Large Fuel Tanker Rover - How Do I LAUNCH It?

[Srpadget]

I'm finally going to poke a bit at the ISRU system. And because I'm such an incurable overdone-infrastructure builder, to me that means a permanent mining/refining rig base[1], a tanker lifter to haul fuel from surface to orbiting fuel depot, and a tanker truck for servicing the tanker lifter from the refinery's storage.

And that means: a rover. A *big* rover. Built around an orange tank and a 2.5m monoprop, methinks. With (ugh) Das Klaw to take the place of proper fuel hoses since I want to restrict this to stock parts and I have NEVER managed to successfully mate 2 docking ports on the ground.

But THAT, in turn, means dealing with the perennial problem: How the HECK do I get the dang rover A) from the SPH to LKO and from low Minmus orbit down to the surface? The wheelbase of my first design is substantially wider than a Mk 3 cargo bay, and (esp if I launch the thing empty, which seems sensible) its CoM is notably off-center for a vertical rocket launch. Not to mention that the axial attach nodes are kind of inaccessible due to fripperies like the claw, command seat, and so forth.

I have never used rovers. Mostly because of the transport-to-destination issue. And now I'm going to have to design (and transport) two different types. (The other, of course, is a prospector with a surface scanner.)

I am tempted to launch and land a "dummy rover" that has all the parts, but "packaged" for ease of transport, then swap it out with the "real" rover after landing and claim the wheels were deployable/reconfigurable. But that feels like cheating to me and I'd like a better solution.

So how DO you competent rover users manage to get your larger creations to their destinations? (I'm asking you successful designers to show off your creations. I trust you won't disappoint...!)

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[1] Yes, I know; it's more efficient to haul ore to orbit than the refined fuels. Personally, I consider that a glitch in the game mechanics and Just Wrong. But regardless, it makes no difference to my core question whether the tanker truck is loaded with fuel or ore. I still gotta launch that puppy.

[Starhawk]

Here's a look at how I dealt with some of the issues.

Docking on the flats is easy.

As far as launching goes, I just used structural panels to balance the weight of the wheels and a fairing to contain it all.

Happy landings!

[GoSlash27]

srpadget,

This seems to be what you're looking for...

yes, believe it or not, this would actually make orbit back then. As would the individual rovers. Flying cars, yo!

These ones went to Eve (hence the parachute packs).

This is from way back in "souposphere" aerodynamics. You could do something similar now with a shroud.

Just lift the rovers in a stack, transfer them to the mass mover as payload, and detach/ deorbit them at the destination.

The "Tylo rover" concept was an all-in-one descent stage, tanker, hauler, bulldozer, exploration vehicle, and ascent stage.

Best,

-Slashy

Edited September 7, 2015 by GoSlash27

[I_Killed_Jeb]

Just launch it vertically inside a fairing. Post pics for us to give more specific advice, but being a bit off center due to wheels is usually very easily overcome with reaction wheels and thrust vectoring. Also, launch your rover empty or mostly empty and the transfer stage mass will just dwarf the payload

[Randazzo]

I usually rotate the vessel so the wheels are eastward facing (towards the open bay doors), that way the slight weight imbalance simply helps with the gravity turn instead of pulling your rocket in weird directions. You can also just roll after lift off, if you want to do so.

[Srpadget]

Starhawk: I assume you landed that tanker vertically, directly onto the Poodle's nozzle, and then used reaction wheels/RCS to tip it over onto its wheels? (A technique which I've used in reverse to right a tipped lander on Minmus...not that I have EVER tipped over a lander on Minmus, of course...).

I'd seen your ISRU setup during my search of the forum archives, and had wondered what the structural panel "winglets" were for. BALLAST for counterbalance, ingenious!

I'll post pics of the designs I've come up with so far, but it will have to be later.

[Starhawk]

Starhawk: I assume you landed that tanker vertically, directly onto the Poodle's nozzle, and then used reaction wheels/RCS to tip it over onto its wheels? (A technique which I've used in reverse to right a tipped lander on Minmus...not that I have EVER tipped over a lander on Minmus, of course...).

I'd seen your ISRU setup during my search of the forum archives, and had wondered what the structural panel "winglets" were for. BALLAST for counterbalance, ingenious!

I'll post pics of the designs I've come up with so far, but it will have to be later.

You are correct. The one other thing is that there is a Vernor engine under the 'nose' of the tanker to allow it to lift off when full. The RCS thrusters used for docking are too weak to lift the full tanker, even on Minmus.

Looking forward to seeing what you come up with.

Happy landings!

[tbarcello]

Here's a look at how I dealt with some of the issues.

Docking on the flats is easy.

http://i.imgur.com/GKJayto.jpg

As far as launching goes, I just used structural panels to balance the weight of the wheels and a fairing to contain it all.

http://i.imgur.com/EUV85yS.jpg

Happy landings!

