The Sperry A-12 autopilot was originally intended for piloted aircraft but was modified for the Regulus missile. It was a large, heavy, densely packaged box of electronics, featuring a large number of vacuum tubes.  The main “box” was about 12” x 12” by 30”, and because of its extreme weight was usually carried to and from the missile by a pair of technicians.

Radio Control

The Regulus radio command control system was the first jet-powered use of a command system developed to control propeller-driven aircraft during World War II.

The system had two modes of operation. The first was known as “beep” control where only an “on” or “off” command was needed. A selector switch with 20 positions worked together with a switch to “decrease” or "increase” the selected function. Selector positions included parabrake deployment (if automatic deployment failed), landing gear up or down, or any of the automatic flight control system functions such as altitude or climb settings.  In more modern computer terms these would be called “toggle” commands.

The second mode was a proportional system, and provided for the variable continuous control of pitch, rate of turn, and throttle settings.


An early as 1945 under Project DERBY, the Navy flew an “Americanized” version of the German V-1, called a Loon. In 1950 Project TROUNCE was established within Project DERBY. Project TROUNCE was the beginning of a new guidance system that used paired-pulse radar signals for transmitting guidance command to the missile. The new radar command control was given the name Trounce.

Design and development of Trounce continued through the Loon program and was to be ready for use in the Regulus program in 1952.

Trounce was not without problems but development continued and the problems resolved.  A rival bipolar navigation system, which required a launch submarine and two picket signal boats near the target, was also flight-tested. In the end, Trounce was the guidance system of choice for Regulus I. As one wit observed, “An ounce of Trounce is worth a pound of  bipolar”.


The missile was usually equipped with a telemetry system sending “down” to the ground receiving station a variety of parameters including airspeed, altitude, engine RPM, control surface movement, hydraulic pressure, landing gear position, etc.

On some occasions a photo observer was used to augment the telemetry system. A photo observer employed a 16-mm black and white movie camera, converted from its prime use as an aircraft gun camera.  The photo observer used conventional aircraft style instruments to show altitude, voltage, airspeed, elapsed time, etc., while the camera took time-lapse pictures of the instruments.  When the missile landed the camera, film was developed and used to document the flight data.

More Regulus I:

General Characteristics for an Interim Guided Missile
Able, Backer, Charlie and FTV-1
Operation Splash and FTV-3
Regulus I and II
Regulus I Subsystems
Airframe, Engine and Fuel Systems
Autopilot, Radio Control, Guidance and Instrumentation
Landing Gear and Hydraulic Systems
Nose Boom, Wing and Fin Fold
Launch Slippers, Parabrake, Smoke Systems and Jato
Interesting Statistics