Aegolius13

Usually when I leave the target vehicle SAS on target mode, it starts rotating wildly rather than following the active ship. So I've had to use hold instead by necessity. Interesting you get any good results from target mode.

Sorry, meant quadcoupler.

Speaking of girders, I needed a girder-ish thing to dangle an Eve rover underneath a skycrane/lander. Then I remembered the rover was packing an RTG anyway. And RTGs are long and narrow. So I just stuck the RTG up vertically from the top of the rover, and used it as the girder. What could POSSIBLY go wrong? (It actually worked without incident). Another one - I was trying to send up several deorbiter/escape pods to my space station in one launch. I eventually decided on turning a (edit) quadcoupler upside down, and plopping the escape pods in each of the holes. Looked like a little muffin tin with little Mk 1 capsule muffins. The aerodynamics on that thing must have been fantastic.

Were there any requirements on what equipment has to be on the satellite? Looks like no on the little contract window. But sometimes I've had contracts fail because I forgot some stupid piece of equipment they wanted, like the seismic accelerometer. If you're sure you've accomplished it, you can always use the console menu to complete the contract.

Does that thing actually roll around with reaction wheel torque? If so... brilliant!

Big S wings do negate some of the weight penalty for adding more wings. But... they still add drag. Lots of drag. So while more wings will help you keep your nose on prograde and reduce body drag, you're paying for it with more wing drag (plus some extra mass). Huge wings may also get floppy, or require strut reinforcement. Keep in mind I was not pitching up anywhere near that far while the Rapiers were in jet mode - with a little wing incidence built in, prograde was just a few pixels below the dot. To build up maximum possible speed by the time the Rapiers cut out, the underpowered plane has to go nearly horizontal (with more powerful jets, I could have been pitching up further while climbing which would put my prograde higher). Then the plan is to turn on the rocket Rapiers (nukes are already on), grab some quick altitude by pitching up, and then ride the nukes the rest of the way. I could keep flying at prograde here, but if I did, my nukes would not be able to keep apo in front of me once the Rapiers give out. Yeah, this causes the plane to stick out fairly far from prograde, but I think it's a sacrifice worth making. And at least air is a lot thinner up at this stage. But the important part, I think, is that you're only lugging the oxidizer up to this point - then it's gone, and will not hinder you in spaceflight. And the work to bring the oxidizer this far up was done with comparatively cheap jet thrust. With more wing, you've got them for the duration. And I would not say it's carrying extra engine - I needed every bit of that Rapier jet thrust to get this thing up to 20km and 1300m/s. Even if you never needed to turn on rocket mode, I would still use Rapiers as my jet of choice - their high speed/altitude performance is much better than the Whiplash, for only .2 tons extra weight and a small ISP penalty. Put another way, for this project atmospheric efficiency was not very high on my priority list. The design process was more like, "can I still get this to orbit with more LF, and less of anything that's not LF?" But again, that's to maximize space range to the utmost limit. For craft that are designed to stay closer to Kerbin, I would probably emphasize atmospheric performance more heavily, such as with more wing, or a Panther/Whiplash to help get it off the ground and supersonic. Not saying a wingier approach can't work - I haven't tried it myself. But it is possible to get good space performance from a wing-lite design. And no doubt, for landing on Duna, the more wing, the better. One other thing - sounds like you may be heading this way already, but there is absolutely nothing wrong with using your nukes to help you to orbit. You're carrying them anyway, so it's like free TWR. Plus even at 20km altitude or so (which is when I usually start them), their ISP is much better than rockets. Plus, with a rocket powered ascent you may end up with more oxidizer than you need. But with nukes, you'll want all the LF anyway so there's no chance of dead weight. I would love to be able to ditch oxidizer entirely, and just transition from jets to nukes. Unfortunately this does not seem feasible with most designs on Kerbin, but you can ride your nukes hard and only bring a small amount of oxidizer for your Rapiers (often less than the capacity you have anyway in bicouplers and adapters). And on Laythe, it is quite feasible to go LF only.

