Browse Topic: Military vehicles and equipment
Future military missions for Agile Combat Employment (ACE) and next generation Special Operations Forces need an aircraft with effective hover and the ability to operate in transonic cruise. Hover requires significant power that can only be mitigated by larger diameter rotors, but large diameter rotors become a detriment to achieving transonic flight. The stop-fold rotor configuration can “make the rotor disappear” in cruise and stands out as the most viable option for meeting these next-generation air vehicle requirements. This paper discusses the progress Bell has made in developing enabling technologies for a practical and scalable high-speed VTOL (HSVTOL) based on the stop-fold configuration. To this end, a unique Track-Guided Test Vehicle (TGTV) was developed at Bell and tested at the 10-mile High Speed Test Track at Holloman Air Force Base. The test vehicle integrates all subsystems required to demonstrate the key technologies in a representative environment, including multi-mode propulsion, folding proprotors, and fly-by-wire transition controls to automatically manage each step of the prop-to-jet (and reverse) process. The TGTV demonstration validated the stop-fold technical approach and generated critical data to substantiate engineering models. Test results provide confidence that each step in the stop-fold transition process is thoroughly understood and that engineering tools can be used confidently for future aircraft design efforts. This paper documents the first known powered prop-to-jet and jet-to-prop transition and represents a significant milestone in vertical flight technology development.
A joint acoustic flight test was conducted by NASA Langley Research Center and the U.S. Army Combat Capabilities Development Command Aviation & Missile Center, with the goal of investigating new methods for acoustic data collection. The impetus for the effort is the anticipated growth of Urban Air Mobility and Future Vertical Lift vehicles. Many of these vehicles are expected to have distributed propulsion systems that may result in unsteady vehicle state conditions even during steady flight. This work examines the acoustic measurements collected during purposefully unsteady maneuvers performed by an MD530F helicopter. A snapshot microphone array design was deployed for this test to capture the acoustic signature on the ground from the helicopter under maneuver conditions. An analysis of the acoustic emissions indicated the presence of blade-vortex interactions, not only during the rolls towards the advancing side of the main rotor, but also rolls towards the retreating side and during pitch-up maneuvers. The strength of the interaction noise was found to be strongly dependent on the acceleration of the vehicle.
ABSTRACT Today’s combat vehicle designs are largely constrained by traditional manufacturing processes, such as machining, welding, casting, and forging. Recent advancements in 3D-Printing technology offer tremendous potential to provide economical, optimized components by eliminating fundamental process limitations. The ability to re-design suitable components for 3D-printing has potential to significantly reduce cost, weight, and lead-time in a variety of Defense & Aerospace applications. 3D-printing will not completely replace traditional processes, but instead represents a new tool in our toolbox - from both a design and a manufacturing standpoint.
ABSTRACT Imagine Soldiers reacting to an unpredictable, dynamic, stressful situation on the battlefield. How those Soldiers think about the information presented to them by the system or other Soldiers during this situation – and how well they translate that into thinking into effective behaviors – is critical to how well they perform. Importantly, those thought processes (i.e., cognition) interact with both external (e.g., the size of the enemy force, weather) and internal (e.g., ability to communicate, personality, fatigue level) factors. The complicated nature of these interactions can have dramatic and unexpected consequences, as is seen in the analysis of military and industrial disasters, such as the shooting down of Iran Air flight 655, or the partial core meltdown on Three Mile Island. In both cases, decision makers needed to interact with equipment and personnel in a stressful, dynamic, and uncertain environment. Similarly, the complex and dynamic nature of the contemporary operating environment faced by the United States Army makes it clear that mission performance depends on systems that are engineered to ensure that the complex systems of people and technology (i.e., sociotechnical systems) can sustain high levels of cognitive performance needed for succeed. This session overview highlights cognitive engineering and illustrates how modeling and simulation can address different aspects of this important field.
