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Found 122 results

  1. Naval Battle League Test your naval prowess in this extravaganza of Battleships, Bombs, and Booms. Rules Rules are mandatory in order to play and be counted on the league table 1- Battles are conducted by exchanging save or persistence files over sharing sites. 2- Each player takes it in turns to engage one target with one ship. Any number of ships may be moved in said turn. 3- Ships engage in order of tonnage, lightest to heaviest. Once all ships are used the cycle repeats. 4- The team with the last ship wins. Ties can be declared with both team's approval. 5- Screenshots or videos documenting all moves are needed to complete a turn. 6- Any mods which affect craft or persistence files are forbidden. 7- No quick-loading except in cases of game bugs. 8- All moves must be done manually, without the aid of autopilots. Previous Iterations Guidelines Guidelines are opt out additions to the rules to create as fair and free from exploits a stage as possible. 1- A ship is officially considered dead when the main body of the ship is incapable of fulfilling two of three goals unaided from other ships or on-board weapons... +Sustaining power +Moving +Firing weapons. 2- Weapons can only be fired from the original ship core and must be used within the the same turn that they are fired. 3- Players are not allowed to control enemy craft. 4- Players are not allowed to intentionally edit the orbit of enemy craft via weapons fire or any other method. 5- Any number of ships may be moved in a turn but only one may attack. 6- Ramming is disallowed. 7- Stealing is allowed under the pretense that the parent ship is dead and the items are disconnected from it. 8- Weapons must be fired between 5000 and 15 meters. 9- Surface to orbit weapons may be fired once per turn if applicable,and are exempt from Guideline 8. 10- A team may forfeit a turn at any point. Carriers Additional Guidelines to ensure carriers remain balanced in combat. 1- The total mass of carriers includes fighters and any other items being carried. 2- Carrier fighters have a mass limit of 15 tons, anything heavier will be included as a seperate ship. 3- Carriers will take their turn at the beginning of a cycle. 4- Fighters may be released from any distance but the fighters must still abide to Guideline 8. 5- Carriers may not use heavy armor on a majority of their area. 6- All fighters must return to the carrier by the end of the turn. 7- Carriers can not use their own offensive weapons. Settings -Body -Guideline exclusions -Maximum number of craft -Maximum total combined mass (These are recommended to be negotiated) Scoreboard MiffedStarfish: 3(5) Spartwo: 1(1) Alphasus: 0(3) Skriptkitt3h: 0(2) Quasarrgames: 0(2) DarkOwl57: -1(1) Sdj64: -1(1) Servo: -1(1) Shadowgoat: -1(2) Username: Score(number of battles) -1 from total for a loss +1 for a win 0 for a tie. Numbers increase according to the amount of players... -1/1 -1/0/1 -2/-1/1/2 -2/-1/0/1/2 ...and so on. Please @, quote, or PM me having completed a battle for updates to scoring Discord There was a demand. https://discord.gg/MDhB35Q
  2. Drakenex

    Real Space: The Missions

    REAL SPACE: THE MISSIONS “The universe is probably littered with the one-planet graves of cultures which made the sensible economic decision that there's no good reason to go into space - each discovered, studied, and remembered by the ones who made the irrational decision.” ― Randall Munroe Pop Chart Labs Join us, @DiscoSlelge, @HooHungLow and me in a journey trough the history of man's space exploration!! This is a series about real space exploration missions complemented with their history, objectives and details about the boosters who launched them. Missions from the past, present and future are planned, always trying to be accurate but without exhausting details, and also keeping stock-alike aesthetics. Guide: Chapter 1 LEO communications - the TDRS Network Mars and Phobos observation - Phobos 2 Operation Paperclip: The German Connection
  3. ¡Buenos días! ¿Como están?, Vengo a darles una invitación para entrar a un grupo de Whatsapp en español de ksp. Si están interesados mandarme un mensaje al privado Saludos
  4. Matteo Bellomo

    We live inside a black hole

    Hello everyone, a few days ago I thought on a theory (the mine one), we could probably live inside a black hole, here's why: The big bang was a sort of an explosion, like a super massive Star colliding on itself making an explosion and the remaining is a black hole, the explosion that has happened that time was the supernova, and the black hole is our universe, then, the matter that black hole "sucks" transforms (inside our universes) into galaxies and stars, this is because it is expanding, and this even means that inside our universe the time goes slower, instead out of it, the time goes faster, this is because when something go near or inside a BH its time slows, because of this our universe expansion slower. The death will be very slow because of Hawking radiation, when the universe will stop expanding it will become always smaller, because of its radiation. This mean that all of our BH in our universe are other "universe", then the multiverse exist, and then, there could be other black holes in other black hole and goes like this. The problem is now to understand what is the first universe o_O I need answers :)
  5. planet-creations

