|
Post by logaritm on Aug 12, 2017 14:37:07 GMT
hey everyone, just started playing the game and im wondering if someone could give me a quick overview of what propeties that make a good anode, cathod and insulator on a MPD thruster?
|
|
|
Post by apophys on Aug 12, 2017 22:55:49 GMT
hey everyone, just started playing the game and im wondering if someone could give me a quick overview of what properties that make a good anode, cathode and insulator on a MPD thruster? That depends on your power level. At low power, you will want your anode and cathode to be light and cheap while being strong enough that they don't break. Also trial and error will show that some materials are marginally better than others at efficiency. This results in potassium, calcium, or selenium, in that order of preference. You will also want your chamber width to be large, so your MPD looks like a plate. At high power (about 1 GW - 1 TW), you need materials that will stave off onset phenomenon for a little while longer. Testing has resulted in the preferred materials being a potassium cathode and a depleted uranium anode. You will want a small chamber width here. At very high power, the stresses get to a point where vanadium chromium steel is probably the only material that makes sense anymore, for both anode and cathode. Small chamber width. As for insulator, the game doesn't check if it can actually insulate. I use polyethylene, because that is a realistic option. I have seen metals being used... For some example MPDs, see my standard modules: childrenofadeadearth.boards.net/thread/1624/ae-catalog-standard-modules
|
|
|
Post by ironclad6 on Aug 16, 2017 15:38:56 GMT
I am finding I can get highest TWR with very small engines. For the most part this works out because I can just use more nozzles on my missiles to maximise thrust. Does anyone know how to maximize TWR on a H/F rocket producing ~1 MN of thrust? I get such back efficiency drop it stops working.
|
|
|
Post by Enderminion on Aug 16, 2017 15:42:03 GMT
I am finding I can get highest TWR with very small engines. For the most part this works out because I can just use more nozzles on my missiles to maximise thrust. Does anyone know how to maximize TWR on a H/F rocket producing ~1 MN of thrust? I get such back efficiency drop it stops working. Apophys goes with small thic engines
|
|
|
Post by jtyotjotjipaefvj on Aug 16, 2017 16:14:22 GMT
I'm more familiar with efficient NTR design but combustion rockets shouldn't be that different. Here's an example engine I've cooked up, pretty close to the 1MN range you want. Here are some pointers I use when making a new engine. -Throat radius should be very small. You might get a better TWR by increasing throat radius a bit and thinning the chamber walls, but the optimum is usually on the lower end. Since nozzle size is directly related to throat radius, you'll want to keep it on the low end. -Injector should be made out of Potassium since it's the lightest material, and have a fairly low RPM and a large size. If you want a slimmer engine, you'll have to make the injector heavier since a narrow injector won't be as efficient. -Adding a gimbal is a tradeoff between engine width and efficiency. Three ungimballed engines are more efficient and behave better for missile guidance, but take more room than a single gimballed engine, and may have worse turn characteristics. -You'll generally want exit velocity as high as possible. This means a stoichiometric ratio of 1 on bipropellant engines. As for the nozzle shape, you can usually find a good balance between diminishing returns on the exit velocity and nozzle weight. -Chamber wall should be made from diamond, since it's strong, fairly light and cheap, and can take high temperatures. -For NTRs, U233 oxide is the cheapest fuel, control rods are generally best made from titanium diorbide (I think). It's a good neutron stopper and can take high temperatures. Your core and control rod masses should be as low as possible to fit into a smaller space. It's also cheaper and lighter that way, so it's a triple win. I can't think of much else right now, maybe others will have something to add.
|
|
|
Post by Enderminion on Aug 16, 2017 20:42:20 GMT
High Neutron Flux, as high as possible, up that before core mass
|
|
|
Post by jtyotjotjipaefvj on Aug 16, 2017 21:14:03 GMT
And obviously maxing out enrichment to keep the core as small and light as possible.
For tiny NTRs you might have to decrease both to get the engine's heat output small enough to work with a smaller injector.
|
|
|
Post by ironclad6 on Aug 16, 2017 23:16:20 GMT
No, that has been really helpful. Thank you.
|
|
|
Post by L5Resident on Aug 20, 2017 9:33:33 GMT
Is there a way to remove the Safety limiters in game? I'm having to redesign every nuclear rocket since my rods and moderators aren't "cool enough".
|
|
|
Post by bigbombr on Aug 20, 2017 10:17:55 GMT
Is there a way to remove the Safety limiters in game? I'm having to redesign every nuclear rocket since my rods and moderators aren't "cool enough". No, but you can use modded materials. A list of materials can be found here, courtesy of Rocket Witch.
|
|
|
Post by Durandal on Aug 30, 2017 3:08:09 GMT
You know, with all these tiny Project Plutos we throw around we don't even need high spec weapons. Just bolt some .50 cals on a crew can and throw on a few blast launchers.
Lotech pirate ship?
|
|
|
Post by bigbombr on Aug 30, 2017 5:55:26 GMT
You know, with all these tiny Project Plutos we throw around we don't even need high spec weapons. Just bolt some .50 cals on a crew can and throw on a few blast launchers. Lotech pirate ship? You just described half of my ships. I tend to stick to below 850 ton spacecraft. Most of those small ships are laserstars or missile carriers.
|
|
|
Post by 𝕭𝖔𝖔𝖒𝖈𝖍𝖆𝖈𝖑𝖊 on Sept 30, 2017 9:19:00 GMT
This is the lightest practical engine I could come up with. Attachments:
|
|
|
Post by Kerr on Sept 30, 2017 9:31:06 GMT
This is the lightest practical engine I could come up with. In what scenario is that kind of thrust practical?
|
|
|
Post by The Astronomer on Sept 30, 2017 9:35:18 GMT
This is the lightest practical engine I could come up with. In what scenario is that kind of thrust practical? When you try to make a small cargo hover over an asteroid I guess
|
|