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Post by newageofpower on Dec 9, 2016 21:41:46 GMT
Why use nuclear-thermal instead of resistojets? You should have enough available power from the (now unused) MPDs, resistojets are way lighter and cheaper, and you can reach higher temperature, and as such higher efficiency. My dual-engines are always MPD/resistojet for this reason. *Blush* I haven't worked on resistojets yet. I've tuned chemical drives, MPDs, NTRs, worked on reactors, lasers, guns and launchers... but haven't touched resistojets yet. I originally didn't want to use MPD/Resistojet, as my warships would be powering Death Lasers with the electricity in combat (and strategic thrusters turned off) and thus the NTRs would be better in this situation. Do you have a handy design basis available? I suppose I could flail around for a few hours to gain an understanding if you don't. You do like ominous ship names, don't you? (Also, does it come with pre-installed hypometric weapons?) I don't think the game can simulate Space-Time weaponry.
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Post by newageofpower on Dec 9, 2016 22:41:17 GMT
Continued from previously: "We at Altarris Heavy Industries understand that not all of our clients are flush with Credits, and perhaps have more humble ambitions. Perhaps they don't need to fly for months across half the Solar System, and thus don't need 200 gigawatts of nuclear energy + an MPD, or don't want to pay for hundreds of Kilocredits of complete, omnidirectional Li-6 radiation protection." "Here, we have a direct comparison between our smallest Civilian tanker, the [Virgo] Heavy Tanker and it's closest equivalent, GE-Hayabusa's LMT. As you can see, our product is not only superior in terms of capacity, and delta V, but also possesses superior acceleration, 2:3 Radiator Redundancy (even better than our Ultra's 1/3 Redundancy) AND most importantly, is priced almost 11 megacredits below General Electric-Hayabusa's offering." "If perhaps you need a little more tankage capacity without jumping into the Gigacredit price range, we at Altarris Heavy Industries have designed the [Virgo] Megatanker." "Carrying an additional 30 kilotons of fuel, the Megatanker still requires the same number of crewmen - and salaries that must be paid - as the Heavy Tanker. The Megatanker has already proven an best-seller, with warlords mindful private citizens who maintain squadrons of thinly disguised pirate vessels Civilian craft converted for privateer duties.
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Post by amimai on Dec 9, 2016 23:00:32 GMT
The main problem with non-MPD designs is that you loose quite a lot of the fuel you are hauling going to your drop point, then a smaller but still significant amount going back to pick up the next load. There is probably a balance for it particularly since a lighthugger cant exactly do "small" runs, but the cost/profit margins would be thinner.
just made a quick design, you would use approximately 2/3 of your fuel with a resistrojet to escape Jupiter, its fairly efficient to get around inside Jupiter orbit, but you would never realistically do a run outside that and make money. The nostalgia for infinity can execute the same manoeuvrer for less then 1/20th of its fuel.
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Post by newageofpower on Dec 9, 2016 23:08:40 GMT
The main problem with non-MPD designs is that you loose quite a lot of the fuel you are hauling going to your drop point, then a smaller but still significant amount going back to pick up the next load. There is probably a balance for it particularly since a lighthugger cant exactly do "smalll" runs, but the cost/profit margins would be thinner. Yeah. These are usually used as "local" craft, or get carried by a bigger Ultratanker (like you've seen on the previous pages), where then it undocks and brings the fuel closer to the target with it's ability to exploit Hohmann transfers (which the bigger craft have... problems with). Bigger tankers are for long distance interplanetary travel, small tankers for a single Hill Sphere. You CAN use it for longer ranged travel, it's just slow and/or eats up an unholy % of the fuel mass.
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Post by lawson on Dec 9, 2016 23:23:42 GMT
It's also occurred to me that the largest slowest shipments would probably be done with unmanned "barges" and use space "tugs" at each end for acceleration and deceleration. No reason to pay a crew to baby-sit 1MT of hydrogen as it coasts for 2.5 years from Jupiter to Luna on a Holman transfer. Any MPD tug that could give a 1MT barge a ~9km/s shove, wouldn't have a hard time using 1-10% of it's fuel to return home or to meet an incoming barge out in interplanetary space.
