Archive for the ‘Army Test and Evaluation’ Category

Why Paper Maps Are Important

September 26, 2019

Wired_RussianMaps_060-new-edit-200x100-e1445899829873I acknowledge we live in the digital age powered by constellations of communication and imagery satellites and am not advocating that this technology be ignored. However, the reality of life on the ground in a pre-combat, combat or post-combat environment may not always lend itself to the easy navigation enabled by 21st century technology. Modern military and civilian life is dependent on Google Maps or other easy GPS powered navigation. Long gone are the days of stopping by the out of town gas station and asking for directions or unfolding the free map from the State Welcome center or even following the AAA Triptik travel planner (for those with a question this is the old school bound travel planner we all followed on our family summer vacations guiding us to the nearest KOA rest stop).

Prague photo by the author

 

So with all this technology in the palm of our hand or on our wrist why bother with a paper map? The military depends on the National Geospatial-Intelligence Agency (NGA) produced maps normally in 1:50,000 scale topographic maps that we all know and love having learned basic land navigation in basic training. This is great for well know battle spaces such as Germany or Korea but the likelihood of defending the Fulda Gap (again – you might have to look that reference up if you are post Reforger era) operating in foreign places NGA map products might not be available or not available to your unit when you get on the ground. For instance in deploying to Iraq in 2004 as an individual replacement and not part of a parent unit I bought a tourist map off eBay to ensure I had a general idea of where I was, where the friendly borders were and how the road infrastructure was laid out.

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Why bother? The mapping programs we all have depend on radio wave communication and computer processing to translate data into images and information we can use to navigate. With our current focus on Arctic Extreme Cold Weather operations we know that extremely heavy wet snow falling at time can affect reception due to multi-path error, which is the result of satellite signal reflection. Another element of extreme cold weather is the impact on battery life and power drain – your device might not work due to loss of power.

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Another critical area of battle space is in built up urban areas or in extremely hilly or craggy areas – real canyons or “urban canyon” effect where the city buildings block the signal. In this case a topographic map which portrays terrain features in a measurable way, as well as the horizontal positions of features is critical. The vertical positions, or relief, are normally represented by contour lines on military topographic maps. On maps showing relief, the elevations and contours are measured from a specific vertical datum plane, usually mean sea level.

Tourist road maps of a region in which the main means of transportation and areas of interest are shown are a great back up. Some of these maps show secondary networks of roads, historic sites, museums, and beaches in detail. They may contain road and time distance between points. The scale should be carefully considered when using these maps.

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Last, the United states military says in addition to an extreme cold weather battle space, the next war may be fought in mega-cities. (24 Jun 2018 Military.com). The services have begun to plan tactics techniques and procedures for US Army and US Marine combat organizations to fight, not just within cities or industrial locations to include subterranean conflict. Wireless signals that are functional on the surface to make phone calls, send e-mails, or find GPS coordinates don’t do well penetrating through the earth. Signals can be obstructed by concrete, water, metal and rebar found in underground construction. To send a signal through an extensive complex, wireless receivers would be needed in a relay at each bend or turn, obviously not possible during an active operation.

Meredith Broussard who in her book "Artificial Unintelligence

When you prep for an operations in an unknown location a bit of research from Meredith Broussard who in her book “Artificial Unintelligence How Computers Misunderstand the World” presents a guide to understanding the inner workings and outer limits of technology and why we should never assume that computers always get it right. She indicates that a deep knowledge of the geography will help you to navigate it and to understand its culture and history. Further, print maps help acquire deep knowledge faster and more efficiently. In experiments, people who read on paper consistently demonstrate better reading comprehension than people who read the same material on a screen. A 2013 study showed that, as a person’s geographic skill increases, so does their preference for paper maps.

Ms. Broussard says that “reading in print makes it easier for the brain to encode knowledge and to remember things. Sensory cues, like unfolding the complicated folds of a paper map, help create that cognitive map in the brain and help the brain to retain the knowledge.”

