elukka
Junior Member
Posts: 73
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Post by elukka on Apr 5, 2017 13:55:17 GMT
The other day I noticed something strange with my missiles: They were getting rapidly destroyed by lasers despite having a heavily armored nose. I looked at it closer and saw what has happening. The ablating armor was generating enough of an impulse to swing the missile around, momentarily exposing its weaker sides before the engine could correct its course, which was enough time for the laser to burn through. Well, that got me thinking, and long story short...
Some things to note: - This isn't a practical propulsion system. It only survives 10-15 pulses and the game doesn't understand it as an engine. Still, it's really neat to me that this works purely as an emergent consequence of the physics simulation. - It doesn't rely on radiation pressure. The ablating pusher functions as propellant. This is why it accelerates at quite a good clip. I centered the camera on a giant 10 MT station I put in the fleet so that you could see that it indeed accelerates. - It actually renders the ablating plasma from the pusher! - Those are probably the coolest sound effects I've heard for an Orion drive. This from a procedural system that isn't designed for this at all. Neat.
It doesn't take much to do this. Take a 5-10 kiloton bomb, put a slab of silicon carbide or amorphous carbon on your ship, watch it go. These materials work much better than metals for some reason. I started with silicon carbide purely because I recalled that it's been suggested for some real life ablative pusher designs. The whole thing is surprisingly sensitive to detonation distance; have the bomb go off 10-20 meters too far and you get almost no thrust. There are almost certainly ways to further refine this since I didn't spend much time optimizing any part of it. I just wanted to see if it was possible.
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Post by samchiu2000 on Apr 5, 2017 14:02:16 GMT
Look cool~ can you use a nuke with smaller yield so your ship can last longer?~
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Post by goduranus on Apr 5, 2017 15:17:16 GMT
Can you post the craft file so we can improve on it? A minor suggestion, the ship wearing out from the pulses may have been due to the magazines cooking off from overheat. Can you try separating the magazines from the launcher and armoring the launcher with a thick layer of good anti-nuke material?
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Post by Dhan on Apr 5, 2017 17:38:09 GMT
What about putting a pancaked NEFP on the back of the nukes to possibly direct the energy a bit better?
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Post by goduranus on Apr 5, 2017 17:40:51 GMT
Ok got my own version up. Doesn't seem to accelerate as fast as elukka's but the pusher plate lasts forever. Ship name is Orion Tester, under stations. Has stability issues, likes to go out of control after launching a hundred or so pulses. Also pretty inefficient in terms of ISP compared to regular rockets. Attachments:Orion Tester.txt (8.46 KB)
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elukka
Junior Member
Posts: 73
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Post by elukka on Apr 5, 2017 17:41:42 GMT
I tried, but I haven't been able to make NEFPs work at all. You can get debris from a shrapnel bomb, but the nuke doesn't do anything to it, it just stays on its original trajectory. Armor or radiation shields don't seem to do anything at all.
To be honest I'm not really convinced NEFPs are even possible in the game. Most of their effects seem to be accounted for by the kinetic energy of the projectile. I'd like to see a design that does work if anyone has one though.
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Post by randomletters on Apr 5, 2017 18:12:47 GMT
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Post by ross128 on Apr 5, 2017 19:33:03 GMT
NEFPs work, the fact that the orion drive works is proof enough of that because they operate on the same principle. A NEFP is essentially an Orion drive with no ship attached. All that's necessary is a nuke and a sufficiently thick chunk of heat-resistant material. Osmium or Tungsten works well.
However, most of the time it's hard to tell their effect apart from a KKV because only the most ridiculously over-engineered armor schemes will ever be strong enough to notice the difference.
Also, you can do it to a much lesser degree with conventional explosives too. An explosive pill with a copper plate in front of it produces a very distinct plume when it detonates, though above 3km/s the gain in performance is fairly small for a conventional explosive.
I don't think a NEFP would be a good idea to boost the efficiency of an Orion drive though. The only reason the pusher plate survives is that it's able to spread the energy of the explosion across the surface of the plate, a NEFP would likely drill clean through the plate and core the ship on the other side.
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Post by morrigi on Apr 6, 2017 2:35:10 GMT
I've seen ideas thrown around about more advanced Orion drives that would use conventional propellant as well as the nuclear blast to produce thrust, since the nuke would heat the propellant and therefore create more thrust. This could also protect the pusher plate to some degree.
Unfortunately, none of that is modeled in-game.
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Post by teeth on Apr 6, 2017 3:07:57 GMT
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Post by teeth on Apr 6, 2017 4:14:37 GMT
Alright, here's my first calculation. It doesn't have glaring errors and it's within the expected range of efficiency, so I think it's correct. I did have to google the equation to do this and I'm not sure if it's the correct one though. This is based off of the orbital test payload to LEO figures. Going to get to work on the interplanetary design next to see what sort of efficiency differences we can see between different yields of bombs.
1180 tons to orbit 9.4 km/s
joules=0.5*WeightInGrams*SpeedInMetersPerSecond
0.5*1070477989*9400
535238994.5*9400
5031246548300
5031.24 gigajoules
24 kt worth of bombs
24 kt=100'416/5031.24=19.95
Roughly 19.95% efficiency
5600 tons to LEO 9.4 km/s
x=.5*5689862689.28*9400
2844931344.64*9400
26742354639616
26742.35 joules to get to orbit
112 kt worth of bombs
112 kt=468608 joules
468608/26742.35
Roughly 17.52% efficiency.
That does it, if these designs are correct and were made by scientists working on Project Orion who had access to the stuff we don't, I say we slap a 15-20% efficiency rating on the Casaba howitzers and call it a day.
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Post by goduranus on Apr 6, 2017 4:29:41 GMT
Wait a minute, I think we've gotten everything wrong. How have you guys been detonating your nukes? I've noticed that my nukes triggered by flares actually fizz out, so what I thought were effects of fission detonations are actually effects of chemical explosives. I noticed the difference between a flare fizzed a nuke and an actual nuke by clicking on the pulse unit and manually detonating the nuke. An actual nuke produces a flash, where as a fizz produces an expanding ball of gas.
elukka's nukes appear to be actual nukes, since they produce a flash, so how does it work? How do you trigger a nuke after a fixed distance?
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Post by Enderminion on Apr 6, 2017 12:52:05 GMT
if you edit the detanator on the warhead, their is a timer which starts when the thing is launched
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Post by goduranus on Apr 6, 2017 14:09:36 GMT
Ah, the tooltip for that said it only get activated when enemies are present, I guess it was lying
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elukka
Junior Member
Posts: 73
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Post by elukka on Apr 7, 2017 16:06:58 GMT
Ok got my own version up. Doesn't seem to accelerate as fast as elukka's but the pusher plate lasts forever. Ship name is Orion Tester, under stations. Has stability issues, likes to go out of control after launching a hundred or so pulses. Also pretty inefficient in terms of ISP compared to regular rockets. I think it lasts because your nukes are not actually exploding. The fuze destroys the nukes and pops the chemical explosives which pushes your ship. The graphical effect is that of a chemical bomb, not the flash of a nuke. You can replicate the result by simply using pellets of chemical explosives instead of nukes. e: Wait, you said as much yourself. I am bad at reading. On the other hand it's actually a much more effective propulsion system than my vastly inefficient Orion. It's actually kinda crazy. I made a ship propelled by TNT and it accelerates faster than anything else. The effective exhaust velocity isn't great, but still. edit 2: Quick and likely somewhat inaccurate math gets me 100-150 s isp and multi-g acceleration out of TNT.
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