Reaction wheel saturation and alternatives

[salaminho]

Reaction wheels in real life gets saturated when they spin too fast and have an external force applied to the craft. RW in ksp 1 are overpowered not because the amount of torque they can apply, but because they don’t get saturated. So you can use RW everywhere you want, some applications would be impossible in real life, like attitude control in aircraft.

• Add saturation to each of three axes of rotation of RW’s.

Alternatives to RW:

• Add Magnetorquer 

 "A magnetorquer or magnetic torquer (also known as a torque rod) is a satellite system for attitude control, detumbling, and stabilization built from electromagnetic coils. The magnetorquer creates a magnetic dipole that interfaces with an ambient magnetic field, usually Earth's, so that the counter-forces produced provide useful torque." https://en.wikipedia.org/wiki/Magnetorquer

It would also be cool if it could take into account the amount of magnetic field on different planets, so it would be useful orbiting some celestial bodies and not so much on others. 

 

• Add Reaction control system that uses only liquid fuel and intake air (for vtol aircraft, like the one used on the Harrier and the F-35B). On previous version of ksp1, the player could use the drain valve to drain intake air and create a little amount of infinite thrust. Create an RCS that uses intake air + liquid fuel would solve the problem. 

 

• Make engines gimbaling more customizable. For vtol aircrafts with tilting engines the automatic gimbaling in ksp1 gets really confused and ineffective when control reference is pointing forward and engines are pointing down. If there was a way to manually set up where engines should point when player input a pitch-yaw-roll command it would open a lot of alternatives for attitude control. 

[OHara]

One way of implementing saturable reaction wheels, is to build them with rotating masses, and connect them to controls so that they stop rotating when the user releases the pitch/yaw/roll command.  (KerbalX link)  The saturation never becomes a problem because the control hook-up does not leave any rotation in the wheels that might accumulate to eventually saturate the capability of the wheel.  They are also easier to use for orienting a probe or pod, because rotation stops when the control-input stops.

The mod Ferram Aerodynamic Research has a nice way of generalising the inputs to control surfaces.  If you select a button in the right-click menu of a control surface, you see sliders to determine how much, and in what direction, that control surface should respond to pitch, yaw and roll.  The picture at right shows an airplane where the rudder responds to roll commands enough to perform what they call 'coordinated turns'.

[salaminho]

1 hour ago, OHara said:

One way of implementing saturable reaction wheels, is to build them with rotating masses,

Nice! I thought about doing this, but I guess I’m too lazy. 

Your reaction wheels are perfect and very illustrative to understand how the real thing works. This should be stock, well done! 

The only problem is due to issue #22946, kal-1000 does not obey SAS command =(. 

[magnemoe]

Now I think reaction wheel saturation is a bit to complex for KSP2 I want them to have an maximum momentum build in. 

In KSP 1 you could easy do an long burn with an off center engine with no problems or even do stuff like having an lander staying upright on Minmus with just lading legs on one side while you are messing around. On the other hand ion KSP1 ion engines having no gimbal and the small probes they are designed for this could easy create problems. 

In real life you have factors like atmospheric and solar wind drag and tidal forces who will saturate reaction wheels on satellites who often has to point towards earth. 
I imagine space telescopes could be run in a way who cancel out saturation.