ABSTRACT The US Army is seeking improvements in the fuel efficiency of their military vehicles.. They have initiated a number of R&D projects aimed at advancing the state-of-the-art of powertrain efficiency including demonstration in a laboratory environment. This effort will set a benchmark for the vehicle integrators, allowing them to improve future vehicle offerings. The SAIC, AVL, Badenoch, QinetiQ and Ker-Train Research team offered powertrain solutions from 7 Tons to 40 Tons that achieved the goal of 44% thermal efficiency and the stringent flexible fuel and emissions requirements. In each of these offerings the team was able to identify modifications to existing engines that allowed dramatic improvements in the thermal efficiency. These efficiency improvements were achieved through a combination of techniques, combustion cycle adjustments using in-cylinder pressure monitoring and precise control of fuel injector timing, and turbo-compounding. For the R&D project, the fuel injector timing will be controlled using commercial engine development hardware and software. The high speed hardware emulates the engine control module but allows the developer to finely tune the fuel injection to maximize the 50% Maximum Fuel Burn point (MFB50) with only limited NOx production. This will be accomplished using a variety of fuels and maintaining the output power to within 2% of the engine’s nominal rating. This paper will describe the fundamental diesel combustion process that must be controlled and techniques for usable power extraction from the waste exhaust gases to provide this performance. It will describe the engine development tools that enable these controls changes to be realized within a vehicle development cycle and retain the baseline engine maturity.
Prior to 1950, use of the helicopter for evacuation was extremely limited, as military top brass often considered it a worthless contraption; thus, rescue was uncertain at best for downed pilots and wounded soldiers stranded behind enemy lines. However, this all changed in Korea, where twelve U.S. Army helicopters from three detachments, working in tandem with seven, newly created Mobile Army Surgical Hospital (MASH) units, would fundamentally change the Army's medical-evacuation doctrine forever. Using several models of the Bell H-13, the Hiller H-23, and the Sikorsky H-5 and H-19, this small band of courageous pilots pushed themselves and their aircraft to their limits, transporting 21,212 critically wounded soldiers for life-saving surgery to various MASH units, cutting the fatality rate from World War II in half. Adopting the 3rd Air Rescue Squadron's motto, "That Others May Live," these pilots and their helicopters were affectionately known to the wounded as "Angels of Mercy."
U.S. Army Combat Capability Development Command Aviation and Missile Center (DEVCOM AvMC) and Georgia Tech Research Institute (GTRI) developed the Mission Systems Flying Testbed (MSFTB) to enable rapid evaluation of innovative technologies and integration approaches against Modular Open System Approach (MOSA) objectives. The MSFTB is a flight test capability to evaluate and demonstrate integration of mission systems to inform Army stakeholders on satisfaction of Modular Open System goals for the Army Aviation enterprise, Future Vertical Lift family of systems, and enduring aviation platforms.
Heavy class attack helicopter development program aims to develop a new generation assault helicopter with high weapon capacity and modern combat technologies. Design requirements lead to a complicated aerodynamic shape. Wind tunnel tests gain importance for validation of aerodynamic design decisions and methodologies. A short test campaign is planned in a high Reynolds number environment which is achieved through pressurization. Generation of aerodynamic characteristics, effect of under-wing stores, effectivity of tail surfaces and main rotor hub interactions construct the base of test plan. Tests are conducted under varying pressure and airspeed combinations starting from 1.1 Bar 100 m/s to 3 Bar 85 m/s. Test results are compared with CFD simulations as a part of validation studies. Reynolds Averaged Navier-Stokes Simulations provide satisfactory results. Improved results are obtained with high fidelity turbulence model, wall modeled very large eddy simulations.
Corrosion occurs in diverse environments mainly on metallic parts. Helicopters are made of a huge percentage of metallic parts and need to have several maintenance steps to guarantee its functioning and its durability. The military helicopters are flying in different kinds of environment, which cover large spectrum of severity of the atmospheric corrosion [1]. In maritime conditions, the most influencing factor is the Time of Wetness, which is a direct result Relative Humidity and Salt loading. The main material used for aircraft and that is suffering from corrosion is aluminium. There are plenty of data to follow the corrosion as a function of the environmental conditions, mainly on the sensitivity with sodium chloride, Relative Humidity, film thickness, etc... [2][3]. The maintenance efficiency on helicopters is dependent on the environmental severity. The U.S. armed forces estimate $10.2 billion in corrosion costs for their aviation and missile fleets during 2016 [4] [5] [6]. The aim of the present analysis consists of defining the Condition Based Maintenance related to corrosion risk to better apply a maintenance program when it is really needed.