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Further “the same is true for a simple practice like tracing out a hiking route on a paper map with your finger. The physical act of moving your arm and feeling the paper under your finger gives your brain haptic and sensorimotor cues that contribute to the formation and retention of the cognitive map.”

For more on this and related topics please find the details at https://www.citylab.com/design/2019/01/paper-maps-digital-navigation-google/581092/

Mechanisms of Fabric Failure

December 5, 2016
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Photo Jonathan Long

Fabric fibers that wear out fast, make garments that fail faster.  Working within the Protective Products and Equipment (PPE) industry, we are inundated with data, test procedures (whether ISO or ASTM or AATCC), and if honest, scratch our heads to understand how data and test procedures can be used to predict future performance. To add complexity, in many cases the ISO and ATSM test methods do not directly correlate because the test apparatus are different.

 

We all know humans are good at measuring things and textile engineers are no exception and excel in this area! If we can develop a scientific test to measure how one type of fiber or fabric performs to another; we are happy. For instance, we are pretty good at measuring several independent elements of textile performance one being fiber tensile strength. We then can compare the results from one fiber to another and claim victorious insight. However in looking at staple fibers which are blended for better performance

nylon-staple-fiber

Photo Jonathan Long

like those found in military uniforms, there are a couple of things that impact strength. Once we compound fibers with other natural or synthetic fibers during the spinning process strength changes. One fiber’s performance shouldn’t be the final determination of how that yarn will perform or how that fabric once woven will perform. However, tensile strength is important (photo NYLON Fiber)

 

To measure tensile strength, common test methods used in the Technical Military Fabrics worlds you find are ASTM D5034-09(2013) Standard Test Method for Breaking Strength and Elongation of Textile Fabrics (Grab) or Test Method D3822 Standard Test Method for Tensile Properties of Single Textile Fibers. While these tests are great for comparing fibers and fabrics I am not sure they really tell the whole performance story. We rely on tests to predict which fabric will perform better in a military environment where fabric failure from rips and tears in high abrasion areas such as the knees, elbows, and seat are common. Tensile strength alone may not answer that question but is the most common place to start.

fiber-micronWhat we do know about tensile strength (or think w do) is that its related to “abrasion resistance” (stated as the number of cycles on a machine, using a technique to produce abrasion) and “durability” (here defined as the ability to withstand deterioration or wearing out a garment fabric in use which includes the effects of abrasion) (1). Higher tensile strength is often thought to indicate better abrasion and durability performance.

In addition to tensile strength we want to measure abrasion and there are three dominant tests.

  1. Martindale Abrasion (ASTM D4966) This test method covers the determination of the martindale-testing-credit-association-contract-textilesabrasion resistance of textile fabrics abraded against crossbred, worsted wool fabric. Fabric samples to be mounted flat and rubbed in an enlarging elliptical T shape using a piece of worsted wool cloth as the abrading material. The end is reached when two yarn breaks occur or when there is an appreciable change in shade or appearance.
  2. Tabor Abrasion (ASTM D4060) This test method covers the determination of the abrasion resistance of organic coatings to abrasion produced by the Tabor Abrader on coatings applied to a plane, rigid surface, such as a metal panel.
  3. Wyzenbeek (ASTM D4157) This test method covers the determination of the abrasion wyzenbeek-test-machine-credit-association-contract-textilesresistance of woven textile fabrics using oscillatory cylinder tester. The Wyzenbeek testing process requires samples of the test fabric to be pulled taut in a frame and held stationary. Individual test specimens cut from the warp and weft directions are then rubbed back and forth using an ACT approved #10 cotton duck fabric as the abradant. The end is reached when two yarn breaks occur or when appreciable wear is reached.

Note to product developers and evaluation teams – both test methods are limited to measuring flat abrasion resistance of a textile. Soldiers are fully three dimensional so these tests don’t consider edge abrasion or other types of surface wear that may occur in soldier uniform applications.

