The rectangular centre section was ply - covered overall but the outer wing panels were fabric covered behind the torsion box .
The rectangular centre section was braced on each side with a pair of parallel steel tube struts from the lower fuselage .
The rectangular centre section , which was braced on each side with a pair of parallel steel tube struts from the lower fuselage , was ply - covered overall but the outer wing panels were fabric covered behind the torsion box .