Starman4308

Literally the exact same logic could have been applied to the Mercury, Apollo, Gemini, Soyuz, Orion, Crew Dragon, and Starliner launch escape systems... and yet those vehicles had them. Why? Because launch is one of the highest-risk operations. In most other situations, you have time to diagnose and troubleshoot issues. During ascent to orbit, you sometimes have less than a second to react to problems that can arise from a very wide selection of machinery. Launch is the most important time to have a robust abort system; the probability of failure is (relatively) very high and the time permitted to troubleshoot is very low. Furthermore: let's assume the LES is basically a Crew Dragon placed near the tip of the Starship, possibly with extra SRMs if a speedy exit from the Starship is required. If a failure of the Starship happens in LEO, you just separate from the Starship and, at your leisure, make your reentry burn. If a failure happens during lunar injection or most of a Martian injection, you just wait until apogee and make a reentry burn. During EDL, you can just have the two vehicles reenter separately.

It should be entirely possible to build it on one consistent axis: Skycrane Decoupler Rover Decoupler and possible spacer Fairing Rocket It may take a bit of fiddling with the staging order, but I'm not sure what your issue is.

I'm reasonably certain that aerodynamic pressure has an effect on engine ignition chance. I was recently flying a Castor-based sounding rocket which got up to pretty tremendous aerodynamic pressures of nearly 200 kPa. My second stage failed to ignite multiple times until I learned to wait a few seconds first, until the aerodynamic pressure dropped below about 20 kPa. Two things occur to me here: 1) It would be nice if the cause of the failed ignition was shown as "Aerodynamic pressure too high!" instead of "Nominal". That would give players feedback on why their rocket failed. 2) While this is something more for the people writing the Test Flight configs, perhaps SRBs should have less penalty to ignition chance based on aerodynamic pressure?

You also get carbon monoxide at the very least, and there's quite possibly still some coking to solid carbon. To get pure CO2 exhaust, you need excess oxygen, and probably also relatively low flame temperatures (as high temperatures favor more mixed combustion products).

I'm assuming you mean "why LOR-LOR instead of EOR-LOR*". *LOR-LOR as in "rendezvous with the lander at the Moon, transfer crew, the lander separately lands, and rendezvous again in lunar orbit". EOR-LOR would be "rendezvous with the lander in LEO, go to the Moon, separate and perform the landing, etc". Both are "LOR" in the Apollo sense of using a separate lander. A big part of this is probably the use of cryogenic upper stages. Every hour your vessels spend in LEO performing rendezvous and docking is an hour that you are slowly bleeding out cryogenic propellants. Easier to just send each part off separately, and use storable* propellants on the purpose-built lunar vehicles for rendezvous and docking. *Or, at least, cryogenics in low- or zero-boiloff tanks.

Weren't there a bunch of amateur astronomers looking at the Mare Tranquiliatis that year? Can't reason why, but apparently they were, and "serenity" is closely related to "tranquility". I'm hoping for something for Kerbonauts to do on extraplanetary surfaces. It'd fit the theme and make me care more about manned landings... well, it will if/when that gets to RP-1 anyways.

The simple solution: once you're close to target altitude, run a PID loop using pitch or throttle to control vertical velocity, keeping it at zero. It's probably not the most efficient way to make a totally circular orbit, but it'll work.

Based on my recent experience attempting to upgrade from 1.2.2 RP-0 to RP-1, use 1.3.1 and follow this guide: https://github.com/KSP-RO/RP-0/wiki/RP-1-Installation A 1.4.5 RP-1 install might be possible, but you'd have to do an awful lot more work to get it functioning. Also, do not install "MechJeb and Engineer for All". First, RO does that for you already. Second, that config adds a 10,000,000-memory kOS disc to every command unit... and that plays havoc with pricing in a weird way that isn't immediately apparent*. *The price of that enormous kOS disc only occurs once you actually launch it. Your 1k-fund sounding rocket suddenly drains all your funds at launch, and then recovers for 200k funds on recovery.

I tend to try to aim my initial gravity turn for 45 degrees at 20 km altitude. You sort of get a feel for how to start the turn to achieve that; with high-thrust first stages, you may be starting your turn at 30 m/sec or less, whereas low-thrust rockets may see you turning at 60-80 m/sec. For low-thrust upper stages, especially long-burning engines like the RL-10, you'll often wind up with a fairly slow gravity turn, and then keeping your nose pitched up about 20-30 degrees above the horizon for several minutes. I know with my Titan* series of launchers, I don't dip the nose below 30 degrees until roughly 8 minutes into flight. *Only tangential relation to actual Titan rockets. The upper stage is a triple RL-10 burning for 470 seconds, the core sustainer stage a pair of hydrolox-variant LR-87s burning for 300 seconds, and has one to six H-1 based boosters burning for 150 seconds. Hydrolox stages have wonderful specific impulse, but the thrust tends to be poor, and since you're losing mass slowly (high Isp), TWR doesn't climb as fast as it does with kerolox/hypergols. Also, I have one rocket that I don't pitch over until at least 200 m/sec velocity is achieved.

