I don&#x27;t know about the B-29 system in particular, but gyroscopic gunsights used on most WW2 fighters were fairly straightforward.  First, you set a selector on the sight to the wingspan of your target (usually there would be presets for common enemy aircraft).  Then you twist a knob (typically on the throttle) that adjusts a ring in the sight until it matches the size of the target - this establishes the range.  Finally a gyroscope provides input on how your aircraft is moving, and since you&#x27;re typically maneuvering to follow your target this is an approximation of the target&#x27;s movement.<p>There&#x27;s a lot of approximation involved, but generally it&#x27;s good enough to hit an airplane sized target, especially on US fighters where you typically have 4-8 machine guns spitting out 50+ bullets per second in a shotgun like pattern.<p>Some relevant links:<p><a href="http:&#x2F;&#x2F;i651.photobucket.com&#x2F;albums&#x2F;uu236&#x2F;ken1926&#x2F;P-51DK_03.jpg~original" rel="nofollow">http:&#x2F;&#x2F;i651.photobucket.com&#x2F;albums&#x2F;uu236&#x2F;ken1926&#x2F;P-51DK_03.j...</a><p><a href="http:&#x2F;&#x2F;www.lonesentry.com&#x2F;blog&#x2F;wp-content&#x2F;uploads&#x2F;2010&#x2F;09&#x2F;target-pattern-right-and-wrong.jpg" rel="nofollow">http:&#x2F;&#x2F;www.lonesentry.com&#x2F;blog&#x2F;wp-content&#x2F;uploads&#x2F;2010&#x2F;09&#x2F;ta...</a><p><a href="https:&#x2F;&#x2F;upload.wikimedia.org&#x2F;wikipedia&#x2F;commons&#x2F;d&#x2F;d7&#x2F;P-47_gun_harmonization_-_two_types.jpg" rel="nofollow">https:&#x2F;&#x2F;upload.wikimedia.org&#x2F;wikipedia&#x2F;commons&#x2F;d&#x2F;d7&#x2F;P-47_gun...</a>