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  1. Starship Launch Expansion About Starship Launch Expansion is a mod that collects Starbase real life launch pads, towers, stands and all the stuff necessary to support your Starship launches in KSP. All the parts are designed to withstand the power of every launch without exploding (hopefully). The mod is in Beta right now so any bugs or suggestions you can contact me through discord. Note: Orbital Launch Pad model is old, revamp is in progress See my roadmap to know what is coming!: SLE Trello Download: Spacedock (Available on CKAN) Github (Source Code) Features Mod Parts: - Orbital Launch Integration Tower - Orbital Launch Pad (revamp in progress) - Test and Display Stands - GSE Tanks - Starbase Sign Required Mods Mods required for SLE to work correctly: - Module Manager - B9PartSwitch Recommended Mods Recommended mods to install with SLE: - Starship Expansion Project for Updated Starship and Super Heavy (Compatible with SLE) - Modular Launch Pads for more real life Launch Pads. - Hangar Extender for a bigger VAB for bigger crafts. - Kerbal Konstructs for static objects for KSC. In game Pics: Changelog:
  2. This thread is for links to standing threads that cover upcoming launches from specific launch providers. These threads usually have links to the latest live launch coverage, as well as discussion about upcoming launches: https://spaceflightnow.com/launch-schedule/ http://www.launchinfo.space/ (this has a countdown to next launch) https://nextrocket.space/ (comprehensive list of upcoming launches) https://calendar.google.com/calendar/[email protected]&pli=1 (cool calendar of launches with links) Rocket Lab: This is not a launch provider, but neither is Sierra Nevada. Has a thread, too (and flies rather a lot). Someday ( ): Unflown Crew/Cargo vehicle threads for spacecraft soon to fly: Unflown Lunar Vehicles: NASA Human Landing System Discussion: Eventually we need some others as well...
  3. How do you launch multiple craft from one pad at the same time ? Hi. I am an old ksp player and I am trying to play an 18 T / 30 Part stock career mode game. My 1st return probe mun lander involves 5 separate craft and to avoid the "Clear Launch Pad" problem I am currently driving them all to the crawler way. This is very time consuming and annoying. I have tried various different google searches but can not seam to find a simple solution. I have also had a good look in the settings/physics/save files but cant seam to find anything relevant. So i am also curious now as to where the defining values for the different levels of Pad & VAB are hiding ? (Size, Mass & Part limit values) It would be nice to upgrade the look of my pad whilst keeping the limits in place. Any mod ideas, setting names or thoughts of any kind would be much appreciated. Thanks very much.
  4. Now with a Push Button : Bored of yelling the launch countdown yourself ? Do you find the launch sequence a little ... lifeless ? So here comes an enhancement for your launch clamps : an authentical launch countdown brought to you by Athlonic Electronics. Installation : - You just have to install the "LaunchCountDown" folder and the "ModuleManager.dll" file in your KSP "GameData" folder. It will upgrade your KSP stock TT18-A Launch Stability Enhancer (aka launch clamp) with a countdown feature. No additional parts needed thanks to the excellent "ModuleManager" plugin (included) from Ialdabaoth/Sarbian. ( credits and updates here : http://forum.kerbalspaceprogram.com/threads/55219-Module-Manager-1-5-%28Nov-11%29 ) How it works ? When building your rockets, you can assign actions (Start Countdown and Abort Launch) shortcut key/button for launch clamps in the action group editor tab. or/and When on the launch pad, just Push dah "Go Flight !" Button. Put your in-game engines volume around 25% for the best launch sequence experience Be aware that it will auto-activate the launch stage once the countdown reach "Ignition" so plan your stage accordingly : -> First stage : Engines AND launch clamps, -> and do NOT wait ignition to put some generous throttle... Mechjeb's autopilot users : Setup your ascension profile, Engage MJ autopilot, Start the countdown, Sit back and relax ^^ When using "Apollo Style" launch sequence : You can set your first stage with liquid fuel engines, and your second stage with launch clamps and SRB. This way you can spool up your main engines (at around 10% thrust) by activating your first stage when "engine ignition start" is announced at T-8 seconds. Gently put generous throttle when "All engines running" is announced at T-1 second. And wait for the release of the clamps and Lift-off ! Known issues : - countdown sequence pause every seconds in KSP x64 (32bit is fine) - you may spend too much time on the launch pad now ^^ - let me know if you find some more... Changelog : v1.8.0 [23 Oct 2019] - Fixed errors (due to Refs .dll split & Net 4.x target) - Recompiled for KSP v1.8.0.2686 v1.7.9 [28 May 2017] - Recompiled for KSP v1.3.0 (b1804) - Bundled Modulemanager v2.8.0 v1.7.8 [12 Oct 2016] - Recompiled for KSP v1.2.0 (b1586) - Removed KSPUtil reference - Removed "using Linq" as advised by Squad - Bundled Modulemanager v2.7.1 Older changelogs : To do list : - auto-detect if no engines are on the current stage to avoid wounds, - add a KSP ApplicationLauncher button - polish the GUI - add a (better) Kerbalish countdown, Chatterer style, - add an advanced mode with detailed launch procedures (checks, engine ignition, ...), - learn to code properly and optimize methods... Download from SpaceDock : Download from Curse thingy : This mod includes version checking using MiniAVC. If you opt-in, it will use the internet to check whether there is a new version available. Data is only read from the internet and no personal information is sent. For a more comprehensive version checking experience, please download the KSP-AVC Plugin. __________________________________________________ https://gnu.org/licenses/gpl-3.0.en.html Source code : https://github.com/Athlonic/LaunchCountDown
  5. (PS4) I've had an issue where occasionally when I try to launch a craft, it will load a completely different vessel. It seems to load the auto-saved craft when this happens. Deleting the auto-save craft will subvert the issue but trying to launch after doing this will sometimes send you to the space center screen, and not the launch pad or runway. It's not a game-breaking bug, but it does get annoying when trying to make modifications to a craft, only to then launch the version with no modifications. Also first post!
