Dr. Hans Lundberg helped pioneer the use of helicopters in geophysical surveys, taking one of the first pre-production Bell 47s on a groundbreaking flight test to prove the technology’s worth.

The multi-talented Swedish-Canadian geophysicist Dr. Hans Lundberg was an innovator, explorer, prospector, and mining engineer — and he also played a leading role in pioneering the use of helicopters in geophysical surveys. 

Born in Sweden in 1893, Lundberg graduated from the Royal Institute of Technology in Stockholm in 1917 with a thesis entitled Electrical Prospecting. He believed that electronic survey methods could be used to locate ore bodies long before exploration geophysics was recognized as a science. 

He developed a new field variation of equipotential surveying while still in Sweden, and this method was credited with discovering major polymetallic deposits in 1918 and 1922. Lundberg moved to New York in 1923 to be a field manager for the Swedish-American Prospecting Corporation, which was looking for mineral deposits in North America and Europe.

Early in his career, he began experimenting with various means to carry his electronic instruments aloft, using balloons, kites, and even gliders — but none of these methods were very practical.

One of his most important assignments was to apply the geophysics techniques he learned in Sweden at the Buchans mine site in central Newfoundland. The existing ore body near the Buchans River had been delineated with diamond drills to identify the location and depth of the mineralization. But using his electronic methods, Lundberg’s small survey party identified two major lead-zinc ore deposits adjacent to the property, which — over the life of the mine — would produce more than one billion dollars’ worth of ore.

Moving to Canada in 1936, Lundberg formed Hans Lundberg Ltd. — his own consulting exploration company — in Toronto. He won geophysics contracts across Canada and the United States.

During the Second World War, the U.S. Navy made many advances in the development of magnetometer technology to detect submerged enemy submarines. Lundberg was one of the first to start promoting the airborne use of this technology in conferences he attended. He envisioned electromagnetics (EM) to be the next step in geophysical surveying using airborne aircraft. 

In September 1945, an article in The Northern Miner stated that an investigation was underway into using helicopters to carry out geophysical reconnaissance with specialized electronic equipment. Fixed-wing aircraft with magnetometers were suitable for identifying major structural features, but a helicopter equipped with instruments would be able to fly closer to the ground to provide the more detailed data required to locate ore bodies. It could also do it in less time than a survey conducted by a ground party, and even land to take rock and soil samples.

A ground-based survey was a very labor-intensive process, especially in wilderness areas. Lines had to be cut out through vegetation to establish a control grid, and electronic equipment had to be manually carried across the property and around physical obstacles to obtain instrument readings.

The first helicopter survey

The Bell Aircraft Company was the first to certify a commercial helicopter: the two-place Model 47 in 1946. A year later, Sikorsky Aircraft followed with its four-place S-51. 

Lundberg joined up with millionaire C.J. Ryan in New York, forming Lundberg-Ryan Air Explorations Co., Inc. to promote the use of the new rotary-wing technology in geophysical surveys.

The company approached Sikorsky and Bell, with the latter being particularly enthusiastic about the use of the Bell 47 for aerial surveys. Company founder Larry Bell met with Lundberg in Niagara Falls and arranged a demonstration flight for him and his wife in the experimental Bell Model 30. Bell also offered Lundberg the lease of a pre-production Bell 47 to use in experimental trials of Lundberg’s newly-designed magnetometer equipment.

“I saw the vast possibilities, not only for the future of the helicopter, but the economic advancement of Canada and the United States,” said Larry Bell in a press release announcing the project. “I readily agreed to cooperate to the fullest by putting one of my helicopters and technical staff at Lundberg’s disposal.”

The experimental tests were to be carried out with the cooperation of the International Nickel Company of Canada in Sudbury, Ontario. It was the beginning of the use of helicopters in the mining exploration industry.

“The range, sensitivity, efficiency, and accuracy of the helicopter-borne magnetometer was tested. It passed on all fronts — with the bonus of completing the surveys in a much faster time than a ground-based crew.” 

In June 1946, a pre-production Bell 47 outfitted with specialized sensitive magnetometer equipment — including a pick-up device, an aerial camera, and amplifiers — flew into Northern Ontario to begin a prospecting expedition.

Over the next few weeks, the team conducted flight tests over designated areas near the Frood Mine under the direction of Lundberg.

The range, sensitivity, efficiency, and accuracy of the helicopter-borne magnetometer was tested. It passed on all fronts — with the bonus of completing the surveys in a much faster time than a ground-based crew. Two hours of flight time was required to complete a survey of one designated area, which would typically require 180 man hours if surveyed on foot. A ground survey normally took three to four months to complete; by helicopter, it could be completed in two to three hours.

Further testing in Quebec showed similar results. “The amount and accuracy of the data made available by the helicopter-borne magnetometer survey exceeds our expectations,” said Lundberg in a magazine article at the time. 

Meanwhile, Lundberg’s son, Sten (a former pilot in the Royal Canadian Air Force) had joined Lundberg-Ryan Air Explorations to become its pilot. Alongside helicopters, he would fly the company’s de Havilland Fox Moth, twin-engine Avro Anson, and later aircraft owned by the survey company, such as a Piper Cub and Cessna 180. 

In 1946, Sten Lundberg was accepted for helicopter flight training at the Bell Aircraft Company’s first training school, where he soloed after 15 short flights and ended with 26 hours and 20 minutes of helicopter flight time. “I found the control and flight was completely different from conventional airplane flying,” Sten Lundberg said during an interview in the 1990s. “It took some time to coordinate flying the helicopter and to be able to first hover.” 

