Question re Symmetry Mode in VAB

[Srpadget]

I frequently find myself stymied in the final phases of a build, due to the way symmetry wants to set itself in the VAB. I was wondering if there is any convenient way around my problem.

The core of the issue is that once something has been radial-attached to a part using radial symmetry, the core part 'remembers' what type/degree of radial symmetry was used and INSISTS that all other radial-attach parts be placed with the same symmetry. And sometimes that's not what I want.

Hypothetical example: Let's say I'm building a lander. Lander can on top, fuel tank beneath that, engine on the bottom. Stick 3 landing legs on the fuel tank using 3-fold radial symmetry. There's the core of a very basic lander. Now for the other stuff we're going to need in order to make it a full-fledged useful spacecraft: pop some small science instruments around the hatch of the lander can, above the lander can I'll put a probe core, axial-attached battery, and a docking port. So far so good. Now a pair of deployable solar panels on the fuel tank, and...NOPE. Can't do it. The moment pointer drags the solar panel over to the fuel tank, POP! The twofold symmetry changes to threefold. It's THREE solar panels, or nothing. Dangit. Rearrange stuff on the lander can, move the solar arrays up there where it's still possible to define twofold symmetry. Okay, how about 4 RCS ports? NOPE. It's 3 or nothing. And COM balance DEMANDS that the RCS ports be placed on the fuel tank...so it's back to the drawing board.

I suppose in this particular instance I could fourfold symmetry and four landing legs (and associated otherwise-unnecessary mass) and this would let me put four RCS ports on the tank. Or twofold symmetry would let me put the solar arrays back on the fuel tank, and I can put four landing legs and four RCS ports via two pairs at right angles to each other. But the two pairs of landing legs (and the two pairs of RCS ports) are likely to be just slightly different in their attachments, possibly leading to a wobbles between two different versions of sitting on three legs. Or worse, the RCS isn't balanced right. Or I can take a lot of time being exceedingly persnickety in my part placement...but that hardly seems like it should be necessary.

Is there some intrinsic reason, perhaps associated with the tree structure of the craft file, that it is NECESSARY for all radially-attached parts on a single part to share the same symmetry? And is there some workaround better than what I've outlined above? I cannot be the only person who's ever wanted to put, say, 3 Thuds, 4 RCS ports, and 2 solar panels all on the same Big Orange Tank...

Edited June 22, 2015 by Srpadget
Mark as Answered

[Mic_n]

Hrm.... shouldn't be.

I quite regularly attach different multiples (eg legs/solar panels/radial chutes) to the same part with different numbers in radial symmetry.

On "child" parts, yes. You can't place three fuel tanks around a central stack and then switch to four-way symmetry to stick some launch stabilisers on them, which makes perfect sense. However you should be able to put for example four fins in symmetry around the tail of a fuel tank, then switch to two-way symmetry to attach a couple of decouplers and boosters in the space between them on that same core stack. I do that sort of thing quite regularly, for exactly the sort of scenario you describe: lander legs, solar panels, parachutes, etc...

[FancyMouse]

you need to be careful - this change happens whenever you hover your cursor over the existing part, so when you place it you need to be careful to avoid hovering over your landing legs

[PKing Zombie Spy]

you need to be careful - this change happens whenever you hover your cursor over the existing part, so when you place it you need to be careful to avoid hovering over your landing legs

This is very annoying certainly. You hover over a part on your way to place some other part, it changes the symmetry n-arity for you. So you go back to change it, then you change it back again. My solution was to use the "x" key. So even when hovering over a part changes the n-lateral symmetry, you can change it, afterwards, once you've moved past it. (Otherwise it's sort of like playing a game of Operation.) I generally avoid learning hotkeys unless I absolutely have to, but I judged this as one situation where I absolutely had to.

I think it would be nice if it only insisted on a certain n-lateralism if you actually placed it on an n-lateral part, instead of just changing on hover.

[Srpadget]

X key. Good to know. I'll note this as Answered.

[Mic_n]

wha? Oh, ok. Never dawned on me that you'd be clicking the icon rather than using the hotkey

So yeah.. hit X to increase the symmetry count, Shift-X to decrease, "C" to enable/disable snap (you should pretty much always have it enabled unless you have something very specific in mind) and "R" to switch between Radial and Mirror modes.

[tutike2000]

Another way is to build only one 'branch' of the symmetrical bit, then use symmetry only when you're done building it.

So let's say if you wanted to attach to your ship 2 SRBs each with 3 chutes on them:

- First place a single SRB

- Then place the 3 chutes via 3-way symmetry

- Then pick up the SRB and reattach it via 2-way symmetry

But yeah. X, shift-X, and C/shift-C are your friend.

Also 'R' to switch from radial to mirror symmetry.

'F' to switch between symmetry around the current part or around the vessel.

F is also useful when using the Offset tool. Try it on a part that was placed on ... let's say the slanted bit of a command pod

C is useful in Offset and Rotate to have smaller increments, not just a few 'steps'.

I wouldn't be surprised if there were other shortcuts I don't know about even today.

I'd also recommend http://forum.kerbalspaceprogram.com/threads/38768-1-0-2-Editor-Extensions-v2-8-21-May (Editor Extensions), for perfect vertical/horizontal alignment, N-way symmetry (20-way, for instance), 15,30,45,60,90 degree snap, etc

Edited June 22, 2015 by tutike2000