Rune

Previous page, in my post just before the one you quote (the one @Jarin was referring to in the paragraph I quoted). And no, I don't have a liquid fuel only bird at the moment, no. The closest thing would be the Espada, my longest-range bird (3.5km/s on LKO with six kerbals for a let's-get-to-lvl3-in-one-flight training mission), but that uses a bit of oxidizer to reach orbit efficiently, and then it uses the nuke for mileage. Much better that way. Rune. Gravity losses are another kind of drag.

That is very sciency of you. You'll get far in this game thinking that way! Yup, that is mighty important. But also mighty simple, these days: fly as close to the ground as you dare until you hit the magical 400m/s, the ascend as shallowly as you can without burning up (very low TWRs can't actually burn up, so you just leave SAS on and let it increase pitch on its own as kerbin curves under you). That is a big change from the days of the souposphere and the slow climb to 10,000m, but once you make it flying SSTOs is actually easier than rockets. Yeah, not exactly what I meant there. Engines now need very little in the way of intakes, so minimizing your intake area cuts into your overall cross-sectional area. Take the Spatha, for example (first pic, the one with four RAPIERs, a small bay, and 20mT+4 kerbals capacity). The four RAPIERs are attached to one precooler each, then the precoolers to each of the four nodes of the Mk3 engine mount (then I moved them around to make them look cool, which took a lot of finagling but is besides the point, you could do it better and easier with a quadcoupler). Long story short, I have four engines happily fed, and my cross section is a single Mk3 tank. If I wanted to do the same thing with one shock cone per RAPIER, I would have a cross section of one Mk3 tank, because of the bay... and four 1.25 tanks, one for each intake. So if you do use engine pods, just one shock cone for each two RAPIERs will be enough, and thus you can halve your frontal intake area. Never mind what I did on the Calymore, that was mostly aesthetic reasons. Rune. Precoolers FTW, basically, there's a reason they are in the final tech node.

I completely and heartily disagree. I launch way more SSTOs than anything else, since they are the cheapest way to put stuff in orbit in stock, reliably. Only when somethign doesn't fit the cargo bay of a Claymore do I consider slapping chemical rocket SSTOs to the sides. Granted, not easy at the level I do it, because I have been doing this basically forever. But building a Big Red SSTO is just a matter of knowing it takes about six RAPIERs, and following the rules I laid, and should be something anyone could do if their put their mind to it and seek some guidance when they hit snags. Here, some examples of incredibly useful SSTOs that take roughly 1/3rd their takeoff weight (usually quite a bit more) to orbit. Note that the Claymore is leaving that station after dropping about 45mT of ore fuel, some commsats, and a few other odds and ends: And just to show that there is another whole kind of SSTOs that people totally disregard (we should have been saying airbreathing SSTOs all along), this is nowhere as cheap, but still cheaper than a disposable rocket: Rune. Mostly what it takes is the desire to do it.

Which is something that has always weirded me out, since you are a veteran that understands that rocketry is all about ratios. Let me throw a few numbers to help you next time: A balanced RAPIER design has around 0.5-0.7 TWR (going by KER or the static thrust), and it is about equal parts payload (the payload could always be extra fuel and/or high Isp propulsion systems for extended range, of course), fuel for the ascent (around ~400kgs per RAPIER of LF for the airbreathing part, and the rest plain LFO), and everything else (engines, wings, cargo bay, control point, landing gear and miscellaneous systems like docking stuff). Other than that, build a sleek plane that looks awesome, and follow the right path to orbit. That last bit is important, RAPIERS are easy as dirt to fly, if you only remember to skim the surface until you get them into their operating speed. With the right TWR (~0.5) and a slight positive angle off the runway, you can actually manage an input-free ascent, just pushing buttons while SAS flies you to orbit. Rune. That last bit is kind of a pain in the ass to engineer, so something to strive for.

Well, I am one of those forum monsters, having played at this game for literal years, but I would still say SSTOing is not impossible for "newbies", if they ask a bit around and approach the subject with some scientific mindset and stamina. Basically, try to figure out what is going on and what the indicators mean, and be prepared for a lot of trial and error, and you can't go wrong! I know I had a bit of a leg up because of my studies, but I got into SSTOs fast. Hear hear! There is a lot of stuff to be said about SSTOs, but there are really only three things to have in mind under 1.2 rules: -The engine for SSTOing is the RAPIER. Accept no substitutes. Nukes are fine if you want to go farther, but nothing beats the payload fraction of a RAPIER design. RAPIER=easiest=most efficient (in stock). -The flight path for the engine is crucial. With a RAPIER, you basically want to do a straight line to orbit, pitching up/down only slightly, or not at all (10º over the horizon is climbing rapidly if your speed is 1,000m/s, and kerbin curves under you), and getting to ~400m/s near sea level, in order to "wake up" the engines. -Sleek, sleek, sleek. For a winged SSTO, drag is your single worst enemy. Things that create lots of drag: unused nodes, not-pointy parts sticking out of cargo bays, intakes. Have as few intakes as you can get away with, as few nosecones, and absolutely no uncapped nodes. Rune. The rest is just making a plane that flies and figuring fuel/payload ratios by trial and error.

