Put the rover above the command module and really.bolt it down with struts?
Interesting idea. Not sure how I would get it to the ground when I land on the moon?
I hadn’t looked properly, so I assumed the rover had its own flight equipment.
Did you intend to hover above the ground,.drop off the rover, and then land nearby? If so you could still do that.
Or give it some weak thrusters, set them at whatever thrust is almost hovering, and have them activate when you decouple it. You can then land the main ship, then context switch over and bring it down?
I had not thought about giving it thrusters. My plan before, was just as I’m about to touch down, decouple to drop it, then land nearby. I really, I just don’t have a damn clue what I’m doing. I desperately want to do all this science in every biome on the moon, so I was trying to make some kind of craft that could land gather science, drive to a rock and bore into it with arm, then take off minus the rover, land somewhere else and repeat. But I just can’t carry or keep enough fuel to do all that. I also feel like I’m at a point of diminishing returns when it comes to adding engines and fuel. So if I barely get there and do one touchdown and barely have fuel to get home, I spent a ton of money on an advanced craft that does almost nothing more than the super basic craft I’d made weeks ago that could land on the moon. I think my creativity is exhausted, maybe partly because I’m exasperated by my current condition post operative, plus this crappy liquid diet I’m stuck on until things heal.
In-situ resource extraction does solve that to a degree, but by time you’re there you don’t really have a need for it. It’s one of the major weaknesses (imo) of the kerbal campaign.
You can’t really biome hop on the Mun without tons of delta-V because the biomes are too big, the gravity is too strong, and the biomes aren’t obvious from the ground. Minmus is a better bet for that because you can actually biome hop there with just a Kerbal jetpack. Also, almost any rocket you’ve built to get to the Mun will also get you to Minmus (it takes slightly more delta V to reach Minmus, but its gravity is less so it take less to establish orbit, land and take off. A trip to Minmus is actually usually less total delta-V than one to the Mun.) And the science there is worth 1.33x what it is on the Mun.
Also:
- You have too many thrusters on your upper stage. You probably don’t need a Mun-relative TWR of 10, and it will be hard to control.
- If you run a bunch of struts from your lander down to the main booster, it would probably stabliize the whole thing.
- Use a stack separator instead of docking ports to decouple the rover. (Unless you plan to re-dock it.)
- With the reaction wheel on top of the lander (and the Thuds’ thrust vectoring), you probably don’t need RCS thrusters, nor the monopropellant tanks.
- You can land directly on those Thud engines. And they’re widely spread so you have plenty of stability. You don’t need the landing legs.
- You should also asparagus stage your boosters, which would net you several hundred extra dV. Feed two of the outer boosters into the other two and stage those away first, then feed the remaining two to the central booster. Run all 5 engines in the 0th stage. You might even be able to replace the outer Mainsails with Skippers if you do that, which would save you a bunch of money.
Wow that is awesome advice/information! I was really feeling vexed about this whole project but am invigorated to give it another go.
The thrusters on the upper stage you mention. Are you referring to the Thud’s? If so, maybe go with 3 and limit their thrust?
Yeah the Thuds. 3 is probably enough, but I never limit thrust on anything but the solid engines, since you have control of liquid fuel engine thrust during flight. I think that capslock which gives you fine control over pitch/yaw/roll, also works for thrust too.
2 more questions for you if you don’t mind:
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Does where you place a reaction wheel on your craft matter? I just assumed it gave you extra control, but now I wonder if where it’s located makes a different to how well it balanced that control.
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The payload fairing currently goes up and over the capsule. Does it need to do that? Is there a way to terminate it right after the Thuds? (of course if I put rover on top it will need to go all the way, but until then am wondering for future designs)
No problem:) My 500+ hours of this game has to be useful for something:)
Reaction wheel torque is localized at the location of the reaction wheel, i.e. that’s where they’ll try to rotate the ship around. I tend to put them at the top of my boosters. It’s only an issue when you’re trying to rotate the whole thing in orbit when not under thrust. You’ll have to see if it’s controllable or not. (If not, that’s a good use case for RCS thrusters.)
You can do interstage fairings. Supposedly they’ll terminate at any cylindrical surface. I haven’t tried this though and don’t have any experience with it. Also note that you can enable interstage nodes on the fairing (button when you right-click the part), which will allow you to secure small parts (like your rover) directly to the fairing truss rather than to the rocket.
