Laser-Guided Bullet Hits Target a Mile Away
ALBUQUERQUE, N.M, Jan. 31, 2012 — A new dart-like, self-guided bullet that can hit laser-designated targets more than a mile away could help war fighters.
Red Jones and Brian Kast, two Sandia National Laboratories engineers — and hunters — developed the self-guided bullet for small-caliber, smooth-bore firearms. They are looking for a private partner to complete testing of the prototype and bring it to market.
The design for the 4-in.-long bullet includes an optical sensor in the nose to detect a laser beam on a target. The sensor sends information to guidance and control electronics that use an algorithm in an 8-bit central processing unit to command electromagnetic actuators. These actuators steer tiny fins that guide the bullet to the target.
A tiny LED attached to a self-guided bullet at Sandia National Laboratories shows a bright path during a nighttime field test that proved the battery and electronics could survive the bullet’s launch. (Image: Sandia National Laboratories)
Most bullets shot from rifles fly straight because of the grooves in the rifle, which cause spinning. The Sandia bullet, however, flies straight because of its aerodynamically stable design, which consists of a center of gravity that sits forward in the projectile, and tiny fins that enable it to fly without spin, just like a dart.
Computer aerodynamic modeling showed dramatic improvements in accuracy. The simulations showed that an unguided bullet under real-world conditions could miss a target more than one-half mile away by 9.8 yards, while a guided bullet could get within 8 in.
Plastic sabots provide a gas seal in the cartridge and protect the delicate fins until they drop off after the bullet emerges from the firearm’s barrel.
The 4-in.-long bullet has actuators that steer tiny fins that guide it to its target. (Image: Randy Montoya)
Because of its small size, the prototype does not need the inertial measuring unit found in most guided missiles, which would have added substantially to its cost.
As it flies through the air, it pitches and yaws at a set rate based on its mass and size. In larger guided missiles, the rate of flight-path corrections is relatively slow, so each correction must be very precise since fewer corrections are possible during flight. The natural body frequency is about 30 Hz, so the scientists can make corrections about 30 times per second. This means that they can overcorrect and, as a result, do not have to be as precise each time, Jones said.
Testing has shown that the bullet can reach speeds of 2400 ft/s, or Mach 2.1, using commercially available gunpowder. The men are confident that, with customized gunpowder, the bullet could reach standard military speeds. A nighttime field test in which a tiny LED was attached to the bullet showed that the battery and electronics can survive flight.
The researchers hope to market the bullet to military, law enforcement and recreational shooters.
For more information, visit: www.sandia.gov
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