Wanderfound

Ballpark figures: √30,000 for small, √60,000 for medium, √100,000 for big. One of the joys of spaceplaning is that 100% recovery removes the need to economise.

Careful you don't bump the wings; snapping one off while in space can make reentry a bit awkward. My stations often have a specialised spaceplane port, stuck out on an extension to provide docking room:

Well, from the POV of "minimum thrust required to go to space", then yeah; it's got about four times as much engine as it needs. But there's nothing wrong with that; why fly a truck when you can fly a sportscar? This is a large part of the appeal of spaceplanes. Because of the 100% recovery thing, the easy refuelling and the efficiency of jets and wings, there's no need to scrimp and save and economise mass like you do with rockets. You can afford to overpower it, you can afford to load up on "luxuries" like science gear and mod parts (TAC-LS, Scansat, etc), you can afford to build omnicapable multipurpose things instead of having to specialise. If I was going for extreme long range, I'd either swap the lateral engines for LV-N's or change the tail bicoupler and engines for a single Mk2->1.25m adaptor and a single LV-N. Do that, and you could fly it direct from KSC to Laythe. But it wouldn't be nearly as much fun to fly. For a longer-ranged but still high-speed design, I'd be inclined to swap the lateral engines for Aerospikes. Any of the engine swaps is going to require a bit of adjustment to maintain the weight balance, but that's mostly just a matter of shifting the lateral tanks a bit forwards or back on the main fuselage. The lack of rigidity in docking ports makes modular engines tricky unless they're low-thrust. LV-N/909s are okay, but if you then swap out to a high-thrust option it'll probably wobble all over the place. This is why the modular bits on the Impatienze are just unpowered trailers: the only thrust on that ship (the lateral RAPIERs) acts to pull the docked sections straight rather than pushing them crooked. As it is, it can easily reach orbit with tanks better than half full, and the demonstration science probes and Fine Print satellites that I stuck in the cargo bay each have a few thousand m/s of ÃŽâ€V of their own. It can launch those satellites from LKO into pretty much any position in the Kerbin system (i.e. Kerbin/Mun/Minmus) without even visiting your space station. If you do go for an orbital top-up, the mothership could take itself interplanetary as well.

:hailMonopropProbe:

Punchcard and vacuum tube version. Or maybe a Babbage/Lovelace mechanical one.

I think I tried that before without luck, but I'll give it another poke.

It actually turned out really well after a fairly mild polish. Shifting the fuel weight forward, beefing up the tail (both vertical and horizontal; the original tailplane wasn't quite up to the job) and repositioning the wings to compensate was pretty much all it needed. There's a really nice plane in there; very fast, handles beautifully and plenty of practical usability. With all of the aero surfaces, position relative to CoM is just as important as the structure of the surface itself. The further that the stabiliser or control surface is from CoM (in the relevant axis, so lateral for roll, longitudinal for pitch and yaw), the more effective it will be. This gives you three options when you need to increase stability: change the surface, move the surface, or move the CoM. As well as reducing the CoM/dCoM offset, shifting the lateral tanks forwards increased the distance between the tailplane and CoM, thereby increasing the tail's leverage. This is also why I used the swept instead of straight tailplane on my version; the sweep increases the distance to CoM. Pulling the lateral engines forwards required shifting the tailplane up out of the line of rocket thrust, in order to avoid the possibility of it getting torched by your own exhaust. The relatively small wings left it wanting a bit of dihedral for roll stability anyway, and doing that on the tailplane further removes it from danger. The added intakes and pure LF supply aren't absolutely necessary, but they do let you get to orbit with more ÃŽâ€V. The only reason for the canards was because you seemed to want fairly rear-set wings; if you pull the wings up close to the intakes, the canards can be dispensed with.

Warning: if you haven't used the EVA jetpacks before, go very light on the thrust (WASD handles forward/back/left/right, Shift and Ctrl do up/down, directions are relative to the camera). Tap the buttons, don't hold them down, and set the spacecraft as a target first so you can track your relative velocity and distance. While it's possible to deliberately or accidentally let go of your rocket, there's also a current bug that causes Kerbals to occasionally be thrown away from the capsule as they exit instead of clinging on as they should. It's a known bug, should be fixed eventually.

Make it a micropayment based game, requiring real cash to launch every rocket.

Good idea, that. Probably not too hard to do, either. Yeah, they respawn on easy mode, but I don't think that'd cut it for a traumatised six year old [1]. [1] Yes, I know, many of them would probably happily mass-slaughter Kerbals like some of us do. But not all of 'em are going to take it that lightly.