Just to add to the advice already given: a.mun rover takes FOREVER to get between the biomes, and it’s quite difficult to drive it over all of the rocks and crevices during time acceleration.
To get all the biomes you could send up a bunch of tiny satellites that are able to land and then take off agaib. They don’t even need to establish orbit, as you could have the Kerbal powered rocket with lots of juice scoop them all up. Thought the further away from an equatorial orbit you get the more tricky that becomes.
Or just antenna back all the results. Obviously that doesn’t work for things like goo.
But yeah: definitely raid minimus for the science!
I came up with a newish design based on the old one which I really really like. Slightly smaller rover with no science but an arm (science is all on lander). Problem is it is it keeps pitching over on itself (head comes down). As the fuel tanks get lighter the pitching gets worse faster.
How might I correct my design for that?
I can’t even get to Aspy stage because it crashes, but I also fear I’ll have to un-asparagus because I’d imagine going from balanced 4 engines on outside to just 2 will further unbalance.
In this design to save weight and space I didn’t even add an “advanced inline stabilizer” since it said the 3-man capsule has one built in. Is that a problem?
Add steerable fins. The design gets top heavy as the fuel depletes and there’s no drag at the base to keep it from flipping over. The Mainsails only have 2° of vectoring, so can have trouble correcting for flip.
Well, the capsule has as much torque as the Advanced Inline Stabilizer, but it might not be enough. Once you get into orbit, with just the capsule torque it might take a realllyyyy long time to turn your ship, and you might have some trouble correcting overshoot. To be safe, you can add RCS nozzles (and monoprop tanks) to the top and bottom of your central booster to assist with turning it. RCS can also help your ship stay stable during ascent.
Nope didn’t work. The odd thing is it always starts tipping to the left. But that seems impossibly weird as I have the craft perfectly, symmetrically balanced (as much as you can with a little rover packed in).
Another odd thing. Since I used the Probododyne Rovemate as a base for the rover, it seems like it’s fighting me a bit as I go into space. I told it to go into hibernate mode and it keeps waking itself up.
One other thing to try, move the booster rockets up the craft, and use docking clamps to stabilize on the pad. Basically try and move the center of lift further up the rocket. The further the center of lift and center of gravity are, the more leverage any perturbance in weighty distribution has.
Whoa OK something really bizarre. So I did everything you all suggested and its still going wonky but I noticed my navball orientatation isn’t right. So while about to go askew I right click my command module and choose “control from here” and the navball snaps back into correct orientation and things are slightly more steerable. What is going on? What is taking precedance over everything else? If it because I built this not starting from the command module but from something else? How do I make my command module the controlling thing so I don’t have to right click and do that every single time I go to launch? I think this has something to do with my docking ports, or the rover which has a command seat but is also a probe.
Yes
You can change the command module to be the root part. You have to click on the “Root” button in the editor gizmo bar (top left of the screen next to the part bar.) Then click any part of your ship that’s not the command pod. (This seems nonsensical, but I believe is intended to allow multiple subassembly hierarchies or something.) Then select the command pod.
Probably this one, or maybe a docking port. The RoveMate core has a control point facing forward, if you use it to build a rover, so if it’s in command, the navball would be facing the horizon rather than facing the sky on the launch pad.
Thank you all !! :)
This was like a murder mystery. I couldn’t figure out why I kept banking to the left when I was trying to do a gravity turn to the right especially with everything well balanced. Then all the controls seemed to just not respond like they needed to. The Navball looked different but I figured my brain was fried from surgery. But re-rooting to the command capsule, the navball is back to normal and and the rocket actually responds like normal. So looking back at it, I was trying to drive the rocket from the rover which was suspended flat and it’s orientation was of course not in sync with the cardinal directions I was used to. All the tippiness was not because it was way too heavy up top… it was because my gravity turns from the dumb probey rover was taking my commands and messing them up.
Off to the Moon now. Yeehaa!
@jpinard Another trick I’ve used in the past to save a flipping rocket design is to turn off the top fuel tank until you get a bit higher in the air, making the fuel from the bottom get used first. Then turn it on when you need it. This has the benefit of leaving the top of the rocket heavy, which helps keep it flying straight…