How does autostrut work?

[SansYT15]

I have just learned autostrut is a thing, and I know that the forums would be a good place to turn to ask. 

So how does autostrut work? When I have the setting on, do I have to set it every time I place something? Can I just ignore it?

[MechBFP]

You have to enable it for each piece. Imagine the struts you can physically place, but instead these are invisible and run from the center of one piece to the center of another piece. 

You can only choose from certain pieces, like the heaviest piece, or the root piece, etc. 

[Loskene]

It's meant as a bodge to fix some other issues with craft stability, use it sparingly, grandparent autostrutting on parts you find unacceptably wobbly. Don't use root or heaviest on anything that has to dock, as sometimes a sudden shift in which part is heaviest or considered the root will cause... incidents.

[sturmhauke]

My general autostrut scheme on spaceplanes (including shuttles and SSTOs) is like this:

• grandfather on wing segments
• root on the aftmost main fuselage part (assuming the cockpit is root)
• grandfather on any booster stages
• none on anything else, especially the cargo bay or anything inside

I also leave rigid attach off in most cases, as I've found that it can lead to a permanently warped airframe.

[Vanamonde]

This question about how to play the game has been moved to Gameplay Questions. 

[Cavscout74]

Grandfather is pretty safe for most parts.  Just about the only time I use root is on the lowest booster engines of large & wobbly rockets.  Very rarely I'll use the "to heaviest" setting

[Superfluous J]

Think of autostrutting as a way to specify points of extra rigidity between parts to make your craft more structurally sound. They are not a hack or a workaround, but a tool. They perform much the same function as the cables and cross-beams on a bridge.

So enable them on parts you want to secure more ... uh ... securely than the single point that you get by default when connecting two parts together. Cycle through the various options of what to strut to, and use the one that you think will do the best job. For booster stages, feel free to use any of the options (though I tend to use grandparent or heaviest, which generally helps attach side boosters to the central stack). For long rockets strutting the engines to root can really help, and I also like to strut the base of a fairing to root.

[XLjedi]

You try to fly your craft without it...  watch as the parts flex and flop around.  Then use it sparingly to stitch your craft together so it feels, looks, behaves like a solid aerospace fuselage.  That's pretty much it.

I use the regular struts when the design/aesthetics call for it.  ...in particular, biplane designs would need real struts between the wings not for just cosmetics, but because the autostrut options would not typically let you create those wing-to-wing connections.

Edited July 24, 2019 by XLjedi