The Lazy Dog (sometimes called a Red Dot Bomb or Yellow Dog Bomb) was a small, unguided kinetic projectile used by the U.S. Air Force. It measured about 1.75 inches (44 mm) in length, 0.5 inches (13 mm) in diameter, and weighed about 0.7 ounces (20 g).
The weapons were designed to be dropped from an aircraft. They contained no explosive charge but as they fell they would develop significant kinetic energy making them lethal and able to easily penetrate soft cover such as jungle canopy, several inches of sand, or light armor. Lazy Dog munitions were simple and relatively cheap; they could be dropped in huge numbers in a single pass. Though their effects were often no more deadly than other projectiles, they did not leave unexploded ordnance (UXO) that could be active years after a conflict ended.
Lazy Dog munitions had precursors in air-dropped flechettes dating from World War I.
Lazy Dogs in their familiar form were descended from projectiles of almost identical design and appearance that were originally developed early in World War II (as early as 1941). The Korean War–era and Vietnam War–era "Lazy Dog" was further developed, tested and deployed into the 1950s and 1960s.
Originally an Armament Laboratory program codenamed Lazy Dog, the weapon's development involved Delco Products Corporation, F&F Mold and Die Works, Inc., Haines Designed Products, and Master Vibrator Company of Dayton. The project objective was to design and test free-fall missiles and their dispensing units for use in bombers and fighters. Lazy Dog anti-personnel missiles were designed to spray enemy troops with small projectiles with three times the force of standard air-burst bombs. The Armament Laboratory worked with the Flight Test Laboratory to conduct wind tunnel tests of a number of bomb shapes which design studies indicated to be the most efficient for storage and release from high performance aircraft.
Experimental Lazy Dog projectiles of various shapes and sizes were tested at Air Proving Ground, Eglin AFB, Florida, in late 1951 and early 1952. An F-84 flying at 400 knots (740 km/h; 460 mph) and 75 feet (23 m) above the ground served as the test bed while a jeep and a B-24 were the targets. The result was eight hits per square yard (approximately nine hits per square metre). Tests revealed Shapes 2 and 5 to be the most effective. Shape 5, an improved basic Lazy Dog slug, had the force of a .50 caliber bullet and could penetrate 24 inches (61 cm) of packed sand. Shape 2 could penetrate 12 inches (30 cm) of sand—twice as much as a .45 caliber slug fired point blank.
The Shape 2 projectile was sent to the Far East Air Force for combat use by mid-1952. FEAF immediately ordered 16,000 Lazy Dog weapon systems. An Air Force Lieutenant Colonel named Haile attached to the Armament Laboratory spent 90 days in Japan to set up local manufacture of the Lazy Dog weapons and train crew members in their use. Project Lazy Dog continued throughout 1952 to determine the optimum characteristics for stable dispersion containers and the feasibility of substituting a Lazy Dog warhead for the explosive nose of the Matador missile. The Lazy Dog program was still ongoing in the late 1950s.
Lazy Dog projectiles could be dropped from almost any kind of flying vehicle. They could be hurled from buckets, dropped by hand, thrown in their small shipping bags made of paper, or placed in a Mark 44 cluster adaptor—a simple hinged casing with bins built in to hold the projectiles, opened by a mechanical time delay fuze. The adaptors themselves were 69.9 inches (1.78 m) long and 14.18 inches (36.0 cm) in diameter. They would be shipped empty, then filled by hand. Depending on how many projectiles could be packed in, loaded weight varied between 560 and 625 pounds (254 and 283 kg), with the theoretical maximum number of projectiles listed as 17,500.
Regardless of how they were released into the air, each "Lazy Dog" projectile would develop an enormous amount of kinetic energy as it fell, penetrating nearly any material upon hitting the ground. Some reports say that their speeds often exceeded 700 feet per second (210 m/s; 480 mph; 770 km/h) before impact.
A variant version of the "Lazy Dog" projectile was developed for the recoilless rifle. However, development was suspended because another kind of flechette solution was used for the recoilless rifle instead.