Northstar1989

It's the virtual memory of a system that really matters. But yeah, I've been running KSP without issue for some time on this system. I had to cut back on the mods when 1.05's heat system changes drastically increased my stock memory usage (hopefully 1.2 brings stock RAM usage back down), but I've never seen one single mod use as much RAM as SXT before... I did originally accidentally install wrong by not removing the files from the nested GameData folder before I realized my mistake and fixed it after booting up KSP once by cutting and pasting the files up the heirarchy. But I still don't see why this mod should be using nearly 300 GB of additional RAM! KSP was only using about 800 MB prior to this with just MechJeb installed... Regards, Northstar

Clearly yes. Look at the earlier posts. ^^^

Ok, so I thought this mod was supposed to not use that much RAM??? I installed it, and my memory usage shot up like 300 MB. Since my system (only 2 GB of RAM- though a much larger virtual memory) struggles to run KSP in the first place, I started getting random crashes, including access violations after I installed this... A possible complicating factor is that I also have the latest FAR installed. Other than that it's just a few small utilities- MechJeb, Kerbal Alarm Clock, and Kerbal Joint Reinforcement... I have never seen such a large increase in RAM usage with a single mod- and I often installed KSP Interstellar, RealFuels, and Real Solar System before 1.05 caused my RAM usage to skyrocket! What exactly is going on here? Regards, Northstar

I hate to be a nag- but is there documentation somewhere that lists all the parts in the mod? Like I said, I'm particularly curious about electric propellers... and large static solar panels.

The energy requirement is simple. Since the standard free energy of a substance is defined as the energy change that occurs during the formation of a substance from its constituent elements in its standard states, and all you are doing is breaking down Methane into its constituent elements in their standard states, it is simply the opposite. The standard free energy of Methane is -50.8 kJ/mol. Therefore the energy required to pyrolyze it back into duatomic hydrogen and graphite is 50.8 kJ/mol of energy. You do know how to do the rest of the math from here, right? Just calculate how many moles are in a more useful unit of mass, such as a single game unit of Methane. Add some reasonable-sounding but arbitrary anount of extra energy to this number to run the pumps and such in the reactor, and to account for energy loss to the external environment before it can be used in the reaction, you've got your energy requirement. Also, I hate to sound like a broken record, but since we're on the subject of energy requirements: the Sabatier Reaction (4 H2 + CO2 --> CH4 + 2 H20) is actually spontaneous without the input of any external energy, and in fact releases heat as it proceeds. Thus it should have a very low energy requirement- the energetic needs of the reactors planned for Mars are mainly due to the need to electrolyze water to recover hydrogen (our reaction *DOES* give players water instead of just Oxygen and reduced Hydrogen consumption, right? Cough, cough, *some* players might want to use the water directly, or to store most of their Oxygen as water- as it doesn't suffer boil-off like Oxygen does with RealFuels installed...) and the need to cool down the hot Methane produced to cryogenic temperatures. While you're adding in Methane Pyrolysis, you might want to go and reduce the energy requirement of the Sabatier Reaction- I'd say by a good 10-20 % at a bare minimum, and probably substantially more than that... Regards, Northstar

@FreeThinker but the ISRU refineries. They start out with their own internal storage tanks... The RealFuels config file I wrote last year allowed, by popular demand, players to change the allocation of tanks (for instance eliminate the Water storage tanks and replace them with extra UF4 tanks if heading to Dres) if they had RealFuels installed. I'm wondeting if (1) the config/compatibility files for RealFuels are still part of the mod and (2) if you had integrated the RealFuels system for changing the tank allocations of a part into KSP Interstellar Extended directly, or might consider doing so... I see that the mod has gone increasingly down the road of focusing on ultra-futuristic technology, but I'm here to try and refocus it on the more "low-tech" stuff just a couple decades away instead of 80 or 90 years in the future again. For instance, when are we going to get Methane Pyrolysis as a reaction? (all we need for it is a new "graphite" resource, which should be solid and thus exempt from the fuel-flow system. Later we can add an additional reaction to clear it using ThermalPower resource on planets with an O2 or CO2 containing atmosphere, or alternatively for Engineer kerbals to manually clean the ISRU out- but this part can wait. I know coding that might take a bit longer, and methane pyrolysis is still useful without a way to dispose if the graphite...)

