Dihedral

For our model to fly correctly, the wing needs to have dihedral. The dihedral is the upward bend we build into the wing which gives the model stability when it is flying. Imagine a bowl with a marble in it, if you tip the bowl a little each way the marble stays inside the bowl. If instead of a bowl, we used a plate, then the marble would roll off the plate if we tipped it side to side. Dihedral acts in the same way on the model. If the model rocks side to side then the dihedral will help to correct it, like the marble in the bowl. There are three kinds of dihedral: tip dihedral, vee dihedral, and polyhedral. For our model we will be using tip dihedral, which is when all of the dihedral is placed in the wingtip portion of the wing (see the plan). Vee dihedral is when the dihedral break is located at the center of the wing or the 'center rib' as called out on the plan. The name of "vee" is given because the shape of the wing, when viewed from the front, resembles a flattened letter "V". Polyhedral is when a combination of the tip and vee dihedral are used together.

Dihedral can be defined in more than one way. It can be specified by angle, or by actual amount. It is correct to say " I have 2 inches of dihedral under each tip." and it is also correct to say " I have 30 degrees of dihedral under each tip." For our model, we will need to place in 30 degrees of dihedral under each tip. 30 degrees was chosen because most students have a 30/60/90 degree right triangle.

To put the dihedral in, we will have to first make a cut into the wing spars with a new sharp single edge razor blade. Use the blade and cut about 1/2 to 2/3'rds of the way through the trailing edge spar just outside of the dihedral rib on the wing. Refer to the plan and see the dashed lines marked "Dihedral Break" on the wings. This is the location you want to cut with the razor.

After you cut through the spar, bend the wing tips upwards to crack the rest of the way through the wing spar. When you are done, it will look as shown below.

Use the 30/60/90 triangle and place it under the wing tip as shown to hold the wingtip at the proper 30 degree dihedral angle. It may be necessary to place a few weights on the wing to hold it down flat on the table. (I chose to use a few coins for the weight.)

Use your superglue, and apply a drop of glue to the dihedral joints.

Then apply the superglue accelerator to the glue joints, and let dry for about a minute.

After the glue dries, then slide a razor under the joint to cut it loose if it happens to glue to the table.

Lift the wing off the table and check the wing tip to make sure the wing tip spars are parallel to each other. You do not want to have the wing tips washed-in or washed-out, or it will cause the model to perform poorly. If your wingtip needs to be corrected then use the razor and cut the joint you just created and raise or lower one of the wingtip spars to make it line up with the other one.