Is the core rocket single stage to orbit? I don't use tweakscale, but I know in stock it's very hard to put any kind of payload into orbit on an SSTO rocket. I would suggest scandalously enormous, radially mounted LF boosters. That way you're still getting some of the benefits of staging.

I doubt you could make two trips without refueling, even with the nukes and the 22 ton-payload. That is, unless you add so much fuel it would likely not fit in a cargo bay. The nuke tug at the top has a delta v of 5192 empty, but that number is going to plummet once you attach the tug to its payload. See @Jarin's two nuke option later in the thread - it has only 1800 delta-v loaded. So the 4-nuke option will pack even less. But anyway, nukes are pretty much the superior option for heavy vaccum cargo hauling. I too don't really like them - they're expensive, underpowered, and don't work with half the fuel tanks (including anything in Mk 2). But that 800 ISP is such a huge advantage, sometimes you have to put up with them.

I've been working on an extreme range SSTO lately. What I've found is that, to maximize range in space, the plane has to be just, barely, capable of getting to orbit. It it performs well in atmosphere, then it's carrying too much dead weight for space. So you want just enough wing to fly, just enough control authority to stay straight and pitch up slightly, just enough nuke power to get you from jet shutoff to orbit, etc. For example, my plane can barely take off by hitting the end of the runway. Then I have to climb subsonic at like 5-10 degrees until reaching 4000 meters or so, then level off to hit the Rapier sweet spot. I also take the bare minimum oxidizer, and plan to run my Rapiers in rocket mode for only the bare minimum kick to allow my nukes to get me the rest of the way to orbit. So what I would try is iteratively removing engines and rocket fuel until you can just barely make it to orbit. It also looks like you have way more nacelles than you need, and way more air intakes. Those are probably adding drag and making your engines work harder. I would not be surprised if one shock cone could feed all the engines you need, but two would be plenty. If you need two Mk 1 nacelles per side, I'd suggesting looking at Mk 2 nacelles with the bicoupler instead. As far as landing gear, have you tried rotating them straight down using "absolute" mode? That usually fixes my issues. But with a 136 ton ship, you may just be overstressing them. Hopefully an engine diet will help with this too. Here's a pic of my non-ISRU unmanned variant. Has almost 5,000 delta-v left after reaching LKO. And here's an ISRU variant I worked on. Capable of getting to Minmus with 1,500 delta-v to spare. (I just forgot the ore tank).

Not totally sure I follow. This stuff should scale in that way - with half the payload, you can theoretically use half the fuel, and half the number of nukes, and end up with the same TWR and delta-v. In practice it does not work exactly like that, because you have to add probe cores, solar panels, etc., but it's relatively close if you don't build extravagantly. My suggestion (4 tanks plus 2 nukes) would obviously offer higher TWR than the 50 ton / 2 nuke option. It's partly a matter of how little thrust you can put up with. I personally refuse to go under about .25 for most non-ion applications, but that's not a hard limit by any means. If you go too much lower, though, you have to either burn well off the node (which hurts efficiency and accuracy) or split up your burn (which is putzy, and can have accuracy problems as well). Yep, you can. It's not going to very different than the Poodle option - slightly less thrust, comparable delta v to the Poodle (inferior ISP offsets lower weight). If in career, you're paying a lot of extra money for atmospheric efficiency you're not using, but if that's no big deal, the Dart is works fine for stuff like this. No gimbal on the Dart, but I'd imagine you have adequate reaction wheels anyway so this probably won't matter. The only significant advantage I see over the Poodle, though, is that the Dart is smaller physically. Though that can be a big difference if you're constrained by cargo bay size. In my Jool 5 I used a Dart in a Tylo descent stage, rather than a Poodle, for the sole reason that only the Dart would fit into my cargo bay. However, when form factor is not an issue, the Poodle is likely going to be better than the Dart for this kind of tug work. The Poodle's niche in this game seems to be hauling medium-ish loads to and from the moons. Plus the Poodle is cheaper and has gimbal. EDIT: one thing to add - you mention that the Dart "uses less fuel." Fuel consumption per second is not really meaningful in most contexts, because when the Poodle consumes more fuel, it's producing proportionately more thrust (and then some), which means you have to burn for less time. And unlike, say a car, KSP does not penalize you for flooring the throttle (at least in space). Stripped of math, specific impulse is basically the ratio of thrust to fuel consumption, so it captures what really matters about an engine's fuel efficiency. Of course, to figure out the right engine for a job, you also have to take into account the engine's mass, and thrust (to get the TWR ou need).