Once upon a time you said you used Regolith. Are you sure it was just for a radiator? Also, what have we done about RealFuels since we swapped over to CRP? We use some of the same resources now- are the RealFuels config files I wrote for Interstellar Extended last year still part of the mod, or did we adopt them wholesale? For example can players now routinely customize what types of fuels and how much of each the ISRU refineries hold in their internal storage, or do they still need RealFuels installed to do that? And, did we adopt any of the boil-off code from RealFuels, or do we still use our own version for things like deuterium boil-off? Regards, Northstar

@FreeThinker alright, great. Do we still have custom resource-abundance maps for the ground-based resources: for instance making sure Lqdwater (actually ice) is only found in the polar craters on the Mun? Also, do we still use Regolith for the Propulsive Fluid Accumulator code? EDIT: Probably going to make a return to using the mod (and many others) when 1.2 rolls out, with its included optimization pass. Ever since the heating changes of 1.05 KSP has just barely managed to run at all on my craptop, without any mods but MechJeb. Maybe sooner if my little brother lets me use his 9 year old gaming rig (which he abandoned here at home- which I've moved back to while I apply to medical schools- when he moved to Colorado), though. It still has impressive specs compared to my much newer laptop... Not much free time even so, though. Regards, Northstar

Hey @FreeThinker, any word on the questions I asked you about ISRU? Namely, what is the underlying system we've currently got it running on? Is it still ORS-based? It's been so long since I took a peak under the hood at it, and I have terrible internet currently, so I'm reluctant to download the mod just to look... Also, an idea I think I mentioned ages past and nothing ever came of... We really should find a way (perhaps by co-opting code from the stock ISRU system) to make asteroids mineable for LqdWater, if we haven't already while I was AWOL. This would play very well with Propulsive Fluid Accumulators around Duna in particular, as it would allow players to collect all the resources needed for the Sabatier reaction (CO2 and Hydrogen) in the vicinity of Duna without ever needing to land mining equipment on the planet or its moon...

So, are any of the propellers in this mod electric?

LH2 keeps just fine if you keep it cold enough. You lose a little, but it's certainly feasible to store a sizeable quantity of LH2 for the duration of a Mars mission... But they're talking ISRU- that means, by *definition* of In Situ Resource Utilization that they're *NOT* shipping it from Earth and just using it to take off again as-is... The most likely source of Hydrogen on Mars is from electrolysis of the substantial deposits of water-ice found in the soil a couple meters down in many places on the planet. And, once you get LH2 on Mars, whether by mining it from the soil or shipping it from Earth in an insulated and actively-cooled container, you *don't* just keep it that way. You react it with CO2 to make Methane (for Meth/LOX combustion) or with CO to make Kerosene- neither one of which needs to be kept nearly as cold as LH2 for storage (in fact Kerosene, you don't have to cool at all!) If you were *really* worried about your precious LH2 boiling off, and you didn't want to mine it on Mars instead, you'd ship Hydrogen to Mars in the form of Ammonia, which has the next-best mass fraction of Hydrogen after Methane and doesn't require active-cooling; or Hydrazine- which has the nice property that it actually *releases* energy when you break it down... Of course in that case, you'd probably just be better off taking a Particle Bed nuclear reactor with you (such reactors were designed for Project Timberwind) and feeding a CO2/O2 mixture through your reactor to get back to orbit (this isn't all that dissimilar to a recent proposal to build a CO2/CO Mars 'hopper' with an RTG as its heat-source...) CO2 is available on Mars without needing to carry out any chemical reactions, and O2 is necessary to clean the soot out of your reactor that tends to form as CO2 pyrolyzes to leave behind graphite... You'd need to coat the uranium pellets in a material that won't oxidize when exposed to hot O2, though- or risk spewing radioactive material all over Mars' surface... Alternatively, you could just use CO2 on its own. Your reactor would gunk up with graphite by the second or third launch back to orbit, so you'd lose all hope of re-using your lander for future Mars missions, but then all you'd have to do is pressurize and cryogenically store CO2 as a liquid in order to have propellant to get you back to orbit. No mean task, but virtually any Mars ISRU plan calls on collecting and storing CO2, and it can be stored at much higher temperatures and in much smaller tanks (due to its higher density) than LH2, which means a solar array sent down with the Mars Cargo Module of a Constellation-style mission should be more than up to the task of collecting and storing the CO2 over a period of several months, or years (if you send the Cargo Module a Hohmann Transfer Window ahead of the crew, to start making propellant for the lander to launch back into orbit in advance...) Regards, Northstar

