Rethinking Propellers

[Periple]

Propellers popped up in Dakota's Top Ten Requests thread a few times and I got to thinking about them. I really enjoyed making propeller and rotorcraft in KSP1 but I thought they were really fiddly and I think they need to be re-thought for KSP2, if they decide to implement them. Here's how I'd go about it!

We should still have torque

It's an important design consideration and getting rid of it would make propellers too similar to jet engines!

Blades should be parameters

Instead of attaching blades to motors and then fiddling with them, the critical things should be parameters on the motor:

• Number of blades
• Size of blade
• Rotation direction (affects both blade variant and motor direction so they always match)
• Reverse rotation switch (for backward-facing props)

These should have a sensible default for each motor size.

Blades should have auto-pitch as the default option

We've had constant-speed propellers with automatic pitch for ages and ages and I think we should have them in KSP as well. There should be an option to switch to manual pitch as well because sometimes you want to. 

Default axis binds for torque and pitch

• Throttle controls engine torque
• Up/Down controls blade pitch (if not set to automatic/constant-speed)

You could reassign these but you shouldn't have to assign them manually every time.

Handle helicopter main rotors separately

You would have to explicitly choose to make a propeller a helicopter rotor. This would change its axis/keybinds and behavior. These could be entirely different parts, or a switch you can flip on a part.

• Constant-speed/automatic pitch would be removed
• The up/down axis would control pitch 
• The roll and pitch axes (QE/WS) would control cyclic

Handle helicopter tail rotors separately

Like for the main rotor, the tail rotor should be either a designated part or a mode/switch you can flip. 

• It has auto-torque to keep it constant speed
• The yaw axis (AD) will control pitch
• SAS will automatically adjust it to keep the craft's orientation stable

In sum

If they were designed this way, making a functional propeller plane would be almost as easy as making a jet plane, as you'd only have to deal with torque. Making a functional helicopter would be fairly straightforward too: install a main rotor and tail rotor (or two counterrotating main rotors), and off you go.

I know that this may sound too much like "easy mode" for some people, but I really think they were too difficult to get into for most people, and even when you knew how they worked, they needed too much manual tweaking to fly. Single main rotor helicopters in particular were really hard to build and even when built right were really squirrelly. I think that with this kind of approach, lots more people would use them, and you'd still be able to set them to "full manual" if you wanted the advanced stuff.

What do you think? 

Edited November 10, 2023 by Periple

[gluckez]

I think the concept of a propeller itself should be considered, it's really nothing more than a wheel with wings attached. introducing specific propeller components is one possibility, but to me there's more freedom if you split this up into it's own seperate parts. A rotating component could be used for artificial gravity for example if you rotate it slower and attach habitation modules, but it could also be used to achieve lift if you attach wings. 
So perhaps a simpler solution would be to use different size, configurable rotators, combined with procedural wings.

EDIT: combine this with the option to save crafts as individual components and you can easily make your own propellors that you can attach to your craft

Edited November 10, 2023 by gluckez

[Periple]

I think there should still be plain old motors that rotate things. I just think that the specific behaviors propellers and helicopter rotors need to have to make it enjoyable to design and fly them are so complicated that modeling them from first principles gets too fiddly. 

One possibility would be to have a mode switch in the part configurator: 

1. Plain motor -- no blades, no control mappings, attachment points at both ends and 2-8 on the side like in KSP1
2. Propeller engine -- as described above
3. Helicopter main rotor -- as described above
4. Helicopter tail rotor -- as described above

Basically, I'd like an easy way to accomplish the following:

1. Toggle constant-speed/auto-pitch - constant-speed/auto-torque - full manual torque/pitch
2. Bind cyclic to pitch/roll and collective to up/down
3. Bind pitch to yaw and make it work as expected with SAS (tail rotor case)
4. Specify the number and type of blades easily
5. Specify the rotation direction of the whole assembly rather than having to do it separately for the blades and the motor
6. Intuitively handle backward-pointing propellers (reverse direction switch)

This should also be easy enough and have good enough defaults that you could assemble a plane or a helicopter, and it would work more or less like you'd naively expect it to work. If you were doing it completely from scratch, the only new thing you'd have to deal with is torque.

Edited November 10, 2023 by Periple

[Sea_Kerman]

why should blade pitch on the tail rotor variant be just bindable to yaw? let us bind anything to anything! 

[Periple]

6 minutes ago, Sea_Kerman said:

why should blade pitch on the tail rotor variant be just bindable to yaw? let us bind anything to anything! 

I think bindings should be overridable. The main problem is making SAS understand that it controls yaw.

[NexusHelium]

I would also personally like the motors and the chopping and moving of the propeller to have sound (From what I remember, it didn't in KSP 1)