3D-Printed Morphing Wings for Controlling Yaw on Flying-Wing Aircraft

The flaps on an airplane wing are used to control the aircraft during flight. These flaps traditionally have at most three articulation or hinge points. Recent studies have shown improved flap efficiency using a conformal flap, which deforms following a curved shape. Much of aircraft improvement comes through increasing its efficiency during flight. This efficiency is generally improved by decreasing the drag force on the aircraft. A potential solution to decrease drag is to remove additional lifting surfaces, such as the horizontal and vertical stabilizer ubiquitous on general aviation aircraft. These additional lifting surfaces are used to trim and control the aircraft during flight. A flying-wing aircraft, which has no additional lifting surfaces, is trimmed and controlled using multiple flaps along the main wing. 3D-printing the mechanisms used to control these flaps has significant advantages. 3D-printing is fast, cheap, easy to repeat, easy to replicate, and produces durable parts. Two morphing mechanisms manufactured using 3D-printing are presented as viable solutions to demonstrate yaw control on a flying-wing aircraft. The Airfoil Recambering Compliant System (ARCS) is presented as a solution for a wing using a single flap with multiple actuators. The Kinetic Internal Nexus Compliant System (KINCS) is presented as a solution for a wing using multiple flaps, each with a single actuator. The final KINCS design used for a prototype flying-wing aircraft is presented

An Alternate Dimensionless Form of the Linearized Rigid-Body Aircraft Equations of Motion with Emphasis on Dynamic Parameters

The equations of motion for an aircraft can be linearized about a reference condition within the assumptions of small disturbances and linear aerodynamics. The resulting system of equations is typically solved to obtain the eigenvalues and eigenvectors that describe the small disturbance motion of the aircraft. Results from such an analysis are often used to predict the rigid-body dynamic modes of the aircraft and associated handling qualities. This process is typically carried out in dimensional form in most text books, or in nondimensional form using dimensionless parameters rooted in aerodynamic theory. Here we apply Buckingham’s Pi theorem to obtain nondimensional parameters based on the aircraft rigid-body dynamics rather than aerodynamics. This approach may be more useful for understanding how aircraft dynamics scale with appropriate design parameters

Simplified Mass and Inertial Estimates for Aircraft with Components of Constant Density

Aircraft mass and inertial properties are required for predicting the dynamics and handling qualities of aircraft. However, such properties can be difficult to estimate since these depend on the external shape and internal structure, systems, and mass distributions within the airframe. Mass and inertial properties of aircraft are often predicted using computer-aided design software, or measured using various experimental techniques. The present paper presents a method for quickly predicting the mass and inertial properties of complete aircraft consisting of components of constant density. Although the assumption of constant density may appear limiting, the method presented in this paper can be used to approximate mass properties of complex internal structures. Inertial estimates for rectangular cuboids, cylinders, spheres, wing segments, and rotors are presented here. The influence of geometric properties of wing segments such as sweep, taper, airfoil geometry, and dihedral are included. The utility of the method is presented and the accuracy is evaluated with various test cases

3D-Printed Wings with Morphing Trailing-Edge Technology

In recent years, various groups have attempted to improve aircraft efficiency using wings with morphing trailing-edge technology. Most of these solutions are difficult to manufacture or have limited morphing capability. The present paper outlines a research effort to develop an easy to manufacture, fully 3D-printed morphing wing. This approach is advantageous due to the low cost, minimal man-hours required for manufacturing, and speed at which design iterations can be explored. Several prototypes were designed and tested and lessons learned from these iterations have been documented. Additionally, printer settings have been tested and catalogued to assist others attempting to reproduce these results. Performