Rotor Issues

[XLjedi]

Tried using the big rotor for the first time and it's pretty much useless at the moment for two reasons...

The first is not too bad, although it seems to be a rather careless oversight.  Hopefully they will fix it in the next patch.  There appears to be no way to link the rotor torque setting to the engine throttle.  Thankfully, there is a fairly simple temporary fix for now, but you just can't do it at design time in the SPH.  You have to open up the .craft file and edit the Rotor.03 part(s) so they will accept MainThrottle as their input. (If interested in controlling the rotor with a throttle like any other engine, I'll show how to do that below.)

The second issue is a bigger problem.  If you attach ailerons to be used as variable pitch blades...  As the Rotor.03 part spins, the ailerons begin spreading out, as if being pulled apart or separated from the spinning hub.  If trying to create a large rotor/prop craft (like an Osprey) the blade separation is significant enough to cause the props to ground strike destroying the blades.  I tried to fix with autostrut and rigid attachment, but neither seems to have any impact.  They need to fix these things so that as the rotors spin blades, the blade diameter DOES NOT INCREASE as the torque increases.  This is a pretty silly one and just needs to be fixed ASAP.

 

Controlling Rotor.03 with your main throttle:
 

Spoiler

 

In the AXISGROUPS section for your Rotor.03 part references it should be edited like this...

AXISGROUPS
        {
            rpmLimit
            {
                axisGroup = None
                axisIncremental = Pitch, Yaw, Roll, TranslateX, TranslateY, TranslateZ, MainThrottle, WheelSteer, WheelThrottle, Custom01, Custom02, Custom03, Custom04
                axisInverted = None
                overrideIncremental0 = Pitch, Yaw, Roll, TranslateX, TranslateY, TranslateZ, MainThrottle, WheelSteer, WheelThrottle, Custom01, Custom02, Custom03, Custom04
                overrideIncremental1 = Pitch, Yaw, Roll, TranslateX, TranslateY, TranslateZ, MainThrottle, WheelSteer, WheelThrottle, Custom01, Custom02, Custom03, Custom04
                overrideIncremental2 = Pitch, Yaw, Roll, TranslateX, TranslateY, TranslateZ, MainThrottle, WheelSteer, WheelThrottle, Custom01, Custom02, Custom03, Custom04
                overrideIncremental3 = Pitch, Yaw, Roll, TranslateX, TranslateY, TranslateZ, MainThrottle, WheelSteer, WheelThrottle, Custom01, Custom02, Custom03, Custom04
            }
            servoMotorLimit
            {
                axisGroup = MainThrottle
                axisIncremental = Pitch, Yaw, Roll, TranslateX, TranslateY, TranslateZ, WheelSteer, WheelThrottle, Custom01, Custom02, Custom03, Custom04
                axisInverted = None
                overrideIncremental0 = Pitch, Yaw, Roll, TranslateX, TranslateY, TranslateZ, MainThrottle, WheelSteer, WheelThrottle, Custom01, Custom02, Custom03, Custom04
                overrideIncremental1 = Pitch, Yaw, Roll, TranslateX, TranslateY, TranslateZ, MainThrottle, WheelSteer, WheelThrottle, Custom01, Custom02, Custom03, Custom04
                overrideIncremental2 = Pitch, Yaw, Roll, TranslateX, TranslateY, TranslateZ, MainThrottle, WheelSteer, WheelThrottle, Custom01, Custom02, Custom03, Custom04
                overrideIncremental3 = Pitch, Yaw, Roll, TranslateX, TranslateY, TranslateZ, MainThrottle, WheelSteer, WheelThrottle, Custom01, Custom02, Custom03, Custom04
            }
        }

The problem is:  by default the servoMotorLimit section above looks exactly like the rpmLimit section.  Notice above that I made 2 small changes to the servoMotorLimit section.  I set axisGroup = MainThrottle, and then I deleted the "MainThrottle" reference from the axisIncremental section on the next row.  This allows your rotor(s) torque to be increased/decreased the same as you would a jet engine.  This should be a setting that is adjustable in the SPH at design time... but it's not.

 

 

[XLjedi]

I just posted an example to the bug tracker, if anyone wants to try it...

https://bugs.kerbalspaceprogram.com/issues/22832

The associated example also includes the edit that allows rotor control with your main throttle.

 

 

[MechBFP]

This is normal in KSP. Spinning parts start flying apart. Try it with a rocket spinning in orbit. 

[XLjedi]

4 hours ago, MechBFP said:

This is normal in KSP. Spinning parts start flying apart. Try it with a rocket spinning in orbit. 

Well... it's maybe time they fixed it then.

[Snark]

Moving to Breaking Ground Support.

7 minutes ago, XLjedi said:

Well... it's maybe time they fixed it then.

Reporting it to the bug tracker, as you've done, is the right thing to do.

However, bear in mind that depending on exactly what's going on, there may not be much that they can do-- for example, it could be a Unity issue. I'm certainly no Unity expert, but my impression is that its physics engine doesn't handle high rotation speeds very gracefully.

If it does turn out to be some physics engine issue, then it's conceivable that "fixing" it may be impractical.

[FleshJeb]

9 hours ago, XLjedi said:

If trying to create a large rotor/prop craft (like an Osprey) the blade separation is significant enough to cause the props to ground strike

I feel you in the rotor expansion, but I like the challenge and the self-governing aspect. I think I may also have figured a way to mitigate it better. (Need to test tomorrow).

In any case, I think you’re using too much rotor for that craft/blade arrangement. I’ve easily gotten 400kn out of one large rotor at 200 RPM (slight expansion). You can either limit the RPM or go to the next smaller rotor and be fine.

Secondly, as I keep reminding people, KSP has terrible lift-to-drag ratios (10:1 wings). You probably need 3x the blade area that would seem to make sense in real life. The extra mass and drag will further help limit your RPM and thus your expansion. If you want to retain real life aesthetics, clip the blades together.

Great find on the throttle BTW.

[XLjedi]

3 hours ago, FleshJeb said:

In any case, I think you’re using too much rotor for that craft/blade arrangement. 

The example craft/rotor was purely for demonstration.  It's configured in such a way to most effectively show how the blades move (no overlapping, etc).