diff --git a/src/constants.rs b/src/constants.rs
index 8166df5..6a132fc 100644
--- a/src/constants.rs
+++ b/src/constants.rs
@@ -1,3 +1,5 @@
+use std::ops::Range;
+
 use crate::WingConfig;
 
 /// Constants
@@ -23,7 +25,7 @@ pub const FUSELAGE_GAP: f32 = 0.4 * IN2MM;
 /// a very large number, used to place unknown objects such that they do not intersect
 pub const INF: f32 = 1000.0;
 pub const RUDDER_HEIGHT: f32 = 5.0 * IN2MM;
-pub const RUDDER_CHORD: f32 = 3.0 * IN2MM;
+pub const RUDDER_CHORD: f32 = 4.0 * IN2MM;
 pub const RUDDER_TAPER: f32 = 0.7;
 pub const RUDDER_STRUTS: usize = 3;
 pub const RUDDER: WingConfig = WingConfig {
@@ -42,5 +44,6 @@ pub const ELEVATOR: WingConfig = WingConfig {
     taper: ELEVATOR_TAPER,
     struts: ELEVATOR_STRUTS,
 };
+pub const MIDSPAR_RANGE: Range<f32> = 0.1..0.4;
 pub const STOCK_HEIGHT: f32 = 25.0 * IN2MM;
 pub const STOCK_WIDTH: f32 = 37.0 * IN2MM;
diff --git a/src/main.rs b/src/main.rs
index de09630..0f53897 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -176,9 +176,17 @@ fn wing(wing_airfoil: &SeligFile, wing_config: &WingConfig, spar: SparType) -> (
             spar
         },
         SparType::Center => {
-            // TODO: negative in struts
             // TODO: taper
-            centered_cube(vec3(wing_config.chord * 0.5, wing_config.length, CARDBOARD_WIDTH), (false, false, true))
+            let mut mid_spar = scad!(Hull);
+            let bottom = centered_cube(vec3(wing_config.chord * (MIDSPAR_RANGE.end - MIDSPAR_RANGE.start) , CARDBOARD_WIDTH, CARDBOARD_WIDTH), (false, false, true));
+            let mut top = scad!(Translate(vec3(0.0, wing_config.length - CARDBOARD_WIDTH, 0.0)));
+            top.add_child(scad!(Scale(vec3(wing_config.taper, 1.0, 1.0)); bottom.clone()));
+            mid_spar.add_child(top);
+            mid_spar.add_child(bottom);
+            mid_spar = scad!(Translate(vec3(MIDSPAR_RANGE.start * wing_config.chord, 0.0, 0.0)); mid_spar);
+            let mut spar = scad!(Difference; mid_spar);
+            spar.add_child(wing.clone());
+            spar
         },
     };
 
@@ -208,7 +216,9 @@ fn strut(airfoil: &SeligFile, chord: f32, width: f32, spar: &SparType) -> Constr
         match spar {
             SparType::Top => topspar_negative(airfoil, chord, 0.1..0.6),
             SparType::Center => {
-                scad!(Union)
+                scad!(Translate2d(vec2(MIDSPAR_RANGE.start, 0.0)); 
+                centered_square(vec2(MIDSPAR_RANGE.end -  MIDSPAR_RANGE.start, CARDBOARD_WIDTH/ chord), (false,true))
+                )
             }
             SparType::None => {
                 scad!(Union)