Submarines - Are We Open to Sneak Attack?
February 1956 Popular Electronics

February 1956 Popular Electronics   [Table of Contents Wax nostalgic about and learn from the history of early electronics. See articles from Popular Electronics, published October 1954 - April 1985. All copyrights are hereby acknowledged.

Submarines first proved their deadly capabilities during World War I and then again in World War II when Adolph Hitler's navy used the formidable U-Boats (Unterseeboot, "under-sea-boat") to torpedo not just military ships but merchant ships in commercial trade routes between the Americas and Europe. Hideki Tojo's navy used subs to conduct surveillance prior to the deadly surprise attack on Pearl Harbor. Their naturally stealthy environment - underwater - proved to be a difficult realm both for detection and for attack. Fortunately, sensor technology developed quickly during the war, and soon a combination of air and sea based methods were in use and proved very effective. Submariners no longer sailed in relative security from being treated to a violent, icy burial at sea. By the mid 1950s, when this article was published, we had detection capabilities that included direct visual, photographic, radar, sonar, and magnetic means.

1956 must have been a big year for the General Electric plant in Utica, New York, where I had my first engineering job right out of college, because I recently posted the Aboard a Radar Picket Plane article that also referenced the location.

Submarines - Are We Open to Sneak Attack?

The modern submarine, capable of submerged travel far from home bases, and capable of delivering missiles and rockets with atomic warheads, is a fearful weapon. Newer versions - featuring atomic power plants - appear even more formidable, and show the need for strong defenses against their attack.

The Russian Navy, for instance, has more than twice as many submarines as the United States, and over seven times the number of U-boats available to the Germans at the start of World War II. In this country, however, every available means is being explored to insure an adequate and capable defense against enemy submarines. Electronic developments, along with the planes, ships and men needed to exploit their capabilities, are spearheading the defense.

While many of our present defense efforts are still shrouded in secrecy, some developments have been released to the American public. The methods so far perfected emphasize the versatility of modern military electronics.

One of the best ways to seek out and destroy penetrating undersea craft is from the air. Our Navy has many types of airplanes, helicopters and blimps especially equipped for this type of duty.

Carrier-based airplanes, carrying the latest in detection gear, can search out the enemy wherever he may hide. Powerful long-range radar transmitters can sweep the surface of the seas and indicate a tiny periscope or snorkel churning through the .waves.

Even if the enemy submarine plunges into the depths, it is not safe from the probing electronic eyes of our fliers. Using "MAD" gear (Magnetic Airborne Detector), the surface can be searched until the equipment receives a signal indicating the sub's hiding place. Then, sonobuoys -sensitive underwater microphones which modulate a radio carrier - are dropped in a pattern around the area. By listening to a receiver in the plane, any future movement of the enemy craft is immediately detected. This same type of equipment is carried in both helicopters and blimps. Used as patrol craft, they employ their slow speed to advantage in relentlessly hunting an enemy down for the kill. The helicopter has an additional weapon known as the "Dipping Sonar"; this sound gear is lowered beneath the surface of the water while the 'copter hovers motionless above it.

Panorama of coastal defense against enemy submarines involves: the strategic deployment of Navy radar picket blimp, carrying search radar; helicopter hovering with its "Dipping Sonar" lowered into water; a twin-engine Sentinel aircraft using MADBOOM (magnetic Airborne Detection Boom); and our own submarine equipped with special sound apparatus. Photo insert at right shows radar units used for detection invading ships or aircraft; scope at bottom registers targets' ranges and bearings on its screen. Across the page, lurking in the depths, is the object of the combined search ... the enemy killer sub.

Surrounding our merchant convoys and naval task forces, destroyers equipped with special long-range sonar equipment probe the surrounding waters for lurking under-sea craft. The type of sonar used here "pings" impulses of sound into the water. Sensitive receivers then listen for a returning echo indicating the presence of an enemy hull. Mast-high radar antennas continuously scan the surface for distant indications of surfaced or snorkeling U-boats.

Modern military warfare has even brought forth a hunter-killer submarine, especially designed to hunt down unfriendly "cousins" that menace our shipping. Equipped with ultra-sensitive "ears," it combines the best in listening equipment with the submarine's natural assets of stealth, cunning, and near-invisibility.

Guarding the approaches to our harbors, an entire array of unique electronic equipment awaits any enemy who tries to penetrate our waters. Far out on the harbor approaches, sono-radio buoys keep a relentless vigil for unexpected visitors. Like the airborne varieties, these devices combine underwater microphones or hydrophones with radio communication. Any sound which excites the sensitive pickup modulates a radio carrier and is noted by monitors on the shore.

The second line of defense is a series of cables laid in a pattern on the ocean floor. Called "Magnetic Loops," they are sensitive to changes in the earth's magnetic field. Any vessel crossing the strands immediately reveals its presence by tracing a pattern or "signature" on a pen and ink recorder on the shore. Behind the loops are strings of hydrophones which are cable-connected to monitor stations on the land. A constant listening watch is kept to insure the detection of even the weakest sound of a hostile nature.

Strategically placed along the harbor entrances are the "Heralds" (Harbor Echo Ranging and Listening Devices). These are remotely controlled sonar transmitters and receivers that constantly ping into the water and reveal the presence of any object by its echo. The heralds are capable of scanning the hulls of entering vessels to make sure that nothing tries to slip in "under the skirts" of a friendly ship.

The next line of defense is an even more ingenious one. Large fields of controlled mines await any "visitor" that gets beyond the sonar barrier. Controlled from the shore, the mines are equipped with hydrophones and other detection devices so that they may choose the most opportune time to blow the stranger to bits. They can be exploded by an operator listening from the shore or can be armed to fire automatically by sound, pressure, magnetic or other devices.

All of this underwater information feeds into the HECP - Harbor Entrance Control post - along with reports from radar operators, lookouts, and patrol craft in the harbor. From this nerve center, the entire defense of the harbor is directed - with both air and surface craft available to take up the battle if a penetration is attempted.

Electronics thus plays a leading role in this relentless battle to perfect our defenses. Men and their, equipment are always ready to defend us against the submarine. This readiness may be the greatest deterrent to another war.

Posted May 2, 2022
(updated from original post on 3/15/2016)