Modeling & Simulation, Testing & Validation THE INFLUENCE OF GROUND COMBAT VEHICLE WEIGHT ON AUTOMOTIVE PERFORMANCE, TERRAIN TRAVERSABILITY, COMBAT EFFECTIVENESS, AND OPERATIONAL ENERGY Robert J. Hart, PhD Richard J. Gerth, PhD 8/22/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited
Modeling & Simulation, Overview Testing & Validation • Introduction – What is a Ton of Weight Worth? – Scope of Current Study • Automotive Performance Analysis • Combat Effectiveness Analysis • Terrain Traversability Analysis • Operational Energy Analysis • Brigade Combat Team Relevance • Conclusions 8/22/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited
Modeling & Simulation, Introduction: Motivation Testing & Validation • What Is a Ton of Weight Worth? * – The challenge presented from the Lightweight Combat Vehicle Science and Technology Campaign was to create appropriate metrics that would better reflect the performance trade with regards to weight. • Operational Considerations – Air and Land Transportability • primarily a function of the mission and what is being transported – Operational Energy • Reducing vehicle weight reduces fuel consumption and improves operational energy efficiency – Freedom of Movement • Greater flexibility and less predictability in the manner in which the system will be delivered to the fight – Combat Effectiveness • The ability of the military force to accomplish the objective *Gerth, R. and Howell, R., "What Is a Ton of Weight Worth? A Discussion of Military Ground System Weight Considerations," SAE Technical Paper 2017-01-0270, 2017, doi:10.4271/2017-01-0270. 8/22/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited
Modeling & Simulation, Introduction: Scope of Current Study Testing & Validation • Examines the impact of vehicle weight on automotive performance, terrain traversability, combat effectiveness, and operational energy. • In every study, three vehicles were studied: M1A2 Abrams, M2A3 Bradley, M1126 Stryker – Each simulation was conducted with the vehicles at 100% of their baseline Gross Vehicle Weight (GVW) and at 85% of their GVW for a total of 6 vehicle/weight combinations. – No other vehicle performance characteristics, such as survivability or lethality were altered. – In other words, it was assumed that the weight reduction occurred through implementation of technology that did not otherwise change vehicle capabilities. • This study IS a theoretical study on the effect of bulk vehicle weight on performance metrics • This study IS NOT a detailed design study for systems already fielded or under development Vehicles and weight alternatives considered in this study. Vehicle Name Weight [% of GVW] 1. M2A3 Bradley Fighting Vehicle 100% 2. M2A3 Bradley Fighting Vehicle 85% 3. M1A2 Main Battle Tank (MBT) 100% 4. M1A2 Main Battle Tank (MBT) 85% 5. M1126 Stryker Infantry Carrier Vehicle (ICV) 100% 6. M1126 Stryker Infantry Carrier Vehicle (ICV) 85% 8/22/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited
Modeling & Simulation, Automotive Performance Analysis: Methods Testing & Validation • The automotive performance metrics studied were: – Top speed (mph) – The maximum speed the vehicle can move on flat terrain (0% grade). A larger value is better. – Speed on 10% grade (mph) – The maximum speed the vehicle can move on a 10% grade. A larger value is better. – Speed on 60% grade (mph) – The maximum speed the vehicle can move on a 60% grade. A larger value is better. – Dash speed (time to cover 50 meters from a dead stop in seconds) – this is a measure of the vehicle acceleration, similar to a quarter mile measurement in automotive. A smaller value is better. – Fuel economy at a constant 30 mph convoy speed (mpg) – miles per gallon of fuel a vehicle can move. A larger value is better. The fuel economy was measured by running the vehicle at speeds in 10 mile increments across different terrains (paved road, secondary road, and cross-country) and measuring their fuel economy. – Vehicle range (miles) – The range of the vehicle. This is proportional to the fuel efficiency. A larger value is better. • GT-Suite Software – Fuel economy and performance modeling simulations of a vehicle. – GT-Suite models of the M2A3 and M1126 Stryker were developed for the analysis. • MATLAB. – MATLAB script was created and used to calculate the performance of the M1A2. • The models were first validated by comparing model performance predictions to test data. After validating, each vehicle model analysis was conducted at the current GVW as well as at 85% of the current GVW, and the mobility metrics were calculated and recorded. 8/22/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited
