Airborne electromagnetic survey system with aerodynamic frame segments; and methods of surveying using such

An airborne electromagnetic survey transmitter frame configured for geophysical prospecting, wherein the transmitter frame is configured to be lifted by an aircraft via a tow arrangement during survey operation in air in a flight direction and with a flight speed, wherein the transmitter frame comprises:

• a frame front section opposite a frame tail section, the transmitter frame configured to support a transmitter coil, the transmitter coil configured to transmit a magnetic moment for geophysical prospecting,
• wherein the transmitter frame comprises multiple connectable frame segments, at least one of the frame segments comprising
• a first connection and a second connection for connecting the at least one of the frame segments to two other ones of the frame segments respectively,
• a structural support providing a rigid structure between the first connection and the second connection, and
• a frame segment surface covering the structural support, and providing the at least one of the frame segments with an aerodynamic profile, wherein the aerodynamic profile is configured to provide aerodynamic properties to the transmitter frame,
• wherein the multiple frame segments are configured to support the transmitter coil so that the transmitter frame substantially defines a shape of the transmitter coil, wherein the transmitter frame is substantially rigid when the frame segments are connected, and wherein when the transmitter frame is towed by the aircraft via the tow arrangement during the survey operation in the flight direction, the transmitter frame has substantially a fixed frame shape and is substantially in a fixed operational orientation when the transmitter frame experiences a true air speed.

A method of geophysical prospecting using an airborne electromagnetic survey system comprising a transmitter frame with a frame front section opposite a frame tail section, the transmitter frame configured to be lifted and towed by an aircraft via a tow arrangement during survey operation in air in a flight direction and with a flight speed, the transmitter frame configured to support a transmitter coil that is configured to transmit an magnetic moment for geophysical prospecting, wherein the transmitter frame comprises multiple connectable frame segments, at least one of the frame segments comprising (1) a first connection and a second connection configured to form respective rigid connections between the at least one of the frame segments and two other ones of the frame segments that are adjacent the at least one of the frame segments, (2) a structural support providing a rigid structure between the first connection and the second connection, wherein the transmitter frame is a substantially rigid frame when the frame segments are connected, and (3) a frame segment surface enclosing the structural support, and providing the at least one of the frame segments with an aerodynamic profile, wherein the aerodynamic profile is configured to provide aerodynamic properties to the transmitter frame, and wherein when the transmitter frame is towed by the aircraft via the tow arrangement during the survey operation in the flight direction, the transmitter frame has substantially a fixed frame shape and is substantially in a fixed operational orientation, the method comprising:

• supporting the transmitter coil that is configured to transmit the magnetic moment for the geophysical prospecting on the transmitter frame;
• lifting, by the aircraft, the transmitter frame via the tow arrangement;
• towing the transmitter frame in the air in the flight direction and with the flight speed;
• and
• operating the aircraft in the flight direction and with the flight speed so that air flow over the aerodynamic profiles of the frame segments provides lift to the frame segments.