Cirocco

I'm not arguing that you *can't* create spaceplanes that are perfectly balanced, my point is that it's very hard to make aesthetically pleasing stock ones that don't use a lot of clipping or some sort of exploit. In order to keep the CoM from shifting in big and heavy spaceplanes (I'm talking like 200 tons and heavier), you need to either put a lot of tanks in front of the plane, smaller tanks faaaaar in the front, or a lot of dry weight in the front. None of those options ar every appealing to me from an aesthetic viewpoint. Angling the thrust is a simple method that also makes sense from a physics point of view. Also I do like the new Mk III spaceplane parts so I would prefer to use them I get what you're saying, but I personally have an irrational dislike for manually pumping fuel or fiddling with stuff in-flight. I want my designs to have a clear way of dealing with every (foreseen) problem without having to improvise or solve it on-the-spot. Well the problem is that my long, heavy Mk III spaceplanes with a ton of engines (including the heavy nuke engines) in the back and tanks more in the middle will often have a tendecy to lawn-dart upon take-off and in early flight, but flip nose-up upon re-entry. They have a CoM that lies near the back, but in order to try and compensate for the CoM shift, I place the CoL as far back as I can. That means CoM in front of CoL on take-off and behind it on re-entry. These problems are much less of a problem when not using the Mk III parts, but I really want to use those. And they're so heavy that adding more fuel tanks to shift the CoM isn't an option because they would make the plane far too heavy and make it require far too many jet engines. There is of course the option of partially draining the MkIII part tanks, but flying an entire mission starting with only partially full fuel tanks seems horribly inefficient to me. I'm perfectly aware that many of my problems are a result of my self-imposed restrictions on design, but if that means I get cool looking planes and a better understanding of design and physics because of them, I'm keeping those restrictions

Right so I'm a pretty big spaceplane nut, I think spacecraft look cooler and more futuristic if they have wings One thing that has been bugging me for the entire time I've been playing KSP though is the shifting center of mass (CoM) that causes such problems in (heavy) spaceplanes: fully fueled means CoM forward and nose-dive tendencies, empty tanks mean CoM far to the back and somersault tendencies. I used to always try to build around this problem by trying the minimize the drift in the CoM due to fuel consumption, but this lead to designs with either large fuel tanks or engines very far to the front and just looked plain ugly in my eyes. And then I saw a post on the forums by Janos1986 and I had an idea: angling your jet engines upwards a few degrees with the gizmos gives you a lot of torque which can offset the nose-diving and troublesome take-offs that heavy SSTO's with a lot of engines in the back suffer from, but they would also make your plane flip out instantly if it comes back into the atmosphere at the end of a mission with near-empty tanks and a CoM that lies super far to the back. But what if you angle all of your jet engines upwards except 2? You leave those 2 horizontally aligned or you might even angle them slightly downwards. Then, when entering the atmosphere with near-empty tanks and a tendency to flip nose-up instead of nose-down, you use those non-angled or slightly downwardly angled engines to compensate. You wouldn't need a lot of thrust anyway because the majority of your mass is gone and hey-presto, stable aircraft at all times, even with extreme CoM shift! Another option is to slide your engines slightly up- or downward, but in my designs this would be somewhat difficult (though with this new info in mind, my designs may change radically ). So what do you guys think? Would this work? Do you already do it? Do you have other ways of compensating for an in-flight shifting CoM other then designing around it so it doesn't move much? Discuss! This came up in a thread under the "gameplay questions and tutorials" section, but I didn't want to hijack the thread so I figured I'd make a new threa about this idea here. Big thanks to Tassyr for creating the original thread, Janos 1986 for giving me the original idea and Wanderfound for kicking my imagination in the butt so it took off

NASA and other agencies already perform aerobraking manouvres, but usually not for aerocapture. Don't shoot me on this if my info isn't fully correct (I'm an engineer, but no spaceflight engineer) but I believe they perform insertion burns and then try to attain the desired apoapsis with several aerobraking passes. If I recall correctly either ESA or NASA performed a test with an inflatable "doughnut" aerobrake to increase surface area so they can perform the manouvre in the future on heavier payloads. Can't seem to find what it was called or which agency performed it right now. - - - Updated - - - they use it to change the apoaps, but I'm fairly certain orbital insertion is still done with a burn. The speeds from interplanetary travel make it too dangerous to attempt an insertion purely with aerobraking. You'd have to go too deep into atmosphere where the aerodynamic forces and heat from air compression would be far too dangerous. again though, not an aeronautics or spaceflight engineer, could be wrong.