    Improve and Help Advance The Space Program

    So I opened up a new space program yesterday. I came up with a good plan for advancements, and I have worked on upgrading the space program until it is fully functional and is publicly open for use. Place your newest addition to the space program please. (the next person down the line may continue) Added a basic VAB.
  6. Welcome to the development thread for the Deep Space Surface Habitat Unit! DSSHU Update 1.4 is now available for download! This was inspired by NASA's ground-based Deep Space Habitat Demonstration Unit. This pack consists of 3 deployable ground-based habitat units. All units have optional compatibility with Kerbal Inventory System, Tweakscale, Connected Living Space and your choice of life support mods; USI Life Support, TACLS or Snacks! Individual habitat features: Habitat Unit 1: 5m expanding habitat Science laboratory Functioning airlock Side docking tube compatible with size 1 stock docking ports WITH SNACKS: Stores soil and snacks WITH USI LIFE SUPPORTS: Provides habitat function WITH TACLS: Contains standard array of life support resources Habitat Unit 2: 5m expanding facility Expanding solar array Multi-mission RTG with radiators Telescopic expanding radio tower Side docking tube Functioning door WITH SNACKS: Stores soil and snacks WITH USI LIFE SUPPORT: Contains life support recycler and fertilizer / ore resource converter. WITH TACLS: Contains standard array of life support resources Habitat Unit 3: 5m expanding facility Functioning greenhouse Storage tanks Side docking tube Functioning door WITH SNACKS: Produces snacks Stores soil and snacks WITH USI LIFE SUPPORT: Agroponics facility with mulch, supplies, fertilizer and storage WITH TACLS: Mimics SETI Greenhouse Provides "nutrients" which handle resource management There are no dependencies for this mod, but if you choose to use any of the included optional compatibility configurations, you will need to also install module manager. There are no wheels on the bottoms of these units, so connecting them may end up being your least favorite part of these habitats. They have plenty of collision meshes, so you should have no problem using something like Konstruction with a forklift and shimmying the buildings into place. Alternatively, you may use something like VesselMover and simply position the building into place and it will dock accordingly. Please do not keep anything attached to the upper or lower nodes when you "Deploy" it. It will explode. I have not added plugin compatibility for moving a connected node while animated. Installation: Extract the contents of the GameData folder into your Kerbal GameData directory. Structure should then read GameData\DSSHU Optional compatibility patches: Extract the desired patches from the "Optional Patches" folder into your GameData\DSSHU folder. IMPORTANT: Only choose ONE life support mod patch if you choose any. Multiple will likely cause unwanted and problematic results. CHANGELOG: Update 1.4 Re-compile for 1.4 New part: 4-way hub/connector USI Life Support Changes: Unit 2 is now the habitat unit Unit 1 is now the recycler Revision 1.1 -Updated optional config patches to use NEEDS: syntax (they will now detect installed mods and apply config files as necessary) - This should allow for CKAN packaging / downloading -Fixed Connected Living Space settings (buildings should now be passable) -Added soil / snacks storage to HDU1 when using Snacks! Download SPECIAL THANKS TO @CobaltWolf and all the other mod devs and thank you for visiting!!! Deep Space Surface Habitat Unit Pack is license CC-BY-4.0 https://creativecommons.org/licenses/by/4.0/
  7. Just saw the movie today and I have a few things to say. That battle at the beginning was dope. Rey's parents being commoners R2D2 playing back the "help me obi wan kenobi" Leia dieing, but not quite Luke dying, but not quite but then for real Didn't really like the new character of Rose. Snoke's ship looking like a city sized B2 Snoke being cut in half That whole sequence i was like "what's gonna happen next!" Good that Kylo didn't get a redemption arc. Snoke felt like a useless character. This all powerful being who can force choke someone on another ship is killed without a flight. I wanted to see more of Captain Phasma. She looked like a powerful character but shows up for like 10 minutes across two movies and then killed. More after I read r/starwars and remember what i've forgotten
  8. sincorchetes

    Hello!

