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

Before GPS, how did aircraft navigate? One important technique was celestial navigation: navigating from the positions of the stars, planets, or the sun. While celestial navigation is accurate, cannot be jammed, and doesn't require any broadcast infrastructure, it is a difficult and time-consuming process to perform manually. In the early 1960s, an automated system was developed for the B-52 bomber to automatically track stars and compute navigation information. Digital computers weren't suitable at the time, so the star tracking system performed trigonometric calculations with an electromechanical analog computer called the Angle Computer.1 The Angle Computer contains complex electromechanical systems. Click this image (or any other) for a larger image. The photo above shows the mechanism inside the Angle Computer.2 Although it may look like a gyroscope or IMU (Inertial Measurement Unit), it is completely different and nothing is spinning. The Angle Computer physically models the…