What is the general rule for determining the appropriate rivet diameter?

The appropriate rivet diameter is best determined by a rule of thumb that relates it to the thickness of the materials being joined, particularly focusing on the thickest sheet. This is crucial for ensuring that the rivet has sufficient shear and tensile strength to maintain structural integrity under load.

Using a diameter that is three times the thickness of the thickest sheet provides a balance between strength and weight. This guideline ensures that the rivet can adequately accommodate the forces applied without risk of failure, while also preventing excessive weight or material usage that could complicate the assembly process.

Other approaches, such as matching the diameter to the sheet thickness or using a smaller ratio, do not provide the same level of structural support. The chosen ratio helps to ensure that the rivet can adequately distribute loads across the joint and align with the design requirements of most aerodynamic and load-bearing applications in aviation.