wumpus

Stopping to refuel for an refueling station orbiting Minmus shouldn't take much more than 200 m/s delta-v (and should be doing the hard part of that empty). The big issue is figuring out the launch windows: you need to plot your course 0~50 days in advance to get the right angle (while avoiding the Mun) to get both the oberth effect (from Kerbin) and keep (nearly) all your delta-v out to Minmus. It looks like a pain. If you can't get that information easily, than it is role-playing to build a station on Minmus assuming you had it. Since the directions of launches are pretty straightforwards (toward or away from Kerbol), you might be able to approximate it close enough to make it worthwhile (although you will have to babysit it while avoiding Mun). Ask me again how this works when I get around to setting up a Minmus base (I'm bogged down enough in career mode grind so that it will be awhile), I wouldn't be at all surprised if I just blasted away from Minmus with minimal gains myself.

Don't touch that throttle! As long as you are pointed in the right direction (a big if) and you aren't on Eve, you are rather unlikely to exceed your terminal velocity. You might want to throttle down if you just can't turn the beast (unlikely with a takeoff TWR of 1.5), but it will only make your ascent less efficient (due to gravity losses). Remember: TWR of 1.5 means wasting 66% on gravity, 1.3 means 77% lost to gravity. Note building a rocket with much higher TWR runs into all sorts of different problems (control issues, high trust engines are heavier giving more dry mass, instability issues are amplified) so getting too close to 2.0 isn't the answer either. The point is that if you already built your rocket with a certain amount of thrust, you shouldn't lower it at *all* for "efficiency" issues, but with higher thrust (these issues become obvious around 1.7 and beyond) you might have to lower your thrust if you want any kind of pitchover (don't count on *ever* doing a normal gravity turn with a high thrust rocket). And of course, on an airless moon (or Moho), there is zero reason to limit TWR (as long as it doesn't cut into delta-v). Just pop up, turn as sideways as you dare (unless on Tylo. Then you are stuck with a proper gravity turn) and hit full thrust. Limiting them on the way down is often done for an more controlled (and often more efficient) landing.

I'm guessing that a huge part of this is lack of computing resources. I'd assume that a real kerbal space program (run similar to NASA) would simply build the first outpost at Minmus, then when using that for refueling, would schedule a de-orbit burn to be in the right place for a exit burn while at periapsis of Kerbin (leaving Minmus when the angle of the orbit lines up with the Huhmann transfer you want is obvious. Getting the orbital size right so you will be around Kerbin at the exact right time is not, and may be optional: note try to avoid Mun's sphere of influence during the wait.

The question is landing without a heatshield, by means of firing a retrorocket. The problem is that such a descent would be worse than a (semi-efficient) Tylo decent (scaled to our solar system, anyway), and vastly worse than an Earth ascent (and the required mass of boosters). Step one would be a pure sideways burn, the reverse of which what if #58 explained (painfully close to an Earth descent, but with neither gravity nor aero (including non-vac Isp) losses. You then pick an acceptable speed downward (lets say 500mph, just because the direction this thread has taken. And also because it is close enough to what [commercial] jets fly at that we can be confidant it doesn't require a heat shield. Assuming we start at 50 miles up (within the Karman line, but still a thin atmosphere) we will then have to burn a constant 1g thrust for 6 minutes. To explain all the issues to a non-Kerbalnaut requires first explaining everything what if #58 did, determining the size of the rocket for the final descent burn (really big), and then trying to imagine the size of the rocket that could do such a feat. If you are lucky, an Apollo booster (the part that took them to orbit) could do the slowdown (obviously) and the command module* could do the 6 minute 1g burn (you might have to soup up the engines, there really isn't any reason for that much thrust in the command module). You could then finish the whole article with a simple comparison about bringing a heat shield to return to Earth or bringing an Apollo rocket. * I think the command module might have done some of the orbital burn. This wouldn't be needed due to the extra delta-v around due to the lack of any gravity losses. PS. In the US in the 1970s, students were exclusively taught the metric system in elementary school (at least in Baltimore County, Maryland). President Carter (a nuclear engineer himself) had made the biggest push for metric since President Jefferson (back when the metric system was new). The most important thing I learned in high school chemistry was something my teacher called the "factor label method", which was how to convert back and forth between units. This is critical since nearly all American engineers and similar who have to calculate with imperial measurements convert them to metric before calculation and then convert them back for labels/purchases/whatever (might not be needed for trivial calculations, but it is nearly always the fallback when you have to change units more than once). The "factor label method" would *still* be critical (even in the metric only world) as it allows you to deal with multiple units (like converting distance to area, and thrust vs. mass) easily. I was shocked how much trouble this gave other engineering students while I simply did my basic chemistry approach and got the right answer. PPS. Is that really where "points" come from, for font size? If I set things for metric do my word processors show fonts in mm?

