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Engineer's Toolbox:
Increasing munitions precision through fuze and power technologies

By Lauren Poindexter, Picatinny Arsenal

To keep up with the demands of advanced warhead technologies, engineers at Picatinny Arsenal in New Jersey have developed an initiative called "Fuze and Power Technologies for Munitions." Its mission focuses on making weapons more precise and effective by improving weapon fuzing and power.

The initiative is best described as four projects rolled into one.

"Each of the projects has its own budget, schedule, and tailored design process," said Craig Doremus, Fuze Division Project Officer at the U.S. Army Armament Research, Development and Engineering Center, or ARDEC. "These are the four areas that we have determined will address the biggest gaps and problems to solve."

Fuze and Power Technologies for Munitions projects.

 

 

The four project areas under Fuze and Power Technologies for Munitions are cutting-edge technologies that will enable increased lethality, range, and effectiveness in all munitions, all while maximizing safety to the warfighter, Doremus said.

A fuze is a mechanical or electronic device used to initiate the explosive train. It can be found in everything from mortar and artillery rounds, to missiles and other projectiles.

Fuzing and power systems are critical technologies in all munition systems. However, there are limited fuzing solutions currently available for advanced munitions and warheads. These new advanced warhead designs and high-accuracy munition applications also have technology gaps, which include:

• The lack of a government-owned technology for high-rate medium-caliber programming and communication schemes to enable multi-mode and high-accuracy air-bursting munitions.
• Current large-caliber fuze-setting technology that does not meet the requirements for higher-speed inductive setting in auto-loading cannons and guided mortar applications.
• Current in-line safe and arm devices are high-cost and high-volume items. They are not easily integrated into enhanced lethality artillery and mortar applications with specialized warhead initiation schemes.
• Limited power technologies are available to meet extended-range, precision-guided, and next-generation artillery fuze power requirements.

To address these gaps, the Fuze and Power Technology initiative aims to develop new technologies that are highly reliable, environmentally friendly, low-cost, small-form-fit, and low-power solutions. The goal is to provide advanced capability while avoiding component/technology obsolescence.

Fuze Enhanced Airburst Response (FEAR)
"Current medium-caliber munitions have a large error associated with the airburst location at long ranges," said Doremus. "ARDEC is working on ways to reduce the error associated with long-range drag by using sensors to determine actual muzzle velocity."

Fuze Enhanced Airburst Response, or FEAR, focuses on medium-caliber munitions, which are fired from weapon platforms found on ground vehicles and helicopters.

"The current airburst window (error) is too large at long ranges to meet current warhead-effects requirements, so we are looking to reduce and correct theses errors within the fuze," said Doremus.

ARDEC wants to create muzzle enhancements to correct for muzzle velocity variations, which will help reduce airburst location error at all ranges.

The technologies they develop will be delivered to other programs such as the Advanced Lethality and Accuracy System for Medium Caliber and other munition programs requiring high-accuracy airburst technologies.

Next-Generation Large-Caliber Setting (NGLCS)
The current EPIAFS (Enhanced Portable Inductive Artillery Fuze Setter) system does not meet current auto-loading speed requirements and is battling component obsolescence issues.

To resolve this issue, ARDEC is working to develop a new-generation fuze setting system that is smaller, more portable, easily upgradable, and adaptable to traditional, auto-loading, and portable applications. ARDEC is accomplishing this through the design and development of an in-house single-board-computer (SBC) and software solution.

Unlike EPIAFS, which uses an obsolete, modified commercial-off-the-shelf computer, the new SBC will be designed for multiple applications and upgradability from the start. "This is important because we need new hardware and software to communicate new and unique data to emerging precision munitions," said Doremus.

Before firing most conventional, and all precision rounds, power and data must be transferred to the munition through a fuze setter.

"The current EPIAFS system utilizes a hand-held wand that is placed over the tip of the fuze, and the control computer sends power and data to the fuze through induction coils," said Doremus.

"They no longer make the computer that is currently in EPIAFS, so we keep refurbishing old units. We are designing our own computer utilizing the latest microchip technology that we can put our own software on. This will allow us to pretty much design and build a custom computer instead of modifying something that already exists and was designed to function another way," said Doremus.

"The benefit to this technology is that the new system will be able to handle both current and future advanced data transfer needs, and will be easily upgradable as new requirements evolve," added Doremus.

"We can add features much easier than we could with the old system. This is going to allow a lot of other munition programs to include precision capability," he said.

Next-Generation Safety and Components (NGS&C)
ARDEC also seeks to develop new low-cost, electronic safe-armed devices that arm the round, but only when the intent is to arm it.

"All lethal munitions have a fuze with a safe-and-arm device," said Doremus. "It's what keeps the warfighter safe when they are storing, handling, or transporting the munition."

"Typically when we fire a munition from the gun, it's the fuze safe-and-arm's job to know that the munition was actually fired and not just dropped and rolled. So, we do a lot of work in sensing the gun launch and flight environments so the round is always safe and won't function inadvertently. We do a lot of safety testing," said Doremus.

With an electronic safe-and-arm device (ESAD), the safe-and-arm system is based on high-voltage in-line electrical components, versus the traditional approach of mechanical out-of-line gear train-based systems.

"What we are trying to do is to make the ESADs cheap enough that we can put them in all calibers of munitions. One solution may be to decrease the voltage slightly to within the realm of standard commercial-off-the-shelf (COTS) components, which are much cheaper, are readily available, and are easy to integrate with existing architectures," said Doremus.

"One of the problems with mechanical safe-and-armed devices is they are more difficult to make and test. There are a lot of tolerances and a lot of errors that can be made. Parts can be left out or misplaced, so it makes them much more difficult to inspect," said Doremus.

Doremus continued, "ESADs have proven to be just as reliable as traditional safe-and-arm devices, but are easier to inspect and test. Another benefit is the ability to disarm, or shut down a system that has been armed, rendering it safe again."

"Our goal is to get the price down to a point in which the ESADs are competitive with traditional mechanical safe-and-arm prices, which makes it easier for program managers to integrate into new projects," said Doremus.

"Our goals right now are targeted toward PGK [precision guidance kit]. We want to be able to fit inside the existing PGK safe-and-arm area and drive the cost down to, if not less than, the mechanical safe-and-arm for PGK," said Doremus.

Power for Advanced Munitions (PAM)
Power for Advanced Munitions' primary focus is on the advancement of thermal battery technologies, such as those used in precision rounds like Excalibur.

"Traditionally, we use thermal batteries in precision munitions, which are a type of reserve battery that doesn't activate and become a battery until post launch," said Doremus.

ARDEC is furthering the thermal battery technology by making these batteries more energy efficient, able to house additional power in the same size, if not smaller, than current batteries.

"What we need to do is make improvements to the chemistries and insulation materials to be able to derive more power and efficiency from the same package," said Doremus.

"Here at ARDEC, we are striving to become the leader in the Army for reserve power. We are doing a lot of research into modeling and simulation, materials, and processes," said Doremus.

Published April 2016

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