This prototype smart bullet very accurately hits laser designated targets at distances of over a mile.
Guided missiles and smart bombs have been around for quite a while. Now, two engineers at the Sandia National Laboratories in Albuquerque, NM, have invented a self-guided bullet. Red Jones and Brian Kast (both hunters) and their colleagues developed a prototype laser guided bullet for small caliber, smoothbore firearms.
How Does It Work?
An optical sensor in the bullet’s nose detects the laser beam aimed on a target. The sensor sends this information to the guidance and control electronics also located in the bullet. Miniaturization allows the sensor and electronics to be included into a four inch long bullet. An algorithm in an eight bit central processing unit commands electromagnetic actuators which steer tiny fins guiding the bullet to the target.
The gun firing the guided bullet does not use rifling to spin the projectile for straight and stable flight. Because the guided bullet must be able to turn in flight toward a target, it does not spin. Instead, it flies straight due to its aerodynamic design consisting of a center of gravity sitting forward in the projectile and tiny fins which enable it to fly stably without spin, just as a dart flies. This also simplifies the design. Plastic sabots provide a gas seal between the projectile and the gun bore, as well as protect the delicate fins. The sabot drops off when the bullet emerges from the barrel of the firearm.
As the bullet flies through the air, it pitches and yaws at a set rate determined by the projectile’s mass and size. In larger guided missiles, the rate of flight path corrections is relatively slow, so each correction needs to be very precise because fewer corrections are possible during flight. Because of the guided bullet’s small size and mass, corrections are made much faster and more often – 30 times per second. Therefore, corrections do not have to be as precise each time and overcorrections are tolerated.
So far, the researchers have successfully proved the design works in computer simulations which show it would result in dramatic improvements in accuracy. Computer simulations showed that a regular unguided bullet under real-world conditions could miss a target located over a half mile away by nearly 30 feet. In contrast, a guided bullet would get within eight inches.
Field testing of prototypes built from commercially available components showed that the battery and electronics could survive the bullet’s launch from the gun. High-speed video recorded the bullet radically pitching as it exited the barrel. The bullet pitches less as it flies downrange, a phenomenon known to long-range firearms experts as “going to sleep.” Because the bullet’s motions settle the longer it is in flight, accuracy actually improves at longer ranges.
Testing has shown that the electromagnetic actuator performs well and the bullet can reach speeds of 2,400 feet per second, or Mach 2.1, using commercially available gunpowder. The researchers are confident it could reach standard military speeds using customized gunpowder.
While there are still engineering issues to be addressed, the researchers are confident the engineering technology is available to solve the problems. Sandia is now seeking to partner with a private company to complete testing of the prototype and bring a guided bullet to market. Potential customers include the military, law enforcement and recreational shooters.
About the Author: Bill Siuru is a retired USAF colonel. He has a Ph.D. in mechanical engineering from Arizona State University. His military assignments included teaching engineering at West Point, commander of the research laboratory at the U.S. Air Force Academy and Director of Engineering at Wright-Patterson AFB. For the past 35 years, he has been writing about automotive, aviation and technology subjects.
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