Defense Technology International - June 2008 - (Page 60)

I THE CUTTING EDGE TECH REVIEW PAT TOENSMEIER Power Projection In a program called PowerSwim, Darpa is ﬁne-tuning an oscillating foil propulsion device that Program Manager Jay Lowell says dramatically improves the efﬁciency of combat swimmers. The system consists of two horizontal foils connected by a vertical hinge. Swimmers strap it onto their shins and operate it with a ﬁsh-like motion similar to bending down and standing up. The action takes a while to get used to, but Lowell cites beneﬁts over propulsion with ﬁns. Swimmers use big muscles like quads and hamstrings instead of calves, increasing the power invested in the device. The foils sweep through water that hasn’t already been pushed aside in a wake, increasing swimming efﬁciency. And the mechanism uses lift to propel a swimmer. Lowell says that for every calorie of energy expended in swimming with ﬁns, 15% goes into forward motion. With PowerSwim, 75-85% of caloric energy goes to forward motion. The device can expand a combat swimmer’s endurance to 3-4 hr. from under 2 hr. with ﬁns, increase speed 50-75% and reduce metabolic output. Prototypes are expected in 2009. I CHIP CHASE/DEFENSE ADVANCED RESEARCH PROJECTS AGENCY 2 U.S. NAVY Repeatable Results Combat swimmers use tools for underwater navigation that haven’t changed since World War II: a compass, stopwatch and kick counts. A program at the Defense Advanced Research Projects Agency (Darpa) is addressing that. The Tactical Underwater Navigation System is developing component technologies and software that will give swimmers the means to accurately gauge distances, depths and water conditions in the littorals, conduct hydrographic surveys and do other tasks for special operations and amphibious landings. The hardware includes a Doppler velocity log, sonar that reads relative velocity between the ground and swimmer; an inertial navigation system; a pressure transducer; a temperature indicator; and a GPS antenna for surface readings. Data from these devices will be processed by software with a Kalman ﬁlter that produces measurements based on known error factors. Darpa plans to assemble components into a 25-lb. unit that can be handheld or mounted on a Diver Propulsion Device. U.S. Air Force Lt. Col. Jay Lowell, program manager, says swimmers will take readings that can be downloaded and converted into 3D maps of the ocean ﬂoor. Preproduction prototypes are due by summer 2009. I 1 ON THE EDGE U.S. ARMY Straight Shooter Riﬂe and pistol manufacturers use various techniques to increase the accuracy of weapons. One metal treatment company claims major improvements in accuracy, maintenance and longevity from cryogenically treating barrels. Results Cryo Inc. of Sterling, Ill., says exposing a barrel to extreme cold relieves stress, removes harmful byproducts and can reduce maintenance by half. The process has been around for years. Owner Steve Kerber says the ﬁrm has been successful treating civilian ﬁrearms, and believes the military will beneﬁt as well. In the process, a barrel is placed in a device that lowers temperature to -300F at the rate of 1 deg./min. The barrel stays at -300F for about 24 hr., after which temperature is raised at the same rate. An undisclosed secondary process enhances the treatment. The main beneﬁt is relieving stress. Kerber says this keeps the barrel stable—and accurate—even when hot from multiple ﬁrings, and maintains the integrity of riﬂing grooves. The Rockwell hardness of the metal stays the same, but molecular changes increase tensile strength, extending service life. I 60 DEFENSE TECHNOLOGY INTERNATIONAL JUNE 2008 AviationWeek.com/dti 3 http://AviationWeek.com/dti

Table of Contents Feed for the Digital Edition of Defense Technology International - June 2008

Defense Technology International - June 2008 Contents Around the World Science Watch Tech Watch Basic Black Self-Defense Fire-Resistant Perfezione Hyperspeed Trial Big Sky Cashing In Digital Links Hang Ten Sea Change Programs Update Two Steps Back Direct Hit Staying Power Potent Stinger Do No Harm Guard Duty The Net Cutting Edge First Person In Review Insight

Defense Technology International - June 2008

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