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Technical Paper

Standard Approach to Identifying and Defining Functions for Systems Development and Safety Assessments

2022-03-08
2022-01-0008
The Safety Assessment Process, defined by SAE ARP 4761, associated regulatory guidance, and the system development process defined by SAE ARP 4754 are built on an understanding of the functions performed by a system or systems. These recommended practices do not provide, or reference, specific guidance regarding function definition, though they do provide some conventional airplane examples. The function is central to the entire development effort, and it is essential that the functions be identified and described such that the development and safety assessment processes can be applied consistently throughout the development program, and beyond. Without a systematic process for establishing and describing functions, the application of the development and safety assessment processes can be complicated by overly inclusive functions and functions applied at the wrong level of abstraction.
Technical Paper

Sensor Printing Enhanced Composites for Intelligent Aerodynamics and Lifecycle monitoring

2022-03-08
2022-01-0006
This paper aims to the development of nanotechnology-based applications for new intelligent aircraft and for increasing the intelligence of actual ones. It is intended to answer the above needs by a new smart aircraft concept, which take advantage of distributed nanotech sensors on structural and aerodynamic components. The distributed sensing system acquires the largest possible amount of data about aerodynamics and structural behaviour with a null impact on aircraft. Two different and complementary applications that make use of the same components are expected: On new aircraft, it is possible to use two different families of sensors: superficial printed pressure sensors and painted strain and displacement sensors on external surfaces and embedded strain sensors in structural composite elements. On existing aircraft, it is possible to use only printed sensors: superficial printed pressure strain and displacement sensors on external surfaces and critical structural components.
Technical Paper

Thermodynamic design of a dual envelope airships for safer use of hydrogen as buoyant gas

2022-03-08
2022-01-0005
One of the main problems toward the take-off of future high altitude airship projects is helium which is both a fossil resource and presents evident scarcity limits at the global level. On the other side, it is well-known that airships are the most energetically efficient flying vehicles. This paper approaches the problem of optimizing the design of a low-cost innovative high-altitude blimp for rapid emergency deployment according to both the first and the second law of thermodynamics. After the general energy balance involving both the propulsion related energy needs and thermal equilibrium of the blimp, an effective irreversibility-based design is performed. the photovoltaic energy production and the propulsive systems are dimensioned to be placed on the top of the cabin. A discussion of suitable materials for the balloon is approached. Permeability phenomena are accounted for and discussed widely.
Technical Paper

Custom Bench Top Testing as a supplement for Reverse Engineering for MIL-Aero systems

2022-03-08
2022-01-0001
Military and Aerospace systems electronics operate with extended lifetimes beyond normal commercial system. It’s not uncommon for printed circuit board manufacturers to go out of business or the integrated circuit manufacturer to discontinue their line of parts. This creates an obsolescence issue for the sustainment of the system. One solution of obsolescence is for an organization to reverse engineer the hardware and then replicate the design. Traditional methods involve continuity checking of the original board in order to create a netlist, schematic, and then Gerber files used to manufacture the board. However, electrical testing is required in order to verify results. This paper explores benefits of leveraging custom bench top testing in conjunction with the reverse engineering processes, to not only verify the results of the continuity checking, but to enhance efficiency and reduce the time to completion of a sustainment effort.
Technical Paper

Removing Stigma from Fiber Optics

2022-03-08
2022-01-0020
While weight savings along with high data transmission rates puts fiber optics in an obvious advantage over conventional copper cables, there is still some stigma in today’s aerospace and ground systems industry. In most cases, this hesitation has been justified by designers and installers fear of damaging “fragile” fiber optic cables, changing of transmission systems, and the cost, time and training associated with repairing downed fiber lines in the field. While all of these reasons are valid and there is still some areas where fiber optics might fall short of the familiar copper cable systems, there are several user-friendly methods and tools available today that can easily mitigate and prevent these occurrences while providing the system designers and users all of the rewards of fiber optics.
Technical Paper

An On-line path correction method based on 2D laser profile measurement for Gluing Robot

