The Werfer-Granate 21 rocket launcher, also known as the BR 21 (the "BR" standing for Bordrakete) in official Luftwaffe manuals, was a weapon used by the German Luftwaffe during World War II and was the first on-board rocket placed into service by the Luftwaffe, first introduced in mid 1943. The weapon was developed by Rheinmetall-Borsig under the leadership of Dipl.-Ing. Rudolf Nebel, who had pioneered German use of wing-mounted offensive rocketry in World War I with the Luftstreitkräfte.