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Post by L5Resident on Oct 11, 2016 22:13:32 GMT
Anyone have some really awesome nuclear thermal rocket engine designs to show off? I've seen some great ones that propel the 500 meter long Super dreadnoughts around the solar system! Can anyone offer some advice with High thrust/TRW deuterium designs?
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tuna
New Member
Posts: 33
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Post by tuna on Oct 11, 2016 23:02:14 GMT
The advice for high trust deuterium thrusters for dreadnoughts is "don't". Deuterium, or hydrogen-deuterium are great propellants for civilian ships, but the instant you want to armor the ship, the density of the fuel matters as much if not more for delta-V as the exhaust velocity. Hydrogen/deuterium are so light that ships carrying them either have minimal armor, or terrible delta-V.
Instead, look at methane and decane. They are IMHO the sweet spot for warship propulsion, having reasonably high exhaust velocity, and reasonably good density.
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Post by redparadize on Oct 12, 2016 14:26:44 GMT
I use only hydrogen-deuterium on all my ship drone and missile.
My ship usually have from 8-9K DV and 0.5-1G of acceleration. Drones are about 9-10k DV and 2-5G and missile 6-12k DV and 3-30G. It is true that these are not super armored. The ship can withstand allot of punishment from the front, but sides are mostly protected against nuke and shrapnel.
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Post by nivik on Oct 12, 2016 15:30:41 GMT
I use only hydrogen-deuterium on all my ship drone and missile. My ship usually have from 8-9K DV and 0.5-1G of acceleration. Drones are about 9-10k DV and 2-5G and missile 6-12k DV and 3-30G. It is true that these are not super armored. The ship can withstand allot of punishment from the front, but sides are mostly protected against nuke and shrapnel. I use decane in my ships and decane/LOX in my drones and missiles. In my ships, it helps minimize my cross section, which both lowers the effective range of enemy weapons and makes each ton of armor contribute more armor thickness. In drones and missiles, it's a good balance between density and efficiency: with drones, the performance isn't that bad compared to methane/fluorine, but I can store more fuel in a smaller volume, which reduces the size and mass of both the launchers and magazines. With missiles, the efficiency is much higher than any monopropellant, which means smaller missiles with more capabilities and larger payloads. That said, I tend to construct my ships with a target dV of about 5k, and rely on tankers if I need more than that.
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Post by captinjoehenry on Oct 12, 2016 15:40:43 GMT
I use only hydrogen-deuterium on all my ship drone and missile. My ship usually have from 8-9K DV and 0.5-1G of acceleration. Drones are about 9-10k DV and 2-5G and missile 6-12k DV and 3-30G. It is true that these are not super armored. The ship can withstand allot of punishment from the front, but sides are mostly protected against nuke and shrapnel. I use decane in my ships and decane/LOX in my drones and missiles. In my ships, it helps minimize my cross section, which both lowers the effective range of enemy weapons and makes each ton of armor contribute more armor thickness. In drones and missiles, it's a good balance between density and efficiency: with drones, the performance isn't that bad compared to methane/fluorine, but I can store more fuel in a smaller volume, which reduces the size and mass of both the launchers and magazines. With missiles, the efficiency is much higher than any monopropellant, which means smaller missiles with more capabilities and larger payloads. That said, I tend to construct my ships with a target dV of about 5k, and rely on tankers if I need more than that. Is decane/LOX explosive? I wonder as I have major issues with my missiles exploding and obliterating my ship.
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Post by nivik on Oct 12, 2016 15:48:46 GMT
I use decane in my ships and decane/LOX in my drones and missiles. In my ships, it helps minimize my cross section, which both lowers the effective range of enemy weapons and makes each ton of armor contribute more armor thickness. In drones and missiles, it's a good balance between density and efficiency: with drones, the performance isn't that bad compared to methane/fluorine, but I can store more fuel in a smaller volume, which reduces the size and mass of both the launchers and magazines. With missiles, the efficiency is much higher than any monopropellant, which means smaller missiles with more capabilities and larger payloads. That said, I tend to construct my ships with a target dV of about 5k, and rely on tankers if I need more than that. Is decane/LOX explosive? I wonder as I have major issues with my missiles exploding and obliterating my ship. Nope! That's another advantage. Neither chemical is explosive, so if your payload is safe, losing a magazine of decane/LOX missiles is just annoying, not fatal. Edit: The major disadvantage is that the lowest amount of propellant you can have is 44.8 kilograms. Propellant tanks only go down to 10kg, and you need 3.48 kg of LOX for every kilogram of decane if you're burning stoichiometric. So there's a hard limit on how small you can make your missiles.
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Post by captinjoehenry on Oct 12, 2016 16:06:22 GMT
That's great! I just redesigned my nano missile to use decane/lox with more or less the same everything other than a bit more cost and a bit more weight and a bit less acceleration but other wise the same! And extra non explosive. It's still a flack missile but it is now much less destructive to me.
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Post by elouda on Oct 12, 2016 16:09:36 GMT
Not deuterium, but this is my current primary thruster for all designs over ~75kt. Smaller than that and I prefer to use a smaller 60MN design.
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Post by ash19256 on Nov 7, 2016 17:51:28 GMT
... That decane NTR is, if the Wikipedia page is correct, producing more thrust at a higher exhaust velocity than the F-1 engines that powered the Saturn V. Really puts this game into perspective, doesn't it.
EDIT: Looking more closely at it, your decane NTR is actually somewhere in the ballpark of 4 times the thrust of the entire first stage of the Saturn V by itself, with a higher exhaust velocity. For anything other than the 75kt ships you push with it, I imagine that engine would be ludicrous amounts of overkill. As is, the smaller design is only a bit under twice the thrust of the S-IC stage of the Saturn V (34.54 MN for 5x F-1A engines as specified, 34.8 MN by actual measurement.)
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Post by coaxjack on Nov 7, 2016 21:10:26 GMT
Not deuterium, but this is my current primary thruster for all designs over ~75kt. Smaller than that and I prefer to use a smaller 60MN design. Weird, I came up with a very similar engine on my own, but I use it on my medium/light warships giving them between 2.0-3.5 g's of thrust...Nothing quite like a ship the size of a small office building being able to lift off from Earth's surface.
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Post by redparadize on Nov 7, 2016 23:15:32 GMT
My biggest have about 17MN if I recall correctly. And they use U-233 not U-235. I never really needed NTR above that, but I sometimes have up to 5 of them. BTW, thats a realy heavy engine, are you sure you need 10cm walls? And why not boron instead?
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Post by Durandal on Nov 7, 2016 23:46:57 GMT
I've got a ridiculous 48MN methane NTR I made for a dreadnought I can post.
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Post by dragonkid11 on Nov 8, 2016 0:09:55 GMT
The 10cm wall is for protection probably, since it's kinda easy for thin layered thruster to get disabled from nuke or other destructive stuffs.
Not sure if thicker layer actually help much though.
Also I fairly sure that any thrust above 1G would be too much for manned vessel. Acceleration kill kept happening, so I just reduce the thrust of my ship to less than 1G
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Post by lawson on Nov 8, 2016 0:35:12 GMT
This series of engines are my go-to big ship thrusters. So far, 1-3 of the cheap 257MN engine has been enough.
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Post by coaxjack on Nov 8, 2016 3:04:45 GMT
The diamond combustion chamber is the only thing able to stand up to the heat and pressure. I tried boron and a bunch of other things but ceramics with the requisite temperature resilience are too brittle. Looking at my design now, there are some things I could rework.
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