Yes, I just don't remember thinking it came down that fast (maybe the plume was much longer and that is all I saw). The main reason I brought it up was I didn't think the rocket hit all that hard, there was a hole, and there was this extremely hot fire nearby.

Yet another idea trying to rescue a broken concept without looking at how it changes the big picture. If you have a nuclear powered spaceplane, why in the world would you burn hydrogen while still in the atmosphere? You can raise the temperature of intake air as high as you please with just nuclear, your Isp is effectively infinite (not by the official definition which only looks at exaust velocity, but more due to the fact that difference between wet and dry weight is theoretically defined by e=mc**2). Once you leave the atmosphere, there is no reason to take along any oxygen, as the Isp of a nuclear rocket pretty much needs hydrogen to get anywhere near 800. There is no reason to drag along *anything* that looks like a SABRE engine. It not only would be dead weight, the fuel would *also* be dead weight. It would be a disaster to bring such a thing along. This is pretty much why the thread has devolved into yet another "what if the skylon (an excuse to use a SABRE) had a non-SABRE engine?" thread.

I can only assume that either the exec had no intention on sticking around and was already soured on ULA (an easy thing to do, but he pretty much ended his employability elsewhere as well). The flip side of things is "can space-x compete with ULA"? On the surface, it seems obvious: space-x is vastly cheaper and both do roughly the same thing. The big difference is that space-x is a startup doing its own thing, while ULA is basically the space arm of the military-industrial complex. Googling "ULA SLS NASA" didn't show much, but ULA is apparently "delivering an upper stage [of the SLS] to Boeing [nice to supply an owner with some more business]". Since this is a relatively large chunk of the NASA budget and unlikely for any of it to go to space-x (well, the various missions may make more sense on a falcon [heavy] but the pork will keep going to politically favored contractors like ULA). As I mentioned in an old thread about the "Death of ULA", the idea of the "space arm of the military industrial complex" going away would be a massive change in US national politics. And a massive change that really doesn't have anyone (other than Musk, who can't get state assemblies to let him sell cars) pushing it. ULA doesn't have to be competitive. They may have to fake it while letting friends in the Capitol building and Pentagon subsidize them, but they don't have to really compete at the things space-x does well (and they are admittedly good at the things space-x does poorly, like launch on time). [PS. I'm seeing some quotes as "you don't have permission to see this". Is this a bug in the new forum software, or was this scrubbed by moderators and merely has the wrong message (it doesn't look like it is coming from an external server, although that is possible).]

Best guess, turn slowly (try to keep the directional heading on the low edge of the prograde setting. Keep gently turning the rocket over until right before it flips over and explodes, then stop. Hopefully the rocket will have some sort of workable gravity turn before going supersonic (at which point you lose control and it tends to just go straight). Going at about a 45 degree turn *through the atmosphere* is important. By the time you get out of the atmosphere, you should be tilted nearly 90 degrees sideways (following prograde is more efficient, but it will likely put you "efficiently" into a higher orbit. Eat the steering losses to get the orbit you want). Sure. As long as you aren't getting those heating indicators (little temperature bars on various parts) turning reddish on you, it is just a graphics effect. If you somehow manage a low-angle "turn 45 degrees before 10km" that I suggested would make sense for such a rocket (and have TWR between 1.8 and 2.0 to take full advantage of it) you might have to worry about your rocket exploding due to heating. Otherwise heating should only be a danger if your engines (and flames) are near fuel tanks.