Can't get enogh of this mining outpost. So hassle-free.

Are you doing any serious roving on minmus, or is it just for docking purpose? If you do, how is this rover tank performance on slopes?

My rover Mun base was doing terribly on slopes.

Off topic though...

[Starhawk]

Can't get enogh of this mining outpost. So hassle-free.

Thanks.

Are you doing any serious roving on minmus, or is it just for docking purpose?

Naw, it's just for docking. Those wheels were used because the better ones weren't available yet in my career at the time. I wouldn't try to do any serious roving with those ones.

Happy landings!

[I_Killed_Jeb]

Launched like this:

And when landed, it looks like this:

Pretty straightforward. My Mun base was delivered via skycrane and surface docked

[Superfluous J]

The trick is to launch it vertically, under a fairing, and to use the offset tool (hotkey 2) to slide the rover so the total COM of the launching rocket is as close to vertically over the COM as possible. You *can* eyeball it from overhead but I would suggest installing RCS Build Aid, which is misnamed because it works on thrust as well. A reaction wheel or two can only help.

Your rocket will be a bit squirrely in atmo but you can mitigate this by filling that orange tank with fuel so the rocket's top-heavy in the lower atmosphere. Then pump the fuel backwards once you need it for a stage.

[tbarcello]

Launched like this:

http://i.imgur.com/rCJQUdi.jpg

And when landed, it looks like this:

http://i.imgur.com/sgQzoCe.jpg

Pretty straightforward. My Mun base was delivered via skycrane and surface docked

http://i.imgur.com/bSUe7x9.jpg

Smaug on Minmus!

[Coyote27]

I usually rotate the vessel so the wheels are eastward facing (towards the open bay doors), that way the slight weight imbalance simply helps with the gravity turn instead of pulling your rocket in weird directions. You can also just roll after lift off, if you want to do so.

Well, the other way to deal with a weight imbalance is to use the rotation tool to tilt the whole thing on its decoupler until the CoM is lined up with the central axis. I'm not sure if this is more wonky or less than other ways of dealing with it, but you can get away with surprisingly asymmetrical payloads this way.

[Sharpy]

My approach: launch two.

[Superfluous J]

My approach: launch two.

https://dl.dropboxusercontent.com/u/3152580/sshots/2015-07-31_00004.jpg

Why launch 1 when you can launch 2 for twice the price?

[tbarcello]

My approach: launch two.

https://dl.dropboxusercontent.com/u/3152580/sshots/2015-07-31_00004.jpg

Dat claw!

[Geschosskopf]

Here's a 2.5m tanker rover with the huge rover wheels. I sent it up with using a 5m rocket (including the fairing) from Space Y Heavy Lifters. Even so, the fairing was way wider than the 5m rocket which caused stability problems. This necessitated rather large fins on the lifter (delta wings with control surfaces). After the deorbit burn, it landed with just chutes, no rockets and ended up about 12km short of the ISRU base so had to drive over. Because it didn't use rockets on the way down, it didn't need a right-angled probe core for the landing.

[Srpadget]

Because you guys wanted to see them, here are my tanker truck designs to date.

First, the one that inspired me to start this thread:

Note the nice wide stable wheelbase...which is going to be dang hard to wrap a reasonably-sane fairing around. Not also how I've cleverly stuck pieces above-center in both front and back in an effort to balance the CG shift caused by the wheels..."cleverly" here meaning "in a way that makes it basically impossible to attach to a launcher"....

Then I went to a clean sheet design, and came up with this aesthetically-pleasing design:

I think this one is actually quite attractive. But sadly, it is if anything an even HARDER beast to launch. I also gave up the Klaw, and thus this design requires I get the docking-port placement exactly right for all components of this refueling system, plus master the art of docking while driving. I managed to dock two of these on the flat grass near the runway, so the "docking while driving" seems doable if I get the port placement sufficiently exact on my refinery and tanker rocket.

After reading the first few replies here, I was inspired by an idea for ballast/counterbalance using USEFUL AND NECESSARY MASS. YAY! And that led to the third iteration:

That RCS tank is placed exactly right, loaded with just enough monoprop, that the CG of that vehicle does not budge as the main tank goes from empty to full. Which I figure means it's close enough to centered that a conventional vertical launch will proceed normally. plus there is nothing on the back end except a taillight, so integration onto the launcher just consists of "slap a decoupler on there and wrap a fairing around it". And not one part on there is serving JUST as ballast/counterweight, seeing as I was going to have to stick an RCS tank on there anyway.

I'm rather pleased by that last. Though I am tempted now to take what I learned and go back to a variation on Concept 2, get it balanced properly, and figure out how to add an aesthetically-pleasing mounting point to its back end to allow a vertical launch. Because that would look SO COOL driving around the refinery base....

