Half a croissant, on a plate, with a sign in front of it saying '50c'
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The barrel less super gun.

A heavy lift haulage for space colonization and tereforming operations. NOT FOR CARRYING HUMAN BEINGS
  (+5, -1)
(+5, -1)
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future space operations are going to require building materials to be delivered to space, cheaply. Some of these materials in bulk are a lot more robust than the same stuff in use. For example, a properly wrapped large roll of Mylar will be a lot less liable to damage at launch than a solar sail would be. and beams laid flat on a cargo deck, will be protected from the bending loads that they would experience if they where to be launched in an assembled unit.

So much for the reason why this invention is needed, next comes the principal (but not the method) of the barrel less super gun.

A cavity shaped charge such as a Bazooka shell, fires a jet and slug of Copper forward with sufficient speed that it can force its way through steel armer. As much force as is imparted to the Coper must be imparted to the shell fragments. Equal bur opposite reaction.
Now imagine for a moment a stack of 10 such shells, firing downwards in quick succession. The first one fires, its slug goes down, and the rest of the stack goes up. As each charge fires in turn its recoil adds to the velocity of the pay load, i imagine this as being like a 10 stage conventional rocket. Albeit a very in efficient one.
A word or two about super guns.
Super guns have the same advantage over rockets as rail guns, namely that all of the fuel is burned at or close to the point of launch, rather than most of the fuel going on lifting fuel. Super guns and rail guns share the disadvantage of having there highest velocity at the bottom of there trajectory, where the air is thickest, conventional super guns also have the problem that the conditions inside the barrel are so extrema as to cause erosion of the barrel.

The basis of my variation upon this theme is to build special flat shaped charges that are a couple of cm deep but tens of metres across. A simple cavity shaped charge is longer than it is wide, because it needs room for the detonation head to grow. I would also recommend using ANFO as the main explosive, with a detonation velocity of between 1100 and 2700 metres per second and a peak pressure of less than 4000 atmospheres. The confinement of the larger part, I'm guessing about four fifths, of the explosive force into the vertical direction is a result of the shape of the thin shaped charges.

Huygens principal, that each point on a wave front may be regarded as a sours of new waves, is applicable to the diffraction of sound waves and water waves and as much as it is to light waves. A zone plate is a special type of diffraction grating, that acts as a convex lens For the moment picture plain parallel sound waves, from a distant source, striking the front of a zone plate and being focused to a point be hind it.

The cargo pod will have heat proofing on its roof. It will be in the shape of a short broad inverted truncated cone. There will be a variable number of cargo decks in side, to allow the cargo to be distributed and supported appropriately. It will sit on a pusher plate supported by light weight sabot. To give you an image of this, imagine the Apollo return module, turned up side down, and scaled up to the volume of a large cargo aeroplane, or bigger. With plastic buttresses keeping it steady

the pusher plate will be a section of composite armer, to protect the cargo pod from shrapnel It will have three layer each made of; a hard but brittle layer (like toughened glass), two sheets of bubble wrap which as bubbles full of water, several sheets of kevlar weave, and a metal sheet.

The zone plate shaped charge.

Each zone plate shaped charge is built on a flat metal plate, the same size as the pusher plate. On top of this is an even number ( possibly 10 to 20 ) of concentric rings. The radii of these rings are related to each other in a very specific way. If we define the radius of the smallest centre ring as 1 unit, then the radius of the second ring is 1.4142 units. That is the square root of two units. The third ring is 1.7320 units. That is the square root of three units, and so on.
These concentric rings are filled or not as follows; the centre circle is left empty, the first annular space has explosives, the second and subsequent even numbed annular spaces are empty, and the third and subsequent odd numbed annular spaces are loaded with explosives.
All of the explosives in a given zone plate shaped charge are detonated at the same time. So looking at it from above it it will look like a massive compression wave coming through a zone plate and having the majority of its energy directed upwards and in over. Unlike in a simple explosion, where the blast travels out evenly in all directions. The same effect will be seen from below.