I would be rather impressed if they knew (and had reasonable confidence in) knowing what actually went wrong. It seems the machine was coming down out of spec (known in advance), and couldn't handle the landing. Judging from the landing video (real time) and the hole in the barge, I can only assume that they burned too little/too late on the landing burn (there was still a visible plume when it hit, so presumably it still had fuel and thrust left in the tank). Note that I'm still assuming the falcon came down hard enough to punch the hole, from memory of the livestream it might have done such only because the rocket had melted/weakened the steel underneath (with presumably 3 times the power as usual). Basically, you have a lot of tolerances the didn't stack up right and weren't expected to stack up right (assuming the rocket was out of spec for amount of fuel for its velocity). Basically it comes down to two things, plus a few external conditions. The rocket's "altimeter" vs. *exactly* how high off sea level it was (same sensors determine velocity). The rocket's thrust vs. precisely needed/requested thrust (note that if there is an error above, then the requested trust won't quite be right. Also expect this to be an iterative process (nearly all control circuits rely on feedback) the falcon may not have time for on this landing. The external conditions would be how far the rocket and barge may have floated off course (due to wind/currents), requiring any more additional fuel isn't going to help things. Space-x may have been counting on the booster to slow down even more in the atmosphere. Since it weighed less than the usual booster, it certainly should have slowed down more, but they didn't have the data until now. What I saw on the livestream was a booster coming down and the livestream cutting out. It wasn't falling terribly fast (considering it was probably supersonic a few of seconds earlier*). I'm guessing it came down to a few milliseconds off on the landing burn and the plume melted a pilot hole in the deck. The falcon just isn't going to land boosters after launching GTO vehicles. * 4g of deceleration should go from mach 1 to 0 in under 10 seconds. With 3 engines running, the throttle range should be something like 3.5g to 7.5g (assuming minimum thrust on one engine gives a TWR=1.5 (we know it is >1) and subtracting gravity).

Probably. What is the average height and how does it compare to the cross sectional area of the base? It all comes down to cross sectional area/mass. If you have a ton of small side boosters, then the average height isn't much. If you have a bunch of side boosters that are at least 1/2 as tall as the VAB, then you still have a tall rocket. Assuming a tall rocket, your best [aero considertaions only] bet is to go horizontal immediately (I'm guessing under 45 degrees before 10km). In reality, wrangling such a beast just isn't happening (I'm guessing you will hit 45 degrees no earlier than 30km). Don't forget that while you can ignore aero losses with your tall rocket, you can't ignore aero heating. Don't blow the thing up. If you build something like Wackjob's "rocket cages", you might manage to tilt the thing sideways and launch at an angle (this will require a ton of launch clamps, and a miracle to miss them all during the launch). My guess is this won't work at all and you will be stuck with aerodynamically inefficient launches (use a lot of AV-T1 winglets). Launching at an angle works great with SRBs in early missions (and fairly hefty TWRs).

Is this still true? I was under the impression that flying at terminal velocity was an artifact of the <1.0 aero model (certainly related bit where you wanted a TWR=2.0 at all altitudes is not). I had to check the date to make sure I wasn't reading a necro thread. While many players may have had fun learning on stock KSP, I don't think the "more boosters" approach is an option with KSP 1.0.5 and beyond. Rockets are fickle, flimsy, and like to flip over. You want rockets with the right TWR and the right delta-v, and you either need to calculate it yourself (an annoying physics homework problem) or let KER do it for you. I'd recommend KER.

You also might want to look at the Space Shuttle procurement. That whole fiasco of budgeting was done entirely before political correctness (and the rise of young earth creationism and other superstitions being taught as "science"). It is simply how NASA (and the US government in general and the military industrial complex in particular) works.

Barges are pretty cheap. Falcon9 landing practice costs $60M. Slapping a few inches of steel over the hole they just put in "Of Course I Still Love You" won't sound cheap, but it won't be visible in the $60M launch cost of CRS-8. As far as I know, they've already retired one barge. It doesn't seem to be a concern to them.

Last I heard (20-30 years ago), somebody did harness "big bang radiation - cosmic background radiation - universal 3K energy", but could only move the nanotech in one direction, not both. Figuring out how to make a repeatable engine sounds like a massive break in conventional physics. The other catch is that the energy involved is immensely small. It would take vast collectors (in volume) to harness such things, solar cells or even sails would beat it by vast orders of magnitude (for going to Mars). Expected uses are nanotech (just to make [re]powering the silly things vastly more convenient) or huge structures that travel between the stars (that otherwise wouldn't be powered by more reasonable things like solar or nuclear energy).

