TARGET SIZE MODELING METHODS ESTCP Project Number: 2005 – MM – 07 Model Overview (Figs. 1 through 3) • Impact Dispersion Model – models locations of impacts around given target point for indirect-fire weapons (Fig. 1) • Fragmentation Model – Predicts distribution of number, mass, and initial velocity of fragments resulting from detonation of single round – Predicts horizontal fragment range based on mass, initial velocity and initial angle of fragments (Fig. 2) – Randomly distributes fragments to model fragmentation “footprint” of the detonation of a single round • Geophysical Model – Models capability of geophysical sensors to detect sizes and densities of fragmentation predicted by fragmentation model – Sensor capabilities affected by geophysical sensor type, platform, and site-specific background conditions (geology, vegetation, etc.) – Size and shape of target area to be used as input to survey design will vary depending on geophysical sensor capability • Target Sizing Model – combines the three components – Overlays fragmentation footprint for single detonation on predicted locations of impacts (Fig. 3) – Boundaries of detectable areas of the target determined by capabilities of geophysical system BACKGROUND Target Size Model Objectives • Develop robust, flexible model to predict size and shape of detectable fragmentation distributions from indirect fire weapons systems • Provide input to determination of search patterns and transect spacing for preliminary investigations • Aid in footprint reduction at suspected munitions response sites Past Year’s Progress • Progressed in the development of the Geophysical Capabilities Component • Analysis to assess the sensitivity of the model results to key inputs • Validation of model against first site in progress GEOPHYSICAL CAPABILITIES COMPONENT Background • Target Sizing Model predicts size and densities of fragments throughout target area; the model predicts some very small fragments and very low densities • Fragment size prediction considerably smaller than UXO or nose/tail pieces that are typically searched for • Real world application of model requires fragments be detected by common geophysical instruments • Ultimate size and shape of target area to be used as input to survey design will depend on geophysical capability Analysis • Literature review and analysis of past studies and experiments (speed and noise evaluations, height tests) to establish baseline understanding of capability (in progress) • Detailed analysis of fragments and dig results from 60mm target at Former Camp Wheeler Non-Time Critical Removal Action (completed) • Field experiments McKinley Range, Redstone Arsenal, Huntsville, AL to collect data over fragment concentrations and transects based on model output (data collection and preliminary analysis complete) • Compare site-specific data against model outputs simulating sites Field Experiments (Figs. 4 through 7) • Fragments from 60mm M49A2 mortars from Former Camp Wheeler used • Preliminary analysis completed (Figs. 4 through 7) • Results: – “Detectable” number of fragments dependent on individual fragment masses – Less than 5 grams – increase in noise – 5 to 20 grams – minimum of ~30 fragments/m2 – 20 to 50 grams – minimum of ~5 fragments/m2 – 50 to 80 grams – minimum of ~2 fragments/m2 – Greater than 80 grams – minimum of ~1 fragment/m2 MODEL VALIDATION Former Camp Wheeler near Macon, GA Brief History • Formerly Used Defense Site near Macon, GA • Established in 1917 as training camp for National Guard units (closed in 1919) • Re-established in late 1940 as an Infantry Replacement Training Center (closed in 1946) • Approximately 14,000 acres • 17,000 trainees and 3,000 cadres at height of use • Contained over 30 ranges, for munitions ranging from 30 cal rifles, machine guns, grenades to 60mm and 81mm mortars Validation Site at Former Camp Wheeler (Fig 14) • Range R-30, a live 60mm mortar range • Approx. 340 unexploded 60mm M49A2 and M49A1 recovered during recent removal action • Recovery depths from surface to 30 inches • Small number of grenade fuzes also recovered • Nearly 16,000 lbs of “OE Scrap” (fragments) also recovered • Weight of recovered fragments recorded for each 50m x 50m work grid Validation Approach • Model the apparent multiple targets based on the locations of the UXO; base number of rounds on assumed dud rates • Sum predicted fragment masses over same 50m x 50m grids • Compare predictions to removal results SENSITIVITY ANALYSIS Objectives • Explore the effect of key variables on the Target Sizing Model • Determine whether simplifying assumptions can be made for some of the variables • Determine whether default values can be used for some of the variables Shape Factor (Fig. 13) (i.e., drag on fragments) • Specifies the area of fragment facing perpendicular to the direction of flight • Fragment range increases as shape factor increases; size of target area increases and fragment density decreases (Fig. 13) • Shape factor of 0.333 is commonly assumed for fragments • Little data is available on actual fragment shapes or drag coefficients • Validation of model with actual field data will be used to determine appropriate shape factor Mark/Mod of Munition (Fig. 8) • Differences in case dimensions can affect size and number of fragments • Differences in filler type and amount can affect size, number and range of fragments • Ideally, these effects will be small enough that same size munitions can be grouped together • Rounds with similar case weights and filler weights could be grouped together • Filler type of secondary importance Number of Rounds (Fig. 9) • Analysis integrated with geophysical analysis results • Ideally, use of this information will allow specification of “Lightly” and “Heavily” used sites • Tentative identification of three levels of site use: – Lightly used site: only part of target box is detectable. – Moderately used site: target box and more distant fragments are detectable, but a gap between two areas – Heavily used site: Continuous detectable area • Effects of VSP “probability of detecting” calculation will have a bearing on final determination of site use levels Probable Error of Impact (PE) and Angle of Fall of Munition (Figs. 10 through 12) • Variables specified in firing table for a given charge level and range; each weapon system type has multiple firing tables, one for each charge level; each charge level has PEs and angles of fall for multiple weapon ranges • Goal of sensitivity analysis of Angle of Fall and Probable Error is to reduce amount of firing table informa- tion required as input to model • Increased probable errors increase impact dispersion leading to larger, less dense target footprint (Fig. 10) • Fragment range increases as angle of fall increases, up to ~68º-70º; then range decreases as angle of fall increases (Fig. 11) • As fragment range increases, target footprint becomes larger and less dense (Fig. 12) • Variability in figure 12 indicates that it may not be possible to develop a single default for these variables – Some entry of firing table data will be necessary – Researching charge levels recommended for each range of fire and only entering recommended ranges for each charge level may provide a way to limit the required number of entries Project Completion Plan • Complete model validation against site data • Incorporate aerial bombing targets into model (dependent on obtaining impact dispersion data for older aerial bombing systems) • Complete incorporation of sensitivity analysis and geophysical capability model into the Target Sizing Model • Document model and model software Sensitivity Variables • Mark/Mod of Munition • Number of Rounds • Angle of Fall of Munition • Probable Error of Impact (range and deflection) • Shape Factor (i.e., drag on fragments) Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 14 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13