Voith Schneider Propeller animation, showing a top-down schematic view of a six-bladed Voith Schneider propeller. The approximate force on the water of each blade is shown by a blue arrow. The net force on the water is vertically upwards, indicating that the propeller itself is moving vertically downwards relative to the water.

The file was made with Pov-Ray version 3.6, with the source file:

#include "colors.inc"           #include "shapes.inc" #macro airfoil() union {polygon { 120, <2.032241, -0.015403>, <2.033186, 0.002328>, <2.029376, 0.019655>, <2.020798, 0.036480>,  <2.007448, 0.052705>, <1.989329, 0.068240>, <1.966455, 0.082997>, <1.938845, 0.096893>,  <1.906529, 0.109851>, <1.869547, 0.121803>, <1.827947, 0.132683>, <1.781785, 0.142438>,  <1.731128, 0.151018>, <1.676052, 0.158386>1.413433, 0.175281>, <1.337759, 0.176334>, <1.258339, 0.176146>,  <1.175324, 0.174747>, <1.088878, 0.172180>, <0.999175, 0.168497>, <0.906403, 0.163761>,  <0.810764, 0.158046>, <0.712472, 0.151432>, <0.611756, 0.144010>, <0.508857, 0.135880>,  <0.404031, 0.127146>, <0.297549, 0.117920>, <0.189695, 0.108317>, <0.080768, 0.098457>,  <-0.028922, 0.088460>, <-0.139048, 0.078448>, <-0.249273, 0.068540>, <-0.359249, 0.058851>,  <-0.468615, 0.049493>, <-0.577002, 0.040570>, <-0.684035, 0.032176>, <-0.789332, 0.024397>,  <-0.892507, 0.017305>, <-0.993173, 0.010960>, <-1.090945, 0.005405>, <-1.185441, 0.000670>,  <-1.276287, -0.003234>, <-1.363118, -0.006310>, <-1.445582, -0.008582>, <-1.523342, -0.010087>,  <-1.596081, -0.010879>, <-1.663504, -0.011030>, <-1.725337, -0.010622>, <-1.781336, -0.009751>,  <-1.831284, -0.008524>, <-1.874995, -0.007055>, <-1.912315, -0.005464>, <-1.943121, -0.003875>,  <-1.967325, -0.002414>, <-1.984873, -0.001203>, <-1.995742, -0.000362>, <-1.999942, -0.000005>,  <-1.997516, -0.000238>, <-1.988536, -0.001154>, <-1.973103, -0.002838>, <-1.951344, -0.005359>,  <-1.923410, -0.008775>, <-1.889478, -0.013125>, <-1.849740, -0.018435>, <-1.804411, -0.024716>,  <-1.753718, -0.031961>, <-1.697903, -0.040152>, <-1.637220, -0.049252>, <-1.571931, -0.059213>,  <-1.502307, -0.069974>, <-1.428623, -0.081463>, <-1.351159, -0.093597>, <-1.270198, -0.106283>,  <-1.186023, -0.119424>, <-1.098920, -0.132912>, <-1.009171, -0.146639>, <-0.917059, -0.160490>,  <-0.822862, -0.174350>, <-0.726857, -0.188103>, <-0.629318, -0.201632>, <-0.530513, -0.214825>,  <-0.430707, -0.227568>, <-0.330162, -0.239755>, <-0.229131, -0.251282>, <-0.127866, -0.262051>,  <-0.026614, -0.271972>, <0.074387, -0.280959>, <0.174900, -0.288935>, <0.274696, -0.295831>,  <0.373550, -0.301584>, <0.471242, -0.306142>, <0.567561, -0.309462>, <0.662297, -0.311507>,  <0.755248, -0.312252>, <0.846218, -0.311679>, <0.935015, -0.309781>, <1.021455, -0.306557>,  <1.105359, -0.302018>, <1.186554, -0.296182>, <1.264873, -0.289076>, <1.340155, -0.280734>,  <1.412246, -0.271199>, <1.480999, -0.260522>, <1.546271, -0.248760>, <1.607929, -0.235976>,  <1.665845, -0.222243>, <1.719898, -0.207635>, <1.769974, -0.192235>, <1.815967, -0.176129>,  <1.857778, -0.159408>, <1.895313, -0.142167>, <1.928490, -0.124504>, <1.957230, -0.106520>,  <1.981465, -0.088317>, <2.001133, -0.069999>, <2.016181, -0.051671>, <2.026563, -0.033437>     pigment {rgb <0,0,0>} 	translate <-.5,.1,0> } disc { 	<0,0,.001>,<0,0,1>,.1 	pigment{rgb <1,1,1>} } }  #end #macro arrow() polygon { 	8, 	<-.5,-.5>,<.5,-.5>,<.5,2>,<1.2,2>,<0,3.2>,<-1.2,2>,<-.5,2>,<-.5,-.5> 	pigment {rgb <0,0,1> transmit 0.5} } #end  #macro prop_element(ang,xofs,yofs,rad) union { object { 	airfoil() 	rotate z*90 	rotate z*-ang 	rotate z*180*atan2(sin(ang*pi/180.0)-yofs,cos(ang*pi/180.0)-xofs)/pi 	translate x*rad } object { 	arrow() 	//scale <cos(ang*pi/180),cos(ang*pi/180),1> 	scale <.5+cos(ang*pi/180),.5+cos(ang*pi/180),1> 	scale .6 	translate z*.3 	rotate z*-ang 	translate x*rad } polygon { 4, <.4,0>,<-.4,0>,<-.1,rad>,<.1,rad>  pigment {rgb <.6,.6,.6>} translate z*-.1 	rotate z*90 } 	rotate z*ang } #end #macro prop(xofs,yofs) union { #declare ang=0; #while (ang<360) prop_element(ang+clock*6,xofs,yofs,5) #declare ang=ang+60; #end disc { 	<0,0,.002>,<0,0,1>,.6 	pigment{rgb <1,1,1>} } disc { 	<0,0,.001>,<0,0,1>,1 	pigment{rgb <.6,.6,.6>} } } #end  camera  {     	orthographic 	location <0,0,10> 	right <15,0,0> 	up <0,15,0> 	look_at <0,0,0>   }    light_source  {  	<0,0,40>  	White *2  	shadowless  }    background {rgb <1,1,1>}  prop(.85,0) 

Pov-Ray was executed with the command

povray +KFF10 +KI0 +KF9 +A0.1 +W240 +H240 -GA vs.pov