A few questions about Airplanes...

[LordFerret]

Unlike other flight simulators I've flown, there seems to be no way (that I know of yet) to link aileron and rudder movements (for auto-coordinated turns). Does anyone know if that is possible?

Also, I've noticed in many pictures of other folks planes that they've built, that they've incorporated dihedral (mostly anhedral angle) in wing placement. Does KSP actually account for and handle the physics of dihedral? How accurate is the flight model's physics for airplanes?

Thanks

[Boomerang]

I've never come across the sort of linkage you're looking for. And although the aerodynamic model is rather... simple... it does account for dihedral angling on the wings and the mounting of the wings in relationship to the CoL. It might not model it terribly accurately, but a dihedral high wing design will be more stable than an anhedral low wing one.

Edit: There are all sorts of threads detailing why the KSP drag model and aerodynamics aren't at all realistic, so you can hunt those up, but essentially, the atmosphere is entirely too thick, relative to the Earth's, and drag is calculated based on the mass of a craft. The shape plays no role in the calculations. So you end up with situations where adding a nosecone to a plane/rocket deceases it's efficiency because you're just adding more mass. Look into the mods FAR or NEAR if you'd like a more realistic drag model.

Edited July 23, 2014 by Boomerang

[Alshain]

If you choose to use FAR or NEAR addons, you can disable controls on the control surfaces (i.e. disable pitch on the rudder and disable yaw on the ailerons) for more coordinated controls. You will be happier with those addons if your using other flight simulators already. FAR goes further and takes wing shape into account for mach aircraft.

Here is a tutorial on stock that explains it's capabilities and differences between it and FAR.

Edited July 23, 2014 by Alshain

[GoSlash27]

LordFerret,

1) No, There are no "auto-coordinating" features to KSP unless somebody's made a mod.

2) Yes, the game does model the effects of dihedral. It also (somewhat) models the effect of wing height, sweep, wing loading and washout. But the results are highly unstable in certain flight regimes because the wings generate drag differently than the parasitic drag of the parts they are lifting.

3) The word I'd use to describe it would be "abysmal". KSP's physics engine wasn't designed to handle realistic aerodynamics and it shows. But you *can* make planes that fly pretty decently despite that.

For best results, build the aircraft minus the wings to be balanced on the fuel tanks so your CoG doesn't move as the tanks drain. Use dihedral to create positive roll stability. Use empennage radius and wing sweep to create positive yaw stability. Do not attempt to use vertical CoL displacement for positive pitch stability, as that will create pitch excursions depending on airspeed. Instead, CoL should be level with CoG and a little behind to make it nose heavy. This will help with stall recovery.

Best,

-Slashy

[LaytheAerospace]

I can't recommend FAR strongly enough, if you plan on spending any real amount of time building and flying planes. Makes it approximate reality far better, and you're rewarded for using realistic designs. Stock KSP planes can be pretty absurd.

[LordFerret]

Thanks all for the input.

In some flightsims you can link the aileron and rudder (I always looked at it as linking the rudder to aileron) so that turns become more 'simpler to manage' - especially when using a keyboard and not a joystick.

Thanks for the link, that's next!

Sound advice, Slashy. Thanks. In spite of what's suggested, about CoL and CoG relationship, I've found I still get 'pitch excursions'. Also, trim does not seem to work as I'd expect it to.

Lots of food for thought and trying out.

[Pecan]

KSP is not a flight simulator. As you will have noticed from the other comments the atmospheric model leaves something to be desired if you are flying planes. To put it simply, KSP was meant to be a space rocket simulator and atmospheric flight always has been very simple in stock. Even with the mods available - principally FAR - the aeroplane model is never likely to be great, it's just not that sort of game.

One thing that should be made clear though (I think you know this but other people looking at the thread might not) is that you can right-click on the control surfaces in the SPH/VAB to toggle whether they work for pitch, roll, yaw or any combination of the three.

[GoSlash27]

Thanks all for the input.

In some flightsims you can link the aileron and rudder (I always looked at it as linking the rudder to aileron) so that turns become more 'simpler to manage' - especially when using a keyboard and not a joystick.

Thanks for the link, that's next!

Sound advice, Slashy. Thanks. In spite of what's suggested, about CoL and CoG relationship, I've found I still get 'pitch excursions'. Also, trim does not seem to work as I'd expect it to.

Lots of food for thought and trying out.

YVW.

That comes back to the drag disparity issue I mentioned. At speeds below terminal, the wings generate more drag than the parasitic drag of the parts and all is normal, but at super-terminal speeds (is that a word??) the situation is reversed and the aircraft becomes highly unstable. That's why it's important to not have a vertical offset between CoL and CoM; it would much rather fly backwards in that regime and the vertical offset generates a torque moment that aggravates it.

Best,

-Slashy