    Good night for everyone, My name is Álvaro, I'm come from Spain. Currently, I live in Mallorca, Balearic Islands. I'm Linux user that's uses Fedora, If somebody needs support get in touch me. Nice to meet everyone! Cheers!
  9. Kerbal space program has been around for a while and there is still no official online multiplayer? Why? This feature is screaming to be added. For example an online sandbox mode where you can play with friends. Not only would this allow current players to enjoy this great game even more, it would generate the company more money. More people would be asking their friends to buy the game so that they can play online with them. So what is up with this?
  10. amankd

    retrofuture [1.1.3/1.2]

    Its here! finally retrofuture space plane parts is for 1.1.3 and 1.2! this is not my mod originally (i am picking it up off NohArk with his blessing) I have fixed the majority of the most obvious bugs but there may still be some lurking around this is still a work in progress the process of updating so i am relying on reports from you fine fellows as to areas that need fixing/balanceing most areas that need focus are; node attchment boyancy heat aero with a side order of what new parts might be considered that might fit in with the new ksp (i was thinking something like a ballast tank and some parts for underwater bases now there is support for it) finally if there are any ideas you have for parts to be retrofuture themed please let me know! anyways hers the mod! images (as i cant seem to embed imgur albums atm)
  11. DrCheezyBlox

    The Soviet Space Program!

    Hello and welcome to my thread! I'd like to introduce you to The Soviet Space Program [SSP] Like you can probably guess its related to communism and rockets. Its a clan i made originally on the game SFS [Kinda like KSP on mobile] and decided to expand it into other space games like KSP. The original idea of it was to make soviet-themed rockets and share them in the server, but it has since then evolved to competitions, roleplay, memes, custom soviet emojis and listening to hardbass/classical soviet music. So if you'd like to share soviet rockets, earn special roles in competitions, shoot some capitalists in the #roleplay chat or even just jam to hardbass, i think you would like to be part of us. Link: https://discord.gg/dAJAnJY (120+ members atm)
  12. Welcome to the development thread for James Webb for Kerbal! James Webb For Kerbal 1.4 / 1.4.1 is now out! WARNING: Update is 100% guaranteed to break any previous saves... REQUIRED Dependencies: Loading functionality made possible by Textures Unlimited by @Shadowmage Functional space telescope powered by Tarsier Space Technologies by @JPLRepo DOWNLOAD 1.4: Download Download Installation: Extract the contents of the GameData folder to your GameData folder. Structure should then read GameData\JamesWebb Optional reflective surfaces: Copy or move the two config files located in the OptionalReflectiveSurfaces folder to the JamesWebb folder I recommend taking a look at the assembly guide to get an idea of where the parts attach to the base structure. Please leave feedback, comments and suggestions and certainly some pictures! Changelog: Update 1.4 Rebuild and recompile for 1.4 Fixed base structure center point / origin Reassembled and exported model with very slightly altered scale Fixed center thrust point Re-aligned all attachment nodes Added 8x attachment points for the RCS thrusters RCS Thrusters now have an attachment node Fixed rear solar panel center point / origin Reduced SAS power Greatly increased SAS electricity cost to promote maneuver accuracy *** Be sure to upgrade to the latest versions of Textures Unlimited and Tarsier Space Technology Revision 1.1 Increased zoom Built-in TSST hard drive Sunshield layers now "rise" into correct final locations Telescope orientation can now be switched between Engines / camera optics with multiple "control from here" options Tweakscale compatibility RCS thrusters 30% larger And please upgrade to the new textures unlimited 0.9.0.2 to fix random exploding fairings. A VERY SPECIAL THANK YOU TO: @CobaltWolf , @Shadowmage, @Beale, @steedcrugeon, @dboi88, @Stone Blue, @Fengist, @JadeOfMaar, @Nertea, @JPLRepo, @Angel-125 and all of the other devs who have been incredibly helpful throughout this entire journey. It was 70 days in the making for James Webb for Kerbal 1.0. KottabosGames YouTube Review Brushes by 'tech brush by DayZee by dariaDZ' KottabosGames Review: Plans for the future include: RSS / RO / RF Configs Additional goodies Stay tuned for more! James Webb For Kerbal is License CC-BY-4.0 https://creativecommons.org/licenses/by/4.0/
  13. I just watched the movie Europa report (IMDB = 6.5) and must say I was pretty blown away by it. It captures perfectly the way a return trip to Europa could be when done in real life. The story itself isn't Oscar worthy or anything, and there were several inaccuracies, but still..I really did enjoy watching it. What did you guys think?
  14. So I have been to Mun and Minmus a ton in KSP, and the only other planet I have visited is Duna. What are some good techniques to plan trajectories to other planets like Eve and or Jool?
  15. Captain_Sly

