OHara

That could be fun. I avoid KSP1's reaction-control-wheels in favor of fins and reaction thrusters -- and I highly recommend trying that because it is fun. Clearly the unrealistic RCS wheels help a lot in making KSP1 accessible. After a while I embraced their over-powered-ness and now use them in space. The supposed metallic hydrogen, though, probably has much higher energy density than any other chemical fuel, so any substitute clusters of chemical engines might have unwieldy tanks to the point of being un-fun. We'll have to see. It seems clear that the design of KSP2 wants to fill a niche between existing chemical fuels and nuclear propulsion, and that the material filling that niche is metatastable enough to move around. So we might say that, in the Kerbal universe, that idea about metallic hydrogen arranging into a very stable hexagonal lattice of filaments is actually true! To be fair, this imagined Kerbal universe goes well beyond what the Brovman 1972 paper speculates, but somebody from Harvard Univ. speculated that far beyond the science, and now the speculation has a life of its own. The same YouTuber has a followup (Why Metallic Hydrogen is so important! [2020]) that goes into the speculative applications including rockets. YouTube comments kindly pointed out the error in figuring delta-V. Another YouTube comment pointed to a 2017 paper (link) that seems to take metastability seriously, so I read it. That 2017 paper does the analogue of figuring how hot you can superheat water above boiling in a clean cup (which I did this morning with violent results when I put in the coffee). That paper is something of a time-capsule, using only results from before 1982, plus what seems to be an assumption that the metal has to first dissociate into single H atoms before forming H2, and working out the pressure where bubbles of H2 in the metal would expand. Living in a universe where those assumptions are true sounds like fun --- lucky Kerbals.

Kopernicus-continued release 1.9.1-9 works with this configuration, but release 1.9.1-10 has some optimizations to scatters that break it. I've entered a bug report on the github of Kopernicus(continued)

Often, we need to guide a craft to land on a flat spot, or land near other craft. It is difficult to guide a craft with the draggy inflated heat-shield, or after full parachutes are deployed. (although I suppose we could double the parachutes, deploy one set, jettison the heat shield, then cut the parachutes) This week I did an Eve rescue, so have pictures of a simple Eve-return rocket that can be made if we use any of the methods above to destroy-or-deflate the heatshield. After the heatshield is gone, it has a 4:1 glide ratio, flying backwards with engines first. I aim the re-entry within 50km of my stranded Kerbal, then I glide to a level spot within walking distance of him, and then deploy the chutes. I tried to adjust this rocket so it could flip around nose-first after re-entry. After many cheats into Eve orbit, I concluded that i would need so much wing area to overpower the heatshield that I would rather make a spaceplane style rescue ship. I also found a craft (left) where I used the heatshield as a ballute above the craft, like Xyphos suggests above. This needed another heatshield below to protect during reentry, and separatrons to move that smaller heatshield clear when we start gliding. MarcusA380 used the heatshield as a wing (link) so maybe there is a way to transition to a glider with the heatshield itself as the wing. Even with these alternatives, we could use the 10-m heatshield more often as a heat-shield like the name implies, if we could deflate or destroy it just once.

One possibility, if you use Microsoft Windows and use a screen-resolution[*] for KSP different to your screen-resolution for windows, is that the KSP screen-resolution occasionally switches back to that used for Windows, which would make your text get smaller at some seemingly random scene-change. [*] 'resolution' meaning density of pixels here, as opposed to the level of detail actually visible, as it would mean in optics. If that is the cause of the problem for you, you can try solutions suggested by others(link link link) but the solutions seem to fail after a while. I just switch my screen-resolution in Windows before starting KSP

I know what I think the question is, and had been hoping someone else knew the answer. The new maneuver panel shows, under 'ejection', the angle of the craft relative to the prograde direction of its parent's orbit. When orbiting Kerbin and planning to go to an outer planet, you have to make your ejection burn some angle 140° or so ahead of the prograde direction of Kerbin's motion, so that you are going in Kerbin's prograde direction by the time you escape the SoI. The trouble is, I want the angle of the planned maneuver, where KSP always gives me angle of the craft (bug report). I have asked but never found anyone who knew how to use this built-in ejection-angle display. A few mods show ejection angles of maneuvers, that work with the planning tools. When orbiting the sun, which has no motion in KSP so no prograde direction, the usual definition of 'ejection angle' makes no sense. While getting the screenshot for the image, I noticed that the reported ejection angle was different on two starts of KSP, just after loading the same quicksave. It looks like the ejection angle shows some random number, maybe from previous use of the same memory, for craft are orbiting the sun.

