<div class="htmlview paragraph">Aerodynamic and structural considerations in the design of these two airplanes are compared with other light aircraft designs.</div> <div class="htmlview paragraph">The designer-builder relationship has some effect on the selection of configurations, materials and construction methods. The designer has the task of taking the many compromises between performance, safety, structural integrity, and weight.</div> <div class="htmlview paragraph">The PL-2 is not only built by amateurs and flown for recreation, but it is also used as a military trainer in several Asiatic countries.</div> <div class="htmlview paragraph">The PL-4, also built by amateurs, has been flown as a sport aircraft, and also selected as an advanced Air Cadet Trainer in Canada.</div>