Glide bomb
Based on Wikipedia: Glide bomb
On September 9, 1943, the Italian battleship Roma was sailing south to surrender to the Allies when German bombers appeared overhead. What happened next changed naval warfare forever. A single weapon—dropped from 18,000 feet—punched through the ship's deck armor and detonated in the forward magazine. The Roma exploded and sank within minutes, taking 1,352 sailors to their deaths. The weapon that killed them wasn't a torpedo or a conventional bomb. It was something new: a bomb that could fly.
What Makes a Bomb Glide
A glide bomb is, at its simplest, a bomb with wings. But that simple addition changes everything about how the weapon works and what it can do.
Drop a conventional bomb from an aircraft, and physics takes over immediately. The bomb follows a ballistic arc—a parabola determined entirely by the speed and altitude of the releasing aircraft and the pull of gravity. If you want to hit a target, you need to fly directly over it, or close enough that your bomb's trajectory intersects the target. This means flying into the teeth of whatever defenses the enemy has prepared.
Add wings and control surfaces to that same bomb, and suddenly it can travel horizontally while it falls. Instead of plummeting straight down, it glides forward, sometimes for dozens of kilometers. The aircraft that released it can turn away and escape while the bomb continues toward its target.
This is what military planners call a "standoff" weapon—one that creates distance between the attacker and the target's defenses. The concept sounds obvious in retrospect, but developing weapons that could actually do this took decades of engineering and cost thousands of lives in experimentation.
The First Attempt: A Torpedo That Could Fly
The story begins in October 1914, just two months into the First World War, when a German industrialist named Wilhelm von Siemens proposed something audacious. Siemens ran one of Germany's largest electrical engineering companies, and he understood both aviation and remote control systems. His idea was to combine them in a way no one had attempted before.
Siemens suggested strapping an airframe—essentially a simple glider—to a naval torpedo. An aircraft would carry this hybrid weapon aloft and release it near an enemy ship. The torpedo-glider would fly toward the target, guided by electrical signals sent through a thin copper wire trailing behind it. When it reached the right position, another signal would trigger the release mechanism. The glider airframe would fall away, and the torpedo would drop into the water to complete its attack run the traditional way.
The company that bore his name, Siemens-Schuckertwerke, had already been experimenting with remote-controlled boats called Fernlenkboote—literally "distance-steering boats"—so they had some experience with the guidance problem. Starting in January 1915, an engineer named Dorner began flight testing various designs, using Zeppelin airships as carrier aircraft.
They tried biplane gliders. They tried monoplane gliders. They tested and modified and tested again for three years. The last flight occurred on February 8, 1918. The Germans planned to use their massive Siemens-Schuckert R.VIII bomber—one of the largest aircraft of the war—as the operational carrier.
Then the Armistice came, and the project died.
The technology wasn't ready. Neither, perhaps, was the world. But the idea—a bomb that could fly itself to a target—had been planted.
The Problem with Ships
Twenty years later, the Second World War presented German military planners with a problem that seemed almost impossible to solve.
Ships are extraordinarily difficult to hit from the air. Consider the challenge: a warship might be 150 meters long and 20 meters wide, but from 20,000 feet up, it's a speck moving unpredictably across an infinite blue background. A near miss doesn't count—water doesn't transmit explosive force the way earth does, so a bomb that lands even a few meters away from a ship might cause no damage at all. You need a direct hit, or something very close to it.
Early in the war, German pilots used dive bombers against British ships. A dive bomber does exactly what the name suggests: it dives almost vertically toward its target before releasing its bomb at close range. This technique dramatically improved accuracy because the pilot could essentially aim the entire aircraft at the target. The famous Junkers Ju 87 Stuka became a symbol of this approach, its distinctive gull wings and wailing sirens terrorizing soldiers and sailors across Europe.
But the British adapted. By 1941, Royal Navy ships bristled with anti-aircraft guns. A dive bomber attacking a well-defended ship had to fly through an increasingly lethal curtain of fire. The accuracy advantage of dive bombing was being negated by the simple fact that pilots were getting killed before they could release their weapons.
