Launching Multiple Orange Tanks

[Greenspan]

I'm trying to launch ~5 orange tanks for refueling/interplanetary booster. I have a bunch of asparagus stages, a middle booster stage, and then an orange tank with 4 more orange tanks arranged radially. The problem is, 90% of the time when I go to launch one of the 4 orange tanks breaks off; especially when the rocket drops a few feet after loading. I have tried the "moar struts" solution with not a lot of luck, I've tried putting structural plates underneath them but they still tend to peel off during launch. I'm also trying to keep the part count down on this final stage as I plan to dock with a second ship or a refueling station. Do you guys have any tips/suggestions for securing orange tanks mounted radially? Whats your solution for launching that much fuel? Thanks

[Hodo]

Are you running a stock game or any mods?

I know getting that amount of mass into orbit is a challenge anyway you play the game. I think the most I got into orbit at one time was 3, and that was in my super heavy SSTO space plane the SP-406. But even that was a challenge.

The biggest problem you are running into is just the shear amount of mass you have that you are trying to get into orbit. It is over 180tons in a single launch. Adding more struts is the best option, but not always a good solution. You may want to try building them in a set of two on top of eachother, and leave out the fifth for now. Or you can try mounting 3 of them around a single 1.25tank and stacking them in pairs to get 6 into orbit. But you are just going back to the initial problem.

Last suggestion is download the Kerbal Joint Reinforcement mod it will help with the weak joints found in the stock KSP game.

[capi3101]

Five tanks at once, eh? 180 tonnes...that's a helluva payload you've got. With something that massive you might consider one of two options -

1) Consider having the vehicle launch itself. I've got a design like this, the Thunderbolt Very Heavy 7, that's the equivalent of four orange tanks plus change (it uses six NERVA engines); it incorporates a series of LV-T30 engines in separable boosters. Now, the boosters don't have enough juice to make it all the way to orbit with the rest of the craft, but it gets it up there far enough and fast enough that the nukes can finish putting it in orbit.

2) Empty the tanks out in the VAB before you launch them. Your 180 tonne payload becomes 20 tonnes, and a trained chimpanzee could launch that pretty easily.

Note that in either of these cases, you'll have to refuel the vehicle once it's in orbit. I have yet to see anybody who has a booster design rated for 180 tonnes, though Temstar has one that can do 160 or so.

[maccollo]

Assuming a mass fraction of 12% you'll need a rocket that weights about 1500 tons. That's pretty big. Not impossibly big, but it's at that level where physics begin to not work.

My favorite way of strutting huge rockets together is like this

The radial stacks are simply attached with modular girder segments that are rotated 90 degrees.

These are fairly sturdy and add a bit of space between the stacks for strutting.

I've been able to construct some positively enormous launchers by doing that, without having to resort to the joint reinforcement mod.

http://youtu.be/h-p8Xtt7-Mc

I should add that as you build larger the number of stable build solutions drops, and if you end up with a build that isn't stable "moar struts" wont work. In fact it can make it worse.

Edited February 16, 2014 by maccollo

[Silverchain]

The latest iteration of my Euryale class makes LKO with roughly six orange tanks worth of fuel, so should be good for comparison.

Euryale 23-Fc

It's 1573 tons on the launch pad and a lot of parts; there are three detachable dockable fuel tanks (3/4 big orange size) and the rest is accessible through docking. 270 tons in orbit (for 5 3/4 tanks fuel.)

Not a very efficient design, ugly, asparagus, lots of stages, but if you want to put fuel in space it works.

[bsalis]

My advice is to go wide, and cut down on the shear forces. Basically have everything lift itself, with fuel feeding inward.

In the design below, I used Skippers on Jumbos. The most shear force would be a Skipper at full thrust against the tank-to-tank bonds, which are a radial decoupler and a couple of struts. Then there are more struts in order to hold the whole thing together.

Like a launch pad facehugger...

This run was 646 ton to LKO. Some launches don't make it... but meh, it's good enough.

[m4rt14n]

My advice is to go wide, and cut down on the shear forces. Basically have everything lift itself, with fuel feeding inward.

In the design below, I used Skippers on Jumbos. The most shear force would be a Skipper at full thrust against the tank-to-tank bonds, which are a radial decoupler and a couple of struts. Then there are more struts in order to hold the whole thing together.

Like a launch pad facehugger...

http://farm6.staticflickr.com/5322/9616077134_cb1c9d1876_c.jpg

This run was 646 ton to LKO. Some launches don't make it... but meh, it's good enough.

http://farm6.staticflickr.com/5323/9612847281_b39ef36d95_c.jpg

Oh god... Why...

LOL. Thats a lot.

[Tokay Gris]

It can be done, although you run into problems keeping the payload together if you use the orange tanks.

I have a launcher that can lift that mass, but not in the form of orange tanks. They tend to break apart on the launchpad.

What did work, though, was using two orange tanks as center column and six "tin cans" in three columns around them.

The launcher itself (no picture right now) is ugly and basically three rings of asparagus staged 3-tincan+mainsail parts. Works up to 218 tons. Will post pictures as soon as I have the time.

[Damaske]

try this, Line up the refill orange tanks in the middle, then build around it using the smaller long fuel tanks and add in your orbtial gear, this is the upper most stage. Underneath that one add in an orange tank with a mailsail engine and 6 rockomax radial engine pods, the white side mounted engines. Add in your staging gear and ad in two orange tanks a mailsail, 8 of the longer smaller tanks with the non vector engines. Below that add three orange tanks a mailsail and then add 6 orange tanks on the outside with skipper engines tie into the larger stack with fuel lines, on the outside orange tanks ad two sets of solid rocket boasters, and launch clamps, Fire the liquid engines throttle up and then stage to let the clamps and fire up the SRBs in one go and you "should" lift right on up and away. Add in struts and other items as needed to keep rocket stabilized and flying true.