To recap. a large cargo pod ( the bigger the better to take advantage of square cube rule ), is blown ( undamaged ) to an orbital hight, by mean of a stack of thin zone plate shaped charges fired in rapid succession

j paul, Aug 15 2011

Stephen Fry on Language Nazis http://www.guardian...brium/2010/oct/24/5
[tatterdemalion, Aug 16 2011]

Another explosive spacecraft http://www.youtube....watch?v=E3Lxx2VAYi8
Useful from about 00:20 [AbsintheWithoutLeave, Aug 16 2011]

The_20Hindenburg_2c_20but_20in_20space [not_morrison_rm, Aug 17 2011]


       Reminds me of Jerry Pournelle's "King David's Spaceship"
normzone, Aug 15 2011

       Project Orion (the original, not the modern space capsule). I believe that was the basis of the Pournelle story as well. It also shows up in Niven's "Footfall".
MechE, Aug 16 2011

       Similar concept in a Stanislaw Lem book, but I'm tarred if I'm gonna read through 'em all to find out which.
Alterother, Aug 16 2011

       // a challenge just to read the text //   

       [21 Quest], are you so easily thrown off by a few misspellings and uncapitalized words? You should be more flexible in your input, language is fluid, it's the meaning that matters.
tatterdemalion, Aug 16 2011

       Bun for tapioca.
Voice, Aug 16 2011

       // tapioca going through a colander //   

       Dry, uncooked tapioca, or cooked - and if cooked, hot or cold ? The difference in viscosity is substantial.   

       On inspecting the text, we suggest freshly cooked warm tapioca would move with about the same fluidity.
8th of 7, Aug 16 2011

       [21 Quest], horsefeathers. I prefer Stephen Fry's approach to this issue, and I wish more people agreed.
tatterdemalion, Aug 16 2011

       //I prefer Stephen Fry's approach to this issue, and I wish more people agreed. //
sp. "i prefur stefun fries aproach too thys ishyou, nd i wysh mre ppl agread.

       From linked article:"I luv langwage and grammer and I am espeshully fond of wurd etimolojies. Meye pashun four langwayge is sew stwrong that at won poynt in mi lyfe, i gayve ceryous thawt to bcoming a lingwhist oar a lecsickograffer (studying the evolushun of langwayje or wurds, of coarse!).
AbsintheWithoutLeave, Aug 16 2011

       [21], I'm pretty sure English is not [j paul]'s original language, and [j], please don't take that as an insult if I'm wrong.
Alterother, Aug 16 2011

       But English is Stephen Fry's first language.
AbsintheWithoutLeave, Aug 16 2011

       // a challenge just to read the text // I didn't find it so.
MaxwellBuchanan, Aug 16 2011

       Same here. I didn't see any challenge to read the text, so I didn't.
lurch, Aug 16 2011

       We are not going to bun, bone or comment further on the idea until we have had a chance to do some math, and possibly a few practical tests.
8th of 7, Aug 16 2011

       Ah, at last we will be able to tell the location of BorgCo's secret R&D Facility.   

       From orbit, most likely.
Alterother, Aug 16 2011

       Thanks for the recap. Maybe put it first so text is less offputting. The idea that a shaped explosion might provide more efficient lift is a neat one. I am reminded of a short discussion on the vagaries of rocket nozzles that occurred here in the context of the N-prize. I do not know enough about how and why shaped charges work to comment further except to comment that I would like to learn more about them, preferably by means of witty and acerbic prose.
bungston, Aug 16 2011

       Like we said, you'll have to wait a few days.
8th of 7, Aug 16 2011

       well, there are always laser guns. -wink,wink.   

       well, this supergun actually uses superconductors to lift heavy materials. it uses no lasers. the magnetism fires the payload to space, i suppose. please someone tell me if i'm wrong. i think this was from useborne's book of the future.
davey l, Aug 17 2011

       ...of course, this linked with the moonstring idea..(see Hindenburg link) now that might take off, or at least crash and burn in an amusing way..
not_morrison_rm, Aug 17 2011

Project Orion is definitely one of the ancestors of this idea. The main differences being; that Orion planed to keep the acceleration down by being super massive, and applying more power continually as it moves through the air. My variation burns all of its fuel close to the ground and then coasts the rest of the way, this means going for as much acceleration as can be survived.

no insult intended and none taken. Sadly English is my only language, unfortunately I will never be its master. When it comes to pointing out the shortcomings in my use of language I much prefer 8th of 7 of finding the mistakes that are funny and being merciless, rather than the school teachers approach.

       davey l
The type of super gun I was referring to is a bloody big cannon. Saddam Hussain tried to get one made a few years back, until Mosad objected.