hm, that IS an interesting idea. It would allow your CoM to be more to the front of the craft, which would solve a lot of problems for heavy SSTO's which need a lot of engines in the back, shifting the CoM very far backwards. I wonder how it would affect your flight behaviour when you re-enter atmosphere with near-empty tanks and a CoM that is a lot more to the back though? If my reasoning is correct, a center of thrust above the CoM would make your plane flip upwards very easily, especially if the CoM moves closer to the center of thrust and the plane becomes lighter. Hang on, as I'm writing this post I just figured something out: what if you angle all but 2 of your jet engines to help with climbing and keeping the nose up when the tanks are full, and only use the 2 non-angled ones upon re-entry and return to the runway? You wouldn't need a lot of thrust anyway when you've lost all that weight from the fuel... This.... this could work.... Holy Kraken if this works the way I think it will... this could solve so many problems I have with in-flight shifting CoM... I must test this when I get home from work!

I think that is where the exhaust hit? Not sure what happened to the rocket itself, but explosion seems unlikely seeing as there would be almost no fuel left upon landing. More likely it just toppled over and was destroyed on impact.

if I recall correctly NASA did conclude that it might be possible, but more investigation is required. if this does prove to be possible, then it could be pretty huge for deep-space probes. Not so much for manned light due to the thrust limitations though.

grats! that thing looks pretty slick too! two suggestions to improve it: 1) add a couple more intakes (the long slender radial ones look really nice) 2) if you use the following placement order, your engines will never experience an asymetric flame-out, and you'll be able to use them in the airbreathing mode up to over 30km height: first place all the air intakes you want a single engine to use, then place said engine. Then place all the intakes you want the next engine to use and then place said engine. Repeat until you've placed all engines and make sure you don't use the symmetry tool or alt-click to copy the parts.

in theory? yes, possible but it would take perfect timing. In practice? no, impossible due to human error and imperfect burns, as well as inherent limitations of the way calculations are made by the program.

ugh, I am really wondering whether or not I should be posting this, but... windowed mode, make sure it isn't fullscreen, no sound. When boss arrives, click outside of window to pull up whatever you have active behind it.

interesting note: in the falcon heavy fully recoverable configuration, SpaceX plans to have the booster cores fire for a few seconds after separation to put them on different courses for recovery. of course seeing as these are liquid engines, it's perfectly possible for them to cut out, seperate and then fire again a few seconds after separation.

As far as I know, there's no active work going into multiplayer right now. I'm guessing that Squad is just doing their updates and work on the code in with multiplayer in mind, i.e. making sure they wouldn't have to re-write the entire thing if they want to integrate multiplayer. I don't think they're actively working on it. Of course, this is pure speculation on my part. I haven't heard any new info regarding multiplayer other then what you already listed. Also, I LOVE your signature pic

Rockomax Jumbo 64: big orange tank Stratus-V Cylindrified Monopropellant Tank : that monoprop tank that looks way too much like the goo canister LV-1: ant engine rockomax 48-7S: OP little engine LV-N: nukes or nuke engines external fuel ducts: fuel pipes every elevon ever: flaps. yes I know it's wrong, I don't care communotrons: respectively called antenna, flat dish thing, round dish thing all science parts: science stuff.

you sir or madam, are absolutely insane. I salute you.

Right so a lot of people have already linked you a lot of stuff. I'll simply say that the link LethalDose provided in post #7 tp the "basic aircraft design" thread is what jumpstarted my aircraft design and what allowed me to go from crash-on-runway to interplanetary SSTO's that never refuel. a few extra pointers: - always make sure center of mass and center of thrust are aligned. Ideally, the center of lift orb should never be fully seperate from the center of mass orb. You can check this by emptying the fuel tanks in the spaceplane hangar and seeing how the CoM moves as you do so. I also have begun using the "RCS build aid" mod recently which shows you the "dry" CoM (all fuel tanks drained) as well as the normal "wet" one. - As many have said beofre, shuttle design the way NASA did it is an incredible pain in the ass in KSP due to its asymmetric design. It's possible and many people have done it before, but it's not easy and usually requires a ton of reaction control engines (vernor engines at the top of the fuel tank to offset the thrust is an often used solution) - airbreathing SSTO spaceplanes are great as cargo haulers to carry stuff to LKO (Low Kerbin Orbit) and for use on Laythe. I would advise against using them for much else. I have some experience with interplanetary SSTO spaceplanes and I can tell you: they're not worth the trouble. They take a ton of design effort, are stupidly big and heavy, are generally less efficient than purely rocket-powered ships and can't really do anything other than the specific task they were designed to do. They may be somewhat cheaper because you don't discard any hardware, but the small cost saving is not worth it. TLDR: use the "basic aircraft design" thread Lethaldose linked you in post #7, use SSTO spaceplanes to haul cargo and kerbals to LKO and nothing else (unless you want to do it purely for the challenge)

