Ideas on how to get this thing to Minmus?

[GregoryNeal]

Hello everyone, I'm not that great at designing rockets, seeing as how I'm still fairly new to the game. However, I have the Kethane mod and am trying to start a mining base on Minmus. My first attempt at creating a Kethane miner resulted in various types of explosions, mostly due to me not being good at moving my lander once it's already landed. So I've decided to switch to a rover that mines the Kethane, then I will send a lander to land in the rough vicinity, drive the rover up, dock to it, and transfer fuel to the lander. In the future I will set up a refueling station around Minmus. The problem is not docking, I can do that so long as I raise the landing gear on my lander:

I just can't think of a way to get my rover to Minmus, I've tried various rocket designs, including this thing (my rover was attached instead of the tank):

This launcher works up until about 10km, where it folds up like a lawnchair, each rocket crashing into its opposite. It's quite a spectacle. Anyway, I just want to hear about any payload delivery systems anyone would find useful for this particular craft. I've been trying to get it up for about 3 days to no avail. Here are some picture, I do not want to modify the actual rover in anyway, however, I don't mind attaching things to it as long as they are decoupled before or after touch down.

I look forward to any ideas you guys may have!

Edited October 6, 2013 by GregoryNeal

[capi3101]

What's the mass on that rover?

You could try something like what I did on the Storax Sedan mission - two four tonne Hellhound 7 rovers, attached radially on either side of a skycrane using LV-N engines. Did a test run of the system to Minmus first, actually; was able to land directly on the engine bells. Pics of the Hound here. You probably could do something similar, with the bonus of having a second Kethane miner available to you.

Seriously, what's the mass on that rover, and where are all its available attachment nodes?

[Captain Sierra]

Yes, grab a part and then take a pic. If we can see the nodes, that opens our eyes to mounting options. Looking at the design, you could probably build another plate underneath it on a decoupler and then add engines to make a hovering platform that it can decouple and drive off of once landed. But seriously, mass please. You might be able to get away with 2 LV-909s but 4 for safety never hurts. Avoid NERVAs if you don't feel like irradiating the planet

[GregoryNeal]

Okay, the rover is 7.98 tons, 68 parts. Here are the available nodes:

Sorry about the wait, I was trying to dock my lander

[Sirine]

Is a milestone for you, try overcome it. Post your .craft file we show you how its done.

[JiWint]

It's just too big.

Gravity on minmus is so low,that you don't even need a lander to land,and get in orbit again

[Spyritdragon]

I advise the good ol "put it on top of a rocket " sollution. Find anything that can get it to orbit. Heavier stuff has been lifted to Kerbin orbit, so try a two-high asparagus followed by one more jumbo, and see if that works. Make sure you attach a docking port to your final jumbo. Once you get to orbit, dock a fuel tug with it, refuel, and off you go :-). For Minmus, you won't really need very much to land and lift off again - a very small skycrane on your rover will do the trick.

[Technical Ben]

If it's too unbalanced for 1, send 2. I'm sure a rocket of around ~160 parst (so and extra 30?) could send 2 rovers (the other ~130 parts) to minmus. Or less.

PS, I can see at least 2 struts that are redundant, so you could shave some partcount from the rover too.

Edited October 5, 2013 by Technical Ben

[Xetalim]

Put it on top of a rocket and make sure the CoM is exactly above the attachment node.

[boomerdog2000]

You could probably attach it to the rocket radially from the node on the bottom of the rover. Or if you don't need 2 rovers attach a fuel tank of approximately the same mass on the other side to balance out the rover.

Edited October 5, 2013 by boomerdog2000
confusing

[Captain Sierra]

I advise the good ol "put it on top of a rocket " sollution. Find anything that can get it to orbit. Heavier stuff has been lifted to Kerbin orbit, so try a two-high asparagus followed by one more jumbo, and see if that works. Make sure you attach a docking port to your final jumbo. Once you get to orbit, dock a fuel tug with it, refuel, and off you go :-). For Minmus, you won't really need very much to land and lift off again - a very small skycrane on your rover will do the trick.

THat's orverkill. I use a 6 asparagus with the equivalent of 14 orange tanks and that can orbit 60 tons easy. He could get away with onion staging with 2-4 boosters max.

[capi3101]

8 tonnes? No problem. I haven't got time to work on a design right this second but I'll attend to it this afternoon.

My first instinct is to use that attachment node on top of that green thing on top of the lander can (I assume that's a Kethane storage tank. The docking port is another possibility, though those big I-beams might make that problematic.

I say that...actually, I'm beginning to think of how you might be able to use them to your advantage in the overall design.