Of course, Space-x needs about 10% of the fuel for the return trip, which corresponds to shockingly close to 10% of the launch weight (of just the booster). This might be a bit less than the mass of the parachute needed, but I suspect the "final design" before space-x gave up the parachutes involved a slightly lower ratio of parachute weight, and a higher speed. The parachute would be then cut (similar to a Mars rover) somewhat before landing. It would then do an extremely short burn to land. Problems: No land option in Florida (you would have to point the rocket directly over inhabited land, and let the parachute drift toward Cape Canaveral. Might be possible to drift toward the Mexican coast from Vandenburg). No precision: While the retrorocket option might give a fairly precise control in a couple of dimensions (vertical and the horizontal component of prograde), it won't really give any sort of correction you need to hit a barge. Even worse timing: One of the reasons I'm less concerned about the size of the parachute is that it will likely be dumped before the landing burn. Doing the landing burn while on a parachute would be rather similar to the three engine burn (way to high TWR) that poked a hole in "Of Course I Still Love You". Dropping the parachute early enough to counteract this (and keep the thing from falling over) might spoil all the benefits of the parachute. As far as I know, for all the obvious problems, space-x went ahead and tried to recover the Falcon (1) via parachute. I can only imagine what the "even worse timing" problems were: imagine a falcon 9 booster trying to land with all 9 engines firing (roughly the TWR of a falcon 1 with its single Merlin firing). I suspect that while doing the detailed design, it became obvious that they weren't going to recover until the Falcon 9 came along and could dial down the TWR of the landing boost to a dull roar. I still think they kept trying to recover the Falcon 1 with parachutes anyway.

Is anybody here a skydiver? Do you know the conditions of Florida? Considering just how flat the place is, I'd expect that wind is a huge consideration for using a parachute in Florida. Reducing the vertical speed is straightforward engineering. The problem is that as you reduce your vertical speed, you increase your horizontal speed (pretty much up to wind speed). I'm guessing nothing will remain vertical with a parachute (hints for KSP play: landing big rockets is easiest if you land them horizontally in the ocean. Kerbin's oceans are salt free). Of course, while it seems easier to get FAA approval for a parachute landing over land, it pretty much means re-entry and deploying chutes over populated areas. Don't think that *ever* will happen, which means the needed precision has to be done over water (I'm sure you could hit the right sized parking lot, assuming you were willing to go asymmetrical and land horizontal. You just will never get the permit).

The catch is that oxygen isn't going to stick around [at the right partial pressure] on a planet with much less than 1g gravity (assuming that nitrogen is pretty much the limit here). Of course, oxygen isn't going to stick around on *any* planet (due to how it loves to oxydize things), you need plants or similar producing it on a regular basis. If the oxygen is slipping away from gravity, there had better be some enormous source of oxygen the "plants" are getting it from. The takeaway here is that you could probably get away with short-term (millenia) teraforming of low g planets, but don't expect a breathable atmosphere on a low-g planet to happen naturally.

The original plan was to recover Falcon (1) with parachutes. I doubt that space-x has made it completely clear if the problem was control, regulation, or getting too wet. If you launch at Florida, prevailing winds are going to be from land to ocean. You have to bring your vessel back into the atmosphere well over land (good luck getting permission from the FAA), drift over Florida, and hopefully bring the thing down on land. If you want a barge landing, you need finer control than most parachutes have (see falling with style comments above). I'm still shocked that they don't carry *any* parachutes, I would think that drogue chutes would weigh less than the fuel burned, and vastly cut into just how tricky the burns are. My guess is that it has more to do with the throttling: anything that provides lift to the rocket makes the suicide burn that much harder. They really do want to support the full weight to reduce the strength of the rocket (and maximize the margin of error for the suicide burn). On the flip side, since Blue Origin *can* hover, they have no interest in parachutes. Remember: throttling is one of those things where KSP vastly differs from real life. Very few rockets throttle at all, and Merlin engines impressively throttle to 60%. This is still too much to hover and they are forced to do suicide burns during landing.

Isn't this a specialized use of what Orbital is planning? To repair satellites, they pretty much need to at least get there with nearly the same sized rig. I'd wouldn't at all be surprised if they announced they could do such a thing (ferry to and from LEO-GTO). Of course, Orbital might be going with a one-shot plan (or simply take a slow mosey around equatorial GTO (anything else would require a ton of delta-v. On second thought, I really expect the equatorial GTO plan. Maybe a follow-up bird might have the delta-v you need for such a thing).

Of course, you go the other way around. A kerbal like creature could claim that you could "land" on Earth, and due to the oceans experience buoyancy to any gravity 1>=your choice>=0. Note that to have an oxygen atmosphere at breathable levels, you will probably need pretty close to 1g gravity (you probably only need somewhere between Denver and Leadville air, or 1 and 2 miles of elevation. Don't know the metric equivilant, but it has to be lower than Everest (i.e. the death zone).