space elevators are sadly impossible because of the 2.5km physics bubble

part stress doesn't accumulate in stock as far as I know. Do you run any mods? FAR or NEAR can definitely do this as a result of aerodynamic forces ripping the wing apart. And with an altered wing come different forces which may result in more destruction, etc. if you don't run any mods, this sounds like a kraken attack. I've heard/seen of other people saying that they suddenly found parts of their spaceships (often spaceplane wings) destroyed after switching to the tracking center and back.

like so many of my fellow players, pretty much the only "unrealistic" feature that I wouldn't mind seeing changed is the aerodynamics model. And I hear that's getting an overhaul in the next update Other features that I wouldn't mind, but could certainly find with mods are life support and beter long range communication (relay sattelites and commsat constellations are cool), though I probably would only get frustrated with signal lag.

I wasn't actually trying to make a real comparison, just show that technological advancement can go much quicker then you'd expect, and that it's a self-strengthening effect. The more advanced technology becomes, the faster we can innovate, which leads to better technology, etc. As for incentives: scientific knowledge is obviously the biggest one. For example: one of the more recent resupply missions to the ISS included a scientific experiment to study the processes in which alzheimer's disease works in microgravity. With the absence of gravity, certain processes which are impossible to observe on earth can be studied which could lead to a breakthrough in Alzheimer treatment. That's a nice incentive for pharmaceutical companies right there. infrastructure and manpower to produce the hardware. With fully disposable rockets, you're throwing all that manpower and money down the drain every single launch. If you can cut down from "fully build a rocket from scratch during the course of several months" to "fill it with fuel and put it back on the pad within a week", costs can be brought down a lot. (obviously this is an exageration for illustration purposes, but you get the gist of it). I believe SpaceX is currently aiming at re-launching the falcon 9 at a third of the cost it would normally be, and if re-usability becomes standard, prices could drop down to 10% of the current ones. Possibly even lower if new technologies surface. Define "a lot". Of course it will always cost millions of dollars to construct a rocket, and obviously spaceflight will always be more expensive than regular atmospheric flight because it simply takes more energy, but it can certainly be done a lot cheaper than it is now. Right now it costs about 4000 to 20 000 dollars to put 1kg in low earth orbit. If that can be brought down to 500, you can theoretically have a ticket for a single person for roughly 40 000 dollars. And that's not including any cost cutting you can expect if dedicated passenger carriers will be developed. Or you can go on a sub-orbital spaceflight for a shorter, but cheaper spaceflight. That's teh route companies like virgin galactic are pursueing I'm not expecting to be able to go to space for a hundred bucks, but commercial spaceflight is becoming a thing. The question I believe is not *if* space will ever be accessible to the general population, but when. And I hope that will still be in my lifetime.

hehe, yeah I know, I'm just happy that we're getting lucky this time

I wouldn't be too sure, depending on your definition of "near future" of course. The wright brothers did their first powered flight in 1904 if I'm not mistaken. The boeing 707 started production in 1958, only half a century later. If the falcon 9 test tomorrow is successful and re-usable rockets become a thing, then cost will go down immensely. And if cost goes down, it will attract more investors, more development, etc. I think the next couple decades will be very interesting in terms of spaceflight and energy/fuel production methods.