The Germans needed a new approach. They needed to hit ships without flying over them.
Fritz and His Explosive Legacy
The solution they developed was nicknamed Fritz-X, though its official designation was the Ruhrstahl SD 1400. The name came from the base weapon: a standard German 1,400-kilogram armor-piercing bomb, the kind designed to penetrate the thick steel decks of battleships and heavy cruisers. To this massive bomb, German engineers attached a set of four wings and a tail assembly containing radio-controlled spoilers—surfaces that could be deflected to change the bomb's flight path.
The concept was elegant. A bomber would approach an enemy ship at high altitude—typically around 8,000 meters, or about 26,000 feet—and release the Fritz-X while still some distance from the target. As the bomb fell, it would glide forward, and a crew member in the aircraft called the bomb aimer would watch its descent and send radio commands to adjust its path. Small spoilers on the bomb's tail would deflect the airflow, nudging the weapon left or right, steeper or shallower.
In practice, this was fiendishly difficult. The bomb fell at tremendous speed, and as it descended, it dropped further and further behind the aircraft that had released it. The bomb aimer had to crane his neck to watch a weapon that was simultaneously falling and receding. The launching aircraft had to slow down and even climb to avoid completely losing sight of the bomb.
And the guidance itself was tricky. As the angle of descent changed during the fall, the same control input would produce different results. If the initial aim was off, there was often nothing the bomb aimer could do to correct it in the later stages of the fall.
Despite these challenges, trained crews achieved remarkable accuracy. In test drops from 8,000 meters, experienced bomb aimers could place half of their weapons within a 15-meter radius of the target—roughly the length of a tennis court. Ninety percent landed within 30 meters. For a weapon dropped from five miles up, this was extraordinary.
The Day the Roma Died
The Fritz-X's combat debut came in September 1943, during one of the war's strangest episodes. Italy had just surrendered to the Allies, and the Italian fleet was sailing south to hand itself over. But Germany wasn't about to let those ships simply change sides.
Dornier Do 217 bombers from Kampfgeschwader 100—a specialized unit trained specifically in guided weapons—found the Italian fleet off the coast of Sardinia. The Roma, one of Italy's newest and most powerful battleships, took a Fritz-X hit that penetrated deep into her hull. A second bomb struck near the forward magazines.
The explosion was catastrophic. The Roma broke apart and sank in minutes. Her sister ship, the Italia, was also hit and badly damaged but survived. In a single attack, a handful of aircraft had accomplished what would have required a major naval engagement just a few years earlier.
The Fritz-X went on to damage or destroy several Allied warships. The American cruiser USS Savannah took a hit that killed 197 sailors. The British battleship HMS Warspite—a veteran of Jutland in the First World War—was struck by three Fritz-X bombs and had to be towed to Malta for repairs. She was out of action for six months. The Canadian destroyer HMCS Athabaskan was seriously damaged. The British cruiser HMS Uganda was hit and put out of commission for over a year.
But Fritz-X had limitations. It was heavy and required a large bomber to carry it. It was designed for armored targets, which meant it was overkill for most ships. And its guidance system required the launching aircraft to fly a predictable course during the bomb's entire descent—sometimes up to 90 seconds of straight and level flight while enemy fighters and anti-aircraft guns tried to shoot it down.
For more common targets, the Germans developed something different.
The Rocket-Powered Alternative
The Henschel Hs 293 was, in many ways, the opposite of Fritz-X. Where Fritz-X was a heavy armor-piercer for battling capital ships, the Hs 293 was a lighter weapon designed for use against convoy merchantmen and their escort vessels—ships with thin hulls but heavy defensive armament.
The Hs 293 looked more like a small aircraft than a bomb. It had proper wings for sustained gliding flight, and crucially, it carried a small liquid-fueled rocket motor. When released, this rocket would fire for about ten seconds, accelerating the weapon and pushing it out ahead of the launching aircraft. Then the rocket would cut out, and the bomb would glide the rest of the way to its target.