Good luck with the maths! I couldn't even guess what all of the variables are?

       Ps the zone plate shaped charge might also be used for tunnelling, and the the water filled bubble wrap might protect against high calibre bullies.
j paul, Aug 21 2011

       // might protect against high calibre bullies //   

       very useful, the next time [21Q], [A0] and [po] gang up on someone ...   

       It doesn't work.   

       If the plates are closely spaced, sympathetic detonation triggers the whole stack at once, even using Baratol. The resulting shock wave destroys the payload.   

       If the plates are widely spaced, any asymmetry in assembly or detonation results in a massive off-centre thrust to the payload, tumbling it instead of lifting it.   

       It does, however, make quite impressive craters, even when stood half a meter off the ground on a cardboard box   

       Oh, and it's quite noisy ...
8th of 7, Aug 21 2011

       How widely spaced would they need to be?
High-precision symmetrical detonation is a mature technology as you well know.
High-precision symmetrical positioning on a scale of 10s of meters is also mature, in ground-based astronomical applications (using dynamic systems).
mouseposture, Aug 21 2011

       // Saddam Hussain tried to get one made a few years back //   

       A section of this never-completed cannon can be found on display at the British Imperial War Museum at Duxford. If none of the docents are looking, you can even reach across the rope and touch it.   

       // the Mossad objected //   

       A gross underestatement. The Mossad leaked information as to whereabouts the gun's components, which were manufactured in separate locations to avoid suspicion, to several countries including Great Britain, Germany, and the US, then they assassinated the supergun's designer, a peculiarly single-minded Canadian named Gerald Bull.
Alterother, Aug 21 2011

       // How widely spaced would they need to be? //   

       More than the height of a standard 500ml aluminium beer can.   

       // High-precision symmetrical positioning on a scale of 10s of meters is also mature, //   

       Well, yes. Admittedly the test setup was somewhat "rough and ready", and millimetric accuracy wasn't achieved. In retrospect, emptying the cans by consuming the contents before putting the stuff in a heap was probably not the best procedure.   

       What did work well was to put 500g of Gellomex on the ground, put a dustbin (trash can) lid over it, put the bin open-end-down over the lid, and then put a traffic cone on top with a tarpaulin stuffed inside to serve as a parachute. Went amazingly high, and the parachute deployed perfectly, although (again in hindsight) it would have been a good idea to tether the traffic cone to the bin ... due to their peculiar weighting and lack of aerodynamics, their post-deployment trajectory is far from predictable (who knew it would travel so far upwind ?).
8th of 7, Aug 22 2011

       // English is my only language //   

       [jp], apologies for my erroneous assumption. You express your ideas* well enough for me to understand, so I don't see what certain other Halfbakers are complaining about.   

       If you want to improve your composition skills to please the nit-pickers (<fake sneeze "21!"/>), I can give you some quick and easy tips. Please request if desired; I don't wish to presume.   

       *frequently very good ideas!
Alterother, Aug 22 2011

       After careful review, [The Alterother] has decided to grant this concept his coveted bun, for sheer big-brass-balls inventiveness in defiance of all common wisdom. [+]!
Alterother, Aug 22 2011

       // I much prefer 8th of 7 of finding the mistakes that are funny and being merciless //   

       IS there any other way of being ?   

       After consideration, we have determined that we too shall award a bun, since despite the fact that the idea is complete and utter bollocks, it did enliven and amuse what could have been an otherwise rather samey Sunday afternoon BBQ. Although it is considered possible that some female attendees did find it just a teeny-tiny bit more bowel-emptyingly terrifying than usual. Particularly when it suddenly became unpleasantly clear that the traffic cone was going to land somewhat closer than expected.   

       "Home, home on the range, Where the drunk pyromaniacs play ..."
8th of 7, Aug 22 2011


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