Down or up wouldn't make much difference; there is no secret engine. The tail of the plane carries a docking port; the drop tanks are just tanks. Their only propulsion is RCS. You could make the final pre-departure payload into a dockable LV-N instead, but then you'd have to deal with the wobbly docking port issue. With the drop tanks as just an unpowered trailer, the thrust from the RAPIERs pulls them straight instead of pushing them wobbly. In theory, there is no limit to how many tanks you can hang off the back. A down facing bay would avoid having to go over the tail, but getting the tank from the bay to docked in the rear only takes a few seconds anyway. Decouple, tap K for RCS up, then N for a bit of back, then I and H to bring it in to the docking port. A single drop tank is light enough that docking is very easy; get anywhere close and the magnets will pull it into place. For a long range multi-tank mission, I'd dock each new tank to the growing collection of docked tanks in orbit, then do the final attachment while controlling the mothership from the rear docking port. But feel free to flip the bay if you like; it shouldn't affect the balance of the ship.

Just to test if I'm understanding it right...a 100% negative AoA setting will attempt to hold the control surface parallel to the airstream regardless of the AoA?

Yeah, I'm not launching a campaign or demanding any sort of immediate change; just noodling about what we might want to happen in future. The thing that actually got me thinking about this was starting to play with Scansat; those multispectral scanners are pricey enough that you can't afford to casually toss them onto disposable probes all the time. Which got me thinking about ways of improving the game balance of components without altering their ISP and TWR characteristics. It's fine for one rocket engine to be the clearly best choice for a particular purpose, but every part should have some use and a reason for being in the game. At the moment, that doesn't seem to be the case to me. IMO, spaceplanes and nukes are both somewhat overpowered in economic terms. Unsurprisingly, they're also the two notable places where the game goes beyond current reality and edges into near-future SF. Although there are plenty of plans for both spaceplanes and nuke rockets, there aren't actually any flying around up there. I don't think that the two points are unconnected; paper rockets always fly better than real ones.

This is already part of Fine Print​, which is being integrated into stock as we speak.

Ditto. I think there's something of a consensus on that point.

In terms of ISP, yeah; nukes stomp all over chemical rockets. But ISP is not the only constraint on spacecraft design. "Big enough to carry a nuke" is not very big at all: (ditch the VTOL and you can make that substantially smaller, too) You don't need big even if you're going to Laythe: And you can still do long-haul spaceplanes without nukes if you're creative with drop tanks: Takes a bit of prep, though; that one is designed to lift its own drop tanks into orbit, but for a serious long haul flight you'd need to lift half a dozen tanks before heading off. That'd work for me, too, especially if combined with a chunky price increase; it might return some economic viability to traditional vertical rocket launches, as well. At the moment, spaceplanes are massively overpowered from an economic point of view.

Greenpeace on your case after you crashed that nuclear rocket into the middle of town? Or do you just hate waiting around for 20 minute LV-N burns all the time? Want to go interplanetary, and want to do it cheap? Get yourself down to the local Kerbodyne showroom and check out the new Impatienze. Unlimited range, plenty of room for science gear and probes, all combined with 350kN of express delivery thrust. Just don't tell the Greenpeace guys about the PB-Nuk's stashed in the cargo bay. Craft file at https://www.dropbox.com/s/a2ugb916a4xgs2f/Kerbodyne%20Impatienze.craft?dl=0 The usual easy Kerbodyne launch. Power up to orbit as usual. No need for the hyper-shallow LV-N approach, although as always a more jet-focussed flight will be more fuel efficient. Only 1,300m/s of delta V in the tanks? How could we possibly go interplanetary with that? Like this: ...and there's another 1,000m/s of delta V. Because the tanks are connected in a linear fashion, in line with CoM, there's nothing to stop you from making the line of drop tanks arbitrarily long. Launch the ship, leave a tank in orbit, fly back to KSC, rinse and repeat. Each tank should only cost a couple thousand Kerbucks to put into orbit. Once you've got the last one up, fill the cargo bay with as much science gear, probes, landers and rovers as you like, then rendezvous with your drop tanks and head off to whichever planet you choose. By default, the batteries and fuel on the drop tanks are locked off; they don't have solar panels, so leave the batteries deactivated until it's time to connect them to the mothership. While you're putting the drop tanks into place, there's no need to worry about fuel efficiency; feel free to climb steep and fast, and don't worry if the RAPIERs switch modes while you're still only at Mach 4. Standard Kerbodyne aero polish.