That's an absolutely and completely false statement about cellulosic biofuel. Even with corn-based ethanol, you only use marginally more fuel than you produce- and that's when you're throwing the majority of your calories away! With crops like Giant Miscanthus you get many times the yield at a fraction of the fertilizer and pesticide usage (almost none, in fact) and don't throw the vast majority of your calories away as farm-waste. As the majority of current farming caloric expenditures are on fertilizer and pesticides, this leaves the calorie balance squarely in the positive even with current farming techniques... As for optical rectennas, this *isn't* next-to-free electrical power, and LH2 is *not* going to ever be a cheap fuel. You bring down the costs of the panels themselves by up to an oder of magnitude with optical rectennas vs. traditional photovoltaics, but installation and maintenance costs are still significant, as are the costs of water-electrolysis equipment capable of capturing and storing the hydrogen on an industrial scale... LH2 is also difficult and dangerous to safely transport or store for long periods of time, and the places you would need it for LH2-based air travel (mainly urban airports) are likely to be a LONG ways from your solar farms. Not to mention, solar panels don't work at night, so the entire argument about using surplus electrical power produced by optical rectennas to make LH2 at night is totally and completely bunk... LH2 might still be cheaper than cellulosic biofuel derived from Giant Miscanthus fed into a pyrolysis unit, but you don't need to completely rebuildair-travel infrastructure for the biofuel option. As the majority of air-travel expense is actually in personnel costs and ground infrastructure, LH2-based air travel makes zero economic sense.

@FreeThinker Awesome! I'll give it a try sometime when I need a longer break from medical school applications... You should probably give the mod a try yourself. Mass drivers are pretty cool and have some sweet uses in setting up a long-term ISRU infrastructure on airless planets or moons. For best results, I suggest after confirming that the mass driver works on the ground on Kerbin sending up a bunch of RocketParts to the Mun or Minmus in Extraplanetary Launchpads and building a giant mass-driver there right on the ground... The easiest such Mass Driver to construct would simply be vertically-oriented and held up with launch-clamps (which you can build off-planet with Extraplanetary Launchpads) that the test-rockets wheeled beneath from the side (ideally, you'd build a sort of tractor-trailer with Kerbal Attachment System to get it there) to position for launch. But if you can build a horizontal mass-driver and come up with a reliable system to position cargo at the loading-end, you can build some very long mass-drivers that provide most of the impulse to get cargo to a low Munar/Minmus orbit... (with a vertical setup, you have to settle either for a shorter and less powerful mass driver, or for launching to a suborbital trajectory with a high Apoapsis and *then* circularizing, which is a less fuel-efficient way to reach high orbits than heading to a low orbit and then raising it...) Regards, Northstar

