Every airplane i design starts shaking when i hit +-150m/s. As far as i know it wasn’t in KSP 1. Is that a bug or just real physics that i need to change something.
#why do airplanes shake above a speed of +-150m/s?
frank pier
dusty barn
In all directions or in a specific direction?
frank pier
all
urban bay
When you have SAS on that can happen. Its not a "bug" per se. The PID on the SAS is not very well tuned yet, so it over-corrects, causing oscilation.
For now, the solution is to fly with SAS off, and/or avoid rolling as much as you can.
Sometimes, disabling and re-enabling SAS helps.
glad panther
is it shaking or only during use of sas?
frank pier
Yeah this is the only vid i have since my clipping software didnt work
glad panther
thats sas, try right clicking the control surface, in this case the rear ones that are flapping, activate advanced controls, then limit the authority to about 7 degrees or so
dusty barn
Yeah it's basically going "I'm way off, no wait I'm way off in the other direction"
frank pier
okay thanks, will try turning it off
glad panther
yeah or limit the authority of every control surface, its stock at way too much and the sas gets overwhelmed
dusty barn
If you're curious about what a PID is in this context, here's the wikipedia-article on it (note, contains calculus) https://en.wikipedia.org/wiki/PID_controller
glad panther
you can still use sas when limiting the surfaces
dusty barn
you can still use sas when limiting the surfaces
Remind me again does that cap the change or also change the scaling?
glad panther
instead of deflecting the surface to 20 degrees, it only goes to 7 (or whatever you wanna use) and the sas doesnt PID like crazy
ive found for small to medium atmospheric crafts about 7.5 degrees on the authority limiter is a sweet spot of stable but maneuverable
look at the front canard, makes it perfectly stable under sas now
dusty barn
Also canards can be quite sensitive due to distance from CoM
vale hazel
I solved the plane flap with sas issue : All you have to do is offset your elevator just a lil from being parallel with the water line of the plane ... I can now have sas active all the time
quiet goblet
When you have SAS on that can happen. Its not a "bug" per se. The PID on the SAS...
The SAS PID needs more steer dampening
quiet goblet
I solved the plane flap with sas issue : All you have to do is offset your eleva...
up or down?
vale hazel
well... it technically doesnt matter but making it pull slightly down means you will have less ability to pull up, so i choose the position that makes it pull up a lil
easier to take off without touching anything
quiet goblet
well... it technically doesnt matter but making it pull slightly down means you ...
I did this to all of my craft in ksp1 because having that angle of incidence made your plane more efficient due to the weird aero model of ksp1. Pretty sure this would decrease efficiency in ksp2 though
vale hazel
sas makes it aim straight but ksp2 doesnt handle stabilization when crossing 0 point so having it a lil off makes sas put it to 0 but will naturally pull up meaning it wont go back and forth between pulling up and down
i have already gone into space with this method so it doesnt drag too much
quiet goblet
i have already gone into space with this method so it doesnt drag too much
Oh what I’m saying is that offsetting your wings by a bit upwards in ksp1 actually made your craft more efficient
but in ksp2 it just produces more drag
vale hazel
wing offset works till you go supersonic then it can make things difficult
quiet goblet
I know that it helps with the SAS though
jovial glacier
you can press alt+s to trim the aircraft nose up or any other key wasdqe to trim those flight control surfaces; modern aircraft will tend towards about 2 degrees nose up at cruise with trim, so if your planes nose is just above the horizon line at cruise altitude and cruise speed after you've trimmed it, and you haven't trimmed it very much, then it is stable in pitch.
flying planes without sas is honestly way more fun