Always glad to be of help. Did you manage to get the ejection seat working again? Rune. I spy struts in those gorgeous ships, tough. You don't yet know about the "autostrut" advanced tweakable, do you? Dragless and massless, FWIW.

I did a thing for a person. I'd say it looks almost as good as what he sent me to fix, but the flames make it kinda difficult to figure out, because she took 3.01 minutes flat to get to a 75km high apoapsis. Rune. The issue was how to get it to orbit. Now it's making orbit without burning up. Progress?

0.6 is a good one, permissive but close to the edge. The absolute minimum (and thus, the most efficient) is somewhere below 0.5, 0.45 or so, depending on how streamlined you are. And anything above ~0.7 will mean that you can burn yourself up during ascent a bit too easily for my taste. So yeah, 0.6 is a good number to shoot for, lets you miss either way and still come up with something good. The only precise way is to bring up the aero info in the right click menus through the cheat menu (ALT+F12, hunt for "enable aero data in action menus" or something like it), but the in-flight visualization tool (F12 to toggle) is a bit more intuitive (and certainly faster), with vectors and such. Mind you, don't trust it too much. The size of the vector is mainly a factor of their node size, so only compare very similar things, and in case of doubt break any ties with the hard numbers of the menu. Rune. Hope that helps!

Yup, the stuff in KerbalX all should work without issues. But of course, if you find anything fishy, please tell me! One can never be sure that all the files are up to date... mostly, because I'm always changing minor stuff. Rune. In fact, I kinda should update the Claymore, I think, I redid the whole fuel balance recently.

I'm glad to see another convert to the "there is a right TWR for SSTOing" club! Oh, and regarding your comments on engine nacelles, Mk3 fuselages can be made short-of-streamlined, if you cap them with mk3-2.5m connectors or you use all the nodes in the shuttle engine mount. I actually went to the trouble of moving them around with KER in my Spatha to have four in a 2x2 pattern without any torque, you can grab an example there with precoolers already installed if you want (so no other intakes required). Rune. The hands-free ascent of a balanced design is really comfortable to pilot, too.

Sure, why wouldn't it? ...wait, you mean this one? Or this one? If either is the case (and I don't see why both shouldn't still work just fine), there is a new and shiny one in KerbalX, which does the same thing the others did (lift whatever you can fit in the bay plus 4 kerbonauts with plenty of margin), but better, mostly because it looks much more like a cute shuttle orbiter. Rune. One of my long-standing names.

This is genius. And if you trick the game hanging both nacelles of the same tiny connection with nooffset, I'd bet it'd work easier and more reliably. Rune. I only noticed myself you could toggle the button in flight, didn't know yet if it worked or not. Good find!

Yup, it's all a matter of enough control authority to overcome your natural stability. So, if you are just barely stable, it's actually pretty easy. Also, you don't need to go the full 90º to the airstream, wings turn into airbrakes much sooner, around 45º AoA. I actually think I have a couple of pics to illustrate exactly the point.... Here we have lots of lift, and are pushing out impact point eastwards: And here, just a few degrees more, and drag starts to dominate, lift goes down the drain, and the impact point moves westwards: Rune. I know, I should have kept the UI up, but you can see I was only about 30-45º over the horizon.