Correction: it's about reducing cost. A small hit in extra upper stage mass may be worth it for lower development cost, especially since I'm pretty sure DCSS evolved from AJ-10 based stages. It doesn't matter if you can loft 500 kg more to GTO if your customers don't need that extra 500 kg... and the Delta III/IV never saw enough use to justify expensive development of an improved upper stage.

Most of that looks to me like an instrument ring, wiring, piping, etc. I somewhat suspect that ring around the LOX tank might be the structural element connecting the second stage to the interstage, and thus has to deal with a fair bit of force. Delta and Centaur came from different companies before they merged into ULA. Different companies, different design philosophies, etc. Common bulkheads for hydrolox stages aren't easy, either; the hydrogen can freeze the LOX, and the LOX can boil the hydrogen.

To my knowledge, what few console games support mods generally only support item-based mods, with no additional code. For KSP, that would basically mean parts packs and nothing else.... not even Module Manager. Those games that do have mods on consoles are generally also big-name titles like Skyrim, with huge audiences, for which the pain of validating mods for a console is worth it. KSP is not exactly a big fish. The console makers like their very secure sandbox, with no risk of Little Jimmy downloading a seedy mod containing a keylogger, the credit card info getting stolen, and Microsoft/Sony/Nintendo getting sued for it.

The scaffolding brought home to me for the first time just how massive the Hopper is. That thing is a monster.

As I understand, wheels are currently one of the bigger bugs in KSP, something about a Unity upgrade. I'm not sure if MechJeb or Kerbal Engineer Redux have been updated to the latest version of KSP, but they provide some additional useful information. Specific impulse has nothing to do with the Oberth Effect. Thrust-to-weight/thrust-to-mass ratio, on the other hand, does. If you're staging mid-burn, your TWR often drops, but that's because the next stage (usually) has less engine power, not because of specific impulse. In general, try to split delta-V evenly: get half the maneuver dV done before the node, and the other half after the node. For gravity turns, there's the Gravity Turn mod, or outright trial-and-error. Unfortunately, not many tips for you, unless you turn to the Dark Side and install Realism Overhaul. Unfortunately for me, it appears the GravityTurn mod copes poorly with Realism Overhaul, as GT uses engine throttling and a lot of real-world engines do not throttle. It also probably doesn't cope well with this:

So, two comments: First, FAR is good for realistic aerodynamics. Sadly, in KSP, this means coupling realistic aerodynamics to very unrealistic part masses. Your typical 1-seat cockpit masses more than an entire Cessna. That means high landing speeds and hilarious amounts of wing and thrust. Second, for rocketry, the three most important concepts are most likely going to be: The Tsiolkovsky Rocket Equation. Quickly stated, the better your specific impulse and full/empty mass ratio is, you more delta-V you get out of a stage. The Oberth Effect. Loosely stated: burns at high velocity gain or lose you more orbital energy, so many maneuvers are best performed quickly at periapsis... though engine mass hurts your total available delta-V (see above). Gravity turns. Basically, gradually turn into your orbital course soon after launch.

I'm not sure you did the math correctly... that, or you're using a mod that changes the Dawn thruster (which IIRC, Near Future Propulsion does). The Dawn has an Isp of 4200 sec, and a thrust of 2 kN. That works out to a xenon flow of 0.0486 kg/sec. Since the propellant is exiting at (4200s*9.8063 m/sec^2), you get a kinetic energy per second of about 41 MJ. Assuming the wiki-listed value of 8.74 E/sec is correct, that means about 4.7 MJ/EC... assuming the ion engine is 100% efficient, anyways. This conflicts horribly with several other calculations (including one of my own) that would suggest about 1-2 kJ/EC, but it's widely known that the ion engine is amazingly overpowered so that people actually use the thing.

Delta-V is, fundamentally, the amount by which you can affect your velocity via propulsive maneuvers. Delta-V is only one part of the story. Atmospheric drag. Non-ideal transfers and general Oberth Effect shenanigans. Gravity assists. Aerobraking. There's a lot more to the story behind a mission in KSP. One of the primary things to consider is the Oberth Effect. The simplest, albeit probably least useful statement of it: "the faster you are going, the more orbital energy prograde burns give you, and the more orbital energy retrograde burns shed for you." In practice, this means that getting a maneuver done in less time often saves delta-V... though adding extra engines on reduces your delta-V (since engines are evil hateful not-propellant mass).