[capi3101]

Okay...mission profile is to safely land eight tonnes of rover on the surface of Minmus. Actually, let's make that sixteen tonnes of rover; the best counterweight for a rover is an identical rover. No return necessary - so 4550 for the launch, 920 for the intercept, 80 to orbit and 240 to land, a total delta-V of 5,790 m/s, with the bulk of that needed for the launch. Surface gravity for Minmus is .491 m/s^2; we'll need that for landing TWR purposes. Kerbin's gravity is, of course, 9.81 m/s^2.

We could probably do this in two bits - a transfer and landing stage and a booster. 1,240 for the xfer-lander is fairly trivial.

Payload (16.0 t)

Lander/Transfer Unit

1x RC-L01 Remote Guidance Unit (0.5 t)

4x Z-100 Rechargable Battery Pack (0.02 t)

4x OX-STAT Photovoltaic Panels (0.02 t)

2x Stratus-V Roundified Monopropellant Tank (0.47 t)

8x RV-105 RCS Thruster Blocks (0.4 t)

4x BZ-52 Radial Attachment Point (0.16 t)

2x TR-18A Stack Decoupler (0.1 t)

4x LT-2 Landing Strut (0.4 t)

2x LV-N Atomic Rocket Engine (4.5 t)

2x FL-T100 Fuel Tank (1.125 -0.125 t)

1x X200-8 Fuel Tank (4.5 - 0.5 t)

Landing TWR: 8.41, delta-V: 1,482.638 m/s, full mass: 29.045 tonnes.

The X200-8 is your base unit. Attach two of the BZ-52s to the sides as low as you can get them, then stick the decouplers on and attach your rovers to them via their docking ports. Place the girder below the X200-8, with the Adapter below it. Stick the other two BZ-52s either side of the girder and attach your FL-T100s and then the LV-Ns to them; the Adapter is what will connect the rest of the ship to the booster (along with a copious amount of strutting; struts are going to be your friend with this design). You might get away with only four RCS blocks - my intent there is only to give you steering authority after SECO on the booster prior to Kerbin orbital insertion. And the legs might not be long enough to reach the ground with those LV-Ns attached, so get used to the idea of trying to land on the bells (its possible, just tricky; the legs will give you something to land on when the engines snap off). Rest of it's utility pieces, of course.

So now we go for the booster:

Payload: 29.045 tonnes

4x RV-105 RCS Thruster Blocks, as low as you can get them in the central stack.

7x Rockomax "Mainsail" Liquid Fuel Engine - one center, six outboard

14x Rockomax Jumbo 64 Liquid Fuel Tank - one center, six outboard, do NOT run fuel lines

7x Rockomax X200-16 Fuel Tank - one center, six outboard, in the middle

7x Rockomax X200-8 Liquid Fuel Tank - one center, six outboard, on the bottom

Launch TWR: 1.62, delta-V: 4544.749 m/s, full mass: 657.745 tonnes.

Struts, struts and more struts.

The delta-V I listed does not count for the change in TWR, so the booster will actually have more fuel than it needs. It's an SSTO rocket, which means if you do switch the design in favor of asparagus or even onion, you'll get even more delta-V out of it. Leaving it as is (an SSTO), you need to watch your gee meter as you ascend; throttle back as it climbs out of the green - you'll need to do this a couple of times. Orbital insertion probably needs to be done at no more than one-third throttle.

Good luck; I hope it goes well. DISCLAIMER: I am not responsible for any UVDs you may experience with any of my designs, nor am I liable for personal injury or physical damage that may occur as a result (virtual and/or actual).

[GregoryNeal]

Haha, thanks for all of the replies everyone, I've tried a couple of designs, one of which blew up almost immediately. I'll post some pics when I actually get one to work. One question though? What's onion staging? I do asparagus staging on all my rockets, but I've never heard of onion staging.

[capi3101]

Onion's a form of parallel staging, kinduva mid-point between serial staging and asparagus. You set up three of four stages in concentric rings around a centerline engine, and run fuel lines going progressively from the outer tanks towards the center. When you stage, you shed off the outer ring, until you're left with just the centerline engine. Onion provides more delta-v than serial staging as a rule and like asparagus lets you use all your engines from the get-go, and is easier to set up than asparagus, but does not provide the same kind of smooth thrust curve as asparagus and produces less delta-v than asparagus.

[GregoryNeal]

Kind of like this?

The fuel lines run from the outside to the inside so that the outer 4 rockets get jettisoned when they run out of fuel. Then it's just left with the payload on top and a transfer stage.

[capi3101]

Yeah, that's onion. That one blew itself up on you, didn't it?

That design might've worked with MOAR STRUTS. Run between the corresponding tanks on each side, one from the top of each tank to the center for starters.

