When made of ductile metal, the HP rocket must have a minimum amount of metallic parts for the purpose of sustaining airframe integrity.
(the HP rocket; must have; a minimum amount of metallic parts; for the purpose of sustaining airframe integrity; T:When made of ductile metal)
the HP rocket
must have
a minimum amount of metallic parts for the purpose of sustaining airframe integrity T:When made of ductile metal