Airframes that have just come off the production line are not usually painted. However, we often see that although their bodies are not painted, their vertical stabilizers are painted in the colors of the ordering company as decided. So why are the vertical stabilizers of airplanes painted first?
Aircraft produced with the latest technology and go through a very long and complex manufacturing process. Usually, airplanes come off the final assembly line in metallic gray or beige. Moreover, the reason why the tails of the planes are painted first is quite logical.
The rudder, which is a movable part at the rear of the vertical stabilizer, is one of the primary control surfaces. For this reason, it is an extremely important part for the aerodynamic structure of the aircraft and must be well balanced.
Its manufacture and paint are very important factors affecting the weight and balance of the rudder.
For these reasons, if the vertical stabilizer paint is mounted on the aircraft in some way and it is desired to be painted later, even minor mistakes in weight and balance sensitivity may endanger the flight risk during the entire service life of the aircraft.
Aircraft tails are therefore often painted prior to delivery to ensure that the rudder is perfectly balanced and the paint weight has been calculated.
Rudder produced and installed without paying attention to the variables we mentioned can create a “flutter” effect. This may cause the rudder to tilt to one side and destabilize the aircraft. Or, it can prevent the pilot from applying the desired maneuver to the aircraft as she wishes.
Airplanes need to use Rudder at every stage of flight. However, they need them most often during take-off and landing, especially when there is a strong crosswind.
This applies not only to the Rudder, but also to the winglet structures at the wingtips. An example of this is the foldable winglets on the wings of the Boeing 777X aircraft.