Start made on the four-bar linkage. I need to remember trigonometry.

model/fourbar.scad

@@ -0,0 +1,35 @@
+// fourbar.scad
+
+include <Library/BentSim/Bike_accessories.scad>
+include <Library/NACAAirfoils/files/Naca4.scad>
+include <Library/skew.scad>
+
+module fourbar_leg(length=1000, chord=100, long_skew=30, lat_skew=30) {
+    // upper pivot needs a complex trig transformation!
+    translate([(length * cos(long_skew) * cos(lat_skew)) - (2 * chord), 
+    length * cos(long_skew) * sin(lat_skew), 0])
+        rotate([0, 90+long_skew, 0])
+        cylinder(h=chord, r=12);
+    
+    // lower pivot: 
+    translate([0-chord, -12, (chord/2) * sin(long_skew) * sin(lat_skew)])
+        rotate([0, 90+long_skew, 0])
+        cylinder(h=chord, r=12);
+    
+    // aerofoil section
+    skew([0, long_skew, 0, 0, 0, 0])
+        rotate([lat_skew, 0, 180])
+        airfoil(h=length, L=chord);
+}
+
+
+module fourbar(length=1000, chord=100, long_skew=30, lat_skew=30, shoulder=650) {
+    translate([0, 0-(shoulder/2), 0])
+        fourbar_leg( length, chord, long_skew, lat_skew);
+    
+    translate([0, shoulder/2, 0])
+        mirror([0, 1, 0])
+        fourbar_leg(length, chord, long_skew, lat_skew);
+    }
+
+fourbar(600, 100, 30, 30, 650);