Small unmanned aircraft and electric vertical takeoff and landing (eVTOL) aircraft have recently emerged as vehicles able to perform new missions and stimulate future air transportation methods. This dissertation presents several system identification research advancements for these modern aircraft configurations enabling accurate mathematical model development for flight dynamics simulations based on wind-tunnel and flight-test data. The first part of the dissertation focuses on advances in flight-test system identification methods using small, fixed-wing, remotely-piloted, electric, propeller-driven aircraft. A generalized approach for flight dynamics model development for small fixed-wing aircraft from flight data is described and is followed by presentation of novel flight-test system identification applications, including: aero-propulsive model development for propeller aircraft and nonlinear dynamic model identification without mass properties. The second part of the dissertation builds on established fixed-wing and rotary-wing aircraft system identification methods to develop modeling strategies for transitioning, distributed propulsion, eVTOL aircraft. Novel wind-tunnel experiment designs and aero-propulsive modeling approaches are developed using a subscale, tandem tilt-wing, eVTOL aircraft, leveraging design of experiments and response surface methodology techniques. Additionally, a method applying orthogonal phase-optimized multisine input excitations to aircraft control effectors in wind-tunnel testing is developed to improve test efficiency and identified model utility. Finally, the culmination of this dissertation is synthesis of the techniques described throughout the document to form a flight-test system identification approach for eVTOL aircraft that is demonstrated using a high-fidelity flight dynamics simulation. The research findings highlighted throughout the dissertation constitute substantial progress in efficient empirical aircraft modeling strategies that are applicable to many current and future aeronautical vehicles enabling accurate flight simulation development, which can subsequently be used to foster advancement in many other pertinent technology areas. / Doctor of Philosophy / Small, electric-powered airplanes flown without an onboard pilot, as well as novel electric aircraft configurations with many propellers that operate at a wide range of speeds, referred to as electric vertical takeoff and landing (eVTOL) aircraft, have recently emerged as aeronautical vehicles able to perform new tasks for future airborne transportation methods. This dissertation presents several mathematical modeling research advancements for these modern aircraft that foster accurate description and prediction of their motion in flight. The mathematical models are developed from data collected in wind-tunnel tests that force air over a vehicle to simulate the aerodynamic forces in flight, as well as from data collected while flying the aircraft. The first part of the dissertation focuses on advances in mathematical modeling approaches using flight data collected from small traditional airplane configurations that are controlled by a pilot operating the vehicle from the ground. A generalized approach for mathematical model development for small airplanes from flight data is described and is followed by presentation of novel modeling applications, including: characterization of the coupled airframe and propulsion aerodynamics and model development when vehicle mass properties are not known. The second part of the dissertation builds on established airplane, helicopter, and multirotor mathematical modeling methods to develop strategies for characterization of the flight motion of eVTOL aircraft. Innovative data collection and modeling approaches using wind-tunnel testing are developed and applied to a subscale eVTOL aircraft with two tilting wings. Statistically rigorous experimentation strategies are employed to allow the effects of many individual controls and their interactions to be simultaneously distinguished while also allowing expeditious test execution and enhancement of the mathematical model prediction capability. Finally, techniques highlighted throughout the dissertation are combined to form a mathematical modeling approach for eVTOL aircraft using flight data, which is demonstrated using a realistic flight simulation. The research findings described throughout the dissertation constitute substantial progress in efficient aircraft modeling strategies that are applicable to many current and future vehicles enabling accurate flight simulator development, which can subsequently be used for many research applications.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The CENTS Program is a Central Test and Evaluation Investment Program (CTEIP) effort conducted by the 46th Test Wing at Eglin Air Force Base, Florida. This project uses advanced internetworking technology to collect data unobtrusively from multiple Line Replaceable Units (LRU's) within an aircraft without the expense of running new wiring. The data is transported to a master network controller using the existing aircraft powerlines at a raw data rate of over 10 Mbits/s. Sensors are integrated into the shells of the LRU's data bus connectors to minimize the number of aircraft modifications required for a test. CENTS began in January 2000 as an OSD CTEIP Sponsored Test Technology Development and Demonstration (TTD&D) project and is currently in Phase 2 of the effort. Phase 1 saw the successful demonstration of the use of MIL-STD-704 power busses to establish a virtual network for data transport. This paper reviews the current status and past achievements of the CENTS TTD&D program as well as describing some immediate potential pay- offs for the Test and Evaluation community in the near-term.

International Telemetering Conference Proceedings / October 26-29, 1992 / Town and Country Hotel and Convention Center, San Diego, California / MIL-STD-1553 multiplex data buses are commonly used to link complex software-controlled systems in modern aircraft. The software in these aircraft is routinely updated; each update requires flight testing. Also, sophisticated weapons and electronic warfare systems which are integrated into operationally-ready aircraft must be routinely evaluated. The simplest way to perform the required evaluation is to record all the data from the multiplex data buses during an operational flight; these data can then be replayed and examined after the flight. Traditionally, some operational systems had to be disabled or removed from an aircraft to allow installation of a data acquisition system. This paper discusses a MILSTD- 1553 multiplex bus Record-All Small Data Acquisition System (RASDAS) installed in a McDonnell Douglas CF-188 fighter aircraft to record all data from two 1553 multiplex data buses without displacing any operational equipment. The specific requirements and constraints associated with evaluating the integrated systems of a CF-188 aircraft are examined; further, RASDAS implementation in this aircraft type is discussed from planning to flight evaluation.

This thesis presents the calibration processes of the pitot-static system, which is a part of the air data system of a military transport aircraft through flight tests. Tower fly-by method is used for air data system calibration. Altitude error caused by the position of the static port on the aircraft is determined by analyzing the data collected during four sorties with different weight, flap and landing gear configurations. The same data has been used to determine the airspeed measurement error. It has been shown that both the altitude and airspeed errors are within the allowable limits specified by FAR 25. Same method is also used for trailing cone calibration that is used for high altitude test flights for RVSM certification.

Model Reference Adaptive Control (MRAC) is a widely studied adaptive control methodology that aims to ensure that a nonlinear plant with significant modeling uncertainty behaves like a chosen reference model. MRAC methods attempt to achieve this by representing the modeling uncertainty as a weighted combination of known nonlinear functions, and using a weight update law that ensures weights take on values such that the effect of the uncertainty is mitigated. If the adaptive weights do arrive at an ideal value that best represent the uncertainty, significant performance and robustness gains can be realized. However, most MRAC adaptive laws use only instantaneous data for adaptation and can only guarantee that the weights arrive at these ideal values if and only if the plant states are Persistently Exciting (PE). The condition on PE reference input is restrictive and often infeasible to implement or monitor online. Consequently, parameter convergence cannot be guaranteed in practice for many adaptive control applications. Hence it is often observed that traditional adaptive controllers do not exhibit long-term-learning and global uncertainty parametrization. That is, they exhibit little performance gain even when the system tracks a repeated command. This thesis presents a novel approach to adaptive control that relies on using current and recorded data concurrently for adaptation. The thesis shows that for a concurrent learning adaptive controller, a verifiable condition on the linear independence of the recorded data is sufficient to guarantee that weights arrive at their ideal values even when the system states are not PE. The thesis also shows that the same condition can guarantee exponential tracking error and weight error convergence to zero, thereby allowing the adaptive controller to recover the desired transient response and robustness properties of the chosen reference models and to exhibit long-term-learning. This condition is found to be less restrictive and easier to verify online than the condition on persistently exciting exogenous input required by traditional adaptive laws that use only instantaneous data for adaptation. The concept is explored for several adaptive control architectures, including neuro-adaptive flight control, where a neural network is used as the adaptive element. The performance gains are justified theoretically using Lyapunov based arguments, and demonstrated experimentally through flight-testing on Unmanned Aerial Systems.

The development of Information Management Strategy is essential for a given organization. For such business the big challenge is to provide adequate information management to improve its efficiency. Flight test business encompasses the execution of experimental test flight on manned aircraft. For such activity information management is vital for risk assessment. A single test flight could produce a large amount of data, therefore the Management Information System (SIG) becomes complex. A SIG model to be used for flight test business is proposed by this dissertation. The adopted model is proposed to provide an efficient information management for the Experimental Flight Test Campaign Executive Process (PECEV). The research process employs an exploratory case study methodology. Such study was executed into a Science and Technology Institution (ICT) that provides experimental flight test services for aerospace research and development. Such institution belongs to an industrial technology cluster located in the metropolitan region of Vale do Paraiba e Litoral Norte in São Paulo, Brazil. The analysis of the current process used to provide flight test services by such institution, employed a documental analysis with qualitative approach. The proposed SIG model was based on the Plan, Do, Check and Act (PDCA) method. Action items were included for process improvement. Based on the proposed model it is expected that this ICT could implement this SIG to allow effective management of PECEV. / O desenvolvimento de uma estratégia de gestão de informações é imprescindível em uma organização. Torna-se um desafio para a organização gerir os recursos de dados, de forma a manter a eficiência de seus serviços. A atividade de ensaios em voo envolve a execução de voos de ensaios em aeronaves tripuladas. A gestão de informações é considerada vital para minimizar os fatores de riscos dessa atividade. Devido ao grande volume de dados proveniente de um único voo de ensaio, os Sistemas de Informações Gerenciais (SIGs) para essa atividade são complexos. Nesta dissertação, é apresentada a proposta de um modelo de SIG para ensaios em voo. O modelo se propõe a apresentar um plano para a gestão das informações do Processo de Execução de Campanhas de Ensaios em Voo (PECEV). A pesquisa apresentada é um estudo de caso, com delineamento exploratório. Foi desenvolvida em uma Instituição de Ciência e Tecnologia (ICT) de pesquisa do setor aeroespacial, que realiza atividades de ensaios em voo. Essa instituição é integrante do parque tecnológico e industrial localizado na Região Metropolitana do Vale do Paraíba e Litoral Norte. Foi elaborada uma análise documental, por meio de uma abordagem qualitativa, para a análise do atual processo de ensaios em voo da ICT. O modelo proposto do SIG foi obtido seguindo o modelo preconizado pelo Procedimento de Gestão para Melhoria de Processos (PDCA). Foram propostas ações para aprimorar o atual processo. A partir do modelo proposto, pressupõe-se que, posteriormente, seja implantado na ICT um SIG que possibilite a gestão eficaz do PECEV.

