SCHEMA:
CREATE TABLE table_21012786_2 (length_weight_of_missile VARCHAR, diameter_of_torsion_spring VARCHAR)
USER:
When the torsion spring diameter is 38.4cm what would be the length or weight of the missile

QUERY:
SELECT length_weight_of_missile FROM table_21012786_2 WHERE diameter_of_torsion_spring = "38.4cm"