  6. This is a development thread for the re-release of "'Mass Accelerator" parts. These parts originally come from the Stanford Torus Mod, which reached version 0.6.1 for KSP 0.90 on Curse on February 20th, 2015 before apparently having its development dis-continued (you can find the old forum thread here). I thought it was *excellent* work with a lot of potential, and worth re-releasing to continue the parts' legacy (Stanford Torus' updates were already coming less and less frequently by the time I created this) and make them available to more players. The mod was released under a CDDL-1 license, which allows anyone to "use, reproduce, modify, display, perform, sublicense and distribute" the content with or without author permission. The license requires that I credit the original author, and re-release the original source code: which is provided below... However, this isn't just a cut-and-paste re-release. While the Mass Accelerator parts do achieve a purpose never realized before in KSP (a functional, part-based Mass Driver), they aren't very realistically balanced... The original parts can only accelerate a 2.5 meter 12.5-ton rocket at roughly 2 g's, whereas the Mass Driver designs for the real-life Star Tram proposal could accelerate a 40-ton 2 meter wide, 13 meter long rocket at 30 g's... The original parts are also darn expensive, heavy (30 tons/piece), and have weak attachments to each other which tend to cause Mass Accelerator stacks to break apart under the acceleration they create... Thus, from the first day I got my hands on the Mass Accelerator part, I went into the config and started making some modifications to make it more realistic. ORIGINALLY: - I increased the acceleration to 11760 kN/s (30 g's on a 40-ton rocket), and increased electricity consumption proportionally (this still needs some re-balancing: the original author states in config-file comments that he aimed for 1 MW per 100 kN/s- which equates to 10% efficiency, but it actually came out to 1 kW per 250 kN/s, if 1 EC = 1 kW). This performance is based on the real-life StarTram gen-1 designs... - I decreased part cost to a more reasonable+realistic level (12,500 funds per part instead of 185,000 funds per part- the new cost equates to the still astronomical figure of $92.74 million/section in 2015 dollars, using the convention of 1 Fund = $1000 1965 US dollars), and reduced the part mass to 10 tons/ring (reasonably accurate for real-life aluminum-based Mass Driver coils). - I also increased the toughness of a stack of Mass Accelerators in various ways (such as by increasing the node size from 2 to 3- as the rings are roughly 3.75 meters in outer diameter, raising the Crash Tolerance from 7 to 9, and tripling BreakingForce/Torque values...) The part-balancing has changes somewhat since (I'm sure you can find the math errors I made above if you look carefully), but anyways, the result is this: a functional Mass Driver part, that, while it still has a few bugs/quirks, works realistically in KSP. Version 1.3.2 is now LIVE. Changes from 1.3.0 include the addition of a readme, NEW SIZES of the Mass Driver part (with internal diameters sized for crafts from 0.625 to 5 meters!), and adjustment of tech node assignments (moved back in the tech tree). https://spacedock.info/mod/1227/Netherdyne Mass Driver Mod [Official] I would like players to let me know how the mod works for them. Let me know if you have any issues- I am still in the process of tweaking this version before "release". Like the Stanford Torus mod this comes from, these parts are released under a CDDL-1 license: so there's nothing stopping you from modifying them and re-releasing them yourself as desired. And, here are some more images of a mission I launched using the Mass Accelerators a while ago... NIGHT LAUNCH in 0.25: (For the curious- the rocket pictured above also utilized a parachute-assisted Space-X style recovery of the launch stage, and travels all the way to the Mun with its payload... The engines produce less than 1 g of acceleration at max throttle when the fuel tanks are full- hence why the rocket has gained barely 3 m/s of speed after climbing more than 3 km...) Regards, Northstar
  7. Hi. I've just bought Kerbal Space Programme Enhanced Edition for the PS4 and some of the commands don't seem to work. I have built the first rocket as per the tutorial but 'O' does not engage the SAS and X does not initiate launch. Please advise.
  8. Like here: https://www.youtube.com/watch?v=lm8e4qVoXmM The things that move the telescope from its launch configuration to on top of the station. Can't find them anywhere. Don't want to have to launch a bulky rocket.
