noun
impact fuze; contact fuze; percussion fuze; direct-action fuze
Military term for a fuze that detonates on impact with a target. The kanji 着発 (arrival/departure) combined with 信管 (fuze) literally suggests a fuze that activates upon arrival.
この砲弾には着発信管が装着されている。
This artillery shell is fitted with an impact fuze.
Compound of 着 (arrival), 発 (departure/activation), and 信管 (fuze). The exact historical derivation is uncertain, but the term likely originated in military engineering to describe a fuze that functions upon contact.