[GregoryNeal]

Nah, that specific one didn't blow up, however, I used this design with my kethane rover and it blew up. I don't know why this one didn't, the only reason I made it was because I was frustrated with the rest of my designs and just threw it together in a fit of rage. I must try that more often

[xoknight]

I did it within an hour of, designing, flying, and landing this this thing with a 8 ton cargo. The whole rocket weighs 700tons at lift off and the lander can carry RCS, Fuel, 3 kerbals (more if you modify it), tested 8 ton cargo hold/rover lander.

To dock the rover to the docking port, de-extend the landing legs.

-I did use mechjeb

Rocket/liftoff:

Cruising stage(to Minmus):

Orbiting Minmus:

Landing:

Landed:

Releasing 8t cargo load:

If you want the download link, tell me and I'll put it up

Edited October 6, 2013 by xoknight

[GregoryNeal]

Okay, I'm in the middle of the flight. The first thing I did was fiddle with the CoM, it mostly just required me to move the drills back some, but I also did some more testing. I decided that it needs a roll cage of sorts. So I built one out of the structural plates. Once I got the CoM where I wanted it. I strapped some rockets and RCS on the side. Then I attached the orange tanker with a smaller fuel tank underneath some mainsails. Here are a couple of pics I've snapped so far. I'll get more when I've gotten closer.

Here is one of the actual redesigned rover. Sorry it's kind of hard to see D:

[GregoryNeal]

I did it within an hour of, designing, flying, and landing this this thing with a 8 ton cargo. The whole rocket weighs 700tons at lift off and the lander can carry RCS, Fuel, 3 kerbals (more if you modify it), tested 8 ton cargo hold/rover lander.

To dock the rover to the docking port, de-extend the landing legs.

-I did use mechjeb

Rocket/liftoff:

Cruising stage(to Minmus):

Orbiting Minmus:

Landing:

Landed:

Releasing 8t cargo load:

If you want the download link, tell me and I'll put it up

Oh wow nice. No thanks on the dl link I like to learn as I go. I'm fairly positive my current attempt will fail due to the fact that I think I'll run out of dv before landing. Any tips on how to get to Minmus orbit efficiently from Kerbin?

[xoknight]

Multiple options for an efficient launch

1. Use multiple launches carrying multiple parts of the lander and land it on Minmus and assemble it there.

2. Use multiple launches carrying multiple parts of the lander and dock it in orbit and send it to Minmus.

3. Use a big launch stages (like the rocket I posted), and make it able to get the lander into a 100km Kerbin orbit with just the launch stage.

4. Use mech jeb

[Specialist290]

The Oberth Effect is your friend here. (Don't worry too much about the math on that page; you won't really need it for a simple Kerbin - Minmus transfer.) Get your craft into a low orbit -- like 70 - 80 km low. Then plot your maneuver node for your trans-Minmus injection burn from that orbit. Target Minmus so that you can see closest-approach markers, and adjust your course using those as a reference until you get an intercept. You can drag the node around the orbit and tweak the values a little until you get it as close to ideal as your patience will allow. (Don't forget that Minmus itself is slightly inclined.) Once you're in Minmus's Sphere of Influence, wait for periapsis again, then plot a capture burn that'll put you in an orbit with a new periapsis close to the surface. Circularize there, and you can effectively pick your landing site from orbit.

I'd also advise you to familiarize yourself with a concept called "delta-v," if you haven't already. These pages at Atomic Rockets do a good job of explaining it, and these three articles are written to help players apply those concepts specifically to KSP. Knowing your craft's delta-v capacity is helpful, because it allows you to use charts like this one to show you how much "oomph" you need at a minimum to get your craft to a certain destination.

You can run the delta-v calculations for your rocket by hand, of course, but doing that over and over again gets tedious. There are mods like Kerbal Engineer Redux (my personal choice) and MechJeb, which will both display delta-v information for you to use while you're building your rockets and while in flight.

Hope this helps

[GregoryNeal]

Awesome, I'll be sure to try and implement these ideas in a little bit. I totally botched my Minmus intercept, ended up orbiting Kerbin a couple of times before I decided to use my remaining dv to crash into Kerbin. However, right as I passed my Kerbin apoapsis, my trajectory said that I was going to figure 8 around the Mun and Kerbin, and was heading for a Kerbin escape trajectory. This gave me the idea to try and land her on the Mun instead of killing Jeb. So I did. I'm going to retry my mission to Minmus with a Beastagon mk3, I'll make it a fair bit heavier to keep it on the ground, I'll add ASAS for flipping control (I flipped a lot during this drive, but survived them all), and a larger wheel base. I'll just take this landing as practice, and eventually set up a Kethane outpost in Munar orbit since I've already landed the damn rover. Thanks for all the advice, I think I have enough suggestions from everyone to successfully get to Minmus! here are some pics of my excursion.

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[Specialist290]

Nicely done! Keep at it -- you'll get there eventually, I'm sure.