  9. What if launching a rocket would be the last thing on your checklist ? This challenge is a bit special, I propose you to build an infrastructure around the rocket, with vehicles, buildings and stuff to prepare launches! Facilities : Fuel services : Mine your own fuel (you can combine multiple fuel tanks to one ISRU using home-made pipelines) +100 Use 3 types of storage for each propellant (each tank is specialized, liquid fuel and oxidizer must be transported separately for safety reasons) +50 Transfer and load fuel in the rocket, once it is ready to launch (payload installed and sitting in vertical position). +150 Build (a) dedicated rover(s) to refuel the launch vehicle (directly or through the launchpad assembly). +50 Launchpad : Bring a launch tower, or a clamp system (similar to Soyouz). +150 Sound suppression system (could be fuel tanks and jet engines aimed at the launchpad to produce smoke during launch). +50 Kerbal's buildings : All Kerbals on site are living in a dedicated building, must have 2 seats per Kerbal and a place to chill after work. +150 Bring an emergency building for Kerbonauts only, must have a lab 2 scientists and 3 seats per Kerbonauts. +50 Drive Kerbonauts to the hospital with a specialized vehicle. +50 Allow tourists to come by and watch launches, must have seats for 5, could be a bus with seats on top, some kind of stands or something else. +50 Launch Vehicle : Rocket : Must be transported empty from KSC, by a fake train, a plane, some kind of trailer, what ever suits you! +200 Provide a screen that it has reached orbit and deployed its payload +100 Launch vehicle is piloted by Kerbonaut(s) +150 Payload : Build a dedicated area to store the payload +50 Mate the payload on / in / below the launch vehicle +200 Bonus Points ! Each building has ladders if needed, com and radiators. +50 Each type of facilities share the same power source through pipelines or connections (could be a solarplant, fuel cells or RTG). +100 Each module / building is launched separately and assembled on site (ISRU, then fuel tanks and so on). +100 Launch vehicle is loaded separately from its transport system. +100 Each vehicle is Kerballed by a well trained driver, crane operator or whatever. +150 Kerbonauts are installed in the rocket using a Kerbonaut vehicle and some kind of ladders / elevator +100 Launch vehicle can be deorbited on the base and refit to be launched again. (optionnal because it's mostly limited to SSTO-type, or you'd have to assemble each stage separately) No rocket engine is used on site to power vehicles or put the launch vehicle vertically. +50 Put a few pics visible to everyone to present your creations and the rest in spoilers. (or imgur whatever!) +50 Modded game has a separate leaderboard. Brown : ISRU, Blue : Fuel tanks, Red arrow : Fuel transport, Green : Clamps and launch vehicle installation, Yellow : Launch vehicle, Orange : Fairing / payload and its installation-system, Purple : Emergency module and Workers office. Not pictured : Fuel rover, ambulance, Kerbonauts vehicle, tourists bus. Launchsite could be shores around KSC, grasslands, desert, what ever suits you! Top score would be 2250. The way you bring modules on site is not very important as long as it is practical enough and doesn't deter you to build beautifull modules! This is my first challenge proposal, all ideas / critics are welcome
  10. Had an idea for a new set of SAS buttons to add to the current set: Flight heading Buttons. Currently you can set your SAS autopilot to prograde, normal, etc., but it would be extremely helpful to be able to align your craft with the compass headings. 90°- (east) 0° - (north) 270° -(west) 180° - (south) While it would have many helpful uses, I currently have the greatest need for it when launching into orbit and want to keep my heading at exactly 90°. The only way to do this currently is to manually keep your marker lined up with the compass. The prograde marker helps, but constantly changes heading while under acceleration.
  11. Hi, so Kerbal Space Program keeps crashing on my pc short after all assets have been loaded to the game. The bug keeps appearing after the 1.7 update. Before that, there was no such problem. I installed the kOS mod, but even before I installed it, the bug appeared several times. However, the bug doesn't appear on every game start. I have added a link to my Google Drive which redirects you to the crash log, the crash.dmp and a copy of my system information. Do you have any suggestions?
  12. I am creating 2 spaceflight-related alternate histories which would include missions directly launched to Mercury. However, there has never been a direct mission to Mercury (all of them have used gravity assists), preventing me from using an existing launch and the synodic period to calculate their launch dates (the only method I know how to use). So, does anyone know any optimal launch dates for direct Mercury transfers?
  13. ----------EDIT - There seems to be a problem at 6:23 - Any one knows whats going on? ---------- Is this a acceptable launch? How do you move things to other categories so i dont slow anything down?
  14. Hey guys when i launch a spacecraft i got crash. Kerbal Space Program [version: Unity 2017.1.3p1 (02d73f71d3bd)] KSP_x64.exe caused an Access Violation (0xc0000005) in module KSP_x64.exe at 0033:6efefbf6. Error occurred at 2018-07-08_004608. C:\Program Files (x86)\Steam\steamapps\common\Kerbal Space Program\KSP_x64.exe, run by furkan. 68% memory in use. 8112 MB physical memory [2526 MB free]. 18352 MB paging file [8791 MB free]. 134217728 MB user address space [134210256 MB free]. Read from location 00001118 caused an access violation. Context: RDI: 0x00000002 RSI: 0x00000000 RAX: 0x00000000 RBX: 0x6a0ec310 RCX: 0x00000022 RDX: 0x6da3f6e0 RIP: 0x6efefbf6 RBP: 0x6da3f679 SegCs: 0x00000033 EFlags: 0x00010246 RSP: 0x6da3f600 SegSs: 0x0000002b R8: 0x6da3f648 R9: 0x00000013 R10: 0x00000000 R11: 0x6fd00020 R12: 0xd5e1c800 R13: 0x00000001 R14: 0x6a0ec310 R15: 0x00000000 Bytes at CS:EIP: 8b 88 18 11 00 00 83 f9 08 74 0a 83 f9 0b 74 05 Module 1 C:\WINDOWS\SYSTEM32\xinput1_3.dll Image Base: 0x00400000 Image Size: 0x0001e000 File Size: 107368 File Time: 2007-04-04_185422 Version: Company: Microsoft Corporation Product: Microsoft® DirectX for Windows® FileDesc: Microsoft Common Controller API FileVer: 9.18.944.0 ProdVer: 9.18.944.0 Module 2 C:\Program Files (x86)\Steam\steamapps\common\Kerbal Space Program\steam_api64.dll Image Base: 0x5d4d0000 Image Size: 0x0003e000 File Size: 235600 File Time: 2018-03-07_045214 Version: Company: Valve Corporation Product: Steam Client API FileDesc: Steam Client API FileVer: 3.42.61.66 ProdVer: 1.0.0.1 Module 3 C:\WINDOWS\System32\DriverStore\FileRepository\nvmii.inf_amd64_bba38e12711c1078\nvoglv64.dll Image Base: 0x5d510000 Image Size: 0x02685000 File Size: 40140888 File Time: 2018-06-25_202558 Version: Company: NVIDIA Corporation Product: NVIDIA Compatible OpenGL ICD FileDesc: NVIDIA Compatible OpenGL ICD FileVer: 24.21.13.9836 ProdVer: 24.21.13.9836 == [end of error.log] ==
