Designing my heavy Launcher... launches fine but pieces break at random.

[ASnogarD]

Not sure if this is the correct place to put this semi rant , semi question , semi scream at the internet and Squad...

(Dont worry not going to swear and tear into the devs)

NOTE: Stock except for Mechjeb2 and B9 parts (both 0.20+ compat

Right, I am ok at tossing small craft into orbit, even docked a pair I launched as a dock practise set... now I want to do a space station, as a half way stop to the Mun (yeah I know I could do a launch and Mun landing in one but my plan was a station for re-fuel).

I have been trying to design a heavy launcher to launch ...heavy loads into orbit, but while I can build ships that can get to orbit easy, as soon as I attach a payload everything goes to hell.

My latest launcher has - 1 x Mainsail , 6 x LT45 as a core with 1 x Jumbo tank and 1 x 400 Rockomax tank, it has 6 x LT35 (?) with 3 x long tanks feeding the main core tanks, and it has 6 x Boosters... as stage 1, with a 400 Rockomax tank and poodle as a 2nd stage controlled with a remote probe (large ring) , ASAS, RCS fuel tank, Battery, Jeb , Info drive...

... then the payload, in this case a single Jumbo tank with some RCS, a probe and a shielded dock port on the top.

All strutted as much as I can logical see is needed.

Thing keeps failing at the large decouplers, and breaking at the decoupler... I had tried some Snr Docking ports so I could manually let my payload off, but the joints swayed like a helicopter rotor and snapped off all the attempts to strut the bugger.

It makes no sense, the ship barely lifts off with 50% throttle but does reach decent heights with good fuel but then... a decoupler will simply break.

I could understand it if it broke at launch when all the boosters suddenly kick in, but at nearly 10k km , just thinking of doing my turn and ... what?!? Wheres MechJech ? What ? Why has all my ASAS gone ? Check flight data and sure enough the decoupler broke squashing the ASAS ring and Mechjeb at the same time.

NO, I am not using time warp, or physics warp (if that is indeed something different) I am just press T - CapsLock - and throttling to 50% - hitting launch.

YES , I has launch stabilisers to hold the rocket, and have some Canards for atmosphere control.

Do I need that Farams mod to sort out the atmosphere simulation, or what ? I have watched a lot of videos, tutorials etc etc and really wanted to try some of the things... do orbits gets dull after a few launches.

Is there some bugs with the structures (I heard something about the orange tanks breaking unless you buffered them with grey tanks for some reason) ?

Am I perhaps putting the ASAS , Probe , RCS fuel, Battery Ring and Decoupler in the wrong order ? There was some difficulty in getting some of the parts to attach to the probe ring and it does seem hollow... so does the decoupler to the fuel tank, perhaps it needs a engine to work as a decoupler ?

I am pretty sure the launcher is solid, I got the design from a picture of one of the fancy launchers with the multiple engines underneath the tank (similar to http://forum.kerbalspaceprogram.com/showthread.php/35856-Launch-Vehicles-Other-Than-Asparagus - first pic), but went for 1 mainsail and lots of LT45 with a ring of droppable LT35 (no gimbals)... I find mainsails overheat too fast and blow through fuel like crazy, so 1 is enough.

Sorry its bit of a rant but I had so many ideas and schemes but I literally cant even get off the ground... the designs I had to scrap because of the joints breaking each time, the fancy yet balanced systems, the awesome habitat with expansion docks to put together...the space tug to cart the components around... all scrapped.

Thats me, thanks for reading.

PS - still a good game, and I know its still in development.

Edited June 16, 2013 by ASnogarD

[Johnno]

I ran into the same issue when I started doing heavier launchers, every piece has its limits and the only way around it is to strengthen your weak points with struts. As the saying goes, MOAR STRUTS. Red tanks have a bug that make engines overheat when attached straight to it, which is why a lot of people put a white tank between the red and engine.

But back to your main issue, structural failures. I've found that once you get to heavy stuff you need to 'stitch' everything together with struts. Each piece needs a few struts connecting it to the next piece, or as some do it every other piece (and then alternate). Payload strutted to top tank, top tank strutted to tank/decoupler below, decoupler strutted to next tank, etc. Once you do really heavy stuff even that's not enough, at which point to spread the load I normally attach cubic octagonal struts (or girders) radially onto the tanks near the bottom/top and connect a bunch of struts to the other side's girder. From the girders I spread out strut connections onto the tank it's on. And in extreme cases, diagonally to another tank's girders.

Here's a demonstration picture from my latest heavy lifter (124 tons to orbit). Hope that helps, good luck and happy struttin'.

[JelloTickles]

Maybe it's the struttage that you have? Did you try strutting every single part together?

[AmpsterMan]

Can we see a picture? They really do speak a thousand words.

[ASnogarD]

Not used to putting pics up but here is one with the payload.

The decoupler that breaks was strutted with 6 x block girders on each end to accept the strut bars, just when the launcher got to just over 10k km ...pop went the decoupler and squashed the ASAS and Mechjeb2 part, completely ignoring the struts, they just broke and vanished.

[Spooks]

Most of the time i have problem whit the rcs tanks use small ones or move it to the top not in the middle hope it helps

[JelloTickles]

Maybe you should just make a new launcher, make one that's not so complicated and it's well strutted and then you won't see it break again. Personally I use a launcher that has 3 of those big grey fuel tanks, and a half big of those grey fuel tanks. Then I put 3 radial decouplers and only put 3 of those big grey fuel tanks. Make sure to strut them real good though.

[ASnogarD]

The RCS tank is at the top, the Orange Fuel tank is the Payload so the RCS cant go higher.

I have tried some new designs but keep hitting new issues...

This is the 'Skinny' series , the nickname is because of the skinny section of the middle of the craft where the fuel payload is meant to be attached (my challenge : get 3 full Orange tanks into a safe parked orbit so they can be either used or hauled off to some space station).

I am testing without payload as I spent nearly a day yesterday with my 'Awesome 4 some' craft trying to get up 3 tanks.... only to discover to my horror the bloody ship itself wasn't capable of leaving orbit even without a payload... scrapped.

Skinny Mk1 - no Payload , gets to LKO barely.

If you look carefully you can see the girders attaching the side tanks and engine to the skinny main section of the craft BUT only the top part of the girder is actually attached, the bottom part is clipping into the main section but not attached , couldnt get the top and bottom part of the girders to attach to the main ship... same with the orange tanks on the girders...either they attach to each other or to the girder but not both even if you align the snap points. Is there any way around this ?

I am a bit of a stubborn sod and wont easily let go of an issue even if I can just bypass it... I want fuel tanks in space and dammit I will get them even if I have to kill a continents worth of Kerbals.

... then I'll see about that Mun trip, hmmm why is the Kerbal Space Volunteer list so empty suddenly... ah never mind, toss in some homeless Kerbals in the pods wont make a difference, not for the first 3004 launches anyways.

[John FX]

This will get a single orange tank to LKO with about 600Dv spare for orbital maneuvers. As you can see there are only four struts securing the orange tank payload. The orange tanks below are `stitched` to each other and the core tanks. I tried to put the parts on (RCS, control and shielded docking port) you say you would like.

http://www./view/d6hzcb1v44di75j/single_orange_tank_LKO.craft

Edited June 16, 2013 by John FX

[ASnogarD]

Thanks , I'll check out your craft design and use it to help design my lifter, or at the very least use it to continue my quest to plant a flag at the Mun.

I have thought of a improvement to my 'Skinny' design... going to have fun trying to put that together but if it works it both bypasses the girder and connecting issues, and even offers chances to slip in some more fuel in the 'body'.