This design solved several problems at once. The rocket gave the weapon enough energy to travel a considerable distance horizontally. Because the bomb flew roughly parallel to the launching aircraft rather than falling behind it, the bomb aimer had a much easier time tracking and controlling it. And because the weapon was designed for ships with less armor, it could be smaller and carried by more types of aircraft.
The trade-off was that the Hs 293 couldn't penetrate heavy deck armor. But most ships at sea weren't battleships. Most were freighters, tankers, and escort vessels—exactly the targets the Hs 293 was designed to destroy.
The Combat Debut
On August 25, 1943, German bombers found a group of Royal Navy and Royal Canadian Navy warships in the Bay of Biscay, the patch of Atlantic Ocean between France and Spain. The sloop HMS Bideford took a hit from an Hs 293, but the weapon failed to detonate properly. One sailor died. Another sloop, HMS Landguard, escaped with slight damage from a near miss.
Two days later, the Germans attacked again. This time the Hs 293 worked as designed. HMS Egret, a sloop serving as an escort vessel, took a direct hit and sank. HMCS Athabaskan—the same ship that would later be hit by Fritz-X—was seriously damaged.
The weapon's deadliest success came three months later. On November 25, 1943, an Hs 293 struck the troopship HMT Rohna during a Mediterranean convoy. The ship was carrying American soldiers to the China-Burma-India theater. The bomb detonated in the engine room, and the Rohna sank within an hour. Over one thousand Allied soldiers died—the largest loss of American troops at sea by enemy action in the entire war, though censorship kept the disaster secret until after the war ended.
The Allied Response
The appearance of guided weapons demanded countermeasures, and the Allies developed several simultaneously.
The simplest was evasive maneuvering. Ships that could maintain high speed were instructed to make tight turns across the weapon's predicted flight path. This forced the bomb aimer to make constant corrections and often resulted in misses. The technique worked, but it was exhausting for crews and couldn't be sustained indefinitely.
More sophisticated were the electronic countermeasures. American, British, and Canadian scientists analyzed captured guidance systems and developed radio jammers to disrupt the commands being sent to the bombs. Nine different jamming systems were eventually deployed in the European theater. Early versions proved inadequate—the Germans used multiple radio frequencies and could switch between them—but by the time the Allies prepared for the invasion of France in 1944, more capable jammers had been developed. The success rate of German guided weapons declined considerably.
The Germans also experimented with countermeasures to the countermeasures. Wire guidance, where commands were transmitted through a physical wire trailing behind the bomb, couldn't be jammed. Television guidance, where a camera in the bomb's nose sent images back to the operator, would have been even more sophisticated. The Hs 293D was equipped with such a television system, but the technical challenges proved too great for wartime development. Even tiny control inputs caused the target to jump erratically across the display screen, making accurate guidance nearly impossible.
In the end, the most effective countermeasure was the most direct: Allied air superiority. By 1944, Allied fighter aircraft dominated the skies over the English Channel and the Mediterranean. German bombers equipped with guided weapons couldn't reach their targets because they were being shot down long before they came within range. The weapons worked, but the aircraft carrying them didn't survive to use them.
Across the Atlantic
The United States developed its own glide bombs during the war, though with more mixed results.
The American approach was characteristically ambitious and scattershot. The Army Air Force launched parallel development programs for both glide bombs (designated "GB" for glide bomb) and vertically-falling guided weapons (designated "VG"). Multiple contractors produced multiple variants, and several saw limited combat use.
The first American glide bomb used in combat was the Aeronca GB-1, which took a different approach than the German weapons. Rather than radio guidance, it used an autopilot—a self-contained system that would try to hold the bomb on a predetermined course after release. The idea was that heavy bombers could release these weapons from far outside the most concentrated anti-aircraft defenses around German cities and still hit their targets.
The first operational use came on May 28, 1944, against the Eifeltor marshalling yard in Cologne. The results were discouraging. Of 113 bombs released, only 42 came anywhere near the target. Most had autopilot failures—their batteries couldn't hold a charge, causing the guidance systems to fail and the bombs to spiral into the ground miles from their intended targets.