    Kerbal Inventory System

    Ive been using Kerbal Inventory System for a while. I love that you can store parts and add them to spacecraft when needed. I want to add a docking node to my space station, but the volume of the node is 782.5L and Kerbals can only hold 250L. So when I transport this part to my station, how am I going to attach it if the kerbal can't hold it. Also is there a way to go into the mod files and change how much a Kerbal can hold?? Thanks
  16. What do you think about Space Shuttles both the US ones and the unflown Soviets one? in comparison to more traditional approach? Soviet did only unmanned flight, on their Shuttle the BURAN Some people consider Space Shuttles to be a poor investment of money that could be invested elsewhere, something more practical, some consider it to be one of the best inventions in human history, so where is the truth?
  17. Is there an other good space shuttle mod other than Cromorant aeronology, CSS, etc If you know reply
  18. Have you ever wanted a Ballistic missile (or orbit-capable budget rocket:D ) that is low-cost and can get 70kg to LKO or LEO(WIP)? "edit :a minor mistake:D" 1.1 m wide and 13 m tall. I am definitely doing something I am planning to make a replica and a kerbal version of the Vector block 0.1 Rocket! This is the progress on the Kerbal version so far! SO WHAT DO YOU THINK? SHALL I CONTINUE ? (that is how the replica will look like) (and for the realplume i will use alcholox) (and planning to do RSS configs if no one wants)
  19. Eskandare

    Resource in Space?

    Hello everyone, is there a way to force a generator to only operate in space or put a resource in space that can be collected by a generator?
  20. The_Cat_In_Space

    I is back

    First of all, hi. With school in less that ten days, I decided to get used to a PC again (as I had been playing games such as GTA V, Star Wars Battlefront II, Star Trek Online, AND Kerbal Space Program - mentioned later) on my Xbox One. You can imagine running a game such as KSP on a laptop, and go, "okay, what about it?" Well you see, I have so many mods in my game, that when I played it after school, I would go and have my shower and by the time I had put on my pyjamas, it had just finished loading. Roughly around 15 mins. My average frame rate is 35, the graphics have to be turned on to 'Low', but I don't care. Cause I have some new wireless headphones, that project audio clearly. Have you ever heard the beauty of the main theme in surround sound headphones while your parents and sister argue over rights to Netflix usage? I can't even hear them, as these block incoming noise very effectively. Also over the holidays, I celebrated my birthday. And I got the best gift of all: The LEGO Saturn V kit. I had to stand on my chair to put the LES in place, my cat knocked it over (resulting in a very miserable Thursday night having to rebuild it, with Ally sitting on the box just watching me, laughing as I have to build it again after her crazy chasing around the house), and I just spent nearly a day building a custom launch tower for it, as I'm putting it on display at the local library with my dad. And for those who were saying "How do you have KSP for Xbox, if it's not in the store?" Well you see, I kinda have it just sitting in 'My Games & App's', ready to be played. I know it's glitchy, there's no debug menu or mod support (yet), but it was fun seeing my mum and dad try to complete the Kerbal X tutorial mission. Mum got off the launch pad, only to crash, but dad actually got into orbit! So, with school fast approaching, I shall be preparing to sit outside my locker for 90 minutes a day, looking at the various stories on the 'Mission Reports' section, and downloading more mods to further push my available RAM size to dwindling proportions (until it gets deleted by the IT department for the quarterly computer check. Many people have said to delete System32 to hide their games, one actually did it). And with that, hello again!
  21. Shadow Wolf56

