/sci/ - Science & Math

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It accelerates for as long as it's inside the cannon's barrel.

>>6055939
l=v^2/(2a)
For v=11.2km/s and a=17g=170m/s^2 you get approximately 370km (spaceship spends about a minute inside).

>>6055967
ouch... impossible to craft then I suppose...?
very sad

>>6055987
Yeah, gun-launch from Earth is basically impossible. The acceleration needed is too high, and what's worse - we've got an atmosphere in the way.

From the Moon, though, it's perfectly doable. The lower the gravity gets, the more practical it is to build huge towers, and the shorter the tower you need.

>>6055995
you can launch stuff from a cannon or on a rail....just not people
unless you do some weird stuff with submerging passengers in a liquid tank, but i dont think that influences G forces

>>6055995
I reckon then we are never doing a true colonization... you cant polute the air with the fumes of somany rockets to make some real, serious moving on equipment-people... that was the reason of my idea.. the current way to escape earth wouldn´t cut it for us if we want to put let´s say 500 000000 people on mars.... it has to be gunned to avoid all the smoke and bad chemicals...... maybe an een longer cannon crafted on horizntal? still we would need new materials to prevent the ship to burn with the atmosphere again.........

>>6056019

>>6056142
what? you can't build a 370 km tower but can build a 35800 km space elevator?

>>6056019
That is... the least of the challenges with space exploration dude

>>6056019
Actually, it's totally possible to make clean-burning rockets. Hydrogen-Oxygen is a perfectly good rocket fuel/oxidizer combo, and LOX-Methane is fairly clean-burning. If your rocket's putting out a lot of nasty smoke, it means it's burning in an inefficient manner. It's only the LOX-Kerosene and solid-fuel shit that puts out a lot of smoke.

>>6055939
>continuous
>implying you shouldn't just send it into low earth orbit where free fall will provide you tangenital velocity
>implying you shouldn't just use booster rockets temporarily from this height to reach escape velocity

>not using mass drivers instead of cannons.

OP what the fuck, do you want to kill someone?

http://en.wikipedia.org/wiki/Launch_loop

TLDR: put it in orbit instead of trying to beat gravity mono e mono

>>6056483
Mass drivers ARE just another form of cannon, though. The only difference is that mass drivers use electromagnetic force instead of expanding gas. But they deal with the same principles and same impracticality; you still need a great honking tower or angled barrel, and it still has to be evacuated, and it still has to be high enough up that the sudden deceleration from slamming into the atmosphere when you exit the barrel doesn't break your payload - or your crew.

>>6056508
Acceleration too high? Build a longer mass driver
>low orbit and assisted launch vs trying to shoot the moon
Sure buddy...the original plan sounds so much more feasible
>implying I'd want to reach a velocity i could easily reach with booster rockets and free fall speed

>>6056142

the elevator endures less stress because of the counterweight in space

>>6056574
>the square cube law no longer exist
Sorry space elevator enthusiast no fucking way you could design a cable that would even be able to hold its own weight in space, not to mention the eventual ground collision of said superstructure

>>6056483
I cant believe we on earth, are not even planning on building a lofstrom loop yet. Launching rockets into space seems so inefficient and expensive

>>6056623
Lofstrom is mechanically unstable for the same reason as space elevators,
>muh square cube
Simply use mass drivers to launch into low orbit (just to break through thicker atmosphere) and let the rockets shine in orbit as they gain natural momentum from free fall.
There is your system..

>>6056529
Yes, and you have the same problem: The mass driver you need is impractically long. Even if you're only looking for a low enough acceleration not to kill your rocket. Solids can take some pretty high G's, but the amount you have to speed them up to punch through the atmosphere and get into a reasonable near-orbital trajectory still requires an impractically long cannon.

>>6056619
>Sorry space elevator enthusiast no fucking way you could design a cable that would even be able to hold its own weight in space, not to mention the eventual ground collision of said superstructure
Why would there necessarily be one continual cable? Wouldn't it be more intelligent to use a series of short cables with their own counter weights?

>>6057369

I don't think you understand how a counter-weighted space elevator works.

You could do it if you held it up with a series of orbital rings, but that requires you to have significant resources in space already.

>>6057397
Nah mate, I do. You could have each cable system just lift up to the next cable system. Since you're going to build some sort of brake in anyway to prevent people from falling all the way from the top in event of cable failure, just use those to hold it in position while some mechanism unhooks you from the lower cable and hooks you to the higher cable. For trips back down, the cables are stowed with the counterweight at its lowest point...and I imagine you'd have motors on each of the winches so you could adjust the position as desired.

So yeah, you can get around the square-cube law in one aspect, but building the big fuck tower is a different issue all together.

>over 9000+ hours in MS PAINT pic highly related

>>6056619
How about carbon nanotubes?

>>6056201
Yes.

>>6057436

Even if you split the lifting cable into sections, you still need the superstructure to reach the full distance from geostationary to the ground. That's where the problem lies. Breaking the lifting cable intro chunks just means there's more weight on this main structure, compounding the problem.

>>6055987
Well it is going to get impossible here pretty, due to global warming.

One way to make a HUGE cannon cheaply, is melt a hole in the Antarctic ice sheet 1000 or so miles long and line that with a thin layer of steel so the ice does not melt.

Then fill the hole up with hydrogen and pop a ramjet carrying it's own oxygen down it.

Only problem with this, is that the ice sheets we'd need to use are melting...

See: http://www.nss.org/settlement/nasa/Nowicki/SPBI110.HTM

Of course, your gun only needs to be really long if you want to have low accelerations so one can send up people, if one's sending up robots, the gun can be much shorter.

>>6056619
>>hold it's own weight
the problem with space elevators isn't building a cable that can hold it's own weight, it's building a cable strong enough to hold onto a counterweight above geostationary orbit. A space elevator is in tension, not compression.

>>6057369
>>6057436

Because in order for the counterweight to support any weight, it must be above geostationary orbit, so it is spinning faster than the earth and centrifugal force will attempt to pull it away from earth.

>>6056623
The problem with lofstrom loops is one needs gigawatts of power to keep the thing from falling down, all the time.

>>6056201
Surprisingly yes, material requirements are actually more for a 370 km space tower than a space elevator. 35800 km is about as long as all the cables in the golden gate bridge

>>6057897
No shit. That's why I added that last sentence talking about how it's the big fuck building that'll screw you.