It isn't bad, but what are you trying to do? $1000AUD isn't much for a complete system replacement. I'm still trying to wrap my head around a 10 year upgrade schedule going on *forever*. I know I had a celery based machine (originally a 300A, then 566) that I re-named "Methuselah" due to just how long it lasted, but until the last 10 years, that type of thing was pretty uncommon. Note that everything that follows assumes you don't have a notebook or otherwise unexpandable item. Typically, you get your biggest gains by replacing the GPU (luckily I'm pretty sure you have a PCI-e bus, that was always an annoyance on late upgrades), but depends a lot on if your non-fps games and whatnot require a GPU (anything that didn't come from phones pretty much uses 3d. I think Civilization switched to 3d 10 years ago). GPUs tend to progress whether CPUs do or not. Is your memory full? Hopefully it is DDR3 and you can fill it up the motherboard cheap. Programmers typically have insane rigs and can't understand why their software slows down on older machines. SSDs are said to be the biggest upgrade money can buy (and they don't have to hold *everything*, just your most important stuff). Basically, it means you never have to wait for the hard drive (unless one of those windows dialogs pops up and windows (or possibly KDE/Gnome) insists on waiting for all drives to spin up). Note that for sufficiently slow computers (i.e. my father's laptop, after clicking on *every* piece of mail that comes his way), you might not see a difference. One upgrade that can't go wrong is the screen. Of course, if you old screen is good enough, then don't bother (because it won't go wrong either, unless it isn't LED). Screen prices seem to keep falling, and since any time spent on the computer involves looking at the screen it is a no-brainer upgrade. Look for LED backlighting to maintain your 10+ year upgrade schedule (I've worked in repair and the only thing I've seen go wrong with LCD panels are flourecent lighting and the inverters that power them). Note that my old college sells (sold? webpage is much less helpful now) surplus LCD panels ultra cheap (LED becomes more important. Check on phone if possible). While such things tend to be smaller than current panels, you could easily buy three for the price of one current monitor and get a lot more real estate (not sure if it works with KSP). Note I haven't mentioned the motherboard/CPU yet. Largely because I am underwhelmed by modern CPUs vs. 2007 CPUs, at least in comparison for 1997-2007 CPUs, or 2016 GPUs vs. 2007 GPUs etc. Once 1.1 comes out and it becomes obvious how well it works with a lot of cores, I'd still hesitate in replacing a 2007 CPU until all my other parts are modern as well. Favorite links: http://www.logicalincrements.com/ (it might be hard to figure out where your CPU/motherboard fits in here, but it would likely be worth it). http://au.pcpartpicker.com/ (can't vouch for the internationalization, but it appears to work).

https://www.quantamagazine.org/20160313-mathematicians-discover-prime-conspiracy/ My guess is the this is either a hoax or an example of p-fishing gone hilariously wrong. Nevertheless, I'm sure vast armies of cranks will research this dry, and might just discover a few things about "math different number systems". Note - the link goes to a paper popularizing a paper that claims that there are distinct differences of the probabilities of last digits of the next prime depending on the last digit of the preceding prime. Should this be real, it would be interesting to see if it extends into other number systems and if it extends any further than the authors were able to check.

That can't be real rocket fuel. The yellow triangle (reactivity) should be no lower than 3... Maybe RP-1 might qualify, but that wouldn't provide "delta-v" on its own.

Compared to gas stations (yes, originally gas stations, but I think other retail places have taken the idea an run with it), shopping centers, industrial parks (especially heavy) that need to light up huge amounts of area to near daylight you won't notice it. Even on Christmas Eve. Also note that Christmas lights should already be LED (red and green LEDs have been around long before anyone thought of CFD light bulbs). It will take many more people with insane Christmas decorations (powered by LEDs) to make a dent in electric use. The power used above is typically mercury lamps, and unlikely to switch to LED anytime soon (and already uses much power). Um, considering this is a space forum, do we have any astronomy buffs here? Just how much extra light pollution do you get during Christmas season?

How did they pull that off? Best guess is that it kept burning its own leads off, and they gave up trying and went to press with what they had. Note, it still has uses for final insertion burn/final correction burn (interplanetary), but the initial excitement of a better RCS thruster goes out the window. I also don't think (even with restarts) it would be all that great for satellite control (PVC thrusters are cheap ion jobs that will eventually get there and you need the solar power anyway) [I'd expect "real" sats to use proper xenon fuel, PVC is pretty inefficient. If you are even thinking about xenon, solids aren't for you.]