Wouldn't a scaled quadcopter still only require 4 smaller rotors than a traditional helicopter, and thus require less expensive gimballing? Anyways, as for MARS ISRU, the Fischer-Tropsch process is great on Mars because you have readily available carbon and hydrogen sources in the atmosphere and the water ice in the soil, and a *very* high value of fuel produced on Mars in that it saves a massive cost getting it there by more traditional means. If you run the Fischer-Tropsch process on Mars, you can easily produce Kerosene and LOX to burn it with (the LOX from electrolyzing the water byproduct, as well as extra water you dig up just for that purpose, or CO2 from the atmosphere) right there on Mars. Since Kero/LOX is a good deal denser than Meth/LOX and doesn't require any heavy/expensive insulation or active-cooling systems for the Kerosene component, it's a superior fuel for a Mars return, even before you consider that Kero/LOX engine technology is already much better-developed and more widely used than Meth/LOX is... It's worth noting that the Fischer-Tropsch Process can also eventually be used to produce feedstocks for the production of structural plastics fit for use in construction of permanent buildings on Mars, as well as to produce petrochemicals for various more mundane uses... So developing the reaction for propellant-production now also has knock-on benefits for eventual base-construction and colonization efforts decades later... Regards, Northstar

By the way, before I move on to what any of yhis has to do with Mars; some more on biomass-crops because they're really fascinating. Here's a list of a few particularly high-yield biomass crops. I suggest reading up more on them when you get the chance: Giant Miscanthus- a relative of sugarcane, this grass grows in dense stands (it basically completely covers the ground) 12-15 feet high. It has low water and fertlizer requirements, excellent pest resistance, yields 6-20 tonnes of biomass per year depending on soil and rainfall conditions, and can be harvested with existing farm machinery designed to collect hay... Arundo Donax- this crop is a cane rather than a thin-stalk grass. It grows 20 feet high, and yields around 20 tons of biomass per acre per year, making it even more productive than Miscanthus in many cases. However is is somewhat less hardy than Miscanthus, a potentially invasive species, and more difficult to harvest and process... Switchgrass- this biomass crop grows in a thick ground cover 4-6 feet tall. It only yields 6-10 tons of biomass per year once well-established and requires extra potassium and phosphorus as fertilizer, but is a reasonably hardy and *very* long-lived perennial grass, remaining highly productive for up to 20 years without the need for replanting... Due to its lower yields, it is best grown only where crops like Miscanthus are not viable, however... In short, plant some Giant Miscanthus or Arundo Donax, harvest it once it's established in a couple years, stick it in a pyrolysis unit, and VOILA!, cheap and sustainable syngas production, along with plenty of Biochar and Bio-Oil... Later, I'll get to what the Fischer-Tropsch process has to do with Mars ISRU. But I'm tired of writing for now, and have given plenty to think about... Regards, Northstar

Biomass gasification and Fischer-Tropsch to produce long-chain hydrocarbons including Octane. From cellulose (the main component of plant biomass). Basically exactly what I was referring to... Interestingly enough there's a lot of overlap between that and soil biology and Mars colonization. For one, you can actually produce the syngas (mixture of CO and H2) needed to run the Fischer-Tropsch process by pyrolyzing the biomass instead of just gasifying it... The advantage of pyrolyzing is you also get: - Biochar, which you can burn like coal (it even looks similar to coal!) or use as a powerful soil amendment to drastically and permanently (at least as permanently as you get with soil anyways. Archaeologists have found patches of manmade biochar-enriched soul in the Amazon over a thousand years old and still going strong... They call it "terra preta" there.) improve soil fertility. It does a bunch of things, including improving soil nutrient/ion and water-retention, reducing evaporative losses from sunlight, and providing an excellent porous microscopic surface for beneficial soil bacteria to grow on... Using it we could make depleted farmland fertile again, and make jungles (which get too much rain- normally causing nutrients to wash right out of the soil once we chop the rainforests down), and deserts bloom (with much less water needed for irrigation in deserts, due to the greatly reduced evaporative losses...) Speaking of, once you cover land up with pressurized and mildly-heated spaces, growing crops on Mars would be a lot like growing crops in a cold desert... - Bio-"Oil", which is really just a suspension of variable-weight tars in water. But it can be refined using existing petrochemical technology as a raw hydrocarbon feedstock into the refining process, and in fact is already done so when it is produced as a valuable byproductof certain industrial processes... All of this is in addition to syngas. So, it makes a lot more sense to pyrolyze at least some of the biomass for the valuable byproducts. It's a positive feedback loop that way, as you can actually plow a lot of the Biochar into the soil to increase crop yields if you're growing biomass crops like those massive 12-foot grasses I talked about before... (essentially, it grows faster and you get more frequent harvests- it doesn't necessarily grow in any thicker or taller...)

