Question: When the torsion spring diameter is 38.4cm what would be the length or weight of the missile
Schema: create table table_21012786_2 (length_weight_of_missile varchar, diameter_of_torsion_spring varchar, PRIMARY KEY (length_weight_of_missile))
SQL: select length_weight_of_missile from table_21012786_2 where diameter_of_torsion_spring = "38.4cm"