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Highly agile, hover capable flapping wing flight is a relatively new area of study in engineering. Researchers are looking to flapping flight as a potential source for the next generation of reconnaissance and surveillance vehicles. These systems involve highly complicated physics surrounding the flapping wing motion and unusual characteristics due to a hover requirement not normally associated with conventional aircraft. To that end this study focuses on examining the various models and physical parameters that are considered in various other studies. The importance of these models is considered through their effect on the trim and stability of the overall system. The equations of motion are modeled through a quasi coordinate Lagrangian scheme while the aerodynamic forces are calculated using quasi-steady potential flow aerodynamics. Trim solutions are calculated using periodic shooting for several different conditions including hover, climb, and forward flight. The stability of the trim is calculated and examined using stroke-averaged and Floquet theory. Inflow and viscous effects are added and their effects on trim and stability examined. The effects of varying hinge location and the inclusion of stroke deviation in the wing kinematics are also explored. The stroke-averaged system was not found to be a direct replacement for the periodic system as the stability was different for the two systems. Inflow and viscosity were found to have large effects on the stability of the system and models accounting for the two should be included in future flight dynamic models. / Master of Science

Dynamic simulations are invaluable for studying system behavior, developing control models, and running statistical analyses. For example, paraglider flight simulations could be used to analyze how a wing behaves when it encounters wind shear, or to reconstruct the wind field that was present during a flight. Unfortunately, creating dynamics models for commercial paraglider wings is difficult: not only are detailed specifications unavailable, but even if they were, a detailed model would be laborious to create. To address that difficulty, this project develops a paraglider flight dynamics model that uses parametric components to model commercial paraglider wings given only limited technical specifications and knowledge of typical wing design. To validate the model design and implementation, an aerodynamic simulation of a reference paraglider canopy is compared to wind tunnel measurements, and a dynamic simulation of a commercial paraglider system is compared to basic flight test data. The entirety of the models and example wings are available as an open source library built on the Python scientific computing stack.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / The yawsonde is a device used at the U.S. Army Research Laboratory (ARL) to investigate the in-flight behavior of spinning projectiles. The standard yawsonde consists of a pair of solar cells and slits that respond to solar rays. The sun is used as an inertial reference to measure the pitching and yawing motions of the projectile. An FM telemetry package transmits the sensor data to a ground receiving station for analysis. The standard yawsonde package is housed in an M577-type artillery fuse body. The spinning motion of the projectile serves as the sampling rate for the measurements. When the spin rate is not significantly higher than the yaw rate, multiple sets of sensors must be used to effectively increase the sampling rate. The pinhole yawsonde sensor was developed for projectiles that require multiple sets of sensors in a very limited space. This pinhole yawsonde consists of a number of sensors located behind pinholes placed around the projectile's circumference. Since each pinhole makes a yaw measurement, many measurements, or samples, are taken with each projectile spin revolution. More pinhole sensors may be added to increase the measurement sampling rate. One application of this yawsonde is to aid in evaluating the performance of tactical devices and inertial systems onboard projectiles with limited space for instrumentation.

This study aims to improve flight simulation of flexible aircraft. More specifically, this thesis concentrates on comparing two flexible aircraft flight simulation models. Both modeling techniques considered use the same aircraft structural and aerodynamic data provided by the aircraft manufacturer. Simulation models were developed and tested using a number of control inputs in both longitudinal and lateral dimensions. Time history responses from the simulations were compared. The effect of increasing the flexibility of the aircraft model was also studied on both models. It was found that the two models produce very similar results for the original aircraft stiffness case. However, the lateral response of the two models diverges as the stiffness is lowered. A number of recommendations are made for further testing and research, based on the conclusions of the study.

This study aims to improve flight simulation of flexible aircraft. More specifically, this thesis concentrates on comparing two flexible aircraft flight simulation models. Both modeling techniques considered use the same aircraft structural and aerodynamic data provided by the aircraft manufacturer. Simulation models were developed and tested using a number of control inputs in both longitudinal and lateral dimensions. Time history responses from the simulations were compared. The effect of increasing the flexibility of the aircraft model was also studied on both models. It was found that the two models produce very similar results for the original aircraft stiffness case. However, the lateral response of the two models diverges as the stiffness is lowered. A number of recommendations are made for further testing and research, based on the conclusions of the study.

