|
Post by goduranus on May 24, 2017 8:10:47 GMT
When you look at a coilgun or railgun in CDE, they don't seem all that unobtainable with today's technology - for one of the bigger guns it's only a couple hundred kilo's of zirconium copper, another couple hundred kilos of Nickel Iron Molybedum, and ten tons of Halfina, supplied with 20MW of power. That's a couple of tens of thousands of dollars in material costs, maybe? Then another couple of thousands of dollars for machining. Or even a million dollars in case some of these need to be high-precision, that's still not alot in the grand scheme of things, compared to what some gun collectors spend for an antique M2 Browning or something. So what's keep people from actually building CDE's railguns and coilguns in real life??
|
|
|
Post by nerd1000 on May 24, 2017 8:31:22 GMT
For railguns the main limitation is the rail erosion problem. I doubt that many of COADE's railguns could fire more than 100 shots before failure IRL. COADE also glosses over a lot of engineering constraints and issues seen in real life. It doesn't model weakening due to heat, materials fatigue, the EMP produced when the railgun fires, the wires you need to conduct the absurd current flowing through your rails, manufacturing constraints (COADE assumes that everything is built using perfect molecular manufacturing methods, though it ignores many other implications of that tech: bulk materials are weak because they have tiny cracks or steps in them that concentrate stress at their tips and propagate through the material to cause breakage if the stress becomes great enough. Our materials should be far stronger if they're assembled so perfectly), the sheer difficulty of producing some materials that are very cheap in-game, et cetera et cetera.
Also our guns weigh somewhere between 60 kilos and 1000 tonnes, yet they fire projectiles that are smaller and lighter than a standard assault rifle bullet. In atmosphere such projectiles would very quickly be stopped or melted by the air, and they'd be very inaccurate even over their short ranges because there's nothing to stop them from tumbling. You can get a longer effective range and more damage from a conventional cannon of the same mass. The US Navy's railgun project is attempting to fire something the size of a regular artillery shell, with a sabot and fin stabilization to allow accuracy over great ranges. Try building a railgun that fires a 8 kg bullet at useful speed in-game and you'll start to see the problem.
|
|
|
Post by dragonkid11 on May 24, 2017 8:58:46 GMT
We can use most of the weapon here because they are made for and often only usable in space.
Also.
MONEYYYYYYYYYYY.
|
|
|
Post by shiolle on May 24, 2017 9:21:01 GMT
In other words, CoaDE engineering is to real world engineering what rp0 KSP is to real world space navigation.
|
|
|
Post by newageofpower on May 24, 2017 22:08:53 GMT
Our hypervelocity sandcasters would do little in an atmosphere.
Our aggressively optimized nozzles would catch fire in atmosphere.
Said nozzles would not function at significant pressure (as in atmosphere)
Our rocket engines would require large amounts of weapons grade nuclear fuel.
Our systems run at temperatures that cause 99.9% of known materials to melt and/or catch fire in atmosphere.
Our safety margins are usually 'lol 10k' and would be implausibly difficult to render safe in an atmosphere with wind and other temp fluctuations.
|
|
|
Post by AdmiralObvious on May 24, 2017 22:49:25 GMT
Our hypervelocity sandcasters would do little in an atmosphere. Our aggressively optimized nozzles would catch fire in atmosphere. Said nozzles would not function at significant pressure (as in atmosphere) Our rocket engines would require large amounts of weapons grade nuclear fuel. Our systems run at temperatures that cause 99.9% of known materials to melt and/or catch fire in atmosphere. Our safety margins are usually 'lol 10k' and would be implausibly difficult to render safe in an atmosphere with wind and other temp fluctuations. Key term "in the atmosphere". I think the weapons/engines, assuming assembled and explicitly used in space would be viable, probably. I think the issue would be more in the range of perfection when it comes down to actually making the stuff. Like a cannon 1 kpa away from rupture would still rupture if somewhere along the line you got a nm less barrel than there should be.