  15. What I have in mind here is the most disastrously bad launch that actually still managed to achieve an outcome you were willing to call "success", and I don't just mean "my kerbals succeeded in escaping alive from the flaming wreckage". What inspired this thread is the launch I just had that is my worst thus far. I was launching a new design of mining exploration lander that was hopefully destined for Duna (which I haven't been to yet) but was currently scheduled for a shakedown tour of Kerbin's satellites. My liquid booster stage had followed a far too optimistic launch profile and after separation I found myself 35 seconds from a 51km apoapsis needing something like 600 dV from the exploration vehicle's NERVs. Fortunately the vehicle in question had strong attitude control (relative to most of my rockets) and plenty of fuel available so all I needed to do was avoid falling too far, burning up, or losing control due to the atmosphere. I tilted to 45° and hoped it would be enough. It was enough to slow the countdown considerably but I still had over halfway to go when I crested. I started dropping and soon enough I had to begin tilting back down to avoid losing control of the craft. As I got close to orbital speed, heating became a serious issue so I set SAS and began rotating to give the stressed parts a break. I bottomed out at about 41km and my new apoapsis was literally almost exactly on the opposite side of the planet from KSC. But hey, at least I was close to my target inclination.
  16. Is there a general rule of thumb as to the optimum altitude/velocity/pressure (Q, I think) to jettison fairings-- where the aerodynamic drag reduction is no longer worth the weight/gravity loss? I don't really need the exact equations-- just a general "feel" for the right timing/altitude. Thinking of firing off a series of sounding rockets to test, but I imagine someone else has done a lot more thinking about it already...
  17. I downloaded the Making History expansion but when I launch it I get a black screen. I asked the technical support and they told me to uninstall and download/launch again. I don't know how to uninstall it on my Mac Could you please help as I was very much looking forward to this expansion. I am not a very experienced user so can you please help me in a simple step by step way? All help is appreciated.
  18. Hello, I am new to these forums so please excuse me if I have posted this in the wrong place or something After using the 32bit version of KSP for some time, I started installing lots of mods and eventually ran out of memory. I am trying to use the 64bit version of KSP, but, even with a completely fresh install (I have uninstalled the game twice), I am unable to even get to a loading screen before I am greeted with an error message that reads: "KSP_x64.exe has stopped working". Please let me know if there are logs or config files that I need to post in order for someone to understand what is happening. For the record, my computer has 16 gb of ram and a gtx 1060, if this matters. My previous post did not follow the guidlines for unmodded bug reporting so apologies, and thank you in advance! https://pastebin.com/CcD1VMBr - this is the ouput.log file
  19. Kerbal Space Program makes history today with the launch of its first expansion! Kerbal Space Program: Making History Expansion adds a wealth of new and exciting content to the game, including a robust Mission Builder that lets players create and share their own scenarios, and a History Pack containing missions inspired by historical moments in space exploration. The Mission Builder is a new feature that puts the process of creating and editing missions in your hands with endless possibilities. You’ll be able to customize your own missions to include launches, landings, rescues, malfunctions, explosions, repairs, and much more. You can set unique victory conditions, add exciting challenges, and place unexpected obstacles to keep other players on their toes as they play through these complex missions. Challenge others to complete your missions by sharing them with the Kerbal Space Program community! The History Pack includes a variety of pre-made missions inspired by humankind’s own space exploration. Now you can spacewalk, pull off a crash landing, and attempt to recreate some of the most memorable moments inspired by historic events. All with our unique Kerbal twist, of course. The expansion also includes a more than 70 new parts and astronaut suits inspired by the Space Race that you can use throughout Kerbal Space Program! Additionally, we’ve kept our promise that all players who purchased the game through April 2013 will receive the expansion for free. To redeem the game click here and follow the instructions. Kerbal Space Program: Making History Expansion is now available on Steam and will soon be available on GOG and other third party resellers. Click here to enter the Grand Discussion Thread for this release. Happy launchings!
  20. This is the core of an inter-planetary spacecraft, other parts will be docked with it in orbit. It is also the heaviest part of my planned spacecraft so if i can get this into a safe orbit the other pieces should be easy but i just can't seem to make it happen. The rockets either do not have enough thrust or are too unstable and crash. I looked at the rocket equations on the wiki but since i am not a physics or mathematics major, they are kinda confusing. Any suggestions? (If you are wondering how a Rockomax 64 only weighs 26.8 tons its because its only carrying liquid fuel, this is going to be an atomic rocket when it is finished.)