For a 22 ton payload, looks like another x32 tank and a Poodle could get you over 1500 delta-v, which is a little aggressive but ought to be enough with careful flying. Adding one more x8 tank might buy a little more insurance, though. Using one Terrier instead only buys you about 30 more delta-v, but TWR is pitiful, so I would definitely go Poodle. Or with nukes, you could do 4 Mk 1 LF fuselages and 2 nukes, for a delta-v of around 1800. TWR is around .3 which is workable. I tried a cross shape, with 2 fuselages inline and, the nukes and remaining 2 fuselages radially mounted. This would keep the rear node free for earlier stages. As far as round trips, keep in mind that you will use MUCH less fuel when the tug is not moving a payload, plus you can aerobrake at Kerbin. So return fuel usage can be quite minimal (pun intended).

Minmus may well be cheaper than the Mun. The ejection burn is a little more expensive, but the injection is cheaper. The bet difference is not significant. So if you have a system that works for the Mun, it should work here too. But lifting a 50 ton payload to the Mun should take a similar amount of engines / fuel.

Two Terriers might slightly beat out a Poodle in delta v, but your TWR would be quite low. Not even sure about that since you lose a little ISP. I would not do three Terriers, and certainly not four (Poodle beats four Terriers in thrust, mass and ISP). You could also look at the Dart as an in-between option vs the Poodle and Terrier. However, the heavier your payload, the more ISP matters and the less engine mass matters. Which is why nukes may make sense in this role, even though you're not going very far. If you're looking at a total mass of 70 tons or whatnot, another ton of engine for Poodle vs Terrier is just not that big of a deal. That's a long way of saying this will take a lot of fuel if you use any LF engine.

Other than nukes, your other major option would probably be a Poodle based rig. But with loads as heavy as 50 tons, nukes will likely come out ahead. Looks like you'd need more than half an orange tank to move 50 tons to Minmus. If and when you move into heavy rockets, I'd consider skipping the tug for Minmus runs and just building an upper stage with enough delta v to get there. But I'm lazy and try to avoid docking. Duna actually takes very little more delta v to reach than the moons, if you hit a good launch window. Especially if you aerobrake to avoid the capture burn. It's more expensive to return from, though.

I don't think you can really math this without simulating pretty much the whole game. Aerobraking performance depends greatly on the ballistic coefficient (is the ship long and skinny or short and fat?), mass distribution, available attitude control, heat tolerance of your parts, etc. Only rarely would I expect to survive pure aerocapture in a ship not designed for it, except probably at Duna. Since the atmosphere is so thin there, you can get low and spread the braking over a long time.

While delta v optimization is important for the big missions, honestly it's not where I'd suggest putting a newer player's learning resources at first. Since the Mun doesn't take that much to begin with, you can overbuild by a fair extent without running into the problems that plague super-size rockets. I think it's better to get a feel for what you have to do in terms of maneuvers and mission requirements, then go back and figure how to build a craft do that stuff efficiently.