|
|
|
Post by The Astronomer on May 24, 2017 22:58:22 GMT
Our safety margins are usually 'lol 10k' and would be implausibly difficult to render safe in an atmosphere with wind and other temp fluctuations. That margin's mine. For others, it's 1 K.
|
|
|
Post by Pttg on May 24, 2017 23:14:26 GMT
An entire degree kelvin? I manually decrease the margins down to fractions of a kelvin. These ships aught to melt down if you shine a flashlight on the radiators.
|
|
|
Post by shiolle on May 25, 2017 9:42:58 GMT
I think the weapons/engines, assuming assembled and explicitly used in space would be viable, probably. I have to say I can't agree with this. For one, materials will loose strength with temperature. That already invalidates a lot of designs. Regarding engines specifically, the game assumes a perfectly uniform flow of propellant. So it doesn't simulates inevitable vibrations. If you think those only happen in atmosphere, watch any SpaceX launch videos and you will find that their second stage engines vibrate even above 150 km altitude. And what happens when you gimbal your engine? Right, it puts non-uniform pressure on the nozzle as long as angular acceleration is not zero. For weapons, gradual degradation in material properties from multiple firings is not modeled. If your gun is able to fire one round, it is able to fire indefinitely. Some gun designs use very thin flat discs as projectiles to keep their mass down. Such projectiles would tumble and crumble in the barrel because the latter does not have a perfect frictionless surface. Projectiles with payload were not shattering as they should last time I tried it. I could list a lot more problems like these, but I hope that is enough to illustrate that no, many CoaDE designs would not be perfectly viable in vacuum.
|
|
|
Post by leerooooooy on May 25, 2017 13:06:31 GMT
I think the weapons/engines, assuming assembled and explicitly used in space would be viable, probably. I bet they wouldn't. The game does not model at all many key factors that would be critical IRL, like materials weakening as they approach melting temperature, and even beyond that the game has bugs and approximations that can lead to nonphysical results, see resistojets violating conservation of energy
|
|
|
Post by ash19256 on May 25, 2017 13:55:53 GMT
I think the weapons/engines, assuming assembled and explicitly used in space would be viable, probably. I bet they wouldn't. The game does not model at all many key factors that would be critical IRL, like materials weakening as they approach melting temperature, and even beyond that the game has bugs and approximations that can lead to nonphysical results, see resistojets violating conservation of energy IIRC, that was due to dissociation of the propellant.
|
|
|
Post by The Astronomer on May 25, 2017 14:06:40 GMT
I bet they wouldn't. The game does not model at all many key factors that would be critical IRL, like materials weakening as they approach melting temperature, and even beyond that the game has bugs and approximations that can lead to nonphysical results, see resistojets violating conservation of energy IIRC, that was due to dissociation of the propellant. I wonder... Is dissociation that powerful?
|
|
|
Post by ash19256 on May 25, 2017 14:40:35 GMT
IIRC, that was due to dissociation of the propellant. I wonder... Is dissociation that powerful? No idea.
|
|
|
Post by argonbalt on May 25, 2017 17:52:03 GMT
Our hypervelocity sandcasters would do little in an atmosphere. Our aggressively optimized nozzles would catch fire in atmosphere. Said nozzles would not function at significant pressure (as in atmosphere) Our rocket engines would require large amounts of weapons grade nuclear fuel. Our systems run at temperatures that cause 99.9% of known materials to melt and/or catch fire in atmosphere. Our safety margins are usually 'lol 10k' and would be implausibly difficult to render safe in an atmosphere with wind and other temp fluctuations. God that sounds so fucking metal though, like the whole time we were basically running war-hammer 40k orc ships, fucking nuclear chariots verging on meltdown and critical failure
|
|
|
Post by newageofpower on May 25, 2017 18:24:44 GMT
IIRC, that was due to dissociation of the propellant. I wonder... Is dissociation that powerful? Possibly. Dissociation of Metallized Hydrogen, for example, is more energetic than standard (i.e. NERVA) nuclear rocketry. Of course, I doubt hydrocarbons are quite as energetic, otherwise a fuel tanker would have yield in the hundreds of tonnes and if terrorists realized this we'd be super fucked.
|
|