Abstract: Launchers of the type that are extensible when readied for use contain projectiles the efficiency of the propellants of which varies directly with their temperature. Prior to the extension of such launchers, they are water resistant and their interiors are thermally insulated and when extended, the rear and front sights become erected. The front sight, prior to launcher extension includes a sight housing in support of a sighting member having a central sighting post. One end of the sight housing is pivotally connected to the interior of the launcher housing and is under the influence of an erecting spring. The sight housing has a slideway extending to an opening through its free end and intersecting a lengthwise chamber in the sight housing.

Abstract: Launchers of the type that are extensible when readied for use contain projectiles the efficiency of the propellants of which varies directly with their temperature. Prior to the extension of such launchers, they are water tight and their interiors are thermally insulated and when extended, the rear and front sights become erected.The front sight, prior to launcher extension is within and thermally insulated by a housing sealed to the launcher and having a chamber in which one end of a bimetallic element is anchored. Above the chamber, the sight housing slidably supports for vertical movement a sighting member having a sighting post and a depending supporting post extending into the chamber and is there connected to the other end of the element.