5.Let's-build/Rotor-Blade.md

@@ -24,6 +24,7 @@ Following variables are used:
 | B                        | 67   |
 | A                        | 33   |
 | D                        | 10   |
+| E                        | 13   |
 | airfoil thickness T      | 10   |
 | a1                       | 10   |
 | a2                       | 3    |