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The Science Behind Building a Space Gun
An anonymous reader writes "Astronomer and gamer Scott Manley (more famous for his Kerbal Space program coverage) has created a fantastic video explaining the science behind building guns that could one day be used to launch payloads into space. It's not as easy as simply making a bigger gun, there's a whole host of unorthodox 'gun' designs which work around the limitations of garden variety propellants."
before the Mossad kills this guy...
In honor of the time before xkcd, but in the style of such:
http://en.wikipedia.org/wiki/From_the_Earth_to_the_Moon
I think it's called a mass driver
They had this technology at the turn of the previous century as shown here: http://www.youtube.com/watch?v=7JDaOOw0MEE
http://en.wikipedia.org/wiki/Proximity_fuze
But for what else can you use this gun? We already have plenty of electronic junk up there and it's made its way there just fine without a gun.
This is probably a case of "it's time to revive a decades-old idea to make a name for myself"...
Why not scale down the LHC and build something that is capable of accelerating something relatively small say 10-100kg fast enough to make it to orbit instead of accelerating atoms to nearly the speed of light.
The problem with conventional rockets is you need to carry the fuel to get in to orbit as well as the fuel to go where you need to. The bigger the ship the more fuel you need to carry to overcome the weight of the fuel.
If you can split the carrying of fuel for your journey from getting your rocket in to orbit you would not need to waste as much fuel lifting itself.
You could set up an automated system that would fire a 10kg payload of fuel every 10 minutes and get what you need over time far cheaper than one big launch.
There was a design on the inter tubes that I can never re-find that used a giant tube in the ocean and a couple valves to make a space gun. Very cool.
Use a particle accelerator to impart lift to a building. A space elevator without super materials.
http://en.wikipedia.org/wiki/Launch_loop
Much better than a cannon, and finally a place where we can put all of that electricity from our power plants that we don't use during trough times to be used again when you get a spike. Just gloss over the energy of a small nuclear device in a moving cable over a 2000km area bit. That's not going to bother anyone...
Science advances one funeral at a time- Max Planck
Oh Scott Manley. I wish you had gotten your PhD. Dr. Manly would be pretty much the best name ever. You could say you have a PhD in Manlyness.
Marianas trench is 11km deep. A neutrally bouyant gun barrel inclined at about 20 gives a barrel length of 30km and is relatively cheap to build (a couple of billion for a few meters diameter).
If you immerse the astronauts in water (body hugging 'bath') they can easily withstand 10-20g for 15-30 seconds. That gives you 2.5-3.5km/s muzzle velocity, and a relatively simple rocket to prvodie the additional 5-6km/s - similar to current rocket second stages.
The gun can also be used at higher g to launch inert payload to orbital speeds without less rocket propulsion.
Guns are ok for lower speeds (up to perhaps 2-3km/s) but ram - accelrators are better than light gas guns for higher speeds.
This would be ideal for sending inert things like oxygen, water, rocket fuel, or some kinds of food. It would even work for structural parts or electronics if they could take the accelerations without damage.
For that matter, one of the problems of a Mars flight is having adequate shielding against the radiation the craft would encounter between Earth and Mars. With a system like this, the cost of getting the shielding up would be as cheap as possible. (I guess the mass of the shielding would affect the accelerations the craft could make and thus affect the length of the trip.)
One problem, as I understand it: a projectile launched from a big space gun would need to have its orbit adjusted or it will return to Earth. Either you need to catch it while in orbit (you get one chance) and add additional acceleration to put it in a stable orbit, or else the projectile needs to have rockets or something to adjust its speed. The video mentioned this issue briefly (the part about Newton figuring out that the projectile would return to the point of launch if no other forces acted upon it).
P.S. I saw proposals for an Apollo-style mission from Earth to Mars: a single giant rocket launches everything in one launch. Why is anyone even looking at doing it that way? Send the craft to space without fuel or consumables; send it up in parts even and assemble it in space. Then, as it is in orbit, fuel it up, load it with consumables, and then when it is ready send it on its way.