Well the lightest Lithium is the obvious candidate to alloy with Hydrogen, only 6 times as heavy as Hydrogen. Intuitively, though, I would think that alloying would make it easier for the metallic monatomic form of hydrogen to re-arrange into H2. The only physical model I've seen for metastability has these columns of equally-spaced H atoms that for reasons I don't understand were not able to shift around to let the H-atoms pair up. Replacing a few with Li in an alloy would make the spacing uneven already. What was your motivation in thinking of alloys? Speculating on what metallic-hydrogen-like material be made significantly metastable in the real world, or thinking of a good lore for KSP2 that lets us suspend disbelief in the least disturbing way, or something else ?

Build id = 02694 is from version 1.8.1 (from just about one year ago) so you would apply two patches in turn KSPx64-Patch-1.8.1-To-1.9.1.exe KSPx64-Patch-1.9.1-To-1.10.1.exe and the directory is the one that contains KSP.exe, which might be down one level from what you might think (image) depending on how you unzipped the game. The patch program gives the same not-so-helpful error message, whether the version of KSP.exe is not there or not the version it expects. I use the update patches, because the downloads are 10× smaller, but in this case you might want to take the time to download the full 1.5-GByte zip file from store.kerbalspaceprogram.com and copy to the new installation your settings.cfg and any subdirectories under saves/ that you want to continue.

All the blades from the Breaking Ground mod have peak lift at 9° angle of attack. (This is a smaller angle than the 30° that give maximum lift for other KSP wings and control surfaces.) I have not found the angle for best lift-to-drag ratio, but would guess 5°. Someone else might have that answer. Or you might decode the sections in the file 'Physics.cfg' that list points defining the lift and drag curves. These are angles relative to the airflow across the blade. As the craft's airspeed changes, changing the angle of the blade on the rotor (like a variable-pitch prop) is important to get the most out of these blades -- especially the BG blades with their narrow optimal angle.

The rule seems to be that only parts in the 'payload' section in the VAB will protect their payloads. If you want to change the rules in your own game, there is a mod to extend the mechanism of protection to other hollow parts (link)

There is a recent description of something very similar on the bug tracker (link) but not a real bug report. I'll mention the very good report in the OP on that bug-tracker item. Version 1.7.3 does not show the problem, but I agree that version 1.10.1 obviously does. Someone else noticed it and revived a very old thread (link). The module-manager patch in that thread ( @PART[*]:HAS[@INTERNAL[*]] {!INTERNAL,* {}} ) solves the low frame-rate for me but of course also removes all views of the inside of the craft (all IVA views). Another workaround is, each time after returning from map view, to EVA a Kerbal and reboard him, or switch to some other craft-or-kerbal in the same physics bubble, then back to the problematic craft. I notice that memory use goes quickly to 98%, which makes me suspect the method of IVA rendering is over-using garbage-collected memory.

A single inflate/deflate cycle would meet the need identified in the OP. The earlier discussion seemed to reach a consensus (or at least average of opinion) that a single charge of inflating gas, plus some way to puncture the inflated shield, was a reasonable balance of realism/expected behavior and game-play usability. The various creative alternatives are, I think, less fun than the other creative things available in KSP. If the inflatable heatshield was easy to use as a heat shield, players could spend the effort solving more interesting problems. The single deflate could be implemented as a deflation, or self-destruction, or even as a drastic reduction in crash-tolerance when we select 'jettison' so that our craft destroys the decoupled inflated balloon rather than the other way around. (There is an option "isOneShot = false" in the configuration file, but changing it seems to have no effect and I have not seen anyone else report any use of that option --- it might be a leftover of an old idea, never implemented.)

