 During the designing and filming process , Meddings ' first priorities were realism and credibility . With the exception of Thunderbird 5 , each vehicle was built in three or four scales . Meddings ' swing @-@ wing concept for Thunderbird 1 was inspired by his wish to create something " more dynamic " than a fixed @-@ wing aircraft . He remained unsatisfied with the prototype of Thunderbird 2 until he inverted the wings , later commenting , " ... at the time , all aircraft had swept @-@ back wings . I only did it to be different . " This decision was made out of personal preference and was not informed by any expert knowledge on Meddings ' part . He described the Thunderbird 2 launch as " probably the most memorable " sequence that his team devised for an APF production . 
