Werfer-Granate 21

Based on the 21 cm Nebelwerfer 42 infantry barrage rocket system's hardware, the weapon was developed by Rheinmetall-Borsig under the leadership of Dipl.-Ing.

This led to numerous efforts to develop weapons that could attack the bombers outside the nominal 1,000 yards (910 m) effective range of their defensive guns.

This weapon enabled the German pilots to attack their bomber targets from a safer distance of over a kilometer, where the risk of being hit was much reduced.

The rocket's huge blast radius also compensated for inaccuracy, and even a non-lethal hit on a bomber by a showering of shrapnel would have psychological effects and perhaps cause it to take evasive manoeuvres that would drive it from the protection of its fellows.

Operationally the weapon had several disadvantages; the launcher tubes produced significant air resistance, which reduced speed, maneuverability, and general performance.