There is a non-obvious workaround involving connecting the 'deploy limit' to one of the 'control axes' -- image at right. I have the keys PageUp/PageDown control the Custom03 axis so I can use them to deflate a heat shield in-flight. I do agree that a simple 'deflate' would be simpler, as did 75% of the people when there was a poll:

At least in the direction of those realms. I read some of the papers over the last week and it seems this was always a remote speculation. The 1935 Wigner and Huntington paper was about electronic structure of dense solid hydrogen. The first result is that, if you can push the H2 molecules close enough, the electronic bonds overlap and merge into a sea of electrons, and the nuclei space themselves equally to minimize the energy of their electrostatic repulsion. Then they say "If the extremely high compressibility [of molecular solid hydrogen] at ordinary pressures ... would hold throughout, the molecular form would be stable [at all pressures]. ... even under the assumption of the most advantageous compressibility at high pressures, the pressure necessary for the transformation is 250,000 atmos. [25 GPa], which is outside the scope of the present technique. The objection comes up naturally that we have calculated the energy of a body-centered metallic lattice only, and that another metallic lattice may be much more stable. We feel that this objection is justified." They go on to speculate about whether layered structures, that violate the assumptions of the calculations they had done, could possibly give a solid monatomic (not H2) a lower pressure. They reference graphite versus diamond as part of this speculation. So in 1935 they estimated metallic hydrogen would be stable above some pressure between 25 GPa and infinity. Their lower bound of 25 GPa is sometimes mis-quoted as their best estimate. The 1972 paper from Brovman, Kagan, and Kholas (English, Russian) is about crystal structures of monatomic hydrogen. They find that the electronic structure favors a long axis to the crystal structure, overcoming the tendency of positively charged nuclei to form cubic lattices where the minimum nucleus-nucleus distances are longer. They find several structures to be significantly, ~10 eV/atom, lower-energy than body-centered cubic, including the white tin structure predicted by later papers. However, their prediction for most-lowest-energy structure is hexagonal, like graphite, except the atoms aren't closely spaced in layers but closely spaced between layers, making 'filaments' of hydrogen atoms in a hexagonal grid. Those filaments are weakly connected to their neighbors so free to slide along their length. This is a very strange structure for a monatomic solid; it reminds me of liquid crystals. The Brovman paper does say (fig 11) that the atoms will spring back to position (positive frequencies phonons) if something disturbs them in any pattern, including atoms pairing up to move toward H2, and these calculations are at zero pressure. They also confirm (p1303) that they expect solid monatomic H to be stable, at zero pressure, against uniform expansion into separate H atoms, which is not surprising. Edwin Saltpeter (1973) references Brovman as finding a 1-eV barrier against formation of H2, but I don't see that in Brovman. The Brovman paper itself concludes "As to the lifetime of the obtained state, which is metastable with respect to a transition to the molecular phase, this question, being purely kinetic and connected with nucleus-formation, remains open." and goes on to mention reasons one would expect short lifetime: light atoms and large binding energy of H2. I didn't find any predictions about metastable states with any quantitative pressures, so this might be one of the mis-quotes in the literature, or I might have missed something. The later papers I've found so far make no mention of that proposed filamentary structure. Later calculations do agree that crystals with a long axis are the most stable. The modern predictions for crystal structure have two atoms per repeat unit (unlike the filament structure with just one) so their analogues of figure 11 from the Brovman paper shows more curves, for the additional patterns of displacement. For densities corresponding to pressures below 250 GPa, the modern calculations show negative frequencies for the displacements that would pair hydrogen atoms. Unlike the situation with diamond/graphite, we can easily see a way for the hydrogen atoms can shift smoothly from metal to H2. Isaac Silvera has done a lot of serious work in high-pressure physics, and has also speculated on the uses of metastable metallic hydrogen. That speculation follows qualifiers[*] like "If atomic hydrogen is metastable and if ..." but unfortunately the speculation is in the same papers as his popular descriptions of serious work. I don't see anyone else working in high pressure physics who even speculates on metastable monatomic hydrogen. Speculation is within the scope of Atomic Rockets, and they file it under "unobtanium". [* Edit: Looking at the 2017 article by Silvera in Science, I read in the first paragraph "other predictions suggest solid metallic hydrogen (SMH) is metastable at room temperature when the pressure is released [Brovman 1972]. The combination of these expected properties makes SMH important for solving energy problems and can potentially revolutionize rocketry as a powerful propellant." That isn't very well labelled as speculation. After reading Brovman, though, I find the leap to proposing this as rocket to be wildly speculative. If the KSP2 team was fooled by this, I can't blame them.] Maybe so. Nothing other than the speculated metastable metallic hydrogen fills the gap between chemical explosives (nitroglycerin, e.g.) and nuclear fuels. It reminds me of the situation with overpowered reaction wheels in KSP1. They make initial game-play a bit easier but are very unrealistic in terms of any performance measures with numbers. Acknowledging that the reaction wheels are unrealistic is a good thing to do, for players who also want know about real gyroscopes.

