Armchair Rocket Scientist

I'm guessing the reason is to make the capsule aerodynamically stable during an abort.

What you're describing is often called a "Torch ship." They are not possible in KSP unless you're using overpowered mods (or Infinite Fuel), and in the real world are impossible with chemical rockets or even NTRs.

A thousand times no. Engineers are apparently already completely overpowered, and making ISRU conversion outright require Kerbals on-vessel is ludicrous.

If I'm not mistaken the SuperDracos use the same fuel that would be used for orbital manuevering on a nominal mission (which naturally isn't going to be used if you abort).

This is the best "complaint thread" I've seen so far.

Well, this vehicle would hopefully be capable of launching a variety of payloads, including manned spacecraft. Putting something manned in the cargo bay of a normally unmanned orbiter would be a death trap, but as the space shuttle has proven launching crew and cargo on the same vehicle means you're not using your full capability on most missions. So, you need separate manned and cargo upper stages, somewhat like this. But having a manned vehicle sitting on the side of your stack is a death-trap anyway, as demonstrated again by the Space Shuttle. So you basically have to have an inline upper stage, as Magnemoe suggests: The main problem I see with this is: where do you put the payload? In a cargo bay? (If so, the fully-fueled second stage has to be capable of acting as an LES in the event of a lower-stage failure, which will require a stronger structure and HUGE engines). If it's on the front, then once the payload is jettisoned the nose of the vehicle would probably be pretty much flat, which isn't that good for reentry. Perhaps a side-mounted inflatable heat shield with a lifting body shape? Like this? It might work, but it still has a lot of the problems of a purely side-mounted upper stage, including LES capability and the heat shield being potentially exposed to falling debris from the fuel tank. That might put a lot of stress on the wing structure, but using the second stage fuel tank as a hardpoint might work better, as long as the payload fairing / capsule is located safely above the tops of the boosters. From what I know, "mostly to orbit" isn't a great situation to reenter from. If you look at a chart of the Shuttle's abort possibilities here,, there are big "black zones" late in the mission. With a lifting body the g-loads might be reducable to safe levels, but flyback would take an absurd amount of fuel. A better option would probably be landing on another continent, possibly with some "boost-forward," similar to the Shuttle's TransAtlantic Abort Mode, or even an Abort Once Around. This option would be most effective when launching beyond LEO. Also, it looks like inflatable heat shields are pretty cool technology: http://www.researchgate.net/publication/238029355_The_ParaShield_entry_vehicle_concept_-_Basic_theory_and_flight_test_development

Yep. Good luck running a jet at 30 km. Really, Kerbin's scale height is pretty small. According to the formula I found on Wikipedia, assuming the same atmospheric temperature as Earth, its atmosphere would have to have a mean molecular weight of 42.4 g/mol. Assuming an O2 and CO2 mixture, the atmosphere would have to be 13% oxygen and 87% CO2. Assuming an Earthlike 21% oxygen, the remainder would need to be heavier than pure CO2, meaning Kerbin needs to have significant amounts of a gas heavier than CO2. Unfortunately there aren't many gases like that: apart from weird organic compounds that won't be stable over geologic time, the only good candidates are Sulfur Dioxide, Krypton, and... wait a second... Xenon. Huh. Does this mean we could use an ISRU converter to extract xenon from Kerbin's atmosphere? tl;dr reason #468 why I like RSS.

Hmm... In real life, something like this would generally be considered an extended mission, which would be a separate contract. Is there anything preventing you from, once you realize you can perform an extended mission on Minmus, going back to KSC and accepting the "explore Minmus" contract?

All righty. CPU: From what I've heard KSP is heavily CPU-dependent and doesn't get much benefit from multiple cores. Is it best to go for the overclocking CPU even if the extra cost means, say, going from a 4GB to a 3GB video card? Also, if I plan on overclocking should I add additional CPU cooling beyond the built-in fan? PSU: Regarding wattage estimations; what I've been told is that the power supply should be rated for at least the sum of the thermal design power of every other component. Is there a recommended safety factor to add to that? Also, what do the "bronze, silver, gold, platinum" ratings mean? Are they essentially reliability grades, comparable to a car having a 5-star crash test safety rating? Thanks for your help!