  21. I seem to start 65-75 meters off the ground whenever this bug occurs (it varies) and I seem to be slowly accelerating towards sea level, but don't move at all. here is a screenshot of the internal view I may be underground, seeing as there is no kerbnet signal. Reverting to launch fixes this bug, but I'm not sure what causes it. I might try and add a KER module to the craft and see what body I'm near. - actually, I just realized I could just use map view. I also seem to have just splashed somewhere, (no parts were destroyed, as far as I can tell.)d After several reversions, I could not get the bug to reoccur, so this is all the information on it I can give right now. MODLIST:
  22. I don't know if anyone ever came up with the idea but I just had the weirdest idea: Why aren't rockets launch assisted by a hydrolic catapult? We all know that most of the fuel is consumed for just leaving the atmosphere, I mean the Saturn V burned through ~13 tons of fuel per second and clearing the tower alone takes a good amount of time. So why aren't rockets assisted in getting some initial velocity? I mean sure, it would be a huge construction but nothing too crazy. So If you manage to boost up the rocket to maybe 50m/s with a 100m high reusable catapult, wouldn't that decrease rocket size or increase the payload? I mean something like this (behold my epic Paint skills):
  23. This is an in-depth tutorial, but still directed to beginner-intermediate players, on how to do a proper launch and gravity turn with the new aerodynamic model introduced as of version 1.0. This tutorial works for versions 1.0 to 1.3. More than giving a script or set of instructions, my goal with this tutorial is for you to gain an understanding of the factors that affect your rocket's behavior during launch, so that you can apply it to any rocket you fly. For that, you'll need to go through the entire post, but I'm also including a TLDR as a "cheat sheet": TL;DR (courtesy of @kBob) 1. Turn ON SAS and set throttle to give TWR of ~1.5. 2. Launch! 3. When your speed reaches 50 m/s, perform a pitch over maneuver (tip towards the East until pointing between 5° to 10°). 4. When SAS stabilizes (i.e. the control input arrows on the bottom left are all centered), turn it OFF. Avoid control inputs and use only throttle to control your gravity turn (throttle up to turn slower, throttle down to turn faster). 5. When your altitude reaches ~40 km, turn SAS ON. Start pitching down manually towards the horizon and adjust throttle to keep your Ap around 45 seconds in front of you. 6. When your Ap reaches the desired altitude, cut your engines, coast to Ap and circularize. ========================================================================================== General Notes on Gravity Turn You all probably know by this point that to get into orbit you need to go up, above the atmosphere, but you also need to go sideways (i.e. horizontally) very fast. To do this, we could launch straight up until we're out of the atmosphere, then point sideways and accelerate to orbital speed. But that would be very inefficient. We want to launch in a way that we gradually turn sideways while we ascend. This is called a gravity turn. The best way is to do a real gravity turn; that is, a turn caused by gravity and aerodynamic forces, rather than one achieved by actively turning the rocket. It is important to keep this in mind. Design Items Before even launching, you need to take these design items into consideration when building your rocket: TWR: Your thrust-to-weight ratio (TWR) at launch should be relatively low, around 1.5. A higher TWR at the beginning of the launch makes it harder for your rocket to turn naturally, as gravity will have less influence on its trajectory, making it fly straight and screwing up your gravity turn. Keep in mind that drag losses are almost negligible in the new aero, unless your rocket is shaped like a brick or you are going extremely fast in the lower atmosphere. Thus, a slightly higher TWR of around ~2.0 in theory is more efficient, but only if the launch profile is flown correctly. The drawback is it makes your rocket less forgiving in terms of control during ascent, and it shortnes your widnow to make a pitch-over maneuver. What usually ends up happening is that you have to force the gravity turn manually, which does generate significant drag (because you expose the sides of your rocket to the airstream anytime you deviate from your prograde vector), and causes steering losses (Dv wasted on changing direction rather than gaining velocity). This reduces overall efficiency and defeats the purpose of having a higher TWR to begin with. A higher TWR also causes increased stress to the craft, inducing wobble and risking a RUD, especially when trying to maneuver. You may experience heating issues too. For these reasons, in my experience, a TWR of ~1.5 is a good sweet spot between efficiency and controllability of the rocket. Smaller and lighter rockets handle higher TWR's better than big and heavy ones and each craft will have its own sweet spot; you are encouraged to experiment. If you find your TWR at launch is too high, either use a smaller engine or just throttle down, and vice versa. As a final note, all rockets will have their TWR go up as the launch progresses due to shedding weight by burning fuel. This is normal and you should manage by reducing throttle throughout the ascent as needed (more on this below). You can check your TWR with the Kerbal Engineering Redux mod (KER) or with MechJeb, or if you're running a stock game, the G Force meter roughly doubles as a TWR meter (if the G Force meter is pointing at 1 your TWR is roughly 1, and so on). Aerodynamic Stability: You want your rocket to be aerodynamically stable. That means that it will have a natural tendency to fly straight, instead of, say, sideways. Any object that flies through the atmosphere will naturally orient itself with its center of mass (COM) facing forwards relative to its trajectory and its center of drag (COD) facing backwards. You can see this in darts, arrows, badminton cocks, etc. Similarly, you will want to have your rocket's COM in front of your COD. To ensure this, add 3 or 4 winglets or wing surfaces with radial symmetry at the base of the rocket, and if possible cover your payload in a fairing to make it more streamlined. If your rocket insists on flipping, you need to add more/larger wings at the bottom. If that still doesn't fix it, it means your COM is shifting back too much as fuel is burnt. The heaviest part of a rocket in KSP is usually the main ascent engine(s), so the COM will tend to move back as fuel is spent. The easiest way to fix this is to add a small fuel tank at the top of the stage that's experiencing the problem and lock the tank in the VAB (right click on the tank and select the green arrows for both fuel and oxidizer). This fuel tank will act as ballast keeping your COM forward. You can unlock it manually in flight when the rest of the stage's fuel is gone so as to not waste it, and then stage as normal. Ascent Profile Once you've implemented the above design items, follow these steps for your ascent: 1. Turn on SAS and set your throttle to whatever will give you a TWR of ~1.5. 