Poof! Appearing as requested! Always glad to help. Great! That's a subject that I've rarely talked about, and one that deserves a lot of consideration. The main thing in order to not blow up is to shed your energy slowly. Brake too fast, and the thermal load will blow you up. So, how do you go about it, exactly? Well, the trick is to do it in the high atmosphere, where the air is thin and the drag is low. That also means, of course, that it takes a long time, so plan accordingly. I use trajectories to more or less plan things, but I put the initial impact point on the continent west of KSC, because I am going to go much farther than if I went 'ballistic' (I.E: prograde all the time). Now, actually you don't need this at all, because if your SSTO is any good at maneuvering you have a huge amount of control about how you fall. Stay prograde, and you will fall in exactly the same way a capsule does, but if you put a bit of an attack angle, you can fall much slower, or use a negative AoA and actually fall faster. The main thing to take form this is, you can control your vertical speed, so you should keep an eye on it. That and altitude are the two only things you have to work with, and they actually sit next to each other on the top of your screen. So brace yourself, because I am going to start reciting numbers that are, of course, very specific to a kerbin reentry. Things start getting draggy below 50kms, so doing anything above that is usually a waste of time, just stay prograde. But things don't start getting seriously hot until about 35-40kms (at orbital speed), so that's the altitude you want to start your braking at. As soon as you get close to 40kms, increase AoA at least as much as necessary to arrest your vertical speed and go more or less horizontal-ish, and you will start shedding speed without increasing your temperature, and in fact your temperature will start to go down. Once you go below ~1,000m/s, it's safe to pitch down and plunge into the lower atmosphere without burning up. Too much. Now, notice that I said 'increase AoA at least as much as...". That 'at least' is very important, because in it lies the trick to not only fall safely, but with a lot of precision, so you can nail KSC every time and really milk those SSTOs with 100% recovery. See, with AoA you not only control the rate of descent, you also control your drag. Go horizontal with the least AoA required, and you will glide more than half the planet before running out of energy and falling to the lower atmosphere, where drag won't let you go very far. But if you increase AoA above ~30º, you will not actually go up, but instead stall the whole wing, reduce lift, and greatly increase drag. Think of it as turning you whole wing into one giant, heat-resistant airbrake (which is why I don't use airbrakes). You need enough control authority to do high AoA maneuvers, but with them you can almost stop on a dime (or at least a continent), and control where you want to fall exactly. So three distinct phases: first, fall prograde until you are approaching 40kms and stuff starts to get hot. Then you pull up, not-quite-leveling the flight (I like to keep vertical speed at about 100m/s, but that's me) and start shedding energy slowly, while you cruise around kerbin as stupendous speeds. If you feel that you are going to overshoot, you pull up sharply to 45º or more, and start increasing drag, and if you are actually going up and worried about it, you can pull down hard, and negate your vertical speed very quickly. Two or three of those pullup maneuvers should get you to the east mountains of KSC with about ~900m/s and ~20kms of altitude, and from there it's basically a straight line to the runway, the lower atmosphere will brake you to subsonic speed by the time you get close to the ground. Rune. And if you still overshoot KSC, use the energy you have to perform a horizontal 180º turn, then glide yourself back. Happens to all of us, and it's way better than blowing up.

Yup, Editor Extensions allows you to do some impossible things in stock (ignoring the offset rules and being able to turn surface attachment on/off seem to jump to the top of my head), but mostly it is just so helpful when building in order to be precise. With the ability to center a part with respect to another in two axises at the press of a key, you can actually build do things like a symmetrical design without using the symmetry option, and still be sure that everything is where it's supposed to be. Mind you, I can build without it. But not so neatly, and not so fast. And both files would work just the same whether I have EE installed or not, of course. I like the looks, but I can't help but feel like you must be leaving some node open somewhere, and that carries a big drag penalty. Then again, you have so much thrust there... Rune. The symmetry options, I don't use them so much. The angle limitations other than 15º increments, OTOH, are a godsend.

That is all very true and all, but let me just add that you can actually use one shock cone per two RAPIERs. About 0.5 "units of area" (whatever they are) per RAPIER, or less, in the high-speed intakes, is what is required for RAPIERs to really shine. Precoolers have 0.5, but hey, you don't have to increase the total frontal area to use them, so they should be the sleekest thing if you can use them. Wow, I totally didn't notice the milestone! In any case, I think that is mostly a function of me posting mostly either stuff for people to DL (which they seem to like), or giving someone advice (less rep/post ratio, but much more satisfying in the end, and if you are nice enough doing it you make lots of forum friends). Rune. Also, my main thing have always been SSTOs, and those are very popular.

Hum. A shorter-duration, high-G launch would have been a better test (at slow accelerations, the differences in weight should get magnified, especially at low speeds), but it is an interesting one. I still pick my intakes mostly on account of looks, the main thing with them is having just enough of them. Rune. Drag/intake area is the relevant figure here, not just drag... except for nosecones.