Fibers have different tensile strength but they also have different elongation characteristics. When considering fiber properties, fiber tenacity should not be viewed in isolation. Fiber elongation is at least as important –  why?  If a fiber cant stretch and recover somewhat, that fiber will break sooner than one that has elongation. Elongation is specified as a percentage of the starting length. The elastic elongation is important since textile products without elasticity would hardly be useable. They must be able to deform and return to shape (2).

fiber-elongation

Photo INTECH

My thoughts about selecting the optimal fabrics and fiber for military technical fabrics are that we should focus more on the mechanisms of failure. How does a fabric fail? I think we can rightly see that a fiber’s tensile strength is critical but so is a fabrics resistance to abrasion – maybe these two measurements can tell us which fabrics are likely to be the most “durable.”

How does failure actually happen? Its related to how a yarn and fabric’s structure is

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Photo Abdullah 2006

modified in use. Lets face it – a fabric that is never used will last a long, long time so its something in use that wears a fabric out. In terms of wear mechanism in textiles, abrasion first modifies the fabric surface and then affects the internal structure of the fabric, damaging it (Manich et.al, 2001; Kaloğlu et al., 2003). Good abrasion resistance depends more on a high energy of rupture than on high tenacity at break. Abrasion is not influenced so much by the energy absorbed in the first deforming process (total energy of rupture), as by the activity absorbed during repeated deformation. This activity is manifested in the “elastic energy” or the “recoverable portion” of the total energy. Thus, to prevent abrasion damage, the material must be capable of absorbing energy and releasing that energy upon the removal of load (3).

The mechanical properties and dimensions of the fibers are important for abrasion. Fiber type, fiber fineness and fiber length are the main parameters that affect abrasion. Fibers with high elongation, elastic recovery and work of rupture have a good ability to withstand repeated distortion; so a good degree of abrasion resistance is achieved. Nylon is generally considered to have the best abrasion resistance, followed by polyester, polypropylene (Hu, 2008) (4).

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Photo Jonathan Long

 

Something to think about is what is the optimal mix between fiber tensile strength and elongation and understanding how that mix performs during abrasion testing. If we find that higher tensile strength and greater elongation results in a more abrasion resistant fabric then we can add another test method to our toolbox to provide insight in failure prediction.  Fabrics with lower yarn tensile strength and lower fiber elongation should result in poorer abrasion testing and in turn wear out faster in wear and use. Lets test it and see!   (Photo natural cotton, key nylon intermediates, hexamethylene diamine (HMD) and adipic acid, Nylon Cotton Yarn and fabric)

 

(1) http://cdn.intechopen.com/pdfs/31704/ Abdullah et al., 006 Analysis_of_abrasion_characteristics_in_textiles.pdf

(2) http://www.definetextile.com/2013/04/fiber-elongation.html

(3) Analysis of Abrasion Characteristics in Textiles by Nilgün Özdil, Gonca Özçelik Kayseri2 and Gamze Süpüren Mengüç; Ege University, Textile Engineering Department, Izmir, Turkey

(4) Analysis of Abrasion Characteristics in Textiles by Nilgün Özdil, Gonca Özçelik Kayseri2 and Gamze Süpüren Mengüç; Ege University, Textile Engineering Department, Izmir, Turkey

Pounds to Grams – not always straight forward in textiles

October 26, 2016

conversion-3Converting weight from one country’s system to another, especially for those of us with military experience in Europe jumps right to converting miles to kilometers where we know its about 1 mile to 1.6 KM – or next converting the price of fuel between gallons and liters? However, when we start talking about weight and working between the United States supply chain (with a few exceptions where companies continue to quote prices in meters and not yards!) we have to convert fabric weight from ounces per square yard to ounces per square meter (lets not get into denier and dtex!).

So why is this important? In the world of military personal protection, there are numerous measurable factors that when combines add up to some notion of comfort and performance.  MOLLEComfort translates into mission performance and staying focuses. At the crux of the issue is human performance and this really means managing the human core physiology. The amount of weight a soldier carriers is a key component to how well the conversion-2core performs and for how long. Weight can also impact how durable a textile material remains although the textile composition may be more important. How a fabric is constructed will also impact how well that material holds up. construction also impacts how air permeates through the fabric which enables the process of moisture evaporation and cooling of the core. Again, a more air permeable fabric may have tradeoffs with a less permeable fabric – but we stray.  We are talking about weight.