2. Launch! 2. As soon as your speed hits 50 m/s, perform a pitch-over maneuver to begin your gravity turn. To do this, tip your rocket towards the East slightly, until it is pointing between 5° to 10°. Don't start pitching over before your speed is ~50 m/s, otherwise you will likely find yourself horizontal within a few seconds, as your winglets won't be biting into the air hard enough to provide stability. The higher your thrust, the more you need to pitch over initially, because higher thrust makes the rocket want to go straight. If you're using a TWR higher than 1.5, your pitch-over should be to at least 10°. 3. As soon as your SAS stabilizes (i.e. the control input arrows on the bottom left are all centered) turn off the SAS. Watch closely for this moment, as you will have only a small window of a few seconds at most before the SAS starts trying to resist the gravity turn. Turning SAS off while it's trying to steer will cause your rocket to become unstable and lose its heading or possibly break up. You should be done with your pitch-over maneuver and have your SAS turned off by the time your velocity is around 100m/s. If you take too long and your rocket is going too fast by the time you're done, it won't want to continue turning (fast rockets like to go straight, remember?) and you'll have to force the turn manually, which is inefficient and causes stress on your craft. As mentioned above, a gravity turn should happen on its own and not as a result of control input. For particularly unwieldy rockets, you can lock SAS to prograde instead of turning it off during this phase. However, stock SAS is far from perfect and it's best to let gravity and aerodynamic forces do the steering for you. If you do use SAS, be sure to disable it before you hit 35 km to avoid you craft from jolting down suddenly when the navball automatically switches to orbit mode, which happens at around 35 km. 4. Enjoy the view while your prograde marker gradually sinks towards the horizon; your rocket will follow on its own thanks to gravity and aerodynamic forces. Try to avoid control inputs during this phase (i.e. no AWSD), just let it fly. If you need to make adjustments, use throttle. Remember, lower thrust means the rocket turns more, higher thrust makes it want to go straight. At about 10 km altitude, you should be pointing roughly to 45° and your speed should be around 500 m/s. If at 10 km altitude you're still pointing above 45°, your TWR was too high and you went too fast and/or your pitch-over maneuver was too gentle. Next time throttle down more or make a more aggressive pitch-over maneuver. On the other hand, if you're pointing below 45° at 10 km, you went too slow and/or your pitch-over maneuver was too aggressive. Next time use higher thrust or do a gentler pitch-over maneuver. If your rocket flips on its end at any point, it's not aerodynamically stable enough. See above under "Aerodynamic Stability" for possible solutions. 5. At around 40 km altitude, turn SAS back on and start steering manually; use pitch and throttle to keep your Ap around 45 seconds in front of you. Any time you're burning above the horizon, you're wasting part of your thrust to gravity instead of gaining horizontal speed; this is called gravity losses or gravity drag. In the initial stages of the launch, you can't help incurring gravity loses because you need to gain vertical speed to get out of the atmosphere. The atmosphere also means you can't steer away from the prograde vector without inducing aerodynamic drag, steering losses and/or destabilizing your rocket. However, by the time you get to ~ 40 km, you'll have enough vertical speed and the atmosphere will become negligible. Thus, at this point you want to begin gradually pitching down towards the horizon. During this phase, you will also start adjusting your time to Ap. It's most efficient to perform your orbital insertion burn right at Ap, so you want to keep it "hovering" only a few seconds in front of you. Of course, you don't want to it to get too close either, otherwise you risk passing it and falling back down into the atmosphere. A time to Ap of ~45 seconds is a good rule of thumb to balance safety and efficiency. To control your time to Ap, use pitch and throttle. If your time to Ap is more than 45 sec, throttle down a bit and point more horizontal, and vice versa. Avoid pitching below the horizon. Continue adjusting pitch and throttle until your Ap reaches your desired altitude, at which point you can cut your engines, coast to Ap and circularize. Note that as you approach orbital speed, there will be a point when your Ap will begin shooting away even if pointing straight at the horizon and no matter how much you throttle down (unless you cut the engines of course). If you reach this point, just let it go until engine cutoff; any efficiency gains from keeping your Ap near you will be negligible by then. Advanced Mode Try doing the ascent and orbital insertion in a continuous burn. This is the most efficient profile (citation needed) and it's extremely satisfying. Easier said than done, though. To pull it off, you need to allow your time to Ap to creep closer and closer during steps 4 and 5, while not allowing it to get higher than your intended orbital altitude. You do this by reducing throttle and lowering your pitch in a more aggressive manner. The closer you are to orbital velocity, the closer you can allow yourself to get to your Ap. You want to hit orbital velocity exactly at Ap. There will be much trial and error and the exact procedure will vary from rocket to rocket, but give it a try!