My other thought is that all passenger ships would also rent out office space. I.e. if you're sending Joe Hotshot to Titan shape up your plastics factories, it makes no sense to pay him for a 6-month vacation when he could tele-commute along the way.
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Post by amimai on Dec 9, 2016 23:42:12 GMT
It's also occurred to me that the largest slowest shipments would probably be done with unmanned "barges" and use space "tugs" at each end for acceleration and deceleration. No reason to pay a crew to baby-sit 1MT of hydrogen as it coasts for 2.5 years from Jupiter to Luna on a Holman transfer. Any MPD tug that could give a 1MT barge a ~9km/s shove, wouldn't have a hard time using 1-10% of it's fuel to return home or to meet an incoming barge out in interplanetary space. My other thought is that all passenger ships would also rent out office space. I.e. if you're sending Joe Hotshot to Titan shape up your plastics factories, it makes no sense to pay him for a 6-month vacation when he could tele-commute along the way. hell something the size of nostalgia for infinity could probably CARRY the a factory in a tiny tucked away corner of its cargo hold. i already set aside some of the ships cargo space specifically for maintenance and engineering supplies/manufacturing systems for the ship. that tiny spot there is 7kt of cargo space set aside for basic ship maintenance, next to it is the staff quarters and auxiliary reactor for the populated sections of the ship. below that is the main bulkhead leading to the dedicated reactor systems powering the main engine.
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Post by cutterjohn on Dec 10, 2016 5:31:54 GMT
Okay, at some point the cost of the nuclear fuel has to be considered and current ingame models do not do this too well. Looking for some rough numbers... 7-50 GWd/t fuel ( source), lets round it up to 100 GWd/t. That is about 8.6PJ/t or TJ/kg. To exhaust propellant efficiently at 258km/s, we have to put ~33 GJ/kg propellant into it. Divide the two, we need ... a kg of nuclear fuel per 261kg of propellant? Give or take a factor of 10 for my rough source number, but isn't nuclear fuel at least many hundreds of times more valuable than propellants? Does this sound off to anyone else? (Of course ignoring that if it is not enforced ingame, we will willingly ignore the limitation) The problem with your number is that modern nuclear fuel cycles generally use only fractions of the material mined to produce energy, and are rarely recycled. Your number reflects this fact. But its technically achievable, even with today's technology, to design reactors and/or fuel cycles that utilize 100% of the power in the fuel. And it has a mind boggling power density. Thorium-232, the most common fissile element, has a potential energy of ~500,000 GWd/t if you burned 100% of it. That's the heat output, mind, not electricity. According to wiki, Thorium-232, the most common fissile element, has an energy density of 79,420,000 MJ/kg. This equates to 919.2 GWd/t
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Post by dragonkid11 on Dec 10, 2016 6:17:22 GMT
Thorium would be VERY nice for all of us on Earth, even today.
Until those Green Peace idiots fucked thorium reactor over and set back humanity for half a century in doing so.
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Post by lieste on Dec 10, 2016 18:54:55 GMT
Funnily enough a similar energy density is found in toothpaste, sugar, water, lead.... but there isn't any feasible way of annihilating the mass to release all this energy. Even with Thorium.
It was somewhere between wishful thinking and a scam, as with solar roadways, and all of the other 'super science' kickstarter projects.
Even those few that technically work (e.g the hover board) are only re-purposing executive toys to make more expensive hipster toys. You can accomplish the same effect (on earth) by using conventional quadcopters rather than magnetic 'quadcopters' and free yourself from the requirement to operate over only ferrous smooth materials, for the same energy input (albeit with a larger package size to lift a human).
Back to nuclear reactions... enrichment is really expensive - it requires mining out huge volumes and discarding almost all of it as radioactive but basically just 'heavy' material to get small amounts of modestly enriched nuclear material. To obtain a few kgs of 'pure' enrichment material is a really huge undertaking, and most current reactors are at around 5% enrichment (with 20% the upper level for special types). Weapons grade enrichment is 90%+, and is really expensive.
