iran et al are not using this way to hurl warheads at neighbours, I would imagine that SECRECY would be hard to ensure given the long run needed and the 'sitting duck' nature of the installation would make it child's play for the potential target nation to destroy such an installation before it became operational (and in the worst case where the first warhead has been sent, the destruction of the site would be pretty well assured not long thereafter).
In any case, as Grumpy has pointed out, the linear accelerator in evacuated tube might be a better way to go....OR EVEN a HYBRID? of the two, with the linear accelerator providing some of the initial speed along a horizontal track and then this curves up a mountain where the last section of track is a railgun type for the final boost to high 'muzzle velocity' and vertical orientation?
It is amusing that two recent science fiction films both had plot elements involving aliens for why we haven't gone back to the Moon:
Moon.
http://en.wikipedia.org/wiki/Moon_(film)
Transformers: Dark of the Moon.
http://en.wikipedia.org/wiki/Transformers:_Dark_of_the_Moon
However, the main reason is because of cost. The Constellation program that would have taken us back to the Moon had a projected cost of $100 billion, which led to it being cancelled.
But the recent push for a more commercial approach to spaceflight has shown that development costs can be cut by as much as 90%(!)
I believe this will lead to more affordable flights to LEO and BEO. In this post to my blog I show a manned lunar flight can be done using the upcoming Falcon Heavy for a cost of a few hundred million dollars:
SpaceX Dragon spacecraft for low cost trips to the Moon.
http://exoscientist.blogspot.com/2012/05/spacex-dragon-spacecraft-for-low-cost.html
Very probably not as there would be no point to it. Crack Pots would just say the photo of Earth rising over limb of the moon in foreground, etc. was done with photo shop & that there is nothing to prove that the moon rocks, etc. were from the moon, & astronauts are paid well to lie, etc. The whole scheme was just to divert billions of tax payer´s dollars into the pockets of the few who staged it all. How can you be so naive as to think man actually walked on the moon when movies show him doing so with credits to the "special effects" department?... I have one question, which I hope someone will answer regarding Moon landing-have scientists ever made and conference or something like that to disprove conspiracy theorists (who think that we have not been on the Moon)? ...
Perhaps the future of space exploration lies in the hands of private enterprises rather than the U.S. government (or any government for that matter). Within this century, space will become commercialized. I have no doubt in my mind.
or the U.S. was warned off by aliens.