  24. The full post for you to enjoy and discuss, from here: http://toughsf.blogspot.com/2017/10/spacex-sfr-small-falcon-rocket.html Performance estimates revised: 24 tons expendable, 12-14 tons recoverable to LEO. The Small Falcon Rocket is a scaled down alternative to SpaceX's Big Falcon Spaceship that fits on top of existing Falcon 9 boosters. We will discuss the advantages and disadvantages of such a design. SpaceX's Big Rockets The BFR, or Big Falcon Rocket, is comprised of the Big Falcon Spaceship and the Big Falcon Rocket booster. It is a scaled down and simplified design based on the ITS, or Interplanetary Transport System. The BFR is a BIG rocket. The ITS was revealed in June 2016, although work on the design has begun in 2013 under the name 'Mars Colonial Transporter'. The ITS promised to deliver 300 tons of cargo to Low Earth Orbit, or up to 550 tons if reusability was ignored. It would have massed 10500 tons on the launchpad. The vehicle had a diameter of 12 meters and a height of 122 meters, making it one of the largest rockets ever plausibly considered. And the ITS was positively massive. The upper stage, called the Interplanetary Spaceship, was supposed to hold 1950 tons of propellant with a dry mass of 150 tons. Without a payload, the mass ratio was 14. The BFR replaced the ITS in September 2017. It is a smaller, more sensible design that SpaceX believes it can actually deliver in the next few years. The diameter is reduced to 9 meters and it will mass 4400 tons on the launchpad. Payload capacity is reduced to 150 tons. The upper stage BFS should have a dry mass of 75 tons, but Elon Musk states that this might rise to 85 tons due to development bloat and overruns. It holds 1100 tons of propellant, giving it a mass ratio of 13.9. It is important to note that despite being up to 78% smaller than the previous ITS design, the BFS stage maintains the same mass ratio. Why? Because we are now going to scale down the BFS again. Why go smaller? How big the BFR's booster would be compared to the Falcon 9 booster. Going big is the best way to reduce the cost per kilogram for sending payloads into orbit. SpaceX jumped from the Falcon 1 to the Falcon 9 because the larger rocket can deliver payloads much more cheaply into space. When first considering options on how to make travel to Mars affordable to the general population, SpaceX immediately came up with a gargantuan tower of rocket fuel over three and a half times larger than the Saturn V! A big rocket is also easier to develop. It is more forgiving of development bloat that increases mass over time as the designs are perfected. It has larger safety margins and room for many backups, such as multiple engines. However, bigger is not always better. The total development costs will be higher, as large components need large factories. It is much more difficult to test the components too, and a full testing regime of the completed rocket will require launching and even destroying a full-scale model many times. Remember the failed Falcon 9 booster landing attempts, and imagine them replaced with a vehicle eight times bigger. There is also the fact that the second sure-fire way to reducing launch costs is to have rapid turnover. This involves loading up rockets, sending payloads into space, recovering the rocket and refurbishing it for another launch in a very small time frame, measured in days or even hours. Rapid turnover and minimal refurbishment would allow the space launch industry to more closely resemble existing airline business models. The main benefit of this approach is that a small number of launch vehicles can handle a large volume of missions, critically reducing the initial cost of the vehicles and reducing the amortization rate. Even if SpaceX manages to develop rockets that liftoff and land several times without needing to go to a workshop, they'd still need to solve the issue that there just aren't enough payloads on the market that need to be lifted into space to fill the BFR, let alone the ITS. For example, even the BFR's 150 ton payload capacity can cover all of last year's payloads in about two or three launches. Three launches is far from sufficient. Elon Musk is betting that the space industry will be able to fill the BFR's cargo bays with new satellites and LEO payloads once the lowered cost per kg is offered to them... but there will be a long delay between the launch costs being reduced and the industry contracts appearing en masse. Cost per kg in orbit is only part of the picture. Waiting for more contracts to appear and bundling them together to use the most of a BFR's cargo capacity is not a good solution. It will force SpaceX to delay launches until the mass delivered to orbit reaches a profitable amount - launching BFRs nearly empty with the usual 2 to 5 ton satellite is surely wasteful and a loss for the company. The SFR The SFR, or Small Falcon Rocket, is a possible solution to the development costs, under-utilization and low expected launch rate of the BFR, or Big Falcon Rocket. The SFR is a scaled down Big Falcon Spaceship sitting on top of an existing Falcon 9 booster. It will carry a smaller payload to orbit, but will have a capacity SpaceX is sure to fill up. Existing Falcon 9 boosters can be mated to a fully reusable upper stage, drastically cutting down on development costs. We will now look at the details of the SFR's two stages. The upper stage is the only new part. It is a BFS scaled down to 3.7 meters diameter, using the same Raptor engines rated at 1900kN of thrust at 375 seconds of Isp. We will call it the SFS, or Small Falcon Spaceship. The Raptor engine. The SFS will be (9/3.7)^2: 5.9 times smaller than the BFS. The dry mass is expected to be only 85/5.9: 14.4 tons. It will be 19.7 meters long. Based on the mass ratios calculated above, the SFS will be able to hold 187.2 tons of propellant. An SFS with no cargo and full propellant tanks will therefore mass 201.6 tons and have a deltaV of ln(14)*375*9.81: 