MAD (Type 4B2, AN/ASQ-1, AN/ASQ-1a, AN/ASQ-3) Magnetic Detectors

Wing-Tip Installation
Wing-Tip Installation

DESCRIPTION: Airborne electronic device designed to detect space anomalies in the magnetic field of the earth produced by ships, submarines, accumulations of iron and steel, direct current power-loops, etc.
USES: For detection of submerged submarines and, overland, identification of large industrial areas for bombing through overcast.
PERFORMANCE: These sets indicate proximity to target only. Reliable range depends on the size of the target, its magnetic condition, the heading of the aircraft, and the amount of background or disturbance noise present. Under optimum operating conditions, it is believed that a 750-ton submarine can be detected reliably at distances up to 400 ft. with 4B2 and somewhat farther with the other sets.
TRANSPORTABILITY: Spares (except tubes) for 1000 hrs. operation, with testing equipment and bulk spares for primary maintenance bases, are supplied. No standard size of shipping carton has yet been adopted, but shipment is transportable in cargo planes.
INSTALLATION: Installed weight (including one 35-lb. recording milliammeter) is 250-275 lbs. for 4B2, 145-170 lbs. for AN/ASQ-1 and AN/ASQ-1a, and 210-235 lbs. for AN/ASQ-3. It is sometimes necessary to remove armor plate and guns in order to reduce the magnetic field of the aircraft to usable levels.
PERSONNEL: One operator per set is needed (the navigator, radar operator or rear gunner can be trained for this work.) To maintain the apparatus, it is believed that at least six men per squadron will be required.
POWER: Primary power is 10 to 13.5 amps., 289 volts DC, from plane's supply.


AN/CRT-1 and AN/ARR-3 Sono-Radio Buoys

AN/ARR-3 and AN/CRT-1

DESCRIPTION: AN/CRT-1 is a floating container, incorporating a non-directional hydrophone suspended on a 20-ft. line below the buoy itself, and electronic equipment including a frequency modulated radio transmitter for transmitting the underwater sounds received by the hydrophone to a receiver (AN/ARR-3) in the plane. The buoy transmits on one of 4 frequencies and has a lifetime of about 3 hours before self-scuttling.
USES: For detection of submerged submarines, and verification of MAD contacts as being submarines and not submerged wrecks.
PERFORMANCE: The radio range is approximately 10 miles when the plane is at 300 feet. The underwater range is equivalent to that of any good underwater sound system which may vary from 200 to 3,000 yards depending on the water conditions. No information is provided on the direction of the submarine.
TRANSPORTABILITY: Each buoy weighs 14 lbs. and the receiver, including a dynamotor power supply, weighs 35 lbs. The equipment can be transported by air in the ordinary cargo type aircraft, there being one package for each buoy and two packages for each receiver. The size of the buoy package is 6" x 6" x 48".
PERSONNEL: In normal operations one or preferably two men are required to launch the buoy and to listen on the receiver.
POWER: Supply for buoy itself consists of four 1.5 v "A" batteries, and two 67.5 v "B" batteries. The sono-buoy receiver operates from a supply source of 24 v DC and draws 70 watts.


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