2022-03-08
2022-01-0016
Gluing is an essential fastening step in the field of aircraft assembly except for riveting and bolting. Generally, the robotic programs of gluing are generated in CAM environment. Due to the positioning errors and deformation of the workpiece to be glued in the fixture, the nominal pose and the actual pose of the workpiece are no longer consistent with each other. The Robot trajectory of dispensing glue are adjusted manually according to the actual pose of the workpiece by robot teaching. In this paper, an on-line gluing path correction method is developed by 2D laser profile measurement. A pose calibration method for 2D laser profiler integrated into a gluing robot by measuring a fixed center point of a standard ball is proposed to identify the position and orientation of the laser sensor, which enables the accurate transforming coordinates between the robot frame and the sensor frame. Meanwhile, the pose of the gluing tool mounted on the end of the robot is calibrated.
Technical Paper

Intuitive Robot Programming and Path Planning based on Human-Machine Interaction and Sensory Data for Realization of various Aircraft Application Scenarios

2022-03-08
2022-01-0011
Human-machine interaction (HMI) technologies enable the automation of various manufacturing and assembly applications while maintaining high flexibility. In this context, human-robot collaboration (HRC) capable robots should no longer function as autonomous systems, but much more as assistance systems or as colleagues for workers. In connection with shorter product life cycles, increasing variant diversity and individualization, the challenge arises to set up flexible robot systems, which can be reprogrammed and commissioned with little effort in a short period of time with preservation of the required accuracies. Therefore intelligent path planning is essential for development of flexible robot systems. In this paper different approaches are presented that allow the worker on the shop floor to rapidly and easily program a robot to implement new motion tasks based on a camera system without programming knowledge. Thereby various points are selected manually on an image.
Technical Paper

Investigation of an Automated Potting Process for High Volume Insert Assembly in Honeycomb Structures

2022-03-08
2022-01-0010
Threaded, potted inserts are commonly used as a standard connecting element for sandwich components, which are used for aircraft interior. Since they often offer the only detachable connection, they are used in very high quantities. To ensure a material bond between the inserts and the honeycomb structure, the joint is filled with adhesive. Despite the high number of inserts, this process is performed manually. Recent research has shown approaches for automated gripping and placement of the inserts by an industrial robot and yields high potential for cost savings and increased productivity. The automated adhesive insertion, so called potting, has not been considered so far, but is an essential contribution to the full automation of the entire process chain. The amount of adhesive varies depending on the type of insert and its position on the honeycomb structure.
Technical Paper

Drag and Power Impacts of Heat Removal in High-Speed Rotorcraft – Trending and Optimization

2022-03-08
2022-01-0056
Current trends in the rotorcraft market favor aircraft with more power consuming avionic and mission equipment, smaller, more efficient propulsion systems, and higher flight speeds. The power consumers are putting a greater tax on electrical systems, but also pushing already stressed thermal management systems. The first goal of this brief study aims calculate and identify major trending of drag and power consumption imposed by equipment cooling on high-speed rotorcraft. Major contributors to these quantities include total heat load, equipment qualification temperature, flow passage sizing and inlet/exhaust orientation to free stream. During preliminary aircraft design, these factors are sometimes disregarded or deprioritized, as they may impose weight increases, design challenges, and schedule issues.
Technical Paper

Design Optimization of Modular Permanent Magnet Machine with Triple Three-Phase for Aircraft Starter Generator

2022-03-08
2022-01-0055
With continuous development in high power density and high efficiency electrical drives, permanent magnet (PM) electrical machine has far-reaching impacts in aviation electrification. The primary barrier to acceptance of permanent magnet machines for safety-critical starter-generator systems is its low fault-tolerance and low reliability (for the conventional designs). Multiple three-phase PM machines exhibit a high fault tolerance because the fault point could be isolated while the remaining healthy parts maintain the operation continuously. This article investigates a modular triple three-phase PM starter-generator comprehensively, including the tradeoff of fault-tolerant topology, optimization design process, analysis of electromagnetic (highlight the post-fault analysis) and thermal behavior, respectively. The triple three-phase segmented topology proposed meet the fault-tolerant requirement along with complete electrical, magnetic, and thermal isolation.
Technical Paper

