Duck for cover, here comes the laser-guided bullet

Figuring out how to pack a processor and other sophisticated equipment into a machine gun bullet has been a challenge, but engineers at Sandia National Laboratories in the US say the miniature guidance system they've developed is a breakthrough.

A bullet that directs itself like a tiny guided missile and can hit a target more than 1.6km away has the potential to change the battlefield for soldiers without costing too much, engineers said on Wednesday.

Sandia technical staff member Red Jones said the .50-calibre bullets are being designed to work with military machine guns, so soldiers could hit their mark faster and with precision.

"Everybody thought it was too difficult to make things small enough. We knew we could deal with that. The other thing was it was going to be too complicated and expensive," he said. "We came up with an innovative way around that to make it stupid and cheap and still pretty good."

Developing more precise weaponry has been a mission for government and industry scientists for decades. Most recently, the research arm of the US Department of Defence has awarded tens of millions of dollars in contracts to companies to develop guided ammunition for snipers and special scopes that account for crosswinds and other environmental variables.

The idea behind Sandia Labs' bullet is rooted more in the M2, a belt-fed machine gun that became standard issue in the US Army nearly 80 years ago. Pairing the M2 with the guided bullet would allow soldiers to hit their mark faster and with precision.

At 10cm long and a 1.27cm in diameter, the bullet is designed to twist and turn, making up to 30 corrections per second.

Jones and his fellow researchers had initial success testing the design in computer simulations and in field tests of prototypes, built from commercially available parts.

With most of the hard science done, Jones said the next step is for Sandia to partner with a private company to complete testing of the prototype and bring a guided bullet to the marketplace.

More than $US1 million in research and development grants have taken the project this far.

Computer simulations showed an unguided bullet under real-world conditions could miss a target about 1km away by nearly 9m. But according to the patent, a guided bullet would get within 20cm.

The design for the bullet includes an optical sensor to detect a laser beam on a target. The sensor sends information to guidance and control electronics that use an algorithm in an eight-bit central processing unit to command electromagnetic actuators. The actuators steer the fins that guide the bullet.

Jones said there are still some engineering problems to be sorted out that will make the bullet more practical - for example, it will have to be tough enough to be dropped off the back of a truck and still work.