    My Space Programme

    Hello and welcome to meh little space programme! Here I will be weekly uploading about my space program. Maybe I should tell you about my status as a space program. Ok, I'm not a real space program owner but hey, maybe one day I will be! Ok, back to the topic, I live on a farm with a airspace that VERY rarely planes pass across.this kinda means that for my rocket launches, I will not need to have airspace cleared or anything. so that means I won't really have a time restraint, meaning I won't have to finish a rocket on time. Also, because I live on a farm, many chemicals are available (because they are used for put killing), but this doesn't necessarily mean they are perfect for using rocket fuel. Also this thread is linked to my other thread: Ok, now lets cut to the chase, and I will start posting my status as a space program! PROLOGUE Back a few months ago I built these mini match rockets and they, because of limited time, flew 30 feet(only half of the expected 60 feet). I then, in the afternoon of that hot day, built these bottle rockets flying 40 metres! (80 feet?) they were made of soap, water and local air(dat stuff you breathe in). We did so many launches that I could not even count!!!(I'm guessing like 80 launches or something) then we started experimenting with petrol! *evil grin* to put it, the petrol we used was not explosive, between it came out it burnt everything it lands on because of the Bunsen burner used to light the petrol up. After this I went into a period of long research... August 13th So today I was looking in the ol' PVC and adapters parts and I found the perfect piece for a hybrid rocket motor! Then I burnt one end with a Bunsen burner until it was alight. then I quickly used an O2 tank as an oxidiser which then created a very hot exhaust... The flame actually turned blue at a point too! I think hybrid rocket motors are the way to go if you are beginning a space programme!!! Sorry I’m discontinuing this ...
  22. Today the Pegasus X 99 project starts, after first flight tests, which were successful.The beginning of a new era of space exploration.The X99 the newest NASA project, reconnaissance, transport and apartment. First Flight ver. 0.7 First Rollout Ver. 0.9 Flight Test Ver. 0.9
  23. Just how sci fi are you? This ship is the.....?? (I know)
  24. Starcow19