More sophisticated American designs included the GB-4, GB-5, GB-12, and GB-13, which used television guidance systems similar to what the Germans were developing for the Hs 293D. The Navy developed the Bat, a glide bomb with an active radar seeker—the first fully autonomous guided weapon, capable of finding and hitting a target without any human input after launch.
The Bat saw combat in the Pacific starting in August 1944, but it had its own problems. Its radar seeker couldn't distinguish between ships in a cluttered environment—multiple targets would confuse it—and even simple radar countermeasures could decoy it away from its intended victim. The technology was promising but immature.
A British Dead End
The British, too, tried their hand at glide bombs, with less success than either the Germans or the Americans.
In 1939, before the war began, two British engineers began working on guided weapons. One was Sir Dennistoun Burney, an inventor and politician who had previously designed airships. The other was Nevil Shute Norway—better known today as Nevil Shute, the novelist who would later write "A Town Like Alice" and "On the Beach."
They developed two concepts: the Toraplane, a gliding torpedo launched from aircraft, and the Doravane, a gliding bomb. Both used the same principle as the German weapons—add wings and control surfaces to an explosive warhead, release it from a safe distance, and guide it to the target.
Despite years of work and countless trials, the Toraplane could never be launched with consistent accuracy. The variability between drops was too great—sometimes the weapon would fly perfectly, sometimes it would tumble out of control. By 1942, the project was abandoned. Shute went back to writing novels.
The Postwar Revolution
After the war ended, the captured German technology—and the German engineers who had created it—sparked an explosion of development in both East and West.
The fundamental concept had been proven: you could release a weapon at a safe distance from a target and guide it to impact. The question was how to make the guidance more reliable, more accurate, and harder to jam.
Through the 1950s and into the 1960s, American engineers refined contrast-seeking guidance—systems that could lock onto a target based on how it appeared visually, tracking the difference between a ship's dark hull and the bright sea around it. The AGM-62 Walleye, introduced in the 1960s, used a television camera in its nose that allowed an operator to see what the bomb "saw" and guide it precisely onto a target. The AGM-65 Maverick, still in use today, refined this concept further.
But contrast-seeking had limitations. It required someone to watch a screen and manually guide the weapon. It worked only in good visibility. And it could be fooled by smoke, flares, or simple camouflage.
The real revolution came with two technologies that matured in the 1970s and 1980s: laser designation and the Global Positioning System.
Laser-guided bombs work on a simple principle. Someone—either in the launching aircraft or on the ground—aims a laser at the target. The bomb has a seeker that detects the reflected laser light and steers toward it. As long as the laser stays on target, the bomb will hit it. This removed the need for continuous manual guidance of the weapon itself; someone just needed to keep the laser pointed at the right spot.
GPS guidance was even simpler. The weapon knows where it is because satellites tell it. It knows where the target is because someone programmed in the coordinates. All it has to do is steer itself from one set of coordinates to the other. No laser required. No visibility required. No continuous human input required.
The JDAM—Joint Direct Attack Munition—combines GPS guidance with a simple wing kit that straps onto an ordinary "dumb" bomb. For a few tens of thousands of dollars, you can turn a weapon that would land somewhere within a hundred meters of its aim point into one that will hit within a few meters. This transformation has made precision air attack routine rather than exceptional.
Return of the Glide Bomb
For decades after these guidance revolutions, glide bombs seemed almost obsolete. Laser and GPS guidance meant you could hit targets accurately without needing to stand off from them—aircraft could fly high enough that anti-aircraft guns couldn't reach them, and the guided bombs would find their targets anyway. Why add expensive wings to a weapon when simple guidance kits would do the job?
The Russian invasion of Ukraine, which began in February 2022, provided a brutal answer.
Ukrainian forces, equipped with Western surface-to-air missile systems, made the skies over their territory deadly for Russian aircraft. Russian helicopters and attack jets that ventured close to Ukrainian positions were shot down in alarming numbers. Cruise missiles—the sophisticated descendants of early guided weapons—were being intercepted by air defense systems.