The better usage of Microwave Beamed Power is for orbital operations, actually. Badically take anything you would normally use a nuclear reactor for and replace it with a ground-based microwave transmitter and a thermal receiver or rectenna. Examples: - Propulsive Fluid Accumulators in Low Earth Orbit - Thermal Rocket propulsion (pure LH2 for 850-1000 s ISP, or Liquid Nitrogen at low to mid 300's ISP for better fuel density, thrust, and the ability to use all the Nitrogen you collected with a Propulsive Fluid Accumulator- which you would otherwise throw out, if you were just keeping the Oxygen for use in chemical rockets...) - High powered electric propulsion (stuff like multi-MW VASIMR, or plasma thrusters using nothing but Nitrogen...) The main problem with using 2 or 3 for, say, a manned Mars mission, is that while you get plenty of power from ground-based transmitters in Low Earth Orbit, the beam will be far too diffuse to produce usable power-levels (unless you want to spend MONTHS on a return-burn) out by Mars orbit... Lasers coupled with optical rectennas (if we can develop them) or existing thermal rocket technology would work better, but then you have the problem that lasers diffuse too much when passing through the atmosphere... (whereas microwaves diffuse more over long distances) Could work nicely for a Lunar tug, though... Propel the thing with ground-based microwaves and Nitrogen (collected by a Propulsive Fluid Accumulator in LEO) sent through a plasma thruster, or even Hydrazine (since it doesn't require active cooling to store) launched from Earth, for ultra-cheap transport of cargo from LEO to Lunar orbit and back... (still have to get the cargo to LEO though, even if you don't have to launch the fuel to get it from there to the Moon if you use a Propulsive Fluid Accumulator for the Lunar transit fuel...)

KSP-Interstellar Extended is based tightly on real-world data (the original Interstellar is not). Like it or not, Microwave beamed power works. But it has a few problems: - It's very expensive (this is accurately reflected in KSP Interstellar). You have to launch a LOT of rockets each year (over 100) to pay back the cost of the ground infrastructure with the lower cost of the rockets themselves. And that's based on CURRENT launch-costs: it doesn't ever pay for itself at all if you compare it to what SpaceX hopes to do, which is cheaper- unless you can develop a spaceplane based off the technology... (which is at least feasible, since microwave thermal rockets can get over 850 seconds ISP with Hydrogen) - It sounds scary. Who wants to be in an air/spaceplane powered by microwaves? Most people still falsely believe your microwave oven give you cancer... - it does, as you point out, create problems for current ATC systems But the engineering and technology DOES work, we know that beyond a reasonable doubt...

Fully in agreement there. I was actually talking about microwave rectennas there, though, because microwaves are less affected by clouds than visual light... Biomass =/= current biofuels technology. What shymung's talking about is producing octane and ethanol from cellulose, basically (or at least I hope so...) That's *very* different and much higher-yield than stupid corn-based ethanol... You can use grasses that grow 12 feet high before you harvest them then, which means you use way less fuel per ounce of biofuel produced than with corn... Current biofuels are just a handout to the corn lobby. Take it from a biologist with a little knowledge of agriculture- corn is about the worst crop imaginable for producing cellulosic biofuel... We can bring the cost of biofuel down an order of magnitude, which could well make it cheaper than LH2 which (which has MAJOR storage issues). And, it has the advantage of not requiring more infrastructure spending. When you look at the true cost of air travel and ignore stupid stuff like government paying for airports (and pretend airlines were footing the bill), ground infrastructure is a HUGE part of air travel costs, whereas fuel is only a tiny portion...

