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October 1949 Popular Science
 [Table of Contents]
Wax nostalgic about and learn from the history of early
electronics. See articles from
Popular
Science, published 1872-2021. All copyrights hereby acknowledged.
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1949 wasn't all that long
of a time since airplane antennas consisted of a hundred feet or more of wire that
was spooled out in the air to trail behind the craft, servicing a CW (continuous
wave) type radio. The pilot tapped out Morse code on a key strapped to his knee
and wrote down the received code as it came in. Prior to landing, the pilot wound
the trailing wire antenna back in - which sometimes was forgotten and got ripped
off by trees. By the time World War II came around, operating frequencies had
moved up in the electromagnetic (EM) spectrum and antennas were accordingly shortened.
Still, a review of airplanes at the time showed wire antennas strung from somewhere
in the forward region of the airplane (over or under the cockpit) or from the wingtip(s),
back to the tip of the vertical fin or tip of the horizontal stabilizer. That was
all OK when airspeeds were south of 200 mph or so, but higher speeds caused
excessive drag in the air requiring more rugged components, which added to weight.
An exposed antenna also was subject to risk of damage from ice, strikes by
foreign objects, and oscillation. This Popular Science
article reports on some of the many advances made in embedding antennas within the
airframe, which was made necessary because of higher airspeeds, reliability, and
the accommodation of an ever-increasing number and types of onboard radios.
Antennas Go into Hiding
There are 16 hidden or flush-mounted antennas
in this Air Materiel Command's C-54 flying laboratory, used to test new developments.
Buried, the antennas add nothing to aerodynamic drag.
Radio and radar devices have been added to airplanes so rapidly that with the
accompanying exterior antennas the planes were beginning to look like flying porcupines.
And in their other role, as gremlins, the antennas were acting as brakes on the
high speeds the Air Force was aiming at.
As one radio expert put it. "When they take the propellers off, then we'll take
off the antennas." Along came jet propulsion, and, true to his prediction. the experts
are burying the antennas to give the speed-of-sound-nudging planes clean-swept exteriors.
As an example, figures compiled for only nine of the 16 hidden antennas on the
experimental C-54 at the top of this page show that these antennas, if mounted externally,
would use up 634 hp. at 600 m.p.h. That's enough horsepower to pull half a dozen
automobiles.
Among the other advantages of buried antennas are the elimination of icing dangers,
added protection against precipitation static, the sealing out of moisture, and
freedom from the threat of aerials breaking off at high speeds and interrupting
communications.
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A zero-drag antenna, buried in a wing tip, is
shown in the above drawing. Plastic section isolates tip from rest of wing. If necessary,
plane's entire wing can be used as an antenna.
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Pickax antenna shown at top of drawing below
was the first type of hidden antenna. Designed to follow conventional curve of plane's
tail, it is protected by a plastic canopy.
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Posted April 22, 2024
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