From one ton of pure Uranium, you get 1ton at 0.7% for no additional cost. for 4% enrichment, you get 130kg of enriched material at 6.25 Separation Work Units for 5% enrichment, you get 120kg of enriched material at 8.85 SWU for 20% enrichment, you get 26kg of enriched material at 45 SWU for 90% enrichment, you get 5.6 kg of enriched material at 227 SWU
You still need to process all 1000kg of material (more when extraction from ore is included). In addition you need to provide the power to produce the enriched product (using energy from other reactors which themselves require enriched materials to operate) and the materials used (Flourine) are not trivial to work with. Afterwards you have a lot of material which is radioactive enough to require control, but is otherwise only very heavy. We use it for counterweights, penetrators and armour elements, but that is largely because it is plentiful and 'waste' product rather than because it is superior to Tungsten or lead.
With dry weight at a premium on space vessels DU is less useful than we find it on Earth and is essentially just waste (for the most part).
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Post by newageofpower on Dec 10, 2016 19:08:35 GMT
The solution, of course, is numerous breeder reactor installations. You can extract a vast amount of energy from DU by putting the stuff in a fast reactor and producing fissionable Plutonium.
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Post by cutterjohn on Dec 10, 2016 22:17:49 GMT
Funnily enough a similar energy density is found in toothpaste, sugar, water, lead.... but there isn't any feasible way of annihilating the mass to release all this energy. Even with Thorium. It was somewhere between wishful thinking and a scam, as with solar roadways, and all of the other 'super science' kickstarter projects. Even those few that technically work (e.g the hover board) are only re-purposing executive toys to make more expensive hipster toys. You can accomplish the same effect (on earth) by using conventional quadcopters rather than magnetic 'quadcopters' and free yourself from the requirement to operate over only ferrous smooth materials, for the same energy input (albeit with a larger package size to lift a human). Back to nuclear reactions... enrichment is really expensive - it requires mining out huge volumes and discarding almost all of it as radioactive but basically just 'heavy' material to get small amounts of modestly enriched nuclear material. To obtain a few kgs of 'pure' enrichment material is a really huge undertaking, and most current reactors are at around 5% enrichment (with 20% the upper level for special types). Weapons grade enrichment is 90%+, and is really expensive. From one ton of pure Uranium, you get 1ton at 0.7% for no additional cost. for 4% enrichment, you get 130kg of enriched material at 6.25 Separation Work Units for 5% enrichment, you get 120kg of enriched material at 8.85 SWU for 20% enrichment, you get 26kg of enriched material at 45 SWU for 90% enrichment, you get 5.6 kg of enriched material at 227 SWU You still need to process all 1000kg of material (more when extraction from ore is included). In addition you need to provide the power to produce the enriched product (using energy from other reactors which themselves require enriched materials to operate) and the materials used (Flourine) are not trivial to work with. Afterwards you have a lot of material which is radioactive enough to require control, but is otherwise only very heavy. We use it for counterweights, penetrators and armour elements, but that is largely because it is plentiful and 'waste' product rather than because it is superior to Tungsten or lead. With dry weight at a premium on space vessels DU is less useful than we find it on Earth and is essentially just waste (for the most part). Thorium reactors have been constructed before, as have MSRs. While I agree many people on the internet can be far too.. ah.. enthusiastic about the idea, its hardly some idea from a kickstarter project. To suggest its on the same level as solar roadways is just completely disingenuous. DU can be used in breeder reactors, a concept that has also been demonstrated. We don't do many of these things on earth for various proliferation and environmental reasons, but there is little concern about that in space.
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Post by lieste on Dec 11, 2016 1:00:23 GMT
None of these reactions come close to annihilating the matter involved though. Mass defects are in the region of 1/50u for fusion reactions and 1/4u for fission reaction chains. (Roughly 3.75% and 0.1% by mass respectively for the fraction of the material that is fusible/fissionable).
Fast breeders and similar 'improvements' to the chain allow more of the non-fissionable materials to be included in this 0.1% mass elimination process, but they don't improve high refinement reaction chains nor do they increase significantly the mass loss from the fraction that does become involved in fission).
Thorium has problems when used for portable 'battery' style reactors for cars etc as it produces hard gamma radiation which would require very heavy shielding to deal with, making the battery very bulky/heavy and dangerous if defective/damaged.