I agree with this though. I doubt LH2 will ever become common for commercial aviation, short of suborbital jumpers. Rather, I made the point about microwave aircraft because I think LH2 is so far-fetched that microwave aircraft are actually more likely (and hey, since they contain no flammable fuels and just use the atmosphete for propellant, they're safer in a crash due to the lack of abundant flammables...)

It's not a matter of the cost of LH2. It simply has too low a density to be practical. Microwave-powered aircraft make sense from a practicality standpoint, on the other hand, if you can bring down the cost to where it beats jet fuel (unlikely). Their primary utility is in building spaceplanes, where their superior performance (when used to power a rocket with LH2 a microwave thermal rocket can achieve ISP's of 850-1000 seconds... And a microwave thermal turbojet has essentially unlimited fuel-economy, as the atmosphere is its only propellant...) justify their massive cost. And microwave-electric aircraft *have* been prototyped- just not at scale. People have built working toy-sized electric helicopters powered by microwaves, and if I remember correctly a tiny thermal turbojet aircraft as well... The thrusters have been tested in laboratory settings as well, and work as expected (which is rare in engineering...) Regards, Northstar

There's a lot that needs to be done with ISRU. Making a better manual on it, for one (which could probably even be made available in-game, much like Kerbal Inventory System's manual). Explaining product ratios in-game is just one thing that needs to be done... I've been AWOL for a while, I know- but if all goes well with my medical school applications and finding work/employment in Boston for the meantime, I'll probably pick KSP back up in earnest in a few months, and become somewhat active in KSP-Interstellar Extended's dev team again... I promise that ISRU will be one of the first things I revisit when I'm all caught up in that situation. After all, a strong desire to maintain/preserve and expand upon the original KSP Interstellar ISRU system was a big part of the reason I joined with @FreeThinker to found this branch of KSP Interstellar in the first place, to expand the awesome mod @Fractal_UK built long ago... We may have started by introducing Propulsive Fluid Accumulators to KSP-Interstellar and working at improving the Atmospheric Scoops, but it was always my intention we'd revisit and improve upon the ground-based ISRU system eventually as well... As for Hydrogen Peroxide vs. Hydrazine, H2O2 is generally a superior propellant. It's about 40% denser than Hydrazine when stored in pure form, it is (much, much) less toxic than Hydrazine, its molecular mass is similar (which means it achieves similar ISP in an MPD thruster), and it is easier to manufacture in ISRU. However it is a strongly oxidizing chemical and quite corrosive (Hydrazine, by comparison, is often used to PROTECT against corrosion and to scavenge oxygen radicals...), which means it can't be safely used in some engines such as many arcjets and some types of nuclear thermal rocket (you'd need special coatings for an NTR, although we abstract this in the mod by allowing many such propellants to be used anyways and assuming use of the proper coatings...) H2O2 also is an inferior Nuclear Thermal Rocket propellant to Hydrazine when utilizing a reactor that operates at very high temperatures- as it only produces 1.5 molecules of gas (H2O and half an O2) per molecule of H2O2 when passed over a hot reactor as opposed to Hydrazine's three. This means the extra thrust it produces scales much less quickly with temperature than does Hydrazine's, and in a sufficiently hot Nuclear Thermal Rocket the reduced thrust and ISP compared to Hydrazine more than outweighs the higher density or easier ISRU... I'm not sure how much of this is currently reflected in the mod (the inability to use H2O2 in arcjets, or the reduced gains from thermal decomposition of the propellant at high temperatures compared to Hydrazine- the balancing if the thermally decomposing propellants in particular are still a bit wacky...) but these are the relative strengths and weaknesses of each propellant in real life. And all of them are relevant in KSP- for instance the restriction on using H2O2 in arcjets... Regards, Northstar