The use of additive manufacturing to produce rotorcraft components is challenging due to demanding material property performance requirements. The need to contend with high cycle fatigue, fretting, and vibratory loading conditions has driven our industry to use high pedigree materials that are fully characterized and with well established and understood processes to transform them into parts. No additive manufacturing processes or materials approach this level of understanding today, making it difficult to utilize the technology to manufacture components designed to be produced using conventional methods. This has limited consideration of the technology in the sustainment segment of our business. Customers have a quite different perspective. Additive manufacturing has been identified by the Department of Defense as a critical technology for the sustainment of their vehicles and weapons systems. Each branch of the military and the Defense Logistics Agency has resources and facilities established to support the proliferation of 3D printing capability. They have all experienced success producing shop aides, tools, prototypes, and surrogate parts to address real time, point of use challenges in depots and in some cases, at or near the battlefield. This success has prompted the DoD to challenge our industry to find ways to utilize this technology to address component shortages due to obsolescence, lost tooling, or a lack of qualified sources. This paper presents Sikorsky's activities and programs that have been initiated to meet this challenge. This will include approaches for component characterization and business case analysis used to evaluate the practicality of using additively manufactured surrogate parts in legacy vehicles.
The current US DoD has recognized that their asymmetric advantage is eroding1. Adversaries have had over 25 years to counter the US playbook and weapon systems (Ref. [1]). The US Army Future Vertical Lift (FVL) programs have identified several key tenets that their airborne weapon systems need to ensure they maintain asymmetric advantage. (1) New and upgraded mission capabilities of their airborne platforms need to get to the field faster (Ref. [2]). One of the current roadblocks to achieving this is the extensive full-system regression testing that ends up being required when there are mission system changes (Ref. [3]). (2) More competition is needed to help generate "quicker, better, faster" capabilities (Ref. [4]). "Vendor lock" inherent in current system designs hinders the speed at which technology advances (Ref. [4, 5]). (3) Improved portability of mission capability across the FVL and enduring fleet (Ref. [6, 7]). The ability to more easily reuse technology will help maintain advantage by eliminating the time needed to develop platform specific solutions (Ref. [4, 6]). The request for Modular Open System Architecture (MOSA) solutions has been a practice to try to address the items above (Ref. [8]). Most air vehicle and mission system providers are today providing MOSA solutions but the required benefits have not yet been fully realized. MOSA standards as they exist today do a very good job of identifying electronics hardware and software architectures. However, they fall short on physical aircraft integration and consistency in architecture among aircraft systems. Minimizing aircraft wiring and structural modifications, increasing speed to fielding, and portability among multiple systems types are all part of integrating highly MOSA compliant solutions. The US Army FVL programs have required a "digital backbone" (Ref. [7, 9, 10]) to address these integration issues and ensure that they can maintain asymmetric advantage. Unique requirements affecting the digital backbone include: - Power and power distribution (Ref. [9]) - Thermal management (Ref. [9, 11]) - Packaging and installation (Ref. [9]) - Air Vehicle data distribution (Ref. [9]) - Mission System data distribution (Ref. [9]) - Isolation of air vehicle and mission system (Ref. [9]) This paper will provide an introduction to the envisioned digital backbone for US Army, Future Vertical Lift aircraft. The paper will also offer discussion of digital backbone impacts on aircraft and avionics size, weight, power and cost, as well as technology considerations to address interoperability, safety, security, qualification, and accommodations for new, as well as, legacy avionics technology.
The U.S. Army monitors the structural integrity of its rotary-wing aircraft fleet through annual evaluations and reporting via the Airframe Condition Evaluation (ACE) program. ACE evaluations capture the location and character of structural defects for each aircraft, which are then available for trending and detailed analysis by engineers with the U.S. Army Combat Capabilities Development Command Aviation & Missile Center (CCDC AvMC). As analytic methods are increasingly advanced through the digital thread, CCDC AvMC has sought to improve available trending, modeling, and analysis tools beyond status quo to provide higher fidelity visuals to both aid communication with decision makers, and also to reveal structural defect trends which may not otherwise be evident. This paper will detail the development and utility of the ACE Color Mapping Application within the ACE Mapping Module and its impact on product support of U.S. Army aircraft with regard to airframe structural integrity.
