The electromechanical angle computer inside the B-52 bomber's star tracker

6 hours ago

Celestial navigation, using stars, planets, or the sun, was a key pre-GPS method for aircraft, accurate and immune to jamming but slow and difficult manually.
In the early 1960s, an automated system for the B-52 bomber, the Astro Compass, was developed, featuring the Astro Tracker to lock onto stars and the Angle Computer to solve navigational calculations mechanically.
The Angle Computer, an electromechanical analog computer, modeled the celestial sphere to convert star coordinates into local azimuth and altitude, using inputs like declination and local hour angle.
The Astro Compass provided a highly accurate heading and assisted in determining aircraft position via the celestial line of position technique, using multiple star fixes.
Navigators used the Air Almanac for celestial data, inputting values into the Astro Compass via a unique interface with knobs and displays to compute star positions.
The system combined mechanical, electrical, and early electronic components, representing a transitional technology before digital computers became prevalent.

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