Dynamics of the Ammonia Spray Using High-Speed Schlieren

2022-03-08
2022-01-0053
Ammonia (NH3), as a carbon-free fuel, has a higher optimization potential to power internal combustion engines (ICEs) compared to hydrogen due to its relatively high energy density (7.1MJ/L), with an established transportation network and high flexibility. However, the NH3 is still far underdeveloped as fuel for ICE application because of its completely different chemical and physical properties compared with hydrocarbon fuels. Among all uncertainties, the dynamics of the NH3 spray at engine conditions is one of the most important factors that should be clarified for optimizing the fuel-air mixing. To characterize the evolution and evaporation process of NH3 spray, a high-speed Z-type schlieren imaging technique is employed to estimate the spray characteristics under different injection pressure and air densities in a constant volume chamber.
Technical Paper

Visualization Techniques for Simulation-Based Dependent Failure Analysis

2022-03-08
2022-01-0032
Failure analysis of engineering systems typically emphasises identification and mitigation under an independent failure assumption with dependent failures treated as the exception rather than the rule. Some frameworks for addressing dependent failures through analysis appear in standards including NUREG 0492, ISO 26262, MIL 1629 A, and ARP4761 amongst others. The purpose of identifying these dependencies is to allow system analysts to determine and quantify the factors that influence dependent fault probabilities. Once defined, failure relationships can be incorporated into a Discrete Event Simulation (DES) of the system, providing a mathematically rigorous estimate of system utility (e.g., availability, reliability). Nonetheless, the output of a simulation must not only provide an expected value of performance but also allow the analyst to identify the downstream impact of probabilistic dependencies between system elements.
Technical Paper

Integration of Big Data and Deep Learning for Weapon Combat Effectiveness

2022-03-08
2022-01-0030
This research paper deals with the importance of Weapon Combat Effectiveness (WCE) analytics and the difficulty in measuring this value in tandem with the added complexity of combat environments. This lack of acknowledgment has resulted in utilizing a limited number of scenarios and limiting other factors such as weapon system configurations. Our group has suggested that collecting big data through a federated Live-Virtual-Constructive (LVC) simulation architecture can provide a good assessment. Specifically, the goal is to intersect the areas of weapon combat effectiveness (WCE), defense modeling and simulation (DM&S), and defense with big data (DBD). This intersection will lead to new WCE analytics. However, our hypothesis goes beyond that: It is essential to use the advantages of deep learning to analyze noise, extrapolation, the vast depth of data, and the nonlinearities of data to enhance the analysis of VC simulations.
Technical Paper

Practical Implementation and Associated Challenges of Integrated Torque Limiter

2022-03-08
2022-01-0038
Evolving of aircraft design towards further electrification requires safe and fault-free operation of all the components. More electric aircraft are increasingly utilizing electro-mechanical actuators (EMA). EMAs are prone to jamming and subsequent failure due to large forces on the shaft. Large forces are generated due to the high reflected inertia of the electric machine rotor. To limit the force acting on the shaft, a torque limiting device is connected to the power train which can separate the rotating mass of the electric machine from the power train. In this paper, a concept of integration of torque limiter and the electric machine rotor is presented to reduce overall volume and mass. It is connected closely with the rotor, within the motor envelope. A commercially available torque limiter and an electric machine designed for actuator application are used to demonstrate the concept. While essential for safety, the torque limiter adds to the mass and size of the overall EMA.
Technical Paper

Information Retrieval for Aviation Applications

2022-03-08
2022-01-0044
There is a recurring need for automatic Information Retrieval (IR) from quality documents, price tags, part markings, receipts, purchase orders and technical manuals - which are otherwise non-parsable. IR coupled with search functionalities has a wide range of applications from warehouses, shop floors, marketplaces to even cockpits in the aviation sector. It helps in semi-automating workflows like document reviews, quality checks, collaborative Q&As and contextual extraction of information. These workflows make laborious tasks more intuitive and easier, thereby reducing the workload of the engineers using them. The paper describes an AI based IR platform which caters to the aforesaid scenarios in a scalable manner and integrates seamlessly with similar problems across different domains.
Technical Paper