For craft in relatively low orbits, KSP uses a frame of reference that rotates with the body being orbited, so Foucault pendulums don't work properly, for example. I think the dividing altitude might be the same one as used to distinguish science results from "in orbit, low" versus "in orbit, high". 55km above the Mün is a 'low orbit'. The Mün is tidally locked to Kerbin, so the frame of reference for low orbits around the Mün would keep pointing at Kerbin

The closest I know of in the game is in the Tracking Station, where the Kerbal icon opens a display of the crew on the currently-selected craft. If that display is not long enough to show all the crew, you can drag the mouse to scroll, and you can close the sub-display for each crewed part in the craft. None of this was obvious to me; experimentation is needed to learn much of KSP's user interface. That might give you what you want, if you combine with Tracking Station Evolved to organize the craft in the Tracking Station by celestial body.

I think that is the more common case where people say 'metastable'. You could turn diamond to carbon if you heat it enough. My father's job was to do the reverse, for industrial cutting diamonds. At ambient pressure, graphite is a re-arrangement of the carbon atoms that has slightly less thermodynamic free energy than diamond, so the thermodynamics allows diamond to spontaneously rearrange into graphite, but not the other way around. The fact that this rearrangement is so awkward, and the energy difference so small, that diamond lasts forever at normal temperature is another important fact, and the usual word for that is 'metastable'. The other metastable materials that spring to mind are white tin (the useful form) and martensite in knife steel, where the metastable form lasts a lifetime unless bend it back and forth to give the atoms an easier way to rearrange.

Yes, it is difficult. Looking back, the strongest source I see for linking that engine to some magnetic nozzle is an informal dinner conversation about the resources they were planning to have in the game, over one year ago. I would guess the game-idea is to have off-Kerbin resources that enable interstellar engines, but the developers may very well have substituted something else for metallic hydrogen long ago, and we probably wouldn't know yet. Okay, I suppose you're considering this context to be physical metastability. So the the dry-ice form of CO2 would be analogous. But usually the physical phase change from solid to gas requires energy input. But metallic hydrogen, as probably found at the core of Jupiter, certainly has different chemical bonds than the low-pressure form of H2. Those H-H bonds are happy to form, and in forming the release that huge amount of energy. That's why I was thinking it more analogous to chemical monopropellant like 2H2O2→2H2O + O2

We acknowledged up-thread that imagining usefully-metastable metallic hydrogen bothers some players, but not others. I can understand some reasons why some players might be bothered a lot. Other metastable materials, like hydrazine and hydrogen peroxide, make fine monopropellants. But the energy per molecule released from H→H2 is ten times larger, near the top of the scale for energies in chemical bonds. Chemical bonds struggled to hold together the diamond anvils that (probably) formed monatomic metallic H, and the energy released overcomes chemical bonds trying keep solid the material in the nozzles. It would be very surprising if the metastable state could be usefully confined by normal materials. In 2010 two academics speculated at a conference (which is fine) that it might in fact be practical. The recent speculation, within the last decade, of something almost too good to be true, with no supporting experimental evidence, makes metallic hydrogen rockets feel just a bit like pseudo-science. My reaction, as a solid-state-physics PhD, to the metallic hydrogen engine as in-game lore was to cringe -- but I can get over it if it fits well in KSP2. Obvious silliness like "mystery goo" doesn't make me cringe, nor do game-play compromises like restartable engines and a dense home planet. I think the reason is that they are obviously fantasy. Metallic hydrogen rockets are in the uncomfortable middle between realistic and fantasy. KSP2 will probably lose only very few sales to the people too embarrassed to be associated with a metallic hydrogen engine. But with this thread now in the KSP2 section, it might be useful to suggest an alternative engine for this niche: a ~200-MJ/kg propellant with exhaust temperature requiring magnetic confinement. My only idea is to imagine some not-yet known isotope (thus obviously fantasy) of hydrogen that decays to 1H in some controllable way, maybe under irradiation, because nuclear decay is where you usually find that high energy density. Probably there is a reasonable alternative at the Atomic Rockets page but it is large and I am unfamiliar. [Edit: looking at Atomic Rockets I see that the more advanced, more speculative, nuclear engines with hydrogen propellant easily have the energy density in their fuel+propellant, and I see a liquid-core nuclear engine was suggested up-thread. In some cases Atomic Rockets reports graphite nozzles were suggested for the very hot exhaust -- I suppose the nozzle has a short lifetime. Hydrogen propellant doesn't ionize very easily so doesn't fit well with magnetic nozzles anyway. Also, maybe a rare off-Kerbin resource is part of the in-game niche to be filled, so maybe that resource could be some other imaginary isotope that produces hot ions. ]