Modeling & Simulation, Automotive Performance Analysis: Results Testing & Validation • M1A2: – 15% weight reduction led to an improvement in top speed of 8%. Similarly, speed on grade increased by 20% or more, and fuel efficiency improved by 12%. • M2A3: – Fuel efficiency improved by an impressive 14% across a variety of terrains. • Stryker: – Significant improvements in speed on grade (10-14%) and fuel efficiency (8%) due to lightweighting. Automotive Performance Results Vehicle Top Speed Speed Dash Fuel Range Speed on 10% on 60% Speed Economy (miles) (mph) Grade Grade (Seconds) (mpg) (mph) (mph) M1A2 --- --- --- --- --- --- M1A2 at 85% wt +8.4% +27.4% +19.5% -6.1% +12.0% +12.0% M2A3 --- --- --- --- --- --- M2A3 at 85% wt +0.5% +15.2% +100% -6.0% +14.3% +14.3% STRYKER --- --- --- --- --- --- STRYKER at 85% wt +0.1% +9.8% +14.2% -5.3% +7.8% +7.8% 8/22/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited
Modeling & Simulation, Combat Effectiveness Analysis: Methods Testing & Validation Combat Vignette: – Blue Force (BLUFOR) consisting of single platoon (4 combat vehicles). The lead vehicle was labeled BLUE1, followed by BLUE2, BLUE3, and BLUE4. – BLUFOR’s mission was to traverse through a village in hostile territory on route to reinforcing another unit (Figure (a)). – Heavy Opposition Force (OPFOR) instigated an ambush scenario, which occurred primarily between points 2 and 3 in Figure (b). (b) (a) • M2A2 Bradley and M1126 Stryker: OPFOR consisted of two squads, or 4 Map of urban ambush vignette from OneSAF with (a) the full route total anti-tank teams . highlighted in red and (b) a close up view of the urban area and ambush. • M1 Abrams: OPFOR was increased to 3 squads, or 6 total anti-tank teams. 8/22/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited
Modeling & Simulation, Combat Effectiveness Analysis: Methods Testing & Validation • For each shot fired by the OPFOR, the OneSAF model would determine if a vehicle was hit, which depended on factors such as: – Weapon/munition, shot distance, angle, vehicle speed, trajectory of munition, etc. • If the result indicated a hit, then the outcome would depend on additional factors such as: – Munition and target pairing, aspect angle, range, elevation, and dispersion. • The following outcomes were considered: i. No Kill (i.e. individual system is still combat effective) ii. Mobility Kill (loss of mobility) iii. Fire Kill (loss of weapons) iv. Mobility + Fire Kill v. Catastrophic Kill (All systems lost – Fire, Mobility, Communications, Sensors, etc.) • Metrics relevant to analyzing combat effectiveness were: – % of simulations where at least 3 vehicles remained combat effective (% CE) – Average number of hits sustained – Time in the kill zone – Average speed in the kill zone – Maximum speed in the kill zone 8/22/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited
Modeling & Simulation, Combat Effectiveness Analysis: Results Testing & Validation Mobility-Focused Analysis: • Hypothesis: Reduced weight improves mobility performance, which improves combat effectiveness. • OneSAF utilized a medium-fidelity physics-based mobility model. – In the OneSAF mobility model, vehicle weight contributes to: (i) acceleration, (ii) ground frictional force, and (iii) weight force due to terrain slope (U.S. Army Materiel Systems Analysis Activity, 2005). – Within the vignette, vehicles remained on road with minimal terrain slope change. Therefore, acceleration was more directly influenced by vehicle weight compared to the terrain type and terrain slope. • OneSAF acceleration was compared to the automotive study acceleration through the dash speed metric. – The 15% weight reduction had similar influence in both models. 8/22/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited
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