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EDIT: Well dang. The forum host doesn't seem to like my Dropbox public links. I may be forced to get a Photobucket account. :-/

EDIT 2: Photobucket appears to have done the trick, yay!

Edited September 9, 2015 by Srpadget

[Superfluous J]

Try imgur. Free, easy, and the forum has support for it via [noparse][imgur][/noparse] tags.

Regarding your tankers...

#1's rough because both ends have something on them, making it harder to mount vertically. I'd put the chair on top and drop the ladder. You'll never use it on Mun or Minmus anyway Then I'd mount it claw-up on the top of my rocket, maybe with a disposable engine for the transfer stage, attached with a docking port so you can detach it but it'll suck the fuel from the tanker itself.

#2 I like the look of, and it's got that docking port right there to stick on the top of your launcher/transfer vehicle.

#3 will mount very well, and will need very little COM shifting.

In all three cases, you'll need to strut the rover to the fairing, which can be a chore. The game doesn't technically support it though it works like a charm. You need to get the fairing all set up correctly, and then attach girders or something to stick out from the rover, through the fairing. Then run a strut from your rover to the girder so the strut goes THROUGH the fairing. Then, remove the girder, leaving the strut there with nothing to connect to. Then, save the craft, an reload it. Bam, your struts will be attached directly to the fairing, making your payload VERY stable.

Once the fairing's gone, the struts will remain (which is a sign Squad never intended this to work) but if you have them on decouplers you can toss the decouplers after you ditch the fairing and all's good.

- - - Updated - - -

I launch a "ship" that is a lot like what you're trying to do only about 3x bigger in my series. Check out the below video, and especially 8:05 on, where I launch the beast into orbit.

At about 10:15 I ditch the fairings and you can see how I used struts and a decoupler, like I described above.

Edited September 9, 2015 by 5thHorseman

[Srpadget]

Oooh, I like your strut idea! Especially the bit about attaching them to decouplers--I've always thought used strut stubs attached to a craft were unsightly.

I didn't get around to revamping Number 2 (which I also think is by far the most attractive of the bunch) today. Maybe tomorrow. Today was the prospector rover, an itty-bitty thing that I don't expect to give me any trouble at all packaging for launch. (Heck, at just about a half-ton it could practically be THROWN into orbit!)

It's a bit short on solar panels; the wheels suck down more power under acceleration than the panels can reasonably recharge during coast. And it'll doubtless have traction/stability issues in spades in Minmus's feeble gravity. But I'm pretty pleased with it as a first effort. And judging by Val's grin during her test drive, she approves of its handling. (Not sure "Jeb and/or Val approve of its handling" is necessarily a GOOD thing, mind you!)

Edited September 9, 2015 by Srpadget

[-Velocity-]

Well, I just usually launch my rovers naked to the atmosphere. It's not like they'll burn up or fall apart. Just center the rocket under their CoG and away you go.

Oh and yea, it's kinda silly to make rovers that don't include their own rockets for landing and ascent. Make every rover capable of landing and ascending back to orbit. There is no real point in not doing so unless you can't imagine any need for the capability (or doing so is almost impossible, such as on Tylo). On low gravity worlds, it's very, very easy to combine the functionality of a lander and rover into one.

Anyway, I don't get why you need a rover at all? The ore never runs out at any location. Because Minimus has low gravity, you can vertically land and dock even "mothership" class vessels to your permanent surface base with a vertical docking port. I use a 2.5m docking port surrounded by a cone made of wing panels, which (rarely, because I'm usually dead-on) helps guide me in to a successful alignment (but it's nice to know the cone is there in case you're a little off). To help hold the ship upright when the base is not on perfectly level ground (it's not needed on Minimus though, because of the flats), there are a set of landing legs surrounding the cone which can grip the docked ship. Here's one of my "motherships" docked to my Ike refueling base:

Besides the convenience and time savings- you entirely skip having to use middleman tankers because you can land and dock even the biggest vessels vertically at your refueling base- it's really fun to bring your big vessels in for a vertical landing at your base.

And it's not really as hard as you might think. Basically, you just come down over the base, then go into a vertical hover/slow descent, and use RCS to align to the dock (vernor engines or whatever they are called can be helpful for really big vessels).

Edited September 9, 2015 by |Velocity|

[Superfluous J]

Anyway, I don't get why you need a rover at all? ... Because Minimus has low gravity, you can vertically land and dock even "mothership" class vessels to your permanent surface base with a vertical docking port.

While not as hard as some may think, it's not as easy as all that. Perfecting the process took me far longer than it took to learn just basic docking, and unlike basic docking you don't have any appreciable way to stop and take stock of the situation during a vertical dock, unless you can land the ship to the side when you need a breather. And any mistake - unless you f5/f9 of course - could destroy your base.

A rover with a claw or well-placed docking port is far less trouble.