science and engineering rant time! number 1 has been answered already so I won't re-iterate what has been said already. As for your second question: it's a combination of several factors. For one, it's impossible to say how long a mission will last because so much is unknown and there are waaaaaaaaaaay too many variables which cannot be foreseen, especially when attempting things that have never been attempted before. Spaceflight is truly cutting-edge: there is so much we don't know and almost every mission is doing somethign that has never been done before. At the time, spirit and opportunity were some of the largest rovers ever sent to mars, and not a lot of rovers had gone before them. Scientists had theories and ideas about the difficulties it would encounter, but there wasn't a lot of real tried and tested information, so NASA is pessimistic and only gives a timeline they're reasonably confident about. Secondly, spaceflight is an industry where quality is of the absolute utmost importance. Things get way overdesigned with several back-up systems and failsafes. If these failsafes are not needed, they can be salvaged or re-purposed to extend mission lifespan, but there's no way to know that on launch. Improvisation is a big part of these missions because the amount of resources to resolve problems is extremely limited. Again, in the case of mars rovers it isn't uncommon to use certain instruments for uses they were never initially designed for, but you use them anyway because it's all you have. thirdly: rovers (and lots of other space instrumentation) are specifically designed not to have an "off" switch. You never know if someone might press it by accident. And especially for rovers with solar panels, it's completely impossible to know how long those solar panels will work. Will they be covered in dust? Will the topography allow for hills so we can angle the panels towards the sun? Will there be fortouitous gusts of wind that clea the panels? Will there be a dustsorm that sompletely covers the panels and kills the mission 2 days in? No one knows. So again, you assume worst case. You also wondered how much extra science could have been done if longer mission profiles were anticipated? Probably not that much. During those ten years, opportunity has been doing everything it can with the instruments it has on board. It doesn't matter if they planned it initially or not, opportunity has been giving us information non-stop for those ten years. If you want to do more in-depth science, you need better instruments. Those are heavier, meaning more money required, bigger scope, bigger mission, etc... Basically you'd end up planning a really big mission without any prior experience, not even knowing if all those heavy and expensive experiments you sent up will even result in good data. This is an example of "scope creep", which is the bane of many projects in any industry. In essence, you shouldn't send a curiosity rover which weighs as much as a small car when you know next to nothing about the risks. Start small, learn from small missions, scale up. That's what spirit and opportunity and their predecessors were for. As frustrating as it can be, it's never a good idea to go with high-risk missions in something as expensive and critical as space exploration. Slow and steady wins the race as it has been said.

depends on the day, when the last update was and how bored I was at work (I tend to start thinking up new designs and mission profiles when bored ) ranges from minutes to 1-2 hours, possibly more if it's a weekend/day off and I'm doing design tests. Especially on spaceplanes. "right, just woke up and had breakfast. Let's just fire up KSP and try this one new design idea before I forget..." *test: aircraft either explodes on runway or fails to properfly take off* "oops, forgot struts. Let's try again" *test: aircraft either still explodes on runway or fails to properfly take off* "right, right, adjust center of mass and gear placement, silly me to forget again." *cue a 10 minute+ flight into higher atmosphere before spinning out of control* "okay it didn't work, but I'm sure making this small adjustment will TOTALLY make it work" *cue another test* "okay so the problem is not what I thought, it's something else. I'm sure THIS time I have it right though" *LOTS more tests ...* "right, I have a rough idea about the atmospheric flight, now to get to orbit and interplanetary" *moar long-ass testing* "whelp, we can get to orbit but not nearly efficient enough. I'll just adjust this little thing and I'm sure it'll be fine" 12 hours later "okay, we can get to orbit and go interplanetary, we're TOTALLY going to make this!" *plane flips out when entering atmosphere with empty tanks* "huh.... oh dear is it evening already?"

ooooh okay, I didn't really follow the news much after the scrubbed launch on tuesday. That's the second time I get all excited for nothing dammit Hope all goes to plan tomorrow. At least it's at a reasonable time for us in Europe, usually US-based stuff happens at silly o'clock in the morning for us

huh, just checked the schedule for NASA TV, appearantly launch is postponed to saturday? Or maybe it's just timezones messing with me. EDIT: nope, I wasn't wrong. Saturday at 3:30 am EST, 9:30 GMT (If I'm not mistaken)

Well yeah, once you hit the upper layers of the atmosphere and switch ot rocket engines you're basically flying a rocket. What is becoming hard for me in the heavy and super-heavy airbreathing SSTO's is getting to that height and speed efficiently. I could easily build a rocket-powered spaceplane and fly it up to orbit, but then I'm basically building a rocket with wings. If I do that I think it would be far easier and more efficient to go the way spaceX is going and use a rocket which I can bring back through powered landing. The goal here is to reduce flight cost even further by eliminating the need for oxidizer and using very efficient engines for a large part of the ascent. The small radius tanks and MkII spaceplane parts both don't weigh that much for their volume. So a fairly large plane built with those was still within acceptable weight class and a decently sized wing meant you could get away with a fairly low TWR. With the MkIII parts however, these things weight a bloody ton and pack a huge amount of fuel. That's great for when you're building cargo haulers which have a large bay and no too much room for fuel tanks, but it becomes a pain when designing large, interplanetary ships without cargo bays: you have a really heavy and compact ship requiring huge wings (or more thrust to make the smaller wings more efficient) and a lot of small engines (seeing as we don't have 2,5m airbreathing engines at the moment). That's a lot of stuff to be attached on a compact ship. Note that I'm not saying the Mk III parts are unbalanced or that I want them changed in any way, they just pose an engineering problem that I haven't yet learned to work around in KSP.