    KSP Career Vlog

    So I have a youtube channel where I've been creating KSP content and figure I'd share it to the Forums. The point of my career is to make money and colonize the Kerbol system. I am playing with a few mods, but they are honestly negligible. I use MechJeb, Alarm Clock, Outerplanets, and this Landing Leg mod I found. I've documented most of my career in videos, with the exception of busy work like refueling and taking up easy routine contracts. Down below I'll post videos of my missions, testing, and crafts. It should be noted that there is no reverts allowed, except for when the Kraken intervenes. The videos are organized from recent at the top to old at the bottom. The recent ones are where you'll find my best KSP missions probably, not that the old ones don't have some good memories, but they mostly exist as documentation. Duna Science Launch: This video shows the launch of our reusable ship infrastructure. I'm not sure how well I like it. The booster is definitely good, but the ship will probably be changed as time goes on to make cargo easier to deploy. Right now we are just loading up the ship in LKO. There it will be refueled. The ship has the science lab for Duna. Minmus Lab In this video clip we land a second Minmus ship down on the planet, this one having a lab. From here we set up the basis of the colonies, having a refueling station and a lab. As we are starting to max out on science at this point, later bases will be more focused on habitation and refueling. Mun Cargo Vessel Return Here we see a demonstration of the Cargo Variant of our Reusable system returning from deploying a lab in orbit of the Mun. This was during the prototyping of the reusable infrastructure. Minmus Mission In a test of the updated vehicle we did a Minmus landing and return, and learned to change where we put our drag surfaces. Minmus Sat Early episode in our space program where we first unlocked the vector engines and made a nice booster stage. ProtoKais Mission Part 1 of one of our more daring missions when we were young with technology. That was a cheaper version of second stage re usability tests. Satellite Launch Here we can start to see the progression of our career as we launched satellites in the early stages of it. Lion Launch Vehicle One of our earliest rocket designs, good for basic satellites Career do or die Moment It was at this point in our career where this mission was the difference between failure and success. If we failed here we wouldn't have enough money to do another mission. First Ship to Orbit The first time we went to orbit
  25. Hi! I've got something new for y'all! Liquid Rhenium Solar Thermal Rocket The maximum temperature concentrated sunlight can heat a material to is 5800K. How do we approach this limit? We will describe existing and potential designs for solar thermal rockets. Solar thermal rockets The Solar Moth The principle of a solar thermal rocket is simple. You collect sunlight and focus it to heat a propellant headed for a nozzle. A rocket engine's performance is determined by its thrust, exhaust velocity and efficiency. A solar thermal rocket's thrust can be increased by sending more propellant through the nozzle. Its exhaust velocity can be increased by raising the propellant temperature. Doing either required more power, so more sunlight needs to be collected. Efficiency will depend on the design. The main advantages of a solar thermal rocket are its potential for high power density, high efficiency and high exhaust velocity. Collecting and heating with sunlight does not need massive equipment - unlike solar electric spacecraft that need solar panels, extremely lightweight reflective metal films can be used. A heat exchanger above a nozzle is compact and masses much less than the electrical equipment and electromagnetic or electrostatic accelerators a solar electric craft uses. Radiators are not needed either, as the propellant carries away the heat it absorbs with it. Put together, a solar thermal rocket can achieve power densities of 1MW/kg while solar electric craft struggle to rise above 1kW/kg. Sunlight would follow the same path as the laser beam here. As the sunlight is being absorbed by a propellant and expanded through a nozzle, there are only two energy conversion steps: sunlight to heat, then heat to kinetic energy. The first step can be assumed to be 99% efficient. The second step depends on nozzle design, but is generally better than 80%. Exhaust velocity will be determined by the root mean square velocity of the gas the propellant turns into. The equation is: Exhaust velocity: (3 * R * Temperature * 1000 / Molar mass ) ^ 0.5 Temperature is in Kelvins. Molar mass is the average g/mol value of the propellant at the temperature it is heated to. R is the molar gas constant, equal to 8.314 J/mol/K. For the very hot gasses we will be considering, we can assume complete dissociation of all molecules. H2 (2g/mol) will become atomic hydrogen (1g/mol), water (18g/mol) becomes a hydrogen-oxygen vapor (6g/mol) and so on. Low molar masses are preferred, with the best propellant being mono-atomic hydrogen unless other factors are considered. These advantages are all the critical elements that allow for travel throughout the inner solar system without requiring vast quantities of propellant. This means smaller spacecraft and lower travel times. Heat exchangers and exhaust velocity The limiting factor for solar thermal rockets is how hot they can heat the propellant. Directly heating the propellant is a difficult task. The lowest molar mass propellant, hydrogen, has terrible absorption. For all practical purposes, it is transparent to sunlight. Seeding the propellant with dust particles that absorb sunlight and heat the hydrogen indirectly through conduction has a major catch: the dust particles get dragged along by the hydrogen propellant flow and increase the average molar mass. A single millimeter-sized carbon dust particle in a cubic meter of hydrogen increases the molar mass from 1g/mol to Indirect heating involved using a heat exchanger as an intermediary between the sunlight collected and