| 摘要 |
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. A slidable connection of a tongue and groove type between the upper end of the housing and the sighting member and its supporting post prevents any misalignment of the sighting post in any position thereof established and maintained by the element so that when the launcher is readied for use, the front sight compensates for the existing efficiency of the propellant.
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