nrlulz
ACF Propeller tool
Propeller tool (from propeller svn) is rather OP, allowing the smallest engines to generate massive thrust. Thrust is increased with inverse log of rpm, and no efficiency limit, and no drag.
Fin tool, on the other hand, requires massive torque to generate enough thrust. Generating thrust with prop angle and efficiency creates huge amounts of drag that acf engines struggle to overcome.
. ACF propeller tool could work as follows:
Tool use
- Propeller modifier is applied to a left-clicked entity
- Settings are grabbed from right-clicked entity
- Tool display (think armor properties tool) shows settings of the prop being looked at
- Tool options for mass?, efficiency?, thrust direction (+ or -), propeller pitch?
Drag
- Increases non-linearly with rpm, and perhaps linearly with radius or surface area
- Simulated by sapping the torque of the engine, similar to how parented weight reduces torque, or by not fully utilizing the torque from the gearbox.
- Could use very weak acf braking for physical drag
Thrust
- Thrust is in direction of hitnormal from when the propeller was applied
- Increases non-linearly with rpm, and perhaps linearly with radius or surface area, possibly increased by propeller mass or inertia
- Engines with more power should be able to achieve higher propeller rpms
Benefits
- Fewer props dedicated to propulsion
- Balanced for acf
Drawbacks
- May necessitate the use of a new tool
- Fin and propeller tool already exist, and it would be up to server owners to encourage or enforce the use of acf propellers
Other Thoughts
- If surface area is part of the calculation, it might make sprops propellers much less attractive compared to a sprops plate. Perhaps area divided by volume would be better? How would makespherical affect this?
- Is there a reason to allow efficiency to be changed/lowered from max?
- Should there be a maximum effective rpm, after which thrust is decreased?
- Option for propeller pitch (tool or input), which would affect drag, rpm, and thrust?
- Option for number of blades?
links http://en.wikipedia.org/wiki/Propeller_(aircraft) http://en.wikipedia.org/wiki/Drag_equation http://en.wikipedia.org/wiki/Drag_coefficient http://web.mit.edu/16.unified/www/SPRING/propulsion/UnifiedPropulsion7/UnifiedPropulsion7.htm http://electricrcaircraftguy.blogspot.com/2013/09/propeller-static-dynamic-thrust-equation.html http://flysafe.raa.asn.au/groundschool/propeller.html
. Please post your thoughts, concerns, balance ideas, etc.
This would be amazing. Something to fix wobbly fin propellers. Seems like it might also be good to get proper thrust oriented gas turbines, and maybe ducted fans or maybe that's reaching too far.
It seems to me that Efficiency, or lift(thrust) proportion to drag should be proportional to surface area/volume, as you mentioned. Of course realistically it comes down to airfoil shapes, but I don't think that's consistent with the way this game works.
Because of the way Make Spherical works on wheels, I think it's reasonable for something similar to affect propellers. You can just simulate an arbitrary pitch, blade width, and number of blades, irrespective of whether you put a sixbladed propeller, simple disk, or a chair on the end of your driveshaft.
Would propellers behave differently in water? You would have very different pitch and blade width, but its fundamentally the same mechanic.
About the 'marine' propellers: I believe that the force on the propeller itself would have to be much higher as the density of water is 999.97 kg/m3, and air is 1.225 kg/m3, but the overall properties should remain the same...