the propellant being heated. So far, designs have required the use of a solid mass of metal that is heated up by concentrated sunlight. The propellant is run over the metal, or through channels in the metal, to absorb the heat. Tungsten is often selected for this task, as it has a high resistance to heat, is strong even near its melting point and has a good thermal conductivity. Testing a Hafnium/Silicon Carbide coating. More modern designs make the most of the latest advances in materials technology to allow for higher operating temperatures. Carbon, notably, stays solid at temperatures as high as 4000K. Tantalum hafnium carbide and a new Hafnium-Nitrogen-Carbon compound melt at temperatures of 4200 and 4400K respectively. However, looking at our exhaust velocity equation, the limits of modern materials technology will only provide a 21% increase over common tungsten. This is the reason why so many propulsion technologies that rely on exchanging heat between a heat source, such as a nuclear fuel or a laser beam, and a propellant using a solid interface are said to be 'materials limited' to an exhaust velocity of 9.6km/s with tungsten, or 10km/s with carbon. THC or HNC would allow for an exhaust velocity of 10.5km/s. This is the deltaV equation, also known as the Tsiolkovsky rocket equation: DeltaV = ln (Wet mass / Dry mass) * Exhaust Velocity Wet mass is how much spaceship masses with a full load of propellant. Dry mass is the mass without any propellant. The wet to dry mass is also referred to as the 'mass ratio' of a rocket. We can rewrite the rocket equation to work out the required mass ratio to achieve a certain deltaV using a rocket engine's exhaust velocity: Mass ratio = e ^ (DeltaV required/Exhaust Velocity) 'e' is the exponent 2.7182... in simpler terms, the mass ratio increases exponentially as the deltaV required increases. Or, put another way, the mass ratio required decreases exponentially as the exhaust velocity rises. It is critical to have a higher exhaust velocity for rapid space travel without requiring massive rockets and towers of propellant. You might also have noticed that 'solid' is a keyword up to this point. Why must the heat exchanger remain solid? Liquid Rhenium There is a method to achieve the true maximal performance of a solar thermal rocket, which is heating up the propellant as far as it can go. This is incidentally the temperature of the surface of the sun (5800K). At this temperature, hydrogen propellant reaches an exhaust velocity of 12km/s. A rare, silver-black metal. Rhenium is a rare metal with a surprising number of qualities, one of which is a very high boiling point. Rhenium melts at 3459K but remains liquid up to 5903K. The trick to achieving higher exhaust velocities is to use a molten heat exchanger, specifically liquid rhenium at a temperature of 5800K. Rhenium is also very stable and does not react with hydrogen even at high temperatures, which is something carbon-based materials struggle to survive. It has already been considered as a heat exchanger, in solid form, by NASA. Here is a design that can use liquid rhenium as a heat exchanger: The diagram is for illustrative purposes only - a functional schematic would be more detailed. Here is an explanation for each component: Solar collector: A very large, very lightweight reflective film based on solar sails that can collect sunlight and focus it through a series of lens onto the heat exchanger fluid's inner surface. Rotating drum: The drum's inner surface contains a liquid heat exchanger. The outer surface is actively cooled. The drum is dotted with tiny channels that allow the propellant to enter the liquid from the bottom and bubble through to the top. It is made of Tantalum-Hafnium Carbide. Fluid surface: The fluid here is liquid rhenium. Its surface is heated to 5800K by concentrated sunlight. The lower layers nearer the drum holding the fluid is cooler. The centripetal forces hold the fluid in place Pressure chamber: The rotating gas mix gets separated here. Dense rhenium vapours fall back down, hot hydrogen escapes. Bubble-through heating: The rotation induces artificial gravity, allowing the hydrogen to heat up and rise through the denser rhenium. As it rises, it reaches hotter layers of the fluid heat exchanger. At the surface, it has reached 5800K. Small bubbles in direct contact with the rhenium allows for optimal thermal conductivity. More detail below. Active cooling loop: liquid hydrogen from the propellant tanks makes a first pass through the drum walls, lowering the temperature below the melting point of THC. It emerges as hot, high pressure gaseous hydrogen. High pressure loop: The heated hydrogen is forced through the channels in the drum. It emerges into the fluid heat exchanger as a series of tiny bubbles. Here is a close up of the drum wall, which contains both active cooling and high pressure channels: The configuration displayed above allows the hydrogen to enter the basin bottom at 4000K, then be heated further to 5800K before being ejected into the pressure chamber. If higher quantities of liquid hydrogen for active cooling are used, the drum and high pressure channel temperatures can be lowered to 3800, 3500, 3000K or lower. This pebble-bed nuclear thermal reactor has most of the components of our solar thermal rocket, except that instead using pebbles of nuclear, fuel, we use a liquid rhenium bed heated by sunlight. If the liquid hydrogen active cooling cannot handle the full heat load, radiators will be needed to cool down the drum below its melting point of 4215K. Thankfully, these radiators will receive coolant at 4000K. Their operating temperature will be incredibly high, allowing for tiny surface areas to reject tens of megawatts of waste heat. Electricity can also be generated by exploiting the temperature difference across the radiators' entrance and exit flows, and at very high efficiency. Operation The design is a Rotating Drum Fluid Heat Exchanger Solar Thermal Rocket (RD-FHE STR). It allows for hydrogen propellant to reach 5800K and achieve the maximum performance of a Solar Thermal Rocket. Liquid rhenium