Flight testing has been the historical standard for determining aircraft airworthiness - however, increases in the cost of flight testing and the accuracy of inexpensive CFD promote certification by analysis to reduce or replace flight testing. A framework is introduced to predict the performance in the special case of a modification to an existing, previously certified aircraft. This framework uses a combination of existing flight test or high fidelity data of the original aircraft as well as lower fidelity data of the original and modified configurations. Two methods are presented which estimate the model form uncertainty of the modified configuration, which is then used to conduct non-deterministic simulations. The framework is applied to an example aircraft system with simulated flight test data to demonstrate the ability to predict the performance and associated uncertainty of modified aircraft configurations. However, it is important that the models and methods used are applicable and accurate throughout the intended use domain. The factors and limitations of the framework are explored to determine the range of applicability of the framework. The effects of these factors on the performance and uncertainty results are demonstrated using the example aircraft system. The framework is then applied to NASA's X-57 Maxwell and each of its modifications. The estimated performance and associated uncertainties are then compared to the airworthiness criteria to evaluate the potential of the framework as a component to the certification by analysis process. / Doctor of Philosophy / Aircraft are required to undergo an airworthiness certification process to demonstrate the capability for safe and controlled flight. This has historically been satisfied by flight testing, but there is a desire to use computational analysis and simulations to reduce the cost and time required. For aircraft which are based on an aircraft which has already been certified, but contain minor changes, computational tools have the potential to provide a large benefit. This research proposes a framework to estimate the flight performance of these modified aircraft using inexpensive computational or ground based methods and without requiring expensive flight testing. The framework is then evaluated to ensure that it provides accurate results and is suitable for use as a supplement to the airworthiness certification process.

The realm of aircraft flight dynamics analysis reaches from local static stability to global dynamic behavior. It includes aircraft performance issues as well as structural concerns. In the particular aspect of dynamic motions of an aircraft and how we understand them, an alternate coordinate system will be introduced that will lend insight and simplification into the understanding of these dynamic motions. The main contribution of this coordinate system is that one can easily visualize how the instantaneous velocity vector relates to the instantaneous rotation vector, the angular rate vector of the aircraft. The out-of-control motion known as the Falling Leaf will be considered under the light of this new coordinate system. This motion is not well understood and can lead to loss of the aircraft and crew. Design guidelines will be presented to predict amplitude and frequency of the Falling Leaf. NOTE: (12/2009) An updated copy of this ETD was added after there were patron reports of problems with the file. / Master of Science

The following work is directed towards an evaluation of aircraft that undergo structural shape change for the purpose of optimized flight and maneuvering control authority. Dynamical equations are derived for a morphing aircraft based on two primary representations; a general non-rigid model and a multi-rigid-body. A simplified model is then proposed by considering the altering structural portions to be composed of a small number of mass particles. The equations are then extended to consider atmospheric flight representations where the longitudinal and lateral equations are derived. Two aspects of morphing control are considered. The first is a regulation problem in which it is desired to maintain stability in the presence of large changes in both aerodynamic and inertial properties. From a baseline aircraft model various wing planform designs were constructed using Datcom to determine the required aerodynamic contributions. Based on nonlinear numerical evaluations adequate stabilization control was demonstrated using a robust linear control design. In maneuvering, divergent characteristics were observed at high structural transition rates. The second aspect considered is the use of structural changes for improved flight performance. A variable span aircraft is then considered in which asymmetric wing extension is used to effect the rolling moment. An evaluation of the variable span aircraft is performed in the context of bank-to-turn guidance in which an input-output control law is implemented. / Ph. D.

To improve the recoverability and survivability of aircraft after damage, a better understanding of the flight dynamics and the structural loads is needed. However, damage can introduce asymmetries that complicate the modeling. An extended vortex lattice code is used to model the quasi-steady aerodynamic forces. The vortex lattice method provides the force distribution which is not available elsewhere. Snapshots from the vortex lattice model are used to generate a reduced order model (ROM). This ROM contains non-linear terms to account for non-linearities that the damage can introduce. The ROM is coupled with equations of motion which are able to account for instantaneous shifts in the center of gravity caused by the damage. This methodology is applied to the generic transport model (GTM) with the loss of a portion of the port wing tip. This model is used to examine the effects of the damage on the aircraft's trim and the stability of that trim. This model is also used to calculate the aerodynamic, inertial, and propulsive loads on the wing as the aircraft is maneuvering. / Master of Science