We don't really need giant space guns to make space access more affordable; we just need practical, reusable craft that can carry a small load to orbit, return, and do it again soon. It must not need man-decades of work to completely overhaul it, as the Space Shuttle needed. Single stage to orbit, two stage to orbit, whatever... but not single-use rockets. Rockets that fall into pieces as they ascend, where you never get a test flight because each flight uses up one rocket, will never give us cheap access to space.
According to Jerry Pournelle, the fuel cost of putting something into orbit is similar to the cost of flying it most of the way around the world on an aircraft. Because the aircraft isn't consumed by the flight, we can do this for much less than the cost of sending something into orbit. Practical, reusable transportation would be a total game-changer.
lf(1): it's like ls(1) but sorts filenames by extension, tersely
you turn in your geek card. in a multi-body system, such as the earth-moon one, there ARE trajectories to orbit from a "space gun"
This would work best as a system to return mined materials back to Earth.
I swear to God...I swear to God! That is NOT how you treat your human!
Well, how do they do it ?? Does the next Star Trek NOT have actors dodging phaser blasts ??
How do people in the real world dodge really fast things like bullets now? By not being in the path of the weapon when it fires.
Of course, by the time of Star Trek, phasers should be able to automatically lock on the target in real time and hit it, no matter how the target dodges.
http://www.youtube.com/watch?v=1IXYsDdPvbo
The entire talk explains not only how easy this would be, but some of the technical challenges around g-hardening. (Protip: use silicone and epoxy)
Slasdot already covered this... Cannon to the Planets
"Say they could" does not equal "can".
They've got a long way to go before they can prove it.
A baseball, per google search, weighs about .142kg and a 120mph baseball is going about 53m/s.
0.5 * mass * velocity^2 gives about 200J.
200J / 1.6e-19 gives around 1.24 x 10^21 eV.
The LHC's protons top out at around 7TeV, or 7 x 10^12.
Your estimate of the LHC's proton energy, sir, is off by a factor of something like 1.78 x 10^8, or in words, by a factor of 178 million, depending on what you think of as a "fast" baseball! (Unless you think of a baseball moving at .009mph as fast?)
Perhaps you were thinking of some cosmic rays, which are reputed to have that much energy? There are cosmic rays that have had 50J of energy, or about energy of a 60mph baseball. But the LHC has about a factor of 10 million to go to reach that class of energy!
--PM
At those speeds you need the barrel, track, or rail straight to extreme precision. Any deviations will set up a wave in the track that will destroy it.
We built a 1000 ft light gas gun and had it happen. A couple hundred feet down the track the projectile existed through the wall of the tube and the tube was bent into a sin wave.
I love Jesus, except for his foreign policy.
The problem we face is that the guns on earth with the highest muzzle velocity is still about 7x below the escape velocity needed to have a projectile stay in orbit.
The Paris gun, created by the Germans in WWII was able to reach a target 130 km away, but the muzzle velocity was only 1600 m/s and already they had to sort their bullets in increasing diameter as the inside of the barrel was worn out with each shot. The fastest gun muzzle velocity I know of is the kinetic penetrating sabot rounds shot from tanks, which reach a velocity of 1700 m/s. Escape velocity is 11200m/s, which is well above this speed.
Catching a projectile from orbit is also not an option as this will slow the satellite with the amount of momentum needed to bring the projectile up to speed, not even speaking about the problems created with something as sensitive as a satellite need to catch a projectile travelling at 7x the speed of current bullets in kinetic tank destroyers.
Does watching this put me on a list of "might be assassinated by Israeli agents"?
-Styopa
What would be interesting is if a 3D printer were used to fabricate the gun.
Of course, by the time of Star Trek, phasers should be able to automatically lock on the target in real time and hit it, no matter how the target dodges.
So why do the crew keep practicing their aim?
Really?!
The Israelis are bad for killing the guy that was going to give Saddam a GIANT GODDAMNED GUN to lob poison gas shells at Tel Aviv ?!!
Bull was pulling a Von Braun and just didn't have the luck of getting a buyout offer at the end.
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
Le Voyage Dans La Lune is a movie made in 1902.