So, there are currently attempts to make the first stages of launch vehicles reusable. I know reusability on the Falcon 9's second stage has been shelved in favor of development of the MCT, and nobody else is even considering it. But let's say I was given the task of designing a fully reusable (aside from a few minor components like payload fairings) launcher. We'll assume the design is a multi-stage rocket, capable of lifting at least 10 metric tons into LEO - enough for a manned spacecraft, a space station resupply, and some GSO, Molniya, or other high-energy satellite launches. The basic design will be 2STO - the second stage of a 3STO design would have a very high burnout velocity, leaving it on a very difficult reentry trajectory. Strap-on boosters may be used to boost payload capacity as high as 20 tons to LEO. The upper stage will only deliver its payload to trajectories of similar energy to GTO - this is because a reusable stage will naturally have a poor mass ratio making it inneficient to send payloads directly to high-energy orbits, and you're throwing away a reusable vehicle if you put out on an Earth escape trajectory. Some type of "kick stage" will be used for high-energy orbits; this may be a cheap hypergolic or solid-fueled stage, or a pricier cryogenic stage where maximum performance is required. Choice of fuels: First of all, hypergolics shouldn't be fueling the main engines of a launch vehicle, because they're toxic, corrosive, and otherwise a pain in the ass to deal with. Kerosene's low specific impulse makes it decidedly suboptimal for upper stages. Hydrolox is very efficient, but a bad choice for lower stages because hydrolox engines have a poor TWR and atmospheric ISP. For upper stages, it may not be the best option either due to boiloff. Methane may offer the best of both worlds, offering reasonable density and insulation requirements (boosting mass ratio compared to hydrolox) as well as decent specific impulse and TWR. In addition, it reduces residue in engines compared to kerosene, making reuse easier, and as a gaseous fuel any leaks or spills are inherently less hazardous. Therefore it will be assumed that both stages will use metholox engines. Stage Recovery: So, I consider there to be four main ways of landing a stage. 1: parachutes (highest vertical speed on touchdown, very poor accuracy, but easy redundancy by using a cluster of parachutes. 2: parafoils (low vertical speed, some horizontal speed on touchdown. Slight cross-range capability, hopefully allowing a runway to be targeted. Any long skinny object like a rocket would have to land on its side, making landing gear design and parafoil suspension a bit interesting. Harder to make redundant.) 3: wings (effectively zero vertical speed on landing, but very high horizontal speed. Wings are very heavy and add a lot of drag during ascent, but offer excellent cross-range capability). 4: propulsive landing (effectively zero vertical speed and horizontal on landing. Weight penalty is that of reserve fuel, not of engines, and is fairly small. In theory adds little mechanical complexity, but as the Falcon 9 has shown additional control systems may need to be added). There are also three main places to land a stage: A: On land (this is the best option for an upper stages, but for lower stages this requires lots of dV for a turnaround manuever) B: In the ocean (requires the least dV and landing precision, but saltwater exposure vastly increases maintenance costs, especially for liquid-fueled stages). C: On a floating platform in the ocean (less dV for lower stages. Precision requirements similar to land, but platform drift and wave action make life much harder. Use of a semi-submersible platform instead of a barge like SpaceX has could make things easier). This gives us twelve options. We can immediately eliminate parachute landing for liquid fueled stages, because the touchdown speeds are unsurvivable for a high mass-ratio stage. An SRB should be okay as long as it lands in the ocean. Winged landing in the ocean is a near-guaranteed crash, and winged landing on a floating platform is unfeasible due to the runway length required. We'll also eliminate water landings of any sort for liquid-fueled stages because they make refurbishment a massive pain. Finally, a winged upper stage would interfere with the vehicle's aerodynamic stability on launch, and is therefore undesirable. This leaves us with: For upper stage: parafoil or propulsive landing on land. For lower stage: propulsive or parafoil landing on land (with boostback), winged landing on land (with flyback), or propulsive or parafoil landing on a floating platform. For boosters: same as lower stage if liquid-fueled. If solid-fueled, glideback and winged touchdown on land, or parachute landing in the ocean. Now, the velocity of the lower stage and boosters will be kept low enough for a tailfirst reentry, but the second stage will be coming back from orbit, and can't just reenter on its engines. So, it needs a heat shield. With a monolithic heat shield, reentry must be nose-first, but what about with inflatables? Can an inflatable heat shield be designed that will cover the engines, and then be deflated in flight to allow for propulsive landing? For a nose-first reentry, how do you turn the stage around for a propulsive landing? Or is it better to just have special landing thrusters for an "upside-down touchdown?" For a launch to LEO, the upper stage must have a minimum orbital operation time of 12 hours (enough for the launch site to come below the orbital plane), but 24 hours is preferable to allow for multiple landing opportunities. For a launch to GTO, the stage must perform a small apogee manuever, aerobrake from GTO into LEO 10.5 hours after the initial GTO insertion, boost its periapse, and wait several more hours before deorbiting, again requiring at least 24 hours of on-orbit operations. Is it best to stay simple and use batteries, or are solar panels worth the weight savings? For that matter, since methane will have a little boiloff, what about siphoning off the gases to power a fuel cell or internal combustion engine (Apparently ULA's Vulcan is supposed to power its upper stage this way). Are there any other ideas you guys have?