Super Flush Torque Controlled Screw

2022-03-08
2022-01-0017
Aerodynamic and cosmetic requirements are more and more stringent on new aircraft programs. External aircraft surfaces should ideally be free of any discontinuities and fasteners are usually local points of concern. While pins or lockbolts generally exhibit flush and smooth head surfaces, screws have inherent driving recesses which remain visible after finish paint application. Such screws are typically used in combination with anchor nuts to attach the panels closing thin wing boxes. The AeroDrive™ screw is a global solution to avoid recesses while improving mechanical characteristics of such structural joints. The AeroDrive™ screw features an additional drive head designed to break at a defined torque during installation, leaving a flush and smooth head surface.
Technical Paper

Accuracy Analysis for a Flow Line Process using a Mobile Holding Fixture for Machining CRFP Components

2022-03-08
2022-01-0041
The aerospace sector is challenged to produce airplanes more efficiently and resiliently in the future. This leads to an increasing demand for improving productivity and flexibility as well as providing solutions for sustainable developments. A bottleneck in production is the machining of large-scale components. Apart from the machining tasks, non-productive tasks like fixture adjustment, component handling, referencing and localization are performed within the machining station and can constitute up to 50% of the overall workload. In the UniFix project, Fraunhofer IFAM is participating in the development of a mobile fixture system for large-scale aircraft components, like vertical tail plane and landing flap components of the single aisle aircrafts.
Technical Paper

Towards an intelligent digital cabin twin to support an aircraft’s retrofit and base maintenance

2022-03-08
2022-01-0046
Aircraft are high value-adding and long-living assets, while aircraft cabins are expensive consumer products tailored to each customer. Vastly changing requirements and needs force aircraft holders regularly to instruct modifications to remain attractive on the market. Adaptations, modifications, and development of innovations are handled by multiple organizations, not by a central organization like the aircraft’s manufacturer or owner. Although the Continuing Airworthiness Management Organization manages all aircraft instance-specific documents as required by aviation regulations, their format and types of management differ. Besides, not all information that arises during a parts design phase is included. That means, overall, the consistent model-based maintenance of data within all phases of PLM up to disposal is not guaranteed.
Technical Paper

Skinny Fixture for Use with A Gantry Riveting Machine

2022-03-08
2022-01-0015
Electroimpact provides a solution of a gantry riveting machine which works in cooperation with a wing panel fixture. The fixture features stringer clamps along the length but also needs to reconfigure so that fasteners can be accessed by the heads of the machine. In a recent development we have made the header boards of the fixture both narrow in width and shallow in depth. This has a large operational advantage. Almost all of the fasteners can be installed without disturbing the tooling. And the motions of the tooling are considerably reduced. This was a cooperative effort of the tooling designers and the machine designers, primarily on the stringer side of the panel. How much of a time savings does this provide in comparison with the previous approach? About 20%. This paper will explain how this was done. We have already implemented this solution on ten systems and more are in progress on major aircraft programs.
Technical Paper

Automatic segmentation of aircraft dents in point clouds

2022-03-08
2022-01-0022
Dents on the aircraft skin are frequent and may easily go undetected during airworthiness checks, as their inspection process is tedious and extremely subject to human factors and environmental conditions. Nowadays, 3D scanning technologies are being proposed for more reliable, human-independent measurements, yet the process of inspection and reporting remains laborious and time consuming because data acquisition and validation are still carried out by the engineer. For full automation of dent inspection, the acquired point cloud data must be analysed via a reliable segmentation algorithm, releasing humans from the search and evaluation of damage. This paper reports on two developments towards automated dent detention. The first is a method to generate a synthetic dataset of dented surfaces to train a fully convolutional neural network. Training machine learning algorithms need a substantial volume of dent data, which is not readily available.
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