Nacelle

Nacelle: A nacelle (derived from an Old French work for a small boat) is a housing for fuel or engines on an aircraft, when the fuel or engines are outside the aircraft body or wings. The big jet engines on commercial airliners are housed in nacelles. This terms is used to in the description of several Star Trek vehicles.

At five hundred meters he armed the nacelle.

As the housing is probably sheet metal or carbon-fiber composite and not capable of inflicting much damage, I assume the implication is the weapon system contained in the nacelle. Alternately, using the original meaning metaphorically, the nacelle could refer to the entire drone.