Aeroelastic scaling methodologies are developed for geometrically nonlinear applications. The new methods are demonstrated by designing an aeroelastically scaled model of a suitably nonlinear full-scale joined-wing aircraft. The best of the methods produce scaled models that closely replicate the target aeroelastic behavior. Internal loads sensitivity studies show that internal loads can be insensitive to axial stiffness, even for globally indeterminate structures. A derived transverse to axial stiffness ratio can be used as an indicator of axial stiffness importance. Two findings of the work extend to geometrically linear applications: new sources of local optima are identified, and modal mass is identified as a scaling parameter. Optimization procedures for addressing the multiple optima and modal mass matching are developed and demonstrated. Where justified, limitations of commercial software are avoided through development of custom tools for structural analysis and sensitivities, aerodynamic analysis, and nonlinear aeroelastic trim. / Ph. D.

Aeroelastic gust and maneuver loads have driven the sizing of primary aircraft structures since the beginning of aviation. Methodologies for determining the gust loads on aircraft have evolved over the last 100 years. There are three general approaches to gust loads analysis: quasi-static, transient, and continuous methods. Quasi-static analysis offers the greatest computational efficiency. A quasi-static formulation referred to as Pratt's Method is the current practice for FAR Part 23 certification requirements. Assumptions made in the derivation of Pratt's Method are acceptable for many conventional aircraft, but additional fidelity from transient and continuous analysis are required to certify FAR Part 25 aircraft. This work provides an assessment of the usability of Pratt's Method for unconventional high altitude long endurance (HALE) aircraft. Derivation Pratt's Method is reviewed and all assumptions are identified. Error of a key curve fit equation is quantified directly. Application dependent errors are quantified by comparing loads calculated using Pratt's Method to loads calculated from transient analysis. To facilitate this effort, a state of the art nonlinear aeroelastic code has been modified to more accurately capture the transient gust response. Application dependent errors are presented in the context of a SensorCraft inspired joined-wing HALE model, and a Helios inspired flying wing HALE model. Recommendations are made on the usability of Pratt's Method for aircraft similar to the two HALE models. It is concluded that Pratt's Method is useful for preliminary design of the joined-wing HALE model, but inadequate for the analysis of the flying wing model. Additional recommendations are made corresponding to subtleties in the implementation of Pratt's Method for unconventional configurations. / Master of Science

The United States Air Force has specified a need for the next generation, High Altitude, Long Endurance aircraft capable of carrying advanced sensor arrays over very large distances and at extreme altitudes. These extensive set of requirements has required a radical shift away from the conventional wing & tube configurations with a new focus placed on extremely light weight and unconventional structural and aerodynamic configurations. One such example is the Boeing Joined wing SensorCraft Concept. The Joined wing concept has potential structural and sensor carrying benefits, but along with these potential benefits come several challenges. One of the primary concerns is the aeroelastic response of the aft wing, with potential adverse behaviours such as flutter and highly nonlinear structural behaviour of the aft wing under gust conditions. While nonlinear computation models have been developed to predict these responses, there exists a lack of experimental ground and flight test data for this unique joined wing configuration with which to benchmark the analytical predictions. The goal of this work is to develop a 5m, scaled version of the Boeing Joined Wing configuration and collect data, through a series of ground and flight based tests, which will allow designers to better understand the unique structural response of the configuration. A computational framework was developed that is capable of linearly scaling the aeroelastic response of the full scale aircraft and optimize a reduced scale aircraft to exhibit equivalent scaled behaviour. A series of reduced complexity models was developed to further investigate the flying characteristics of the configuration, test avionics and instrumentation systems and the develop flight control laws to adequately control the marginally stable aircraft. Lessons learned were then applied the 5m flight test article that was designed and constructed by the author. In the final stage of the project, the decision was made to relax the aeroelastically scaled constraint in order to allow additional softening of the structure to further investigate the nonlinear behaviour of the aircraft. Due to the added risk and complexity of flying this highly flexible aircraft the decision was made to produce the final aeroelastically scaled article at the 1.85m scale. This model was designed, developed and ground tested in the lead up to a follow on project which will see additional flight testing performed in conjunction with Boeing Inc. / Graduate

No description available.

The Boeing Joined-Wing SenorCraft is a novel aircraft design that has many potential benefits, especially for surveillance missions. However, computational studies have shown the potential for nonlinear structural responses in the joined-wing configuration due to aerodynamic loading that could result in aft wing buckling. The design, construction, and flight testing of a 1/9th scale, aeroelastically tuned model of the Joined-Wing SensorCraft has been the subject of an ongoing international collaboration aimed at experimentally demonstrating the nonlinear aeroelastic response in flight. To accurately measure and capture the configuration\'s potential for structural nonlinearity, the test article must exhibit equivalent structural flexibility and be designed to meet airworthiness standards. Previous work has demonstrated airworthiness through the successful flight of a Geometrically Scaled Remotely Piloted Vehicle. The work presented in this thesis involves evaluation of an aeroelastically tuned design through ground-based experimentation. The result of these experimental investigations has led to the conclusion that a full redesign of the forward and aft wings must be completed to demonstrate sufficient geometric nonlinearity for the follow-on Aeorelastically Tuned Remotely Piloted Vehicle. This thesis also presents flight test plans for the aeroelastically tuned RPV. / Master of Science

The development and implementation of a flight test program for an unmanned aircraft is a multidisciplinary challenge. This thesis presents the development and implementation of a rigorous test program for the flight test of a Geometrically Scaled Joined Wing SensorCraft Remotely Piloted Vehicle from concept through successful flight test. The design methodology utilized in the development of the test program is presented, along with the extensive formal review process required for the approval of the test plan by the Air Force Research Laboratory. The design, development and calibration of a custom instrumentation package is also presented along with the setup, procedure and results from all testing. Results are presented for a wind tunnel test for air data boom calibration, propulsion system static thrust testing, a bifilar pendulum test for experimental calculation of mass moments of inertia, a static structural loading test for structural design validation, a full taxi test and a successful first flight. / Master of Science