|
|
Post by concretedonkey on Jun 13, 2017 3:44:39 GMT
So this is the drone and carrier version of the trumpeter: drone internals : price is 3.26Mc and it could be further optimized. Missile payload is decresed from the manned version to 130 M 9Cs 200 Bs and 200 As. Guns have been cut to modest 15km/s 565kg mounts that are not going to win any awards for speed or rate of fire, but are cheap, light and relatively accurate. Defensive laser drones have been cut to only 3, a newer decane fueled version to be able to refuel them from the capital drone. I added something that I was missing on the manned version - a laser. And the carrier itself: Price is 82Mc, mainly because of the drones. Ship itself is just a drone taxi, has minimal armor and no weapons. Its been ready for days now but I was going in circles with the new propellant. Methane, as good of a ballance as it was offering me for NTR, just wasn't cutting it for thrust for MPDs. Especially on low power. I tried Neon, Argon, Water but for the moment the best ballance I've got is with decane. Initially I tried switching to decane for the missiles too but for the moment I switched only the A version : even if its 10kg heavier it still a bit better in everything else. Not the same story for the B and C versions however: as you can see the mass and the price quickly escalated with the fuel amount and since there wasn't any armor around the drop tanks I wasn't really winning anything so for the moment I'll stick with methane for the longer legged versions. I rarely refuel missiles anyway. Both the drone and the carrier can do 1.8mg with the new MPDs and even if its hideously inneficient (for MPD) the drone's engines still give up to 30km/s delta V. The other thrusters there are NTRs with 8.4km/s delta V and modest 460mg acceleration. The carrier has another engine arrangement, since there was more power available the mpds there are much better, giving her about 57km/s delta V. I also gave her 5 relatively large resistojets for better delta V compared to NTRs. I tried the same arrangement with the drones, that gave me 10km/s delta V with 2x50mw resistojets but I prefered to be able to fire the laser while dodging so I stayed with the NTRs. This decane development was largely due to discussions in this forum after my last post. Peon...my warship has 1200 km/s dV.....at .35g Fusion 4tw!   I will go fusion the moment qswitched goes to fusion, which is what, 10 years for now ?  On a more serious note , anyone on team pentane ? |
|
|
|
Post by apophys on Jun 13, 2017 5:19:13 GMT
I will go fusion the moment qswitched goes to fusion, which is what, 10 years for now ? On a more serious note , anyone on team pentane ? I'm pretty sure we'll still be saying that in 10 years. /jk I used to be solidly on team decane; now I'm all for neon and HD. |
|
|
|
Post by concretedonkey on Jun 13, 2017 5:48:26 GMT
I will go fusion the moment qswitched goes to fusion, which is what, 10 years for now ? On a more serious note , anyone on team pentane ? I'm pretty sure we'll still be saying that in 10 years. /jk I used to be solidly on team decane; now I'm all for neon and HD. decane is nice and all, especially when I go back to making ships with more armor, but its expensive. I'm trying pentane now and frankly its pretty decent balance for all drives. Managed to cut the price of everything with 10 Mc with it. P.S. And as always I'm at least a month behind everybody alternative-propellant |
|
|
|
Post by dwwolf on Jun 13, 2017 8:21:40 GMT
Deuterium and Helium...just saying. 😎
|
|
|
|
Post by bigbombr on Jun 13, 2017 9:04:30 GMT
Methane FTW. Because passive armour is not cost effective, but cheap propellant that performs well in NTR's, resistojets and MPDT's is. IRL it's easy to get, easy to store and easy to use. Noble gasses would be a pain to acquire in large quantities, denser hydrocarbons require more refinement and water, while plentiful, has a somewhat disappointing exhaust velocity.
|
|
|
|
Post by apophys on Jun 13, 2017 11:10:17 GMT
Methane is indeed excellent as a multipurpose propellant with realism in mind.
But within realism constraints, the absolute best imo would be carbon dioxide (as a purely MPD propellant). Density is terrific, it can be directly siphoned from the atmosphere of Venus, it can be more or less directly picked off Jupiter's moons as dry ice, and human crew can slowly refill the propellant tanks for a little extra dV.