In many areas of human endeavor achieving the same or better performance with lessconversion-1 weight is usually a good thing and so it is with combat uniforms (to a point). So we need to know how to communicate current weight as accepted by US Military Specifications into a scale that international militaries can understand and use – enter grams per square meter.

The formula is pretty strain forward – one ounce is equal to one sixteenth of a pound or 16 drams or 28.349 grams.  WAIT – don’t use that formula! While a great formula for cooking recipes and drug measurements, it wont work for textiles because we have to consider the meter and yard lengths. Bates Jungle Boot

The answer is 1 gram = 0.03527 ounces. The textile geniuses assume we are converting between ounce-force/square yard and gram-force/square meter.   The derived unit for pressure is the pascal.  1 pascal is equal to 3.00750253989 ounces per (square yard), or 101.971621298 grams per (square meter).   The super smart people at http://www.ginifab.com/feeds/ozyd2_gm2/ helped me out with an example.

Question : If a fabric is 5.5oz/sq yard, how much is the weight in grams/sq meter ?
Answer : 5.5 oz/sqyd x 33.906 = 186.483 gm/sqm   conversion-4

And the mystery of converting ounces per square yard to grams per square meter is solved!

You know that Picatinny helmet rail?

August 9, 2016
ACH w NVG Mount
Army Combat Helmet (ACH)

 

I am working on a project that includes mounting a new piece of video kit on the Army Combat Helmet (ACH). While looking at one of my developmental helmets from 2005 shook my head a bit and considered all that is old comes back around.  This time the subject is the Picatinny rail.  When the ACH was introduced into the US Army inventory after some modification of the “Mitch Helmet” used in the previous years by US Army Special Forces, the basic version included just the Night Vision Goggle (NVG) mount. THe ACH as first fielded is a far cry from the helmets worn in combat today.

Rail pic b

At the time. the US Army program office for Soldier Clothing and Individual equipment located at Ft Belvoir, VA was looking at each piece of Soldier gear and considering how we could make it better, lighter, or more durable.  Soldiers were being asked to carry numerous new pieces of gear that needed batteries, antennas, lights and so forth.  Operating these new devices “hands free” would be a bonus – especially when you already had your hands full! I talked this challenge over with one of the ACH producers Mine Safety Appliances Co (MSA) and Russ Suchy – he came back to me with a prototype rail system shown below for the ACH.  I don’t know how long this development had been in the works before I diagramed out a pencil drawing of the ACH showing where I thought a rail could be applied. My point was the attachment mechanism for the rail use had to use the pre-existing mounting hard wear and holes. More holes in the helmet = bad.

ACH w Pict Rail v2

Informal internet research finds that the rail itself may stem from work by the “A.R.M.S. company in the early 1980s and Otto Repa in standardizing the Weaver design,” but I cant provide the exact references.  I did review the Mil-STD-1913, dated February 3, 1995 document and can see that at least as far back as 1995 rail capability was known to the US Army.  Interestingly this MIL Standard was focused on small arms.  Picatinny was the supervising office.

Picatinny Arsenal’s role in naming the rail during test and evaluation which created the military standard could be as simple as the official documentation. The MIL STD as recorded on the lowly DD-Form 1426; dated 1989 was overseen by Picatinny. Who knew that the rail would grow to such popularity in use?  Now days on most any special forces blog site you can see variations of how the Picatinny rail has been adopted for helmet mounts.

Rail pic a

MSA’s role changed when Revision Military announced in June 2012 the purchase of MSA’s North American ballistic helmet business. The purchase included the acquisition of MSA’s U.S.-based helmet manufacturing equipment and operations located in Newport, Vermont.

Regardless of whether its MSA, Revision, Gentex, Crye, or a host of other excellent combat producers, the fact that the Picatinny rail seems to be here to stay is without question.  Just look at the variations in helmet mounts (and not even mentioning weapon and hand guard rails!) and you can see that the creative adaptation has not stopped!

Rail pic c