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I was playing around with a simple plane with infinite fuel enabled, in order to test the effects of dihedral and high vs low wing, but I was getting some extraordinarily weird results. I was expecting the high wing dihedral arrangement to counteract sideslip disturbances and make the plane not tend to bank into level turns, but that wasn't what was happening at all. This was my test craft: It is, as far as I can tell, completely symmetrical around the longitudinal axis. Reaction wheels were disabled and I was flying without SAS. Ignore the radial parachutes on the bottom, I was trying to balance out the high wings to neutralize torque from the engine thrust axis being off center mass, but they have no effect on the test and I just removed them. After taking off and trimming pitch neutral, I was getting a very noticeable and annoying roll tendency to the left, and I just couldn't figure out why. I could trim it out, sure, but where was it coming from? On my actual planes I was planning to fly with SAS on (for autotrim, mostly) and I find that making the plane as stable as possible without SAS on helps a lot with making it fly well. After investigating if there was asymmetric drag or lift going on somewhere and scratching my head for a bit I discovered this little bit of weirdness: if the wings are set to autostrut to heaviest part (the engine), the plane consistently rolls to the left. If they are set to autostrut to the root or grandparent part (the cockpit in both cases), the roll tendency is much less pronounced but still there. With autostruts disabled, the wing configuration does what I expected, and the plane is quite well-behaved in level turns - just bank it over 20-30° in either direction and it will quickly stabilize in a clean turn with no sideslip by itself with no input other than the pitch trim, and it has a weak tendency to bank out of the turn and return to wings level regardless of turn direction. Rigid attachment of the wings seems to have a similar effect of making the plane tend towards to rolling left, but the effect is quite weak and it could easily be a mistake on my part (my testing methodology is hardly all that scientific and the testing environment isn't exactly controlled). What is going on here? Why does this happen? Surely autostruts don't actually have drag (even if they did, I don't think that would cause this). I've seen some discussion of some old symmetry joint rigidity bug that could have similar effects but I couldn't find it on the bug tracker. Here is the craft file for the test aircraft (with autostruts and rigid attachment off) in case you want to play around with it yourself. To reproduce my test conditions, take off (it is pretty nose heavy at low speed but you have more than enough pitch authority to counteract that) and get into stable level flight, without SAS, with nose pointed at horizon. Adjust pitch trim so that the plane maintains level flight. I did my tests at quite low AoA - around half a degree. Bank the aircraft left or right and observe how it behaves in a turn. Now, while you're in such a turn, autostrut the wings to the heaviest part and observe the roll tendency. It's more noticeable in a right hand turn because then the high-wing dihedral tendency to return to wings level combines with the tendency to roll to the left. It is also more noticeable at higher speeds.

They aren't just phantom forces; already they have their spatial position defined in the ship, and apply their forces as physical objects. I think then that 3 things should change: first, they should also be an option only on the VAB/SPH, not flight! Strutting parts isn't magic! Then, they should appear visually as regular struts, and add mass to the ship. That way they feel like an actual part of the design process, you choose which parts strut to which, but it abstracts away having to pick the exact point of placement, and makes it easier to move tanks around and not have to re-configure your whole strut scaffolding. Regarding autostruts that cross over other parts of the ship, it doesn't seem to be a problem to me: Physically, they have no colliders, so the only change (relative to current autostruts) in the ship's physics will be the added mass, no Kraken invited. Visually, having a strut clipping through a part shouldn't be different from a series of parts strutted to each other. (I've edited the question after some feedback and added the poll. I didn't know you could add multiple questions, I think it makes perfect sense to split the question and poll for each individual change, since I'm proposing 3 that are related but could be implemented independently. I tried to rationalize each choice the best way I could, elaborating more than just "Yes/NO!", but not going the "No, because I'm stupid duh" route either. I hope I did a good job there )