|
|
|
|
Post by bigbombr on Jun 13, 2017 11:49:41 GMT
Methane is indeed excellent as a multipurpose propellant with realism in mind. But within realism constraints, the absolute best imo would be carbon dioxide (as a purely MPD propellant). Density is terrific, it can be directly siphoned from the atmosphere of Venus, it can be more or less directly picked off Jupiter's moons as dry ice, and human crew can slowly refill the propellant tanks for a little extra dV. You don't think waste CO 2 is better of being recycled into O 2? And doesn't what you say also mostly apply to H 2O? Good density, easy to find (From Venus and the Moon all the way to the Oort cloud) and probably a better exhaust velocity in most drives than CO 2. And the water in your propellant tanks can also be used for life support and radiation shielding. |
|
|
|
Post by The Astronomer on Jun 13, 2017 13:04:48 GMT
Who still use ion drives these days? XD
|
|
|
|
Post by apophys on Jun 13, 2017 13:48:37 GMT
You don't think waste CO 2 is better of being recycled into O 2? And doesn't what you say also mostly apply to H 2O? Good density, easy to find (From Venus and the Moon all the way to the Oort cloud) and probably a better exhaust velocity in most drives than CO 2. And the water in your propellant tanks can also be used for life support and radiation shielding. Converting CO 2 to O 2 takes machinery or plants/algae. Which takes mass. More efficient to haul O 2 and recycle CO 2 as propellant. The raw atmosphere of Venus is 96.5% pure CO 2 , with nice pressure. And you can skim it in a solar-powered atmospheric glider above the sulfuric acid clouds. That is cheap. Water on Venus is only 20 ppm, and largely as sulfuric acid. Water would indeed be my second choice for a realistic propellant, due to easy asteroid sources (Luna has that annoying gravity well, which would require a mass driver or similar to get propellant off). I'm ignoring other drives than electric ones because of dV. When you have over 100 km/s dV, you're not limited to Hohmann transfers, and travel times are reasonable. That's a huge advantage for opening up space to mining and colonization. The lack of high acceleration is an acceptable trade-off. |
|
|
|
Post by ash19256 on Jun 13, 2017 20:16:45 GMT
You know, also taking into account apophys 's pseudo brachistochrone trajectory in the homecoming threads with his MPD ships. |
|
|
|
Post by Hicks on Jun 14, 2017 17:23:05 GMT
CO2 huh? I gotta test that in my fleet for the NTR/MPD combo. Hmmmmm, maybe I'll buckle down and make a CO2 resistor jet. Do NTR/resistor jets get better than 6km/s dV with CO2? I've been a methane NTR/MPD girl since October, but CO2 is intriguing.
|
|
|
|
Post by thorneel on Jun 14, 2017 20:02:01 GMT
The thinnest possible missile. I expect Hydrogen Peroxyde - RP1 to be the best combination for this kind of compactness. The engine has something like 0.5° of gimbal, as anything more causes the missile to go derp. Careful remote control settings may help, but this engine is more or less the smallest possible anyway, and it needs to stay below 1° to avoid increasing its radius too much. This is the KKV version, but it is trivial to add a small flak charge, or even a small <100t nuke for a small mass and dV price. edit: comparison for size and export file Nice1...looks decent to counter enemy missiles. Any specific guidance changes on the controller? The guidance is pretty standard for missiles, I haven't spent much time mucking with those in general. I found this one serviceable, but it can most probably be improved! |
|
|
|
Post by The Astronomer on Jun 14, 2017 23:12:25 GMT
You don't think waste CO 2 is better of being recycled into O 2? And doesn't what you say also mostly apply to H 2O? Good density, easy to find (From Venus and the Moon all the way to the Oort cloud) and probably a better exhaust velocity in most drives than CO 2. And the water in your propellant tanks can also be used for life support and radiation shielding. Converting CO 2 to O 2 takes machinery or plants/algae. Which takes mass. More efficient to haul O 2 and recycle CO 2 as propellant. The raw atmosphere of Venus is 96.5% pure CO 2 , with nice pressure. And you can skim it in a solar-powered atmospheric glider above the sulfuric acid clouds. That is cheap. Water on Venus is only 20 ppm, and largely as sulfuric acid. Water would indeed be my second choice for a realistic propellant, due to easy asteroid sources (Luna has that annoying gravity well, which would require a mass driver or similar to get propellant off). I'm ignoring other drives than electric ones because of dV. When you have over 100 km/s dV, you're not limited to Hohmann transfers, and travel times are reasonable. That's a huge advantage for opening up space to mining and colonization. The lack of high acceleration is an acceptable trade-off. Long missions benefit from having a scrubber instead of hauling more air. |
|
|
|
Post by apophys on Jun 15, 2017 5:37:35 GMT
Long missions benefit from having a scrubber instead of hauling more air. Removing CO 2 from the cabin atmosphere is essential no matter what; the question is what to do with it afterward. "The carbon dioxide removal system (CDRA) on the ISS works to remove CO 2 from the cabin air and dump it overboard [...]. In the future, collected and concentrated CO 2 will feed the Sabatier Reaction." www.nasa.gov/pdf/146558main_RecyclingEDA(final)%204_10_06.pdfMy argument is that, when your propellant happens to be CO 2, machinery for coverting collected CO 2 is unnecessary, with the knowledge that extra hauled oxygen will become propellant CO 2 and is not a waste of mass. CO2 huh? I gotta test that in my fleet for the NTR/MPD combo. Hmmmmm, maybe I'll buckle down and make a CO2 resistor jet. Do NTR/resistor jets get better than 6km/s dV with CO2? I've been a methane NTR/MPD girl since October, but CO2 is intriguing. It is absolutely terrible in NTRs (~2.95 km/s) and resistojets (~3.52 km/s). It has high average atomic mass, so such performance is expected. But that's just fine, because I only care about MPDs (which perform well with more or less anything). Think of CO 2 like neon, but more realistic to get huge quantities of. |
|
|
|
Post by Hicks on Jun 15, 2017 15:49:34 GMT
Still, a CO2 NTR should have a better TWR, which is the entire point of the NTR in a dual drive setup; MPDs don't have the thurst to doge anything in terminal guidance. Hmmmmm... and a resistor jet would model a bi-modal NTR... but then I'd have to choose between thrust and the laser... GAH! I'm gonna have to learn resistor jets now. Oh well, it's a good problem to have.
|
|
I will go fusion the moment qswitched goes to fusion, which is what, 10 years for now ?
