June 23, 2007 Researchers at Sandia National Laboratories in California have emerged as key players in a state-of-the-art program for the U.S. Army that focuses on the design and manufacturing of a lightweight, high-caliber, self-propelled cannon system.
The weapon system, known as the Non-Line-of-Sight Cannon (NLOS Cannon) is fully automated and can fire at a sustained rate of six rounds per minute. The vehicle, once completed, must be light and agile enough to fit three vehicles comfortably onto a C-17 cargo aircraft.
According to Sandia researcher Nipun Bhutani, who serves as project manager for the lab's NLOS-Cannon work Sandia's primary contribution to date has been a critical adjustment to a laser ignition system that serves as the heart of the NLOS-Cannon vehicle. The cannon is part of Future Combat Systems (FCS), the Army's premier modernization program.
This system is being developed by BAE Systems, as part of The Boeing Company/SAIC led FCS Program.
Laser ignition unit: key to better precision, overall performance
The laser ignition system was developed by the Armament Research, Development and Engineering Center (ARDEC), in collaboration with Kigre, Inc. The unit is mounted on the back of the cannon's gun barrel, where a laser beam is fired through an opening mechanism (the breech) to ignite the charge and launch an artillery shell. However, says Bhutani, the recoil force and shock of the projectile (bullet) discharge had caused an increase in observed failures during early prototype testing.
"The laser ignition system offers much better precision, rapid fire, and automation than the mechanical method, and it's safer," says Bhutani. "But it's obviously not going to be an effective long-term solution if reliability cannot be maintained."
Instead of abandoning the laser ignition concept in favor of traditional, mechanical ignition, the Army called in experts at Sandia, who deal with shock issues surrounding a wide range of components.
Isolation system absorbs shock from gun discharge
To absorb the force from the discharge, Sandia and ARDEC jointly proposed a new isolation system between the laser and the breech. Vibration isolation systems are widely used to protect sensitive devices from vibrations or shock produced in their environment. Typical examples include isolating delicate laboratory experiments from floor-borne vibrations, or isolating a car body or airplane frame from engine vibrations.
Sandia, in collaboration with BAE Systems and ARDEC is developing an isolation system for the NLOS Cannon that acts much like a filter and results in much lower shock levels.
In addition to the isolation system, Sandia's researchers then went several steps further and incorporated the lab's modeling and experimental capabilities that are leading to hardening of the laser igniter.
Modeling leads to full systems approach
In an effort to develop the most optimal isolation system possible, Bhutani says the Sandia team needed to model the physics and inner workings of the laser system components. This involved modeling the gun loads and other physical dynamics inside the laser ignition system, particularly as it is fired.
Sandia is a National Nuclear Security Administration laboratory.
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