Sten Lundberg was the first Canadian to attend the class and received the very first commercial pilot rating issued by the Canadian Civil Aviation Branch. Lundberg-Ryan Air Explorations also recorded the first Canadian to be trained on helicopter maintenance, in the form of Frank H. Williams, a former RCAF maintenance engineer.

Developing the Bell 47B-2

Following the promising results of the geophysical survey test flights in the summer, Lundberg-Ryan ordered two modified Bell 47B geophysical survey helicopters, designated the Bell 47B-2, in September 1946. Hans Lundberg ambitiously hoped to have three or more Bell 47s flying magnetometry surveys by November.

“The system turned out to work so well that the company never returned to using helicopters for aerial surveys.”

The Bell 47B-2 differed from the standard Bell 47B in having a clear 55-inch-wide (140-centimeter-wide) plexiglass bubble cabin enclosure, one 24-U.S. gallon (90-liter) fuel tank aft of the engine, and special ore detection equipment installed. The type was eligible for an NR certification (R for restricted) due to its much smaller fuel tank. 

It was powered by the Franklin 6V4-178-B3 engine (capable of producing 178 horsepower), and had four-wheeled landing gear (like the Bell 47B). The helicopter had a 12-volt electrical system and a fuel pump to transfer fuel to the engine. The model could be converted to a Bell 47B-S by the installation of floats, but the cabin heater had to be removed, and horizontal stabilizers were required. An installed irreversible system on the fore, aft and lateral cyclic lessened feedback from the main rotor to the cyclic stick. The main and tail rotors were constructed of wood.

The maximum weight for the Bell 47B-2 was 2,200 lb. (1,000 kg), and it had a cruise speed of 85 mph (130 km/h), with a never exceed speed of 92 mph (150 km/h).

The aircraft’s ore detection equipment was quite complex, with the magnetometer and azimuth drive located in front of the plexiglass bubble. They were enclosed in a plastic covering, and two rods passed through the main canopy enclosure to attach them to the cabin. The top rod connected to an azimuth control gear box on top of the instrument panel console, while the other rod attached to the bottom. The fluxgate compass transmitter, magnetometer and recorder were located in front of the passenger seat. There was also a camera viewing hole beside the seat (a camera and a compressor were located behind the engine in the tail boom). The azimuth servo, fluxgate compass amplifier, and inverter were installed within the fuselage.

Flight tests soon began with the magnetometer installed. Hans Lundberg followed the tests closely, and was able to accompany the pilots in some of the early flights as the months went by. 

However, in late 1947, C.J. Ryan withdrew his backing from the company, forcing Hans Lundberg to cancel his orders with Bell. The one flying aircraft was dismantled, while work on the second was stopped, and that aircraft was also taken apart. The type certificate for the Model 47B-2 was cancelled on June 15, 1950.

New directions

Hans Lundberg then started a new company in Toronto called Lundberg Explorations Ltd. He still believed in the huge potential of helicopters for airborne surveys, and in the fall of 1947, leased a Bell 47B-3 to carry out geophysical surveys in Northern Ontario.

Hans Lundberg visited the International Nickel Company of Canada’s holdings in Sudbury again, where a magnetic gradiometer he had created was examined and tested. It used a flux-gate detector with gyroscopic orientation control, was compact, and also light (weighing less than 100 lb.). It had a sensitivity of 10 gammas.

Several flights were made with the gear in a Bell 47B-3 at a height of 100 feet, and the results were satisfactory. No means of in-flight control was provided with the equipment, but it was light, portable and could be used in any small aircraft.

Lundberg’s new company was very pleased with the results of the surveys, and the usefulness of the airborne magnetometer as a tool to the geologist could not be overstated. Hans Lundberg was on the right track.

In the summer of 1948, he flew to Sweden, where he had obtained a new contract to complete airborne helicopter geophysical surveys. The surveys spanned a million acres of mining territory north of the Arctic Circle in Lapland, in which iron and other base metals were hoped to be found.

Sten Lundberg was to fly a newly-purchased Bell 47D on the contract. Work began in July and was scheduled to run to October. The aircraft was flown as low as safety would allow, between 20 feet and 100 feet (six and 30 meters) over timber and mountainous areas. The flying technique demanded a lot of practice and familiarization, while maintenance was intensive and any parts took a long time to arrive from Bell. However, the instrumentation and the magnetometer proved to be more than satisfactory.

By the end of August, Sten Lundberg had flown over 96 hours on the project, and things were going well. Then, as he attempted a landing using soft floats, he crashed — but escaped unscathed. 

Within a few days, a Noorduyn Norseman fixed-wing was brought in on floats to complete the contact. In using the Norseman, Hans Lundberg discovered that the metal structure and magnetometer on conventional aircraft presented a constant that he could cancel out. The system turned out to work so well that the company never returned to using helicopters for aerial surveys. 

The company continued to use fixed-wing aircraft for airborne geophysical survey work well into the 1960s, continuing to advance their capabilities with upgrades of Hans Lundberg’s magnetometer and electrical equipment. Over the years, helicopters became an important tool in advancing airborne magnetometer surveys in the search for natural resources — just as he first predicted in the mid 1940s.

Hans Lundberg produced over 70 scientific papers in his lifetime, gave numerous lectures, patented over 20 inventions and did all this while supporting research, helping new generations of geophysicists advance their branch of science.

Hans Lundberg passed away in 1971 in Toronto, but his legacy continues. In January 2020, he was inducted into the Canadian Mining Hall of Fame for his contributions to the Canadian mining industry and his development of modern geophysical survey practices. Notably, he was the first to see that helicopters could be used to conduct geophysical surveys.