Two suggestions to help for Mun landings. First, practice on Minmus first. It is a lot more forgiving, and if you can aim for the flats, you'll get a good landing spot. Two, set SAS to surface/retrograde from lunar orbit and leave it on until you've landed. You don't need to steer beyond that. It's not the only way to land but it's a good way, and then you only have to worry about the throttle.

Not sure, but only way to know is try. You could always make a copy of your save and skip forward. Aerocapture is a lot harder than regular aerobraking since you have to do it all in one pass. But if you can engine brake into an elliptical orbit, then you can take it nice and slow with multiple passes. You could also try getting gravity assists from the Mun and Ike to save some fuel for breaking. But it's not gonna be a huge difference.

I'd be most worried for the period when you had deployed one lander but not the other. But it it's tolerable then, cool! One bright side of the low TWR of nukes is your reaction wheels don't have as much work to do to stay centered. Unbalanced mass/thrust is one of my irrational pet peeves (which is actually a good idea for a discussion topic), so I may have gone a tad overboard in combating it. Plus, the giant bay adds to the "mothership" ambiance, I guess.

Thanks! At the end of the day, the ion lander probably did not save me all that much weight. The Vall lander had enough delta-v to do both Pol and Bop in one go, so the marginal mass cost of using it instead would have been just another 800 units of fuel (~4 tons - I had some empty oxidizer capacity in one of my adapters). That would also save duplicating the lander cans and so forth. But... the ion lander was just so perfectly suited to those planets, I couldn't help myself. I feel you on Laythe uni-taskers. Unfortunately, you really have to go Rapier on Laythe, and it's just an awful engine for vacuum flight. Putting wings on decouplers is one option to trim down the weight if you plan to reuse in vacuum only. I'm working on that concept with a ridiculous 4-kerbal, ISRU-capable rocket-plane hybrid that would land on each moon, with wings and jets rigged to detach after Lathe. Development thus far is... troubled though. The Mk 3 cargo bay arrangement was pretty much the only way I could come up with to hold everything together in a way that kept the ship from being floppy AND the mass aligned with the center so I could fly straight. That seems less problematic with only two landers, since for example, you could do one in front and one behind your ship. But that cargo bay was HEAVY (6 tons for the long version, and that was with some draconian cuts to the Tylo/Vall lander to keep it short enough to fit). But Mk 3 in general was great for keeping part count (and ensuing floppiness) low while still packing lots of LF to feed the nukes.

Ions might make sense for an upper stage, even if you use fuel cells for power. Their effective ISP is still tops. One you change planes, TWR ain't gonna matter much since you won't be hitting any celestial bodies. Nukes below that, probably. Agree a Jool assist will probably be of use.

I did a separate lander for Bop and Pol - tiny little ion-powered thing with ridiculous delta-v. In hindsight I probably could have skipped out on even sending the mothership to the outer planets, and gone Laythe-Bop-Pol-Laythe or something like that with the ion lander. I have honestly not found a great use for ions in any other situation yet, but cannot recommend them enough for Pol/Bop duty. Maneuvers are cheap enough you can just pack a couple batteries and an RTG and not have to worry about replenishing your electricity in realtime. And TWR was sufficient for those itty bitty moons. My mission report at:

Laythe can be done smaller than Tylo, especially if you go the plane route. But it likely takes a dedicated lander, wings can be harder to accommodate, and it's a little tougher to get a good landing spot. You can potentially combine Tylo and Vall landers on some fashion - my ascent stage on the former doubled as the Vall lander. Also worth noting you can potentially save mothership fuel by letting the landers do some of the transfers. E.g., skip Bop and let one lander do Pol and then backtrack.

Vectors must be very dense (see thread raging in the suggestions forum about the missing turbomachinery), but they're a little expensive for ballast.

I think that would work, as long as you keep track of everything. You could also try a near zero payload test craft. But at some point, a large scale dress rehearsal with the real ship is worthwhile, especially if the final mission is going to be in your "real"game with other stuff going on. I kept finding little issues with my Jool 5 over a couple run throughs.