The Russians needed a way to deliver heavy explosive payloads without exposing their aircraft to Ukrainian air defenses. Their solution was remarkably simple: take existing unguided bombs—the FAB-500, weighing 500 kilograms, or the enormous FAB-1500, weighing 1,500 kilograms—and strap on a cheap guidance kit called UMPK.
These kits include folding wings and a GPS-based guidance system. They're crude compared to American precision weapons, but they're cheap and they work. More importantly, they allow Russian aircraft to release their weapons from within Russian-controlled airspace, well beyond the range of most Ukrainian air defenses. The bombs then glide—sometimes more than 60 kilometers—to their targets.
The effects have been devastating. In February 2024, Ukrainian forces withdrew from the town of Avdiivka after months of fighting. Ukrainian Commander-in-Chief General Oleksandr Syrskyi cited Russian glide bombs as one of the primary reasons for the retreat. The weapons were destroying Ukrainian defensive positions faster than they could be rebuilt or reinforced.
In October 2025, Russian forces used a new variant called the UMPB-5R against the city of Lozova in Ukraine's Kharkiv region. This weapon was reportedly launched from approximately 130 kilometers away—more than twice the range of earlier glide bombs—further reducing the risk to the launching aircraft.
An Old Solution to Modern Problems
What makes glide bombs so effective is the same thing that made them effective in 1943: they exploit a fundamental asymmetry between offense and defense.
Modern air defenses are designed to shoot down aircraft, cruise missiles, and ballistic missiles. Each of these targets has characteristics that make interception possible. Aircraft are large and relatively slow. Cruise missiles have jet engines that produce heat signatures. Ballistic missiles follow predictable trajectories.
A glide bomb has none of these characteristics. It has no engine, so it produces no heat signature and minimal noise. Its small size gives it a tiny radar cross-section—it's hard for radar to see. It moves fast but not so fast that it's easy to predict where it will be. And it's in the air for only a short time—a few minutes at most—giving defenders little time to detect, track, and engage it.
The only reliable way to defeat glide bombs is to shoot down the aircraft that carry them before they get within range to launch. But that requires air superiority—the ability to control the skies over the battle area—which is exactly what Ukraine lacks over much of the front line.
For countries that don't have complete air superiority but want to deliver heavy ordnance against enemy positions, glide bombs offer an almost irresistible value proposition: take your existing stockpile of cheap, dumb bombs and make them smart enough and long-ranged enough to hit targets without risking expensive aircraft.
It's a concept that Wilhelm von Siemens would recognize from his 1914 proposal. A century of technological revolution later, the fundamental idea remains the same: a bomb with wings can reach places that aircraft cannot safely go.
The Proliferation Problem
Today, glide bombs are being developed by countries around the world. The United States fields the AGM-154 Joint Standoff Weapon, introduced in 1998. India has developed both winged and non-winged variants under its DRDO program. Pakistan fields several designs including the H-4 SOW. Germany is developing a family of weapons called HOPE/HOSBO. Russia continues to refine its UMPK kits and develop new variants.
The technology is mature and relatively simple. The guidance systems use commercially available GPS receivers and inertial measurement units. The wing kits can be manufactured with basic aerospace metalworking capability. Even the most sophisticated variants cost a fraction of what cruise missiles cost.
This accessibility is both the weapon's appeal and its danger. In World War II, only Germany had the industrial and engineering capability to field guided glide bombs. Today, dozens of countries could develop similar weapons if they chose to.
The Roma's fate in 1943 demonstrated what guided weapons could do to even the most powerful warships. Eighty years later, the same basic technology is reshaping land warfare in Ukraine. A bomb with wings, dropping silently from a clear sky, carrying a ton of explosives to a precise set of coordinates—the concept has proven remarkably durable.
As air defenses grow more sophisticated, the weapons designed to defeat them will grow more sophisticated in turn. But sometimes the most effective solution isn't the most complex one. Sometimes it's just a bomb with wings, gliding toward its target while the aircraft that launched it turns for home.