The demonstration and testing of tactile cueing is the subject of a common research undertaking by the U.S. Army Combat Capabilities Development Command Aviation & Missile Center (CCDC AvMC) and the German Aerospace Center (DLR). The primary objective was to test a torque protection system with both a stick shaking cue generated with an attachable stick shaker and a soft stop cue generated by an active inceptor system. It was tested by five pilots in flight on the RASCAL JUH-60A helicopter and by four pilots in the ground-based simulator of the ACT/FHS (H-135) research helicopter based on a common set of high performance takeoff mission profiles. The qualitative evaluation showed that the soft stop provided a greater workload reduction than the shaker and was the preferred cue. However, a shaker cue is a promising alternative when the application of an active inceptor system is not possible.
The Army's Future Attack Reconnaissance Aircraft (FARA) program is much bigger than the two ambitious high speed helicopters that Bell and Sikorsky will now get more than $1 billion to build. At least five other major moving pieces must come together on time to turn the final aircraft, whoever makes it, into a working weapon: - a new Improved Turbine Engine built by GE; - helicopter-launched mini-drones called Air Launched Effects (ALE); - a new Long-Range Precision Munition (LRPM), with the Israeli Spike-NLOS as the initial version; - an Integrated Missile Launcher (IML) to launch both the missile and the drones; - and the underlying electronic framework of standards and interfaces to plug it all together, the Modular Open Systems Architecture (MOSA). *Recently, FARA has added a 20mm Gatling Gun being developed by The Advanced Rotorcraft Armament and Protection System (ARAPS) program team at the U.S. Army Combat Capabilities Development Center (CCDC) Armaments Center The Army is "not just focused on the air vehicle, but focused on the weapon system," said Brig. Gen. Walter Rugen, Future Vertical Lift director at Army Futures Command, in a call this morning with reporters. [1] While some have questioned the viability of fielding the FARA in ten years, e.g. by 2028, others have offered reasons on why the plan for a next-gen recon aircraft needs to be accelerated. Who knows how much money will be available to the Army for sustaining its aviation fleet as budget walls close in over the next several years? Trilliondollar deficits have a way of impinging on defense budgets. What is proposed, though, is that the Army compress its development schedule for a new armed recon rotorcraft so that our soldiers begin to be better equipped against the likes of Russia and China somewhere around 2025, rather than after 2030. A whole lot can happen in ten years. We don't need another Army development program to be overtaken by events. (2) However, since the FARA will likely be in service for a half-century or more, it makes sense to conduct rigorous analysis up front to ensure that what is fielded has the capabilities to provide the most value for the warfighter and the taxpayer. Prior to spending billions of dollars and decades producing the FARA aircraft, it is prudent to spend the time to determine what the right solutions should be. Many projects fail when the initial requirements are not well thought out and the ramifications are not clearly understood. To solve the tension between these conflicting desires, designers need to iterate the design sensitivities with operational analysis to show the pros and cons of each attribute, alone and in concert, but ultimately the Army must prioritize its requirements and potentially make hard trade-off decisions.(3) The major objective of this paper is provide a methodology for the necessary understanding of the push and pull of technology readiness and application through trade studies and operational analysis early to avoid disappointments and to minimize FARA slippages and cost increases. This will be accomplished by reviewing Lessons Learned from the AHIP/OH-58D Kiowa Warrior and the LHX/RAH-66 Comanche development programs. While the authors were directly involved in these programs as Army Aviation engineers, managers and senior executives, the major emphasis for this paper will be to address how the government-industry teams brought these programs successfully through initial development. Fortunately, for the AHIP/OH-58D Kiowa Warrior Development Program there are excellent documentation of the government-industry team participation in References 4 and 5. While the authors strongly endorse the lessons learned in these documents, they will have a few of their own. For the LHX/RAH66 Comanche Development Program there is considerably less documentation; however, the authors will provide Army and their lessons learned. It is hoped that this paper and the referenced documents will be read, and the lessons learned by both government and industry involved in the FARA development program.
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