Even if you take out the interplanetary factor: I can fly a spaceplane KSC-Mun-KSC without refuelling, if I design it as a dedicated long-range design with big tanks and minimal engines. Stick an LV-N on and I can do it in something the size of a fighter. In LKO the LV-Ns aren't necessary, but they're still better. A medium size (i.e. two jets, one nuke) nuke spaceplane will hit LKO with over 6,000m/s of ÃŽâ€V in the tanks. I'm fine with LV-Ns being better at their specialist role. I just don't want the conventional rocket options to be so bad in comparison that they're useless.

So: how expensive is "very expensive"? I'm thinking of at least a x10 cost multiplier, probably more.

BTW, just for comparison, the original aero analyses [1] of OOPS Mk3, in high-res so you can read them. With all of these analysis numbers, the moment they go from green to red is the moment that they pass zero. But, for some things, negative is good, while for other things positive is good. And there is such a thing as too much of a good thing; an overly stable plane is a non-manoeuvrable lawn dart. So, small numbers good, large numbers bad. So, Mach 5 at 25,000m; about where your jets max out. Tends to flip itself over aggressively in the roll axis when its sideslipping too much. Increase wing length or add some dihedral. Should straighten out aggressively when sideslipping hard, but doesn't. Add more vertical stabiliser. Tends to slip sideways at an increasing rate when you're trying to level the wings. Dihedral and vertical stabiliser. This one is saying that the faster you straighten out, the more you should sideslip (it's the inverse of the second one). Again, vertical stabiliser (AKA a big tailfin, as far back as possible). This is saying that there's a tendency to pitch-up as Z-direction (down) velocity increases. Keep in mind that a plane doesn't have to diving in order to have a high Z-velocity (actually, diving reduces your Z-velocity because of the reduced AoA). Because of the AoA required for lift, planes are always flying slightly down relative to the axis of the plane. Either add some more tailplane (horizontal stabilisers, again as far back as possible) or remove some lift from the front of the craft. [1] Sontaaw, I hope you don't take this the wrong way. It's not intended as a criticism of the original design; I just thought that it made a useful teaching moment. The original was much closer to flyable than most stock-aero based designs are.

You're right that placement is tricky, but for an example of what a small probe can do from LKO: Still had the FL-R10 tank half full. And that was from circular LKO, not an elliptical boost. Put the ellipse on, and you'll get comparable range from a Kerballed craft if you make it capsule + science and not much else. The easiest way to set the ellipse involves first launching your carrier vessel into circular LKO. Then, set an interplanetary manoeuvre for it. This will let you know roughly where the periapsis needs to be. Then, cancel the manoeuvre and burn near the node to raise your opposing periapsis as high as possible and drop the probe. The required ejection angle will move somewhat while the probe is going to apoasis and back, but with a bit of experience and/or experimenting (very cheap if it's spaceplane-launched microprobes) you can compensate for that. You don't have to get the ejection angle perfect; the Oberth boost will more than compensate for any minor imperfections.

Things have been a bit blatant over there lately. Hence the international reaction.

The missing question here is: why are you in a high circular orbit in the first place? If you can, launch a rocket or spaceplane with a cargo bay into an orbit as elliptical as you can make it while still keeping enough ÃŽâ€V to drop your periapsis for an aerobrake. Drop the interplanetary probe when you cut thrust; kick off the probe's own engines when it hits periapsis. Do this right and you can send a full collection of science instruments to any planet you choose with no on-board fuel apart from a small monoprop tank.

Tangential, but slightly related: This reminds me of a quote from G.K. Chesterton, responding to a comment along the lines of "we shouldn't expose children to fantastic fiction, because it will make them afraid of monsters". Chesterton's response was: "Fairytales don't teach children that monsters exist. They already know that monsters exist. Fairytales teach them that monsters can be killed." Yeah, evil is a thing that exists (although the manifestation is usually more subtle, nuanced and complicated than the mythological portrayal). You don't need theology to recognise that.

That'd work for me as well, if done successfully. Hopefully the Kerbin science nerf is coming with the added biomes of .90, but the integration of Fine Print is going to reverse that somewhat by making science available for satellite launches and aerial surveys. I don't mind people getting good tech while just futzing around in LKO; it's what I do myself these days, as the lack of interplanetary biomes makes planet-hopping primarily a sightseeing exercise (and I've already seen 'em). I just want for there to be some reason for the existence of non-nuke vacuum rockets.