From Wikipedia:
"At a meeting of astronomers, their president proposes a trip to the Moon. After addressing some dissent, six brave astronomers agree to the plan. They build a space capsule in the shape of a bullet, and a huge cannon to shoot it into space."
Wikipedia
Machine gun Jetpack
If you haven't checked out What-if yet, do it now!
Slashdot's rate-of-post filter: Preventing you from posting too many great ideas at once.
how about electro magnetic projection such as with maglev trains and rail guns?
As in a "gun" (weapon) used in space, which is to me a MUCH more fascinating engineering and design problem. In space, inertia and recoil are a bitch.
Missles probably impractical because they rely on aerodynamic forces to steer (nozzle alone isnt enough to change course/ uses too much fuel), whch leaves us energy and projectile weapons. Turrets can't whip around. Anything kinetic needs to dissipate the recoil which will favor recoilless designs, but those have their own complexities (current designs still have -some- recoil, which while negligible on the surface would have a magnified effect in space). the classic problem of what to do with the heat buildup.
I honestly think space combat will favor a design that is the fusion of two "obsolete" technologies, that of battleship and bomber, though i'm thinking more medium/dive attac bomber. the battleship classic standard is that of dishing and taking damage; this translates to a large mass, and more mass has advantages for absorbing both recoil and heat. the bomber side from the concept of lobbing essentially dumb munitions (bombs or "depth" charges) on a calculated physics trajectory. Though the trouble there, is there no fluid medium to tranfer the energy, so the munition either absolutely must impact the target directly, or cast out a large amount of shrapnel (which would complicate the battlefield for the attacker too).
The list goes on. Fascinating.
The guy who said the election was rigged won the presidency with the second-most votes.
sequentially detonated propellant... Hmm... It seems to me we're getting closer to the design of rockets :)
Hokey religions and ancient weapons are no substitute for a good blaster at your side, kid.
Wait a minute. What are we talking about again?
Necron69
...that is used to launch a gun into space, which in turn that gun (in space) could be used to shoot at stuff back down on Earth. Now imagine a beowolf cluster of these guns in space ;-)
Yeah, I know we have treaties against weaponizing space, but in the end all treaties get broken anyway, and whoever is first to get such a gun into orbit will have a huge tactical advantage.
http://www.youtube.com/watch?v=QShvDj12xBc
"This is the concept for a 10,000 Meter ( 30,000 Foot), ballon-supported space gun.
The tube or barrel is 0.6 Meters (2 feet) in diameter, so it is intended for launching very small payloads.
It is unknown how plausable this is,.
The goal is to get above 10K meters, as the atmosphere is less than 50% as dense as sea level, thus friction should be low and momentum from accelleration up the tube or barrel should encounter less resistance."
It's such a funky concept, I know. But I think it is at least rather different than most space gun concepts. Skepticism and criticism is most welcome.
Just trying to think outside the sphere.
...will we see this in Kerbal Space Profram?
a gun is not feasable, because any human in the projectile launched would become a ... ... take me down for yes, it will sting u in orbit .. ALIVE : )
"nano-scale-thin-flat-pizza".
interesting enough the human body is 70? 80? 90? percent water and water does not compress.
so if the most of the projectile for once were not destructive, one could fill it with water (heavy) and
put a human inside.
unfortunately all we know about accelerating humans inside a water-bubble boils down to
errr
anyways if you would like to take a bet for a jellyfish to survive a launched from a 50 kilo water enclosing projectile (launched at ludecrase 1000g)
to orbit alive
It was clear that the founders intended such.
I was expecting to see a Gyrojet remake.
Dr. James Powell, co-inventor of superconducting Magnetic Levitation (MagLev), is also a co-inventor of a system called StarTram, that uses similar electromagnetic technology to launch manned and unmanned vehicles into space.
Links: http://en.wikipedia.org/wiki/StarTram
http://www.startram.com/
This is also described in the book "The Fight for Maglev"; see http://www.amazon.com/Fight-Maglev-America-Century-Transport/dp/1468144804/ref=sr_1_1?ie=UTF8&qid=1330015138&sr=8-1