Ignore that too unstable working on new design at this moment.

If you wish If i have time i can try to bogger something together that will take full orange tanks into orbit.

Damaske

CEO of The Mass Key shipyards

Edited February 17, 2014 by Damaske

[DrMonte]

I'm trying to launch ~5 orange tanks for refueling/interplanetary booster. I have a bunch of asparagus stages, a middle booster stage, and then an orange tank with 4 more orange tanks arranged radially. The problem is, 90% of the time when I go to launch one of the 4 orange tanks breaks off; especially when the rocket drops a few feet after loading. I have tried the "moar struts" solution with not a lot of luck, I've tried putting structural plates underneath them but they still tend to peel off during launch. I'm also trying to keep the part count down on this final stage as I plan to dock with a second ship or a refueling station. Do you guys have any tips/suggestions for securing orange tanks mounted radially? Whats your solution for launching that much fuel? Thanks

Orange tanks might brake off if you mounted them on each other. You should use girders between them. Then it becomes very stable structure.

If you would like to go for performance it would be nice to reuse those 5 tanks as a fuel for launcher stage. Then the station will become the core of the launcher. Few rounds of asparagus and you're up.

0.23 version is very helpful with fuel management. Launch it empty and your station will weight less than 30t.

Search for "Leviathan Engineering" for heavy load lifting examples. Not all examples (usually none) posted in answers are a good examples.

[O-Doc]

The key is the girders which give you flex on physics load. Struts and clamps have zero flex so, if your design is all struts and clamps then, your rocket will become 'unhinged' on the launch pad. Ive been messing around with leaf spring cages for large payload rockets. There's still much more testing to go. Here's one example to come out of this testing program. NB: I'm also using docking ports for added give between the launcher and payload.

Javascript is disabled. View full album

[Damaske]

Holy jeb that thing is huge ! ! ! !

I have an launch craft that can lift 5 cans up but they are needed for the final stage into orbit and I drain just aboot 4 tanks. But i think the Kraken likes the launcher as it has been nothing but tons of trouble for me trying to get it up a second time. I CAN confirm the scaffold trick as I used it for the main stage. Will try one more attempt that I have been thinking for lifting five full orange cans into orbit. Also at what orbit do you want this rocket to go I'm shooting for 120km right now.

Edited February 18, 2014 by Damaske

[Greenspan]

Nice, thanks for the help everyone the girders fixed the problem. Also, I was putting struts from the bottom of the radially mounted tanks to the stage below, I found that since they were rigid they were shearing off the tanks after load, removing those struts helped a lot too.

This is what I ended up with:

Also, I discovered that with that much mass at one end it starts to become unstable once I get down to the last few asparagus stages, I had to add some extra torque wheels at the bottom of the orange tanks to help stabilize, otherwise the gravity turn was pretty dicey.

210 tons to orbit! Woot! Not the cleanest design, I had to add some extra fuel/SRB's to get the final bit of delta-v needed w/ ~2 TWR but it's pretty stable and I think meets my needs for now. I want to try that facehugger design now! LOL

Edited February 18, 2014 by Greenspan

[Damaske]

soooo, then you no need help with making a new design? I have been trying to make a none asparagus staged rocket for you. would you still be interested in my work or should I mothball it? If you would like me to press on, what orbit attitude are you trying to go into? I've been trying to go for a 110km or 120km orbits right now.

[ksbes]

If we look for root cause, we wil see, that problem is in weight of orange tank. It's mass is 32t. But when you accelerate it's wheight might be 48-64t (if you are sane, if not - up to 320t). While link strenth is the same as for all other nodes.

So, i thought, why struggle with links, while I can directly strugle with the weight? And I put some (many) radial engines on this tanks and it helped me alot. It is better to put, say, 8 radial engines on 4 orange tanks, then wire them with half a handred of links.

It reduces total deltaV, thogh.

[Himynameisjake]

Javascript is disabled. View full album

Got annoyed with the design I sent you, so here's a much better one.

http://www.fileswap.com/dl/ZEvWWBV6Qz/

Caution, it is a framerate hog, with almost 1500 parts without a payload, this means that (at least on my computer) the first couple stages are a no-go for physics warp. The file I linked here includes a 7 Jumbo tank with asparagus style staging. With that payload it has a whopping 4838 atmo and 5701 vacuum delta-v, you can get the 254T payload to an orbit of 620km without touching the fuel in the payload. It has flight controls (RCS and SAS*6), 6k Battery life and 6 RTG's to keep you powered up until forever. It's also so stable I just launch it from the platform, no Launch Stability Enhancers. Some of the strutting could be prettier, but that's as nice as I'm making it tonight. The center booster is set to 25% thrust limit and has its own RCS pack because it has a tendency to flail about when it pushes that big of a load by itself. The Mainsails are separated from the tanks by an octagonal strut to allow them to cool properly, meaning you never have to reduce thrust on any of the other engines. Zero fails thus far, lifting much more than you were originally looking for.

Edited March 9, 2014 by Himynameisjake
Much better ship design.

[Oskar-]

(edit: added embedded images)

This is one of mine, from way back in 0.19

http://imgur.com/urymqyH

And with the six oranges in a 265km orbit

http://imgur.com/JiI451T

Edited March 9, 2014 by Oskar-
image embedding

[Himynameisjake]

Bonus shot, any particular place you want your five full jumbo tanks sent op? That wasn't even being as efficient as I could have been, and timed right, you could send 5 tanks almost anywhere.