It is, but only after you have the game running for a long time in one session. Craft not in the current scene don't slow down physics simulation of the game, but of course load/saves take longer because the file is bigger, including the persistent-file being saved at each scene-change, and you start to run out of memory (link to bug report) after many loads and saves which will eventually slow everything down, until you restart KSP. I have played the same career save since version 1.0, so now my tracking station is very full, and I like the ... personality that has built up in that save. My favorite mod to organize it is Tracking Station Evolved. It is challenging, in a fun way, to plan flights so that no debris is left in orbit (or you can delete debris in the tracking station) and I do retire bases that are abandoned and no longer interesting.

These are bugs. The bug-tracker (link link) sometimes has suggestions for how to avoid or work around bugs --- in these two cases I don't see any suggestions better than what you've found. The SM-25 service module often needs fuel lines to access fuel from tanks inside it. The bugs with shrouds are partially resolved in the later PC versions, but that fix might not have made it to the console versions yet.

One other common cause is SAS, if the 'control from here point' is far from the strongest control actuators (RSC or reaction wheels). Maybe after redockings you were left with a control point sensor that wobbles one way, while the reaction wheel is wobbling the other, as part of the hula dance. Then SAS tries to slow down the wobble of the sensor, but does so by commanding a torque on the reaction wheel that instead increases the amplitude of the hula dance.

Well, if the cylinders are somehow constrained to remain parallel, then yes the dynamics are the same as 2-D gravity. But with force decreasing as 1/distance rather than 1/distance² , 2D gravity is different. The energy required to pull bodies apart increases without bound as log(distance) so as Pds314 says there is no escaping a body. The orbits are no longer ellipses (but I think flattened at the far side -- probably someone will do the numerical integration and post an example). The long axis of an eccentric orbit will no longer stay in one orientation (because the Lenz vector is no longer conserved) so the orbits will draw more complicated patterns.

1) Sometime between 1.7 and 1.10, cargo-bays and fairings stopped protecting enclosed separate craft from the airstream. So now the drive mechanism Spinner of the spinner feels the airflow and its drag. Many stock bearings used fairings to hold their moving parts, so all of these are affected. Also, we can no longer safely re-enter with rescued Kerbals and parts loose inside a cargo bay, because they will feel re-entry heat. No-one has reported this on the bug-tracker yet, but it would be nice to recover the old behaviour. 2) The landing gear used to kick violently when compressed all the way (bug 20682) but that stopped happening with version 1.8 Here, I don't see how to make the Cannon function as it did, without a behaviour that would not be welcome in normal use of landing legs.

Is it easy to explain what part of the Kerbalism mod's science-system makes you like it? Maybe the distinction between measurements and samples? Or maybe the choice between analyzing and recovering samples makes it interesting? The mapping of the ScanSat mod is kind of an 'experiment', and I like it better than any of the stock experiments. I like how scanning depends on orbital mechanics, which is the core of the game. Every player has the same world to explore in KSP, which is great for sharing between players, but then players choose between looking at the wiki and others' stories, or staying unspoiled to do their own exploration. The ScanSat maps add more feeling of exploration, because even if I saw on KerbalMaps where I wanted to set up a base, I still want to get my scanners out to have an in-game map ready when the base arrives. I don't like any of the KSP1 experiments, probably because the in-game motivation of advancing the TechTree makes so little sense to me that it is not motivating. If the experiments were to make something visible in-game (temperature measurements filling in a temperature-versus-altitude plot visible at the KSC) that would be motivating to the completionist in me. I would be happy without any experiments at all used for advancing the Tech Tree (if KSP2 has one). Technology, as distinct from Science, advances by practice, so it seems natural that using parts at one stage in the Tech Tree would unlock the next stage. 'Using' could be funds contracts, plus science points if there are points, earned using craft containing the parts.

Something has gone wrong in the release process. The source code is back in the state where no atmosphere-heating star is ever found, and some change (that I don't see in the source) gives a null reference when it tries to load 'Sirona' from the Grannus Expansion Pack. It looks like neither the github code nor the released dll matches what you tested, if you saw the multistar heat fix. Slow down; it will be fine.