Yeah, that's a plane with a lot of control authority and not enough rigidity in the longitudinal axis, then SAS can be a handful because your controls can invert/overcorrect when the torque on the plane is big enough. In those cases, lowering your control input will usually help. Another thing that helps is a CoL very close to the CoM, so the control torque can be kept to a minimum (you also save on drag quite a bit). Of course, for that you need a CoM that either stays in place or moves forward, but with the new fuel flow rules that is easy to do. As to the SSTO, nice-looking first try. Now go about finding the limits! Payload fraction, dV on orbit, lowest drag... that kind of stuff. Oh, and a couple of tips: Tip#1: shock cones have the least drag per intake area, and a single of those can feed two RAPIERs. Less intake area=less drag. Drag is king in SSTOs. Tip#2: With enough streamlining, 0.4~0.5 TWR designs can perfectly well go supersonic at sea level in less than a minute and basically run a straight line to orbit form there. And of course, low TWR=low engine mass=more mass for other stuff. Taildragging is just letting him settle into a climb without touching SAS on takeoff, meaning the plane never goes outside of it's neutral point and it applies less control torque in a steadier fashion. Which lets him get over the real issue, which is that the plane has too much control authority for its rigidity, and starts 'swimming' like a salmon as soon as you apply serious control input, throwing SAS into disarray. A solid, stable-but-not-too-much design with just enough control authority to turn a few º/s, and most importantly enough structural rigidity, and you'll actually be able to maneuver with ease, which is much better. Rune. It's an entertaining rabbit hole you got yourself into.

Yup, the only really important bit is that you have to have your CoT (Center of Thrust, the result of adding all the thrust vectors on your ship) going exactly through your CoM (Center of Mass), or you will be creating some torque that you will have to counteract. The key for this is fuel flow, because it will change the mass distribution of your ship, or in other words move the CoM. A good trick is to arrange the fuel tanks in a symmetrical fashion around the CoM. This can be easily seen in @Cupcake...'s designs (the are very symmetrical in a lot of axises), but really, as long as the fuel drains symmetrically, you will be fine. Notice how I'm balancing the weight of the cockpit here, all the way in the front, with the engines slightly to the back, and I leave the variable-mass cargo bay smack in the center of the bird, arranging fuel tanks with identical capacities around it, front-back (Mk3 LFO) and side to side (the wings, for LF): That means that no matter the fuel and/or cargo situation, the CoM stays in the same place, and the thrust torque is always zero, or as close to it as KER and the UI will let me go. It also does wonders for the aerodynamics, because you can place the CoL very, very close to the CoM without it going in front of it at any time, decreasing the amount of control authority you need. Here, a much simpler design form long ago, still attached to its upper stage: Rune. It sounds fancy explained like that, but once you get the principle, it's rather simple, like levers. The CoM is the pivot, and you have to balance things out.

Hehehe, yeah,that's a classic. Shown here in the good old pre-1.0 days: There is also a 1.2-compatible version. It doesn't like to get that big, tough (it gets the jitters if you have too many modules connected), so I'm limited to more... modest builds: Rune. The lag situation, however, has improved... a lot.

If you take care of drag, a low TWR gives you a better mass ratio, as long as you make your speed run at sea level to go over 400m/ to open up the RAPIERs. Nothing simpler than an ascent that is basically a straight line, IMO. My benchmark for VTOL SSTO in 1.2 is this, even tough it has a tad high TWR: Rune. So, you know, 1 RAPIER and ~9 Junos per mT of payload. More or less.

Slightly what? I know I was showing the guts, but... Rune. I guess it's good to have high aspirations?

I was about to offer the same suggestion: Rune. A great reason to develop the SSTA module for the Orca was using it as a miner in the Dunian and Joolian systems.

LOL! Great screenie. And a big rock you have there! Congrats on the potato wrangling. As to the shielded docking port, it has nothing to do with thermal resistance (the RTG powering the Klaw would blow up much sooner anyway), and everything to do with aesthetics (I love the shielded port), and performance (active docking ports keep on checking for nearby ports to magnetize). As to the Espada, a quick test makes me think that the 1.1-1.2 drag changes actually affected it just enough to kill it. It should get to 400m/s at sea level to really wake up the RAPIERs, but instead it hangs tantalizingly close, not wanting to go over 250kN which is where RAPIERs really 'wake up' (get increased thrust with altitude, instead of decreasing). I'll see if I can do somethign about it, but the whole design was close to the edge, TWR-wise, so I might have to revise it a lot. OTOH, maybe taking out a few draggy parts, like the radiators, will do.... hang on a second, I still have KSP open. [15 mins later] Yup, I've got it back. Change the intakes for shock cones, and maybe take out the radiators, and it'll go back to being able to go over 400m/s at sea level. Also, autostrutting the main wing takes care of the bothersome elevon oscillations it likes to get when the dynamic pressure gets high enough. Rune. The bad part about high-performance designs is that they are finicky.

Woa. I know next to nothing about IR, but that looks like a million bucks... and about the same time of man-hours to put together. Rune. Kudos!