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| Also known as | Autopilot servo amplifier |
|---|---|
| Developer | Helmut Hölzer |
| Manufacturer | C. Lorenz AG, General Electric, Scientific-Research Institute No.885 |
| Type | Electronic analog computer |
| Release date | 1941 (1941) |
| Introductory price | 6 ℛℳ |
| Units shipped | ~6000 |
| Power | 40VAC @ 500Hz |
| Dimensions | (inches) : 13" x 9.75" x 7" (mm) : 330 x 247.6 x 177.8 |
| Weight | 32 lb (15 kg) |
| Successor | Redstone LEV-3 |
Designed in 1941 by Helmut Hölzer, it was the first fully electronic computing device, used to implement Hölzer’s V-2 rocket stability control logic during powered flight.
It differentiated the voltages from the vertical and horizontal gyros to sense the gyro platform's divergence from its original orientation in pitch and yaw and roll, and output amplified correcting voltages to the steering servos for the exhaust vanes and external rudders.
Technical concepts tested with the smaller A-5 research rocket included use of the Siemens Vertikant stability control system with rate gyros. Scaling these up for use with the V-2 proved expensive and difficult to produce.
From his experience with remote control stabilization circuits in the mid-1930s, Hölzer realized he could implement an electrical approximation of a stability control equation by processing the inputs 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.
Development history
In 1935 while student of the Technical University at Darmstadt, Germany, Helmut Hoelzer was also a novice glider pilot, and wanted a way to measure his ground speed. He theorized that using electronic circuits, mathematical operations like integration or differentia- tion could be implemented. The system input would come by measuring voltage from a capacitor attached to a three axis mass-spring damping system. He wanted to build it as an undergraduate project, but professors at the University talked him out of it.
He wasn't able to revisit this work until 1939 when a civilian draft pulled him from a position at Telefunken in Berlin work at the German army rocket R&D site at Peenemünde under the technical direction of Werner von Braun.
A gyroscopic course control was planned to control the planned A-4 SRBM. Gyros couldn't account for crosswinds, and so a radio remote control was planned to address this. Hoelzer was assigned to work on this task.
Soon after, Dr. von Braun told the remote control lab staff that all four companies contracted to develop the gyroscopic control system said that their calculations showed that it would be unstable in flight.
The companies were using parts intended for aircraft and that some, particularly the servo motors that would move the rocket thrusters, were too slow. Unlike aircraft, the rocket had only 60 seconds of powered flight to correct course deviations. A solution would involve. either faster servos or the addition of rate gyros. These changes required time and money not available to the A-4 project.
Hoelzer, Otto Mueller, and others in their lab told Von Braun that they could have a solution the next day. They expanded the design of the electronic simulators they developed to the test the remote control system into a prototype automatic stabilization computer. Hoelzer estimated that the cost would be only a few Reichsmarks per copy, rather than several thousand for added rate gyros. Subsequent bench testing validated this "computer control" approach.
Technical details
Production
The Mischgerät was produced at the C. Lorenz AG company’s Berlin-Tempelhof factory, and shipped to Peenemünde and later Mittelbau-Dora for integration with the A-4 missile.
During the Hermes program testing of captured V-2 rockets in the US, prime contractor General Electric built 80 additional units using local components at their Schenectady, NY facility when the project ran out of German-made examples to equip otherwise completed missiles.
The Scientific-Research Institute No.885 built an unknown number of units using local components to equip the first Soviet SRBM, the R-1, itself a local recreation of the V-2.
Operation
Postwar use
Surviving examples
- Australian War Memorial
- Deutsches Technikmuseum Berlin
- White Sands Missile Range Museum, V-2 Building
See also
Notes
References
- ^ Gerovitch, Slava. "Glossary of Institutions of the Soviet Space Program" (PDF). MIT. Retrieved 2025-01-05.
see 'Scientific-Research Institute of Space Instrument Building (NII KP)'
- ^ Hoelzer, Helmut (1990). "50 Jahre Analog Computer" (PDF). Foundation for German communication and related technologies. NL. Retrieved 2025-01-05.
- Tomayko, James (1985-09-01). "Helmut Hoelzer's Fully Electronic Analog Computer" (PDF). Nonstop Systems. USA: IEEE. Retrieved 2025-01-05.