What are you planning to do with this compuer? Please be as specfic as possible. Play KSP (no duh) with a hardcore realistic install using a bunch of mods. Most likely Windows 7/8, but if I can't fit within the 3.5GB memory limit I may have a Linux install for 64 bit KSP. I also plan on using this computer for Solidworks and other CAD stuff, as well as X-Plane 10 and Space Engine. What is your budget? US$1000 Does this include a copy of Windows? Does this include peripherals (a keyboard, monitor, mouse, speakers, etc.)? I already have a mouse and speakers, but I will need to purchase a keyboard (will be selected at a storefront based on feel) and a monitor (1080p). Are you from the United States or a different country? Are you ordering from your own country or from across borders? Wherever you may be from, does the store that you are planning to order from have a website? It's okay if it isn't in English, we can manage. If you are from the United States, do you live nearby a Microcenter? I'm in the US and have access to a Microcenter. The sources will be sites like NewEgg and Amazon, which are in English. Do you have any specific requests with the build? Do you plan on overclocking? If yes, do you have a specific goal in mind? Only if necessary to get good performance. Would you prefer the build to be particularly small? A mid-tower case is fine. Would you prefer the build to be particularly quiet? Not particularly quiet, but it shouldn't sound like an industrial box fan or anythhing. In general, do you prefer this to be a computer that you can spend money on now and let it rest, or a box built for continuous upgrading? I do want upgrade capability eventually, but would like to get 2-3 years of use before I starting to upgrade components. Do you ever plan on utilizing NVIDIA's SLI or AMD's CrossfireX technologies? These features, with a compatible motherboard, allow a user to link multiple identical graphic cards together for added performance. In real world terms, this lets you buy a second identical graphics card down the line as a relatively cheap and easy way to gain a fairly large boost in performance. However, this requires buying a SLI/CFX compatible motherboard and PSU now, which may result in slightly higher initial cost. No. (OPTIONAL) Have you already looked at or considered any parts (it's okay if you haven't)? If so, please list your top 1-2 choices for each category. If you've only picked out a few of the below, just list those. CPU: Based on my research it sounds like an intel i5 quad-core is almost certainly the best in this price range Motherboard: Whatever's compatible with the other components. RAM: 16 GB, (2x8 GB). I've heard good things about this one. Graphics Card: Not sure what brand to buy, but I'd like to have 2-4 GB of VRAM, since that's recommended for X-Plane. Does more VRAM also help KSP when you're using stuff like RSS and EVE that makes the game a bit more graphics-intensive? Power Supply: Whatever's compatible with the other components. Case: Whatever's compatible with the other components. Hard Drive: A 1 TB, 3.5" HDD. Solid State Drive (optional): At least 120 GB. Will this provide space for the OS, all the games and programs mentioned, and a couple other things like web browsers without becoming overfilled? Mouse (if necessary): Already have one. Keyboard (if necessary): As mentioned, I'll probably be getting a fairly cheap keyboard from a MicroCenter, Best Buy, or similar store. Monitor (if necessary): A 1080p monitor, probably 20-24".

Wouldn't the flame first burn a hole in the insulation, then heat tank wall until it ruptures, spraying fuel into the LV-N's exhaust stream? (or even worse, spraying oxidizer or monoprop into the exhaust stream, creating even more heating?)