does not boil at 5800K, so it remain liquid and can be held inside the basin by simple centripetal forces. Vapor pressure of rhenium at 5800K (0.was determined to be low enough for our purposes. A surface of rhenium exposed to vacuum at that temperature would lose 0.076g/cm^2/s, or 762g/m^2/s. It is unknown how much centripetal force affects the loss rate of rhenium. The pressure chamber would operate at several dozens of atmospheres of pressure, which is known to increase the boiling point and reduce the evaporation rate of fluids. The same techniques used in Open-Cycle Gas Core nuclear reactors to prevent the loss of uranium gas can be applied to reducing the loss of rhenium vapours. At worst, the rhenium heat exchanger loses 0.76 kg of rhenium for square meter per second of operation. Looking at the designs below, the mass flow rate is measured in tons of hydrogen per second. This is a ratio of 1000:1, to be improved by various rhenium-retaining techniques. It should also be noted that rhenium is a very expensive material. A tungsten-rhenium mixhas very similar thermal properties and is much cheaper. Sunlight at 1AU provides 1367W/m^2. A broad-spectrum reflecting surface such as polished aluminium would capture and concentrate over 95% of this energy, so more than 1298W would be available per square meter. Solar sails materials such as 5um Mylar sheets are preferred, massing only 7g/m^2. More advanced materials technology, such as aluminium film resting on graphene foam, might mass as little as 0.1g/m^2. The 'Solar Moth' used inflatable support structure for its mirrors. Based on data for the Solar Moth concept, we have estimated that a solar thermal propulsion system can attain power densities of 1MW/kg. So, each square meter of collector area will require another 1.29 grams of equipment to convert sunlight into propulsive power. Performance Robot Asteroid Prospector We will calculate the performance of two versions of the RD-FHE STR. The first version uses modern materials and technologies, such as a 7g/m^2 Mylar sheet to collect sunlight and a 167kW/kg engine power density. The second version is more advanced, using 0.1g/m^2 sunlight collectors and a 1MW/kg power density. Modern RD-FHE 5 ton collection area => 714285m^2 927MW of sunlight focused onto the drum. 5.56 ton propulsion system Exhaust velocity: 12km/s Thrust: 123.4kN (80% efficiency) Thrust-to-weight ratio: 1.19 Overall power density: 87kW/kg Advanced RD-FHE 5 ton collection area =>50000000m^2 64.9GW of sunlight received 64.9 ton propulsion system Exhaust velocity: 12km/s Thrust: 10.8MN Thrust-to-weight ratio: 15.75 Overall power density: 928kW/kg The principal argument against solar thermal rockets, that their TWR is too low and their acceleration would take too long to justify the increase in Isp, can be beaten by using very high temperatures and very low mass sunlight collectors. For example, a 50 ton propulsion system based on the modern RD-FHE STR design, would be able to push 100 ton payloads to Mars (6km/s mission deltaV) using only 97 tons of propellant. It would leave Earth orbit at a decent 0.24g of acceleration, averaging 0.32g. The departure burn would take only 20 minutes. Using the advanced version of the RD-FHE solar thermal rocket would allow for a positively impressive acceleration of 3.1g. With 12km/s exhaust velocity, multiple missions that chemical rockets struggled to do with low-energy Hohmann transfers can be avoided. A chemical rocket such as SpaceX's BFR might achieve an Isp of 375s, which corresponds to an exhaust velocity of 3.67km/s. It would need a mass ratio of 5.13 to barely produce enough deltaV for a Mars mission. Earth to Destination. If our solar thermal rocket is granted the same mass ratio, it would have a deltaV of 19.6km/s. This allows for a Mars mission to be completed in under two months (10km/s departure, 9km/s insertion). It is also enough deltaV to reach Jupiter with a single stage. Other benefits include a vast reduction in the propellant-producing infrastructure needed to supply orbital refuelling depots and the ability to land on Mercury. Alternative versions: Blown hydrogen: Instead of bubbling hydrogen from the bottom of the liquid rhenium basin, hydrogen is blown into the pressure chamber from the top. It is heated by simply passing over the fluid heat exchanger. The advantage is that the rotating drum does not have to be riddled by microchannels, allowing it to be stronger and rotate faster, which would reduce rhenium losses, and also accept a higher rate of active cooling by leaving more room for liquid hydrogen channels. Another advantage is that there is less chance of hydrogen bubbles merging and exploding in showers at the surface, dragging along rhenium as they escape. The disadvantages is vastly reduced heat conduction rate between the rhenium and the hydrogen. This would require a long and thin pressure chamber to increase the time the hydrogen stays in contact with the rhenium, potentially making the propulsion system heavier than it needs to be and forcing sunlight to enter the chamber at very acute angles. ISRU propellants: Instead of hydrogen, other gaseous propellants might be used. Nitrogen is a good choice, as it is inert and only reduces the exhaust velocity by a factor 3.7 compared to hydrogen. Powering a hydrogen extraction process on Mars requires huge areas of solar panels. Nitrogen is easily sourced from Earth's atmosphere by gas scoops. Other options, such as water or carbon dioxide, are also viable and available on other planets. The advantage is that non-hydrogen propellants are easy to contain and are much denser than hydrogen, so their propellant tanks can be lightweight and small. They are easily sourced and only need to be scooped up and filtered, unlike hydrogen that has to undergo electrolysis. The disadvantage is that there propellants cannot serve as expandable coolant for the rotating drum. A radiator using a closed gas loop is necessary - helium is a likely candidate. This adds mass. A lower exhaust velocity also removes the principal advantage the RD-FHE STR has over other propulsion systems.