9708m/s. The Vacuum-optimized Raptor engine is quite large, with a nozzle opening 2.4 meters wide. It is unlikely that more than one such engine can be fitted under the SFS. It will provide enough thrust for an initial Thrust-to-Weight ratio of 0.96, which must be compared to the current second-stage initial TWRs of 0.8-0.9. For retro-propulsive landing, we will not be able to fit, or even need, the sea-level version of the Raptors. Instead, we will use two of the existing Merlin-1D engines with 420kN of sea-level thrust, but possibly with a lower pressure rating as the thrust generated makes them too powerful for landing. The alternative is the SuperDraco engines with 67kN of thrust and 235s sea-level Isp. Rocket engines in the Raptor + 2x Merlin configuration would represent 13.2% of the overall dry mass, or 8.1% if the Raptor + 4x SuperDraco configuration is used instead. The Raptor engines are assumed to have a TWR of over 200, so their mass should be lower than 969kg. There are no numbers on the SuperDraco's mass, but it should be at most 50kg. These ratios seem not too outrageous when compared to the 7% engine-mass-to-dry-mass ratio in the BFR's original design. Merlin-1D engines. The SFS's mass is based on the 85 ton figure for the BFR's dry mass, but this is a cautious estimate with room given for development bloat and mass budget overruns. The BFR's design on paper gives a dry mass of 75 tons instead. Using the on-paper mass, the SFS could have a dry mass as little as 12.7 tons. The SFR's booster is the Falcon 9 Block 4. The booster will mass 22.2 tons when empty, and can hold 410.9 tons of propellant. This gives it a mass ratio of 19.5. The nine Merlin 1D engines have a sea-level Isp of 282s and an vacuum Isp of 311s. Because the booster stage does not spend a long time at sea level and performs most of the burn at high altitudes with negligible air pressure, we will use 300s as a low-ball estimate of the average Isp. The true average might be a few seconds higher. Taken all together, the SFR will mass 634.7 tons on the launchpad without any payload in the SFS's cargo bays. It stands 89.7 meters tall. We will now calculate how much cargo it can lift into Low Earth Orbit in expendable or reusable mode, and where else it can go. Performance To achieve a Low Earth Orbit, we will set the deltaV requirement as 9400m/s. In reality, it could be achieved with as little as 9200m/s, but we want decent safety margins. Expendable mode is the easy part. It assumes every bit of propellant is consumed and the SFR's stages left dry. Using a multi-stage deltaV calculator and setting the Falcon 9 Block 4's Isp to 300s and the SFS's Isp to 375s, we work out that the booster provides 1899m/s of deltaV and the SFS provides 7488m/s for a total of 9388m/s with a payload of 13.7 tons. Recoverable mode is harder to calculate. The propellants cannot be completely used up: some must be kept in reserve to perform a retro-propulsive landing burn. BFR landing. A landing burn by the SFS requires that about 300m/s of deltaV be held in reserve. This represents 1.65 tons of propellant with Merlin-1Ds or 2 tons of propellant with the SuperDracos. The Falcon 9 booster needs to retain 15% of its propellant reserve to make an ocean landing. This gives it a deltaV of 3910m/s, which is largely enough to cancel most of its forwards velocity and make a very soft landing. However, holding back 61.6 tons of propellant means it boosts the SFS by much less. In recoverable mode, the SFR's cargo capacity drops to 9 tons. If the SFS follows the paper designs more closely and achieves a dry mass of 12.7 tons, it will have cargo capacities of 16.7 tons in expendable mode and 12 tons in recoverable mode. The SFS could achieve a deltaV of 2500m/s after launching on top of a recoverable Falcon 9 booster and without any payload. This is not enough to reach the Moon, so the range of missions the SFR can take payloads on is limited to Low Earth Orbit. Smaller rockets might solve the problem of having to crane down cargo from the top of a tower. However, if it is refuelled in orbit, then the entire Solar System is available. It can deliver 50 tons to Low Lunar Orbit (5km/s mission deltaV). It can send 35 tons to the Mars Low Orbit (5.7km/s mission deltaV) or 21 tons to Mars's surface (6.7km/s mission deltaV). Refueling the SFS will take between 16 and 20 tanker launches. With 14.4 tons of dry mass and a propellant capacity of 187.2 tons, the SFS has a maximal deltaV of 9.7km/s, enough theoretically to put itself far above Jupiter or even Saturn. Conclusions The SFS is a limited vehicle. It is restricted to Low Earth Orbits and can deliver payloads of 9 tons, up to 12 tons, at most. It is far from the multi-purpose machines the BFR or ITS promised to be. However, it is enough to dominate the medium lift launch market, as it is fully recoverable. The re-use of existing Falcon 9 boosters and the smaller number of Raptor engines (one per rocket) will drastically slash the development costs compared to something like the BFR. The smaller payloads are easy to fill, meaning every launch is profitable. Multiple launches promises rapid turnover and a maximization of the return on investment on the craft. With re-fueling, the SFS in orbit can complete missions that require it to send decent payloads to the Moon and Mars. With minor improvements and operating in fleets of multiple vehicles, it can even match the payload capacity of the BFR to various destinations. What do you think?
  25. We have the runway and the launchpad, but what about a third place to launch your crafts? This could sprout a whole new set of parts, crafts, and vessel types, and open even more possibilities. Maybe a dock for all your sea operations? Or the helipad on the VAB as a separate place for all your VTOL crafts? Maybe even a garage to test your rovers and cars! What do you think it should be, and do you support the idea of a third one?
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