First, you'd need Principia installed. Sun-synchronous and analogous orbits work because of equatorial bulges... something not modeled by stock KSP. Second, such orbits may not be possible even then. Ike would require precessing by one degree every three minutes, and Gilly would require precessing by a degree every 15.5 minutes. That would require a very, very strong equatorial bulge; Earth SSO orbits have to precess less than one degree per day. Third, if the goal is to maintain near-constant communication with Kerbin, there are simpler methods of achieving that. I think he's talking about orbits that precess to maintain a constant orientation w.r.t. the parent body (Eve, Duna), much like how real-world sun-synchronous orbits precess to maintain a constant orientation w.r.t. the Sun.

If you look at the article I linked, that $300,000 figure I quoted includes shaping. My guess is that Tour de France bikes cost $20k due to the complex shapes involved, and possibly because the manufacturer can charge $20k. Meanwhile, a Falcon 9 fairing is a relatively simple shape, likely meaning easier manufacturing... and I'm not even sure it's carbon fiber, it might be some other type of composite. EDIT: Added three extra zeros initiallly.

That is indeed the mighty Rocketdyne F1 engine. What you see wrapping around the middle of the nozzle is the exhaust manifold for the gas generator. Specifically, the F1 is a gas generator open-cycle engine, where some of the kerosene and LOX is diverted to power the turbopumps. The fuel-rich exhaust from the gas generator was then routed into the nozzle mid-way; the relatively cool generator exhaust gases would keep the nozzle extension cool, rather than requiring active regenerative cooling. The exhaust gases themselves are the dark band underneath the nozzle. Also, I'm not sure how much aerospace grade 304 steel costs, but SpaceX has in the past been willing to use non-aerospace-grade materials, something that may have contributed to the failure of CRS-7.

Not necessarily true. There are two effects going on that partially work against that. First, as you increase altitude, a fixed scan angle will cover a wider strip of terrain. Second, With SCANSat, the primary mod implementing any sort of terrain scanning, there's a mechanic where your scan angle is narrowed if you're at less than the optimal altitude. A similar effect goes on for "look down and take screenshots"-type mapping: as you go up, you see more of the planet at once. The actual optimal altitude varies on a lot of factors: scan angle, whether the scan angle is fixed with altitude, planet radius, planet mass (and thus orbital speed at X altitude), and sidereal rotational period. With slowly rotating Venus, for example, the optimal is "high as you can get without compromising scan angle". With almost any orbit and scan angle, you're spending around a hundred days twiddling your thumbs waiting for Venus to rotate under you. With a very small body such as Gilly, however, a high orbit might mean it's rotating under you plenty fast; the limiting factor is how fast you can go from pole to pole.

Based on a 2-ton estimate for fairing mass, and a cost of carbon fiber from this article, I estimate the bulk material of the fairing to be roughly $300,000. What I've heard is that each fairing costs $5 million a pop. Wherever the remaining $4.7 million is coming from, it's not from the bulk material, but rather in things like: Ensuring no contaminants will get onto valuable payloads Telemetry sensors Fairing separation machinery Testing fairing separation machinery to death, so that $500 million satellites don't fail because of a fairing issue. As such, I strongly doubt they would save any money whatsoever by making a second, steel-based fairing manufacturing line.

Regenerative cooling is effectively "free" from a mass standpoint (other than the plumbing involved). The cooling material is propellant that's going to the combustion chamber anyways, and is therefore wonderful propellant mass, rather than hateful not-propellant mass. Also, it's basically free heat, letting you ramp up combustion chamber temperature a bit without needing additional combustion. For a hydrolox engine, that's definitely a neat perk; the preferred exhaust gas is unburned hydrogen, so if you gain additional heat from regenerative cooling, you can run a little bit more fuel-rich while maintaining chamber temperature.

Originally, likely just MechJeb for dV and some maneuver planning. After making a large Mun space station, and I think launching something towards Duna, I decided "This isn't hard enough", so I installed Realism Overhaul. I backtracked a bit, and went for 6.4x/Real Fuels. Haven't really looked back to stock-scale systems. They just feel too puny to me now.

Remember when the Space Shuttle was going to fly a gazillion times a year, and come in on time and under budget, and the US government was mandating that satellites be launched on the Shuttle? Remember when the Falcon Heavy was going to be ready to fly in 2011? We've seen this dog and pony show before. Musk's timelines would be highly optimistic even without unforeseen events, like, say, a new booster design failing. Like they often do, something that would cause a significant interruption in schedule as the cause of failure is investigated, likely requiring redesign, causing the schedule to slip even further. A 2023 manned launch mandates these things: No new legislation to say "hey, we actually need safety standards now that NASA and Roscosmos are not the sole providers of manned launch services". No unforeseen delays. Starlink delivers on time, and customers actually buy their services. No unforeseen snags in re-use of the Superheavy and Starship. Nobody complains about the huge number of Starlink satellites, putting political pressure on Starlink/SpaceX. Venture capital and loan funding comes in on time in sufficient amounts. I put less than 1% odds on things working out this well for SpaceX. EDIT: Whoops, forgot commercial crew delivery isn't there yet.