It's what NASA uses on the International Space Station for their test-gardens of edible crops, *precisely* because of its high mass-efficiency. Soil is heavy, and so is water- but you save a lot of mass by griwing crops in nothing but a nutrient-enriched mist... On a completely unrelated note, @FreeThinker this is the thread where I listed useful ISRU reactions (and important tweaks to existing reactions- like reducing power usage by the Sabatier Reaction in KSP-Interstellar Extended since it's actually a spontaneous reaction that releases heat, and only requires heating if the insulation is poor in order to maintain a high temperature and thus a faster reaction rate...) that should all be included in KSP-I Extended. Although it appears most of them are now in KSP-I Extended, Methane Pyrolysis is still unimplemented (but marked as planned, I see) and the Fischer-Tropsch reaction isn't even marked as planned (the ability to manufacture Kerosene from Carbon Monoxide and Hydrogen would be awesome for players using Real Fuels with KSP-I, as KeroLOX can be used with a much wider variety of engines than MethLOX, and is much denser and more storable than MethLOX or HydroLOX...) Both these reactions would be great to include... Regards, Northstar

LH2 is also dangerous and difficult to handle, and has enbrittlement problems. You'll see passenger jets flying on thermal turbojets powered by cheap/portable fusion reactors or microwave beamed power relayed from orbiting satellites (the latter of these two we could already do with today's technology- but not economically with current launch-costs or the price of microwave transmitters...) long before you see them powered by LH2 combustion... Regards, Northstar

The fishtailing behavior is clearly the result of known bugs. The most important of these is probably the symmetry stiffness bug. I can confirm that I have experienced this bug many times. Sometimes even on a plane that worked before until I detached and re-attached the wings in 2x symmetry in the exact same spot as before in order to get a closer look at something on the fuselage... The problem is clearly with the symmetry settings leading the wheels on one side to flex more than another, and if yoy zoom in on the wheels while driving on the runway you can often even see the bending differently... The wings themselves also occasionally flex differently- again a known and longstanding bug... Some designs are more vulnerable to differential wing and wheel flex than others. Sometimes not though- there have been times where I had two identical saves of the same craft with different names (in preparation for loading a cargo onto one that I was still designing) and one would always fishtail on the runway while the other would not, despite being identical designs. So clearly the fault somehow becomes associated with the craft file on a particular computer/ KSP install (copying the file to another computer will not always replicate it- making this an extraordinarily difficult bug to track down...) And, I doubt the issue is MY design expertise. I'm very good at plane design- I even designed a working SSTO spaceplane in Real Solar System 6.4x with FAR and RealFuels installed (I was actually the first to EVER do so without cheating- another player was the 2nd a few months later...) Admittedly it took 6 major design iterations (and countless minor tweaks) to get to that point, and it wasn't until the 4th that I could even go orbital, and the 5th until I had some semblance of re-entry stability (revisions 4, 5, and 6 were all efforts to improve stability during re-entry. #4 could make orbit but would spin out during re-entry and was only recoverable with a lot of save-scumming and near-perfect piloting...) Building a RSS spaceplane is about the hardest challenge you could ever undertake (there's a reason we've never built a working true HTHL spaceplane in real life, and some question if it's even possible... My spaceplane used slightly futuristic, next-gen fission reactors in nuclear thermal rockets and turbojets- stuff that's about 35 years out in real life, had 5 distinct engines, and even then a numerical analysis indicated I would have had to sacrifice about half the cargo to provide enough margin for pilot error to be able to make orbit in RSS full-scale...) so I don't think a lack of design skill has been behind so many of my planes spinning out or flipping on the runway- especially given how often simply re-attaching the wings could fix it... My point is, give the poor kid a break. It's not HIS fault the wheel and symmetry code is still as buggy as honey left out on an August night... Regards, Northstar