At least it would be usable if H&S wasn't a thing I guess, while the claims for EM drive were just patently hyperbolic and ridiculous. "Hovering buildings", "flying cars", "Inexpensive launch to LEO" etc... just don't stack up on the minuscule thrusts produced by huge input powers. Having thrust confusable with experimental error isn't consistent with space launch vehicles... Potential use for RTG/reactor equipped satellites to permit minor adjustment burns without limited reaction mass, but that seems to be about it for now (aside from curiosity value).
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Post by newageofpower on Dec 11, 2016 3:29:14 GMT
I'm a little sad there's no competition in this thread and that nobody is posting up resistojets."For the first time since the Genocide of Mars by the USTA Navy, Altarris Heavy Industries is once again offering it's famous line of [Cygnus] Naval Support Vessels - now newly improved due to consultations with thorneel Laboratories!" "Due to the ludicrous efficiency of Decane-based Resistojets, swapping out the old NTRs has improved acceleration beyond most capital ships! Though the price of our newly improved [Cygnus] Ultratanker is an nontrivial 1.0 Gigacredit, 2% of all profits from this line will be paid to Thorneel Incorporated as royalty fees." Note: While the heavy civilian craft of the Virgo line have seen enormous increases (over 50%!) in "acceleration mode" due to advanced Resistojet employment, they are not capable of exceeding 0.162g due to the limitations of Methane based resistojets."As will all Ne Plus Ultra designs, the Ultratanker can achieve incredibly rapid Interplanetary transit times under MPD drive, and comes with interplanetary-transit level "CancerBGone" radiation protection. Carrying over 310 KT of Decane, the Ultratanker also can carry 3 kt of cargo mass if your attack fleets are running low on ammunition or need replacement parts for critical components." "The Ultratanker still retains it's distinctive double reactor section design; the reasoning being that if a foolish captain gets the aft section shot off, he can pull out a replacement 100 GW MPD (consuming less than 35kg of cargo space, and included for FREE in every Ultratanker) and still have dV. Where Civilian ships prefer the single reactor compartment for ease of maintenance, our Decane tankers are naval support vessels." "For more economical, short-distance refuelling, the Cygnus line also includes Heavy and Mega tankers, which are sometimes carried along with an Ultratanker for an interplanetary mission." "Just as our [Virgo] Methane Heavy Tanker utterly destroyed General-Electric/Hayabusa's Large Methane Tanker, so does our [Cygnus] Decane Heavy Tanker annihilate their Decane Tanker. With nearly ten times the acceleration and almost 8kt more fuel capacity for less than two Megacredits of cost, nobody in their right mind would choose the inferior GE-Hayabusa product over our Altaris Heavy Industries' excellent vessels. "A single Heavy tanker, however, is usually insufficient to refuel more than a single squadron of thirsty warships. Security Corporations and small Governments often prefer our Megatanker over the Heavy Tanker, for this reason - and of course, the fact the larger tanker still requires the same number of crew is a significant boon."
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erik
New Member
Posts: 34
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Post by erik on Dec 11, 2016 15:37:48 GMT
I present the Nostalgia for Infinity! Built during the golden age of interstellar trade, the Nostalgia for Infinity, a veritable flying city capable of holding over 10,000 passengers in the lap of luxury while also carrying over 150kt of trade goods and up to 1/2 of its fuel tank for trade purposes is one of the largest freighters ever built. Capable of making a round trip to Jupiter Wasn't Reynold's Nostalgia about 4 km in length?
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erik
New Member
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Post by erik on Dec 11, 2016 16:04:01 GMT
I'm a little sad there's no competition in this thread and that nobody is posting up resistojets.Alrighty, heres my methane tanker. Those are 7.53 km/s methane resistojets, 11 of them at the aft and 4 smaller ones for roll and turning. The tanker carries 10 kt of Methane, dV 31 km/s for cost of 17.3 Mc. The reactor there is not super min-maxed, it should have service life of about 3 years at full power output meaning the ship can fly to destination and back home using all of that dV, without needing to replenish its nuclear fuel.
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