Two flash lidars, integrated from a number of cutting-edge components from industry and NASA, are lab characterized and flight tested under the Autonomous Landing and Hazard Avoidance (ALHAT) project (in its fourth development and field test cycle) which is seeking to develop a guidance, navigation, and control (GNC) and sensing system based on lidar technology capable of enabling safe, precise human-crewed or robotic landings in challenging terrain on planetary bodies under any ambient lighting conditions. The flash lidars incorporate pioneering 3-D imaging cameras based on Indium-Gallium-Arsenide Avalanche Photo Diode (InGaAs APD) and novel micro-electronic technology for a 128 x 128 pixel array operating at 30 Hz, high pulse-energy 1.06 ?m Nd:YAG lasers, and high performance transmitter and receiver fixed and zoom optics. The two flash lidars are characterized on the NASA-Langley Research Center (LaRC) Sensor Test Range, integrated with other portions of the ALHAT GNC system from around the country into an instrument pod at NASA-JPL, integrated onto an Erickson Aircrane Helicopter at NASA-Dryden, and flight tested at the Edwards AFB Rogers dry lakebed over a field of human-made geometric hazards. Results show that the maximum operational range goal of 1000m is met and exceeded up to a value of 1200m, that the range precision goal of 8 cm is marginally met, and that the transmitter zoom optics divergence needs to be extended another eight degrees to meet the zoom goal 6° to 24°. Several hazards are imaged at medium ranges to provide three-dimensional Digital Elevation Map (DEM) information. / Master of Science

International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / Current changes in the way that large flight test systems are utilized have affected the industry’s methodology in both the early design phases and in the implementation of nextgeneration hardware and software. The reduction of available RF spectrum, the implementation of packet telemetry methods and systems, and a desire to implement commercial-off-the-shelf (COTS) hardware are only some of the considerations that telemetry systems integrators and product houses have to face. This paper describes how test methodology changes affect current large systems design at both government test ranges and at airframe/missile manufacturer test facilities. In addition, consideration is given to the area of increased processing power as it affects hardware and software design, the leveraging of such current and future telecommunications technology as network switch technology and compression, cross utilization, standardized technology, and the movement toward platform-independent software.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Upgrading or replacing production systems is always a very resource-consuming task, in particular if the systems being replaced are quite specialized, such as those serving any Flight Test Ground Station. In the recent past a large number of Ground Station systems were based in Digital’s VAX/VMS architecture. The computer industry then expanded very fast and by 1990 realtime PCM data processing systems totally dependent on hardware and software designed for IBM-PC compatible micro-computers were becoming available. A complete system replacement in a typical Ground Station can take from one to several years to become a reality. It depends on how complex the original system is, how complex the resulting system needs to be, how much resources are available to support the operation, how soon the organization needs it, etc. This paper intends to review the main concerns encountered during the replacement of a typical VAX/VMS-based by an Intel-Windows NT-based Ground Station. It covers the transition from original requirements to totally new requirements, from mini-computers to micro-computers, from DMA to high-speed LAN data transfers, while conserving some key architectural features. This 8-month development effort will expand EMBRAER’s capability in acquiring, processing and archiving PCM data in the next few years at a lower cost, while preserving compatibility with old legacy flight test data.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The US Government originally funded the development of the Common Airborne Instrumentation System (CAIS) to address industry-wide compatibility, maintenance, and commonality issues. Although initially targeted for US Department of Defense (DoD) programs, CAIS is also being used throughout the world in many commercial applications. This paper provides a fresh look at the evolution of the CAIS concept starting with some historical background of the CAIS Program, an overview of the CAIS System Architecture and recent trends in the use of “Commercial Off The Shelf (COTS)” products and technology.