Mischgerät (V-2 guidance computer)

Designed in 1941 by Helmut Hölzer, the Mischgerät (mixer device) was the first fully electronic computing device, used to implement Hölzer’s V-2 rocket stability control equation during powered flight.

It differentiated the voltages from the Vertikant (yaw and roll) and Horizont (pitch) gyroscopes to sense the gyro platform's divergence from its original orientation in pitch, yaw and roll, - and more crucially derived the rate of divergence - and output amplified correcting voltages to the steering servos for the exhaust vanes and external rudders.

Technical concepts tested with the smaller A5 research rocket included use of the Siemens Vertikant stability control system with rate gyros. This approach didn't scale well for the larger and higher performance V-2.

From his previous glider ground speed indicator concept in the mid-1930s, Hölzer realized he could implement an electrical approximation of a stability control equation by processing the signals of lower cost position gyros using a network of resistors, capacitors, and tube amplifiers. The resulting device offered better performance, lower weight, and 1/280 the cost compared to competing approaches.

Hölzer expanded upon the Mischgerät design to develop the first general purpose electronic analog computer, which he used to perform 2 DOF flight simulations with examples of the Mischgerät.

The name "Mischgerät" suggested a simple signal mixer, a cover for the true capability of the device.

The Mischgerät analog electronic computing approach became the base from which American and Soviet engineers built much more sophisticated and accurate rocket flight control systems into the 1960s.