Since the isps for liquid engines are now comparable to kerolox IIRC, why not just reduce the LV-N's specific impulse to around 600 s, to simulate a nuclear-thermal rocket using hydrocarbons as fuel?

That's hilarious. I guess nobody ever uses staging view for things like rendezvous and landing. It's not like being able to see the ground or the other ship is useful for something like that, right?

People saying "Just add a whole bunch of radiators" may be my new pet peeve. Not all of us are running the game on a supercomputer; if your computer can handle 200 parts without becoming a slideshow, having to use fifty of them on radiators just to make two engines operate at full throttle is utterly ridiculous, and I would consider it game-breaking.

This would be incredibly useful, AND realistic. For example, through the end of the Apollo program astronauts were almost always originally trained as pilots, but were also given some science and repair training. It's ridiculous that right now a Kerbal can't simultaneously know how to drive and change a tire.

If I'm reading his post right, he does have multiple sets of control surfaces, and wants to have one set be flaps while the other is steering on one mode, but then be able to use both sets for steering when hard maneuvering is required.

Meh, if he's old enough to understand the joke he's old enough to hear it.

This talk makes me very glad that I'm going to be playing with RealFuels and x10 RSS configs.

Actually, you can survive vacuum exposure for over a minute, and remain conscious for around 10 seconds, assuming you don't try to hold your breath - if you do, the pressure differential will almost certainly cause fatal lung trauma - fortunately an astronaut would probably be trained to empty his/her lungs in the event of a decompression. This means that if a Kerbal removed his/her helmet, he/she would have about 10 seconds to put it back on (although it would take time for the suit to repressurize, meaning loss of consciousness is inevitable) and another Kerbal would have a window of 30-60 seconds. This is assuming kerbals have mammal-like metabolism; if they have a slower metabolic rate, they might survive hypoxia for longer periods. Source: http://www.geoffreylandis.com/vacuum.html Anyway, it seems like a silly thing to add to gameplay. At best, only give Kerbals the option to remove their helmets on Kerbin with pressure over 0.50 atm.

This is a nice idea. However, in Career Mode I also think that more information should become available as the Astronaut Complex is upgraded (simulating improvements in EVA suit technology).

This is probably one of those "1.1" updates, but I'd recommend implementing it by means of a "randomize" button in the crew selection interface of the VAB/SPH. When pressed, it could randomly assign available kerbals to each seat in a crewed module. (doing this one module at a time means that you can, say, manually assign crew to the MK3 cockpit on your spaceplane, randomly fill the Hitchiker in the Cargo Bay, and leave the science lab you're launching empty). The button would ordinarily select crew regardless of role. However, if the vessel currently has no Kerbal of a certain role assigned, that role would take priority (e.g. if Jeb and Bill are in your MK2 plane's cockpit, the first Kerbal assigned to the passenger cabin will be a scientist if one is available. In addition, by right-clicking the randomize button, you could override this and force the game to assign crew of a certain role. Finally, using shift-click or alt-click, you could tell the game to randomly fill the remaining seats of a partially filled module, instead of the default which is booting any already-assigned crew out of the part and assigning new ones. Possibly the right-click menu could also allow you to tell the game to prioritize high or low experience.

Honestly that isn't bad a sin. In my experience, usually when a failure happens the command module can detach safely with just an upper stage because KSP doesn't simulate stuff like exploding SRBs flinging showers of burning propellant that melts parachutes. Plus, all rocket engines have lower TWRs in KSP than in reality, so an LES ends up being very heavy.

OPM is compatible with Real Solar System, right? As soon as 1.0 comes out I'd like to build a "realistic x10" config (little things like giving everything realistic densities, making gas giant moons not excessively large compared to their parents).

Anyone want to calculate the ISP of baking soda and vinegar? I'm going to guess it's in the single digits. When you want a "safe" rocket engine, you use what is called a cold gas thruster: basically a bottle of compressed nitrogen or helium attached to a nozzle. IIRC these can get ISPs over 100. Even then, to get any payload into a suborbital space trajectory, you generally need something like APCP or a hybrid rocket. Baking soda and vinegar are on the same level of energy as soda and Mentos; at BEST, you get a vehicle that can propel itself off the ground for a few seconds.