Seventy-five years ago this month, these British enthusiasts are operating their radio controlled planes, as shown on the cover of the February 1951 issue of Practical Mechanics.

The magazine carried the first in a series of articles regarding the hobby. It noted that technical expertise in radio was not a prerequisite. Indeed, the author had heard from more than one retailer to the effect that they preferred selling their equipment to those who were not technically inclined. The radio “expert”, it turns out, would often try to tweak the equipment to the point where it wouldn’t work any more.

The article noted that while licenses were required in America, that was not the case in Britain, as long as the users stuck to certain wavelengths. In didn’t specify them, but from the size of the antennas shown, they appear to be VHF.

Seventy-five years ago, the cover of the February 1951 issue of Radio Electronics shows what is recognizable to most pilots and radio enthusiasts as a VOR installation. Apparently, the name VOR (VHF Omni Range) hadn’t caught on yet, as the article uses the term “omnirange”. The Civil Aviation Administration had begun the process of installing them, and the price tag was estimated at a whopping $1.5 billion.

I’ve always thought the VOR was a very clever invention. It allows a pilot, armed with relatively simple passive equipment, to know the exact direction from the ground station. Unlike radio direction finding, there is no 180 degrees of ambiguity. You know right away the exact bearing to the station. This is accomplished by two signals from the VOR. There is an omnidirectional signal, as well as a directional beam that sweeps at a defined rate. By measuring the phase angle between the two incoming signals, the receiver instantly tells your bearing.

The particular station shown on the cover was at Erie, PA, and the photographer was Avery Slack.

Shown here is an artist’s conception of a possible solution for communications with aircraft on transatlantic routes. Aircraft equipped with only VHF radio experienced significant gaps when they were incommunicado while crossing the ocean. There were some plans to extend their VHF range by use of directional antennas aboard the aircraft, but there were still gaps.

One proposed solution was two to four floating communications platforms mid-ocean. They would be linked by cable to shore. With these, aircraft could be continually in line-of-sight communication.

Of course, HF communication is also available on aircraft. But the article noted that this communication was not 100% reliable, due to occasional HF blackouts and the vagaries of HF propagation.

For those stationed on these platforms, it looks like a lonely assignment.

The illustration appeared in the October 1965 issue of Radio-Electronics.

This young woman is now close to 90 years old, but she is shown here, on the cover of QST for August 1940, inspecting a radio controlled aircraft. The accompanying article by Clarence E. Bohnenblust, W9PEP, (probably her father) describes the radio controls. He was approached some time earlier by one C.H. Siegfried, who designed and constructed the gasoline-powered airplane, with a request to design radio control gear. For a transmitter, a 20-watt five meter unit was used. Onboard the aircraft, the superregenerative receiver shown here was used, and could reliably pick up the signal a mile away.

It was determined that four controls were necessary: rudder left and right, elevators up and down, motor speed high or low, and motor shut off. This was accomplished with an elaborate system of cams, operated by a pulsed signal from the transmitter. For pulses, an ordinary telephone dial was used. Each pulse moved the cams one notch, and they were held in place as long as the carrier was received. When the carrier was cut, it reset to a neutral position, ready fpr the next command.

The magazine notes that the airplane was successfully demonstrated at the ARRL Midwest Division Convention in Wichita in April, and was going to be seen again at the ARRL National Convention in Chicago later that year.

Shown here 75 years ago, on the cover of Radio-Electronics, June 1950, is Margaret Latham, of Beane Radio Service, Newark, New Jersey. She is shown engaged in a typical aircraft servicing operation at the Newark airport.

She penned an article for the magazine in which she noted that the “service technician must have a genuine interest in aircraft and the people who fly them, as well as a thorough knowledge of the principles of radio, because as often as not he is called upon to cancel his own personal plans to complete repairs on an aircraft radio.”