Install the elevator and rudder and clamp them in a neutral  position. Verify the neutral position of the control stick  and rudder pedals in the flight deck and secure them in  order to simplify the connecting and final tensioning of  the control cables. If the biplane has a center section for the upper wing, it  must be aligned as accurately as possible, because even the  smallest error is compounded at the wing tip. Applicable  cables and turnbuckles should be connected and the tension  set as specified.  [Figure 2-97]  The stagger measurement can  be checked as shown in  Figure 2-98 .  The lower wing sections should be individually attached to  the fuselage and blocked up for support while the landing  wires are connected and adjusted to obtain the dihedral called  for in the specifications or plans.  [Figure 2-99]  Figure 2-98.  Measuring stagger. Figure 2-99.  Measuring dihedral.  Figure 2-97.  Center section alignment. Plumb bob Stagger measured in inches Level aircraft Plumb line Ruler Plumb bob Stagger Lower wing hinge fittings Spar 90° 90° 90° CENTER SECTION 9 8 7 6 5 4 3 2 1 1 2 3 4  5 6 7 8 9 Distance “Y”  same both sides Straight edge -  clamp to firewall Fuselage centerline Level Top view Front view Z Z X X Plumb bob Ruler Distance  “X” same both sides Both tie rods “Z”  same length Note: A 1" rise in 57" equals one degree of dihedral Depicted angle 4 ° Measure upper wing dihedal Dihedal board Spirit level Lower wing  dihedal in inches Measuring dihedral (in inches) Measuring dihedral (angles) To increase  dihedral shorten landing wires Plumb bobs or weights Wood blocks (2" x 4") X 1 X 2 X 1 X 2 Upper wing with 0° dihedal -  string must touch blocks Landing wires 4° 4° can also use  dihedal board with a level Plumb bobs or weights Use straight edge and bevel protractor 4° 57" 2-58