Rocket won't "connect"

[PanzerschreckLeopard]

New here, but I\'m trying to make a rocket with 5 motor in the first stage, one centre and 4 placed on the sides. All are LV-T30 with 4 fuel tanks. I did not use radial decouplers, as that would mean the centre rocket wouldn\'t fire til the other 4 detatched. Problem is, the game apparantly thinks the fuel tanks for one of the strap-on motors is supposed to go to the centre...meaning it looks fine in shop, but once on pad, one of the outer rockets will not be 'connected' and thus won\'t fire, and so be left behind when it lifts off and flips over immediately after. Any help?

[Vanamonde]

Are you sure the problem is with the tanks? On the pad display, one of the engine icons is grayed out. That means that that engine is already broken, usually because the engines weren\'t all placed at the exact same height, so once on the pad, the weight of the rocket falls on the engines unevenly and breaks one (or more). It would help if you could post some closeups of the engines and maybe the .craft file.

[PanzerschreckLeopard]

It looks exact in the shop...as close as I can get...

[Capt'n Skunky]

It\'s better to place the 4 outer engines slightly lower than the center anyway, they will handle the load bearing much better. This will ensure the center engine doesn\'t snap off because it\'s lower.

Cheers!

Capt\'n Skunky

KSP Community Manager

[Bluejayek]

If you use radial decouplers you can always adjust the staging afterwards by dragging the icons on the right so they will fire at the same time as the central engine.

Do you know about symetry? The button at the top left lets you select 2, 3, 4, 6, or 8fold symetry where the parts will automatically be placed symetrically, so you don\'t have to fiddle with getting the heights all the same.

Good luck and happy flying!

[PanzerschreckLeopard]

Which symmetry would be best for this. 4 or 6?

[UmbralRaptor]

You\'re using the demo (0.13.3), right? If so, build the center set of tanks/engines first, and then copy it with alt+left click and symmetry.

You can also drag parts (most notably engines, parachutes, and decouplers around on the stage listing if you want to mess with the firing order, etc.

edit: Which is best depends on what you\'re doing. 6x will let you launch more mass, 4x will be smaller/easier to control. If control is getting excessively hard, replacing the centerline LV-T30 with an LV-T45 will help.

[Markus Reese]

Like skunky said, the centre engine is the lowest point in the structure by the looks of things. This means that central nozzle is holding the entire weight of the rocket. When it loads the launchpad, you probably hear a sound as that section breaks off from some sort of initial impact/load.

[PanzerschreckLeopard]

I got it now, and it was never the centre that broke

[Vanamonde]

I reproduced this rocket from the screenshots. At first it wouldn\'t take off at all, but when I moved the outer engines up just a little, it took off fine. Is that the 'sticky pad' I hear people talking about? I then spaced the outer engines with small hardpoints (which are better for this than radial decouplers because you can\'t accidentally discard them). It flew just fine then, unless I shifted the outer engines too high, in which case the middle one broke and looked like what PanzerschreckLeopard was getting. (I also placed some RCS thrusters, since it looks like those had been left off of the original.) 4x symmetry looks just fine.

Here\'s my copy of your rocket, if you want to look at it:

[PanzerschreckLeopard]

What\'s a craft file?

[UmbralRaptor]

@Vanamonde: Sounds like the sticky pad bug.

@PanzerschrekLeopard a .craft file is how various types of saved ships are stored in KSP. They\'re under /KSP/Ships/ in 0.13.3, and split between /KSP/Ships/VAB/ and /KSP/Ships/SPH/ in 0.15.2.

[Vanamonde]

What\'s a craft file?

And you can add those files as attachments to a post, as I did with mine. If you want to look at that one, copy it into the 'ships' folder of your KSP folders, as UmbralRaptor says. Then it will appear in your VAB as a saved ship the next time your play the game. I tried to make it just like yours, but it might be a little different. I flew that version to orbit, by the way, so it should work just fine for you. ;D

@Vanamonde: Sounds like the sticky pad bug.

That\'s odd. I\'ve never run into it before.

[Fridgecake]

I find a way to solve this issue to to add a decoupler and then a tricoupling underneath all of your engines. This way it sits on those, and therefore a large surface area/less important part of the rocket, which should stop it snapping off.

Just have those decouplers in the same stage as your first rocket boosters so as they fire they decouple the tricoupler from the engines and you fire on as normal not carrying any additional weight.