Airborne Electro-magnetic recording device 1952.
This wooden device had its origins in an airborne electromagnetic project at Continental Oil Company from 1952 to 1954. At the conclusion of work at Conoco, the equipment was sold to Aero Service Corporation in Philadelphia. Airmag may have acquired this unit from Aero Service since both were in Philadelphia. This drogue with an electromagnetic receiver coil was towed beneath an Avro Anson twin engine aircraft. The Avro Anson was a plywood aircraft, making it better adapted for airborne electromagnetic purposes than conductive aluminum aircraft. The source coil was wrapped around the aircraft fuselage and powered by a vacuum tube amplifier of about 300 watts at somewhere around 500 Hz. The original receiver coil was mounted on the wing tip, but wing motion during flight encouraged the use of a drogue device to increase the source-receiver spacing. The drogue was designed by an outside consultant and built in the carpentry shops at Conoco. Wiley Haggard of Spring, Texas, clearly recalls the construction phase of this device. Enclosed within the drogue is probably a vacuum tube preamplifier to drive the electrical cable. This project was directed by Dan Mitchell, now deceased. Other involved were Graydon L. Brown, Reginald Childers (mechanic) and James K. Buttram (pilot) who live in Ponca City, Oklahoma.
Electromechanical device used in electrical potential exploration ('Megger')