[Srpadget]

Anyway, I don't get why you need a rover at all? The ore never runs out at any location. Because Minimus has low gravity, you can vertically land and dock even "mothership" class vessels to your permanent surface base with a vertical docking port.

I think you may have mis-worded that statement slightly. You meant that YOU can vertically land and dock. Me, I'm doing well (even on Minmus, where everything is easier) to make a first landing within a kilometer or so of the intended target, then make another hop to get under 100 meters. Vertical docking in even a feeble gravity field? For me to pull that off would not need piloting, so much as dark rituals involving the sacrifice of the ship's engineer to the Kraken.

And, to be honest, I *did* start the original post with the admission that I'm addicted to overdone infrastructure building. So to me, the whole "fixed refinery, tanker rocket, tanker truck, refueling station in Minmus orbit, refueling station in LKO, and nuclear tug hauling full tanks down the gravity well and empty tanks back up the well"? That's a FEATURE, not an inefficiency.

[-Velocity-]

While not as hard as some may think, it's not as easy as all that. Perfecting the process took me far longer than it took to learn just basic docking, and unlike basic docking you don't have any appreciable way to stop and take stock of the situation during a vertical dock, unless you can land the ship to the side when you need a breather. And any mistake - unless you f5/f9 of course - could destroy your base.

Incorrect (at least about the time-pressure part). On low gravity worlds like Minimus, your spacecraft can sit in a hover for literally hours if it's using LV-N(s). Maybe only 20 minutes if you're really low on fuel... that is plenty of time to take stock, I would hope! It's actually quite easy and leisurely. Now, vertical docking on the Mun would be quite a bit different, it's got more than three times the gravity of Minimus, I think. Maybe that's where you did it that gave you a bit of trouble?

- - - Updated - - -

I think you may have mis-worded that statement slightly. You meant that YOU can vertically land and dock. Me, I'm doing well (even on Minmus, where everything is easier) to make a first landing within a kilometer or so of the intended target, then make another hop to get under 100 meters. Vertical docking in even a feeble gravity field? For me to pull that off would not need piloting, so much as dark rituals involving the sacrifice of the ship's engineer to the Kraken.

And, to be honest, I *did* start the original post with the admission that I'm addicted to overdone infrastructure building. So to me, the whole "fixed refinery, tanker rocket, tanker truck, refueling station in Minmus orbit, refueling station in LKO, and nuclear tug hauling full tanks down the gravity well and empty tanks back up the well"? That's a FEATURE, not an inefficiency.

It's honestly not hard to dock vertically in a weak gravity field- or at least, it's easier than you probably think it is. I'm a veteran KSP player and I WAY over-estimated difficulty of it myself. If you find it easy to dock in deep space then you should be able to dock vertically in a weak gravity field with relative ease too. Maybe you should try it- just fire up sandbox mode or something. Get over your target, kill your transverse velocity. Now, you can go into a hover by keeping your spacecraft vertical and cancelling out gravity with your engines. Minimus has such a low gravity it is easy to do this. If you have 2000 dV on your ship, that's 2000 m/s / 0.5 m/s^2 = 4000 seconds of hover time. Unlike what 5thHorseman says, there is absolutely no rush, and you can take your sweet time. You can now control your vertical velocity with either engine thrust or RCS, or a combination of the two. Once you've cancelled out gravity, it's not much harder (or even much different) than docking in deep space; in fact, because you're always going to be approaching with perfect or near-perfect axial alignment with your docking port, it may even be easier in some respects than docking in deep space, as the axial part of docking alignment is already taken care of for you!

I would definitely recommend the docking cone though, even if you can hit the target perfectly. Why- well, sometimes the docking ports won't catch, and you'll need to wiggle your ship or take off slightly and settle back down before the docking ports finally latch into each other. The cone keeps the ports aligned during this.

Edited September 10, 2015 by |Velocity|

[Superfluous J]

Incorrect. On low gravity worlds like Minimus, your spacecraft can sit in a hover for literally hours if it's using a LV-N. Maybe only 20 minutes if you're low on fuel... that is plenty of time to take stock, I would hope! It's actually quite easy and leisurely.

No, it can't. Unless you have a mod that sets your vertical velocity to 0, in which case we are talking about different things. Yes, with the Vertical Velocity Control mod you can hover for hours. You can go get a cup of coffee while hovering if you so choose. If you're controlling your ship with the keyboard, though, you're going to be tapping shift and control the whole time, going up and down as you go. And if you're not used to doing that (and who is, out of the people who've never tried this before?) then it's a new skill to learn and new muscle memory to train. And the penalty for making a mistake could include the destruction of your base.

I understand what you're saying. Landing on docking ports is my preferred method to do ISRU. I've done it dozens of times and am totally comfortable with it. Not one little bit of that changes how hard it was to learn and perfect.