foamyesque

Ran across a discussion of it on a forum back in 2011. Was hooked right away.

There's multiple reasons why not to, starting with the fact that a plane needs to do more than just follow its nose into the ground like a dart or arrow would. I would be very interested in seeing the craft that you claim flip with CoPs well behind their CoMs; I have produced planes that will execute loops by aggressively inclining the tail fins and getting an angled lift vector as a result, but OP's wings are flat.

That just means theirs would be even more stable. And you want pictures from other flight regimes? Fine by me, as I took some on my way up to Mach 3.5 (wasn't re-entry: was an infinite-fuel powered takeoff, wherein my aerodynamic stability was sufficient to overcome a massive thrust offset): Maybe let's try something with a CoM *way* ahead of the CoP? You may note the continued lack of flipping. This is so trivially observable, both IRL and in KSP, that I have no idea where you're getting the idea that a CoP well behind a CoM will lead to flips.

I've built more planes in KSP than I really care to think about, including various shuttle replicas. I promise you I'm right, and to prove it, I mocked up a replica (I don't have his mod parts, but for proving this point it is irrelevant): You may note the complete lack of flipping happening.

What? No, that's the opposite of true. If there's a problem it's going to be lawn-darting from excessive aerodynamic stability, not flipping.

So for reasons probably best left un-examined, I'm building a ship with a very large part count. The save file, which still exists, is 7.7MB. However, if it (or a significant portion of it, which I tried saving as a subassembly, at 7.6MB) is in a save list, that list becomes blank (or in the case of the subassembly fails to load at all). Craft file: https://www.dropbox.com/s/71d0ikzbeuxo5o7/Tiny Eve.craft?dl=0 Subassembly: https://www.dropbox.com/s/c0voq7r8r27kubz/Eve lower stage.craft?dl=0 Any suggestions, aside from "don't build that big"? EDIT: In fact, the SPH GUI for assembly is borked as well; changing the function filter category from pod to something else, for example, produces no result.

Honestly, for Minmus, I'd just attach a fuel tank and some engines -- probably monoprop & RCS quads -- to the thing and land it with those. As a bonus, since you're running an ISRU operation, you can then use it to fly around at will.

Probably, since you only really need roll lock, but a tri-adapter will be sturdier, and would guarantee you're locked in all three axis if the docking ports themselves didn't already take care of yaw/pitch.

You can in fact create closed rings with docking ports. However if you require *exact* alignment, you want to use a tri-adapter hooked into three docking ports. That should lock you to exactly the same orientation every time.

I have a question though: Why no nosecones? You can place them directly on those docking ports and rig an action group to decouple them all at once, probably during a coast-to-apsis phase to reduce debris & keep them from being jammed against the rocket from thrust. You could probably also improve your aerodynamics by putting adapters on top of those big Kerbodyne tanks. There's nothing to be done about the girders except reducing the count, but you might want to investigate doing that as well, since it looks like you only need one girder's worth of separation.

It depends entirely on what you want to do and what you have available to do it. A launch to LKO generally only requires two stages (.6TWR/1400m/s dV minimum upper, 1.2TWR/2400m/s dV minimum lower), but what your mission may require beyond that can be basically anything. Do you need an interplanetary ejection stage(s)? Landing stage(s)? Return stage(s)? You can easily wind up with machines running around with eight, ten, or more stages once you start accounting for drop tanks, boosters, crossfed staging, etc.

In principle, an unmodified Spark engine can lift 0.2t of mass over and above its engine mass, at Eve sea level. A launcher is therefore theoretically possible, but I, for one, should not like to see what kind of monstrosity would be needed to make it work.

Really? Prove it: There's points for a sea-level Eve return up there

I've found them useful in a few scenarios other than docking: Orbit trimming (where even turned way down the main engines aren't precise enough and/or would require rotating the whole craft a bunch), landing on small bodies (e.g. Minmus, where they can effectively be your main engine and/or allow different landing configurations that a main-engine/RW only combo would not), soaking thrust offsets in certain asymmetrical craft, and -- and this is actually my primary use outside of docking! -- control during a cobra reentry. Vernor RCS in particular are the lightest way to manouver really big things, because you don't need a dedicated tank for them and they have much more control authority for their mass than reaction wheels manage. If that's the scenario, just disabling the tanks on the payload should give you the result you want. Be thematically appropriate, too.

Dry mass is just a question of adding more engines -- if you can SSTO any amount, you can SSTO any amount, unless you get burned on structural overheads. A 4-cmd-seat payload isn't particularly large, though. Anyhow, some proof of concept:

The Spark is a SSTO capable engine on its own, if I recall correctly, so the Junos might just be dead weight. The problem is that there's going to be a fair amount of overhead mass needed to keep the drag low. I'll do some poking about.

The last time I can recall Kerbin's atmosphere ending abruptly was back when it stopped at ~35km. Now that was a sharp transition... but it went away when the atmosphere was booted up to 70km and they significantly reworked the drag model, back in 2011.

While I appreciate the joke and point -- that not all SSTOs are spaceplanes -- the OP very kindly included pictures of the actual craft they're trying to find the ascent path for. A gravity turn would not be optimal

I've actually found it useful for checking the orientation of certain particularly important parts: Probe cores and docking ports, particularly, where it's really easy to accidentally invert your controls.

I'd favour the zoom climb. NERVAs already have awful thrust, you don't want to kneecap that further by hampering them with drag. Turn on the nukes as the Whiplashes start to fail to reduce the proportion of thrust you lose to drag losses, point your nose 30 degrees or so to the horizon, and get yourself up above 40km ASAP, then level out again for the orbit insertion.

???

Uh... Yes, you could, but a. it sounds like they need an elevated area, b. landing in the ocean proper as opposed to the fringes means you need to be stable in flotation, which is an additional design constraint, and c. you can't ISRU in or near Eve's oceans (they're locked to 0% ore), so you've got to land fully fueled, which makes entry and soft-landing much trickier.

I have a dynamically unstable multi-hundred ton plane. Flying it on the keyboard is... an experience.

I actually find myself often turning my control deflections up, for purposes of keeping my nose where I want it during re-entry. In general, spaceplanes will try to bring their nose prograde, which is a great way to wind up overheating your craft coming back from space; I prefer to fly with a 45 degree or better angle of attack. There are several ways to do this, and doing it purely aerodynamically is somewhat challenging. Higher control deflections (especially on control surfaces that are not all-moving), use of all-moving control surfaces for larger CoP shifts for the same control deflections, a flap system to move the CoP forward, etc all help. I tend to prefer canards over conventional tails, since they put more mass towards the nose of the plane, usually require less control surface for the same control authority, are less vulnerable to colliding with terrain, are more likely to be lined up vertically with the CoM (reducing inertial coupling), and have no chance of interfering with or being destroyed by engine exhaust. And while lots of people will say a fixed vertical stabilizer is enough, in my experience that's only really true of small craft, where pod torque is enough. Induced yaw is murder on your flight dynamics and a rudder is the most powerful tool you've got to control it. If you need ailerons for your roll control, you should be putting a moving rudder on. You don't necessarily need a large rudder -- a number of my small-to-mid weight planes use a single small elevon part, with no fixed component at all, as their rudder -- but it's a good idea to have something.

CoM shift, incidentally, can be majorly reduced -- or even eliminated entirely -- if you can arrange matters such that you have an equal amount of variable-mass torque, relative to the CoM, on either side of your CoM. In practice the simplest way to achieve this is to put equal amounts of fuel equal distances in front of and behind it, with fixed masses (engines, control pods, gear and so on) arranged so that they keep the CoM in the middle of the fuel tankage. This, except on the very smallest crafts where a pod is the payload and can counterbalance a rear-mount engine, usually means you want your engines as close to the center of the plane as possible, as they are by far the heaviest and densest pieces of kit on most planes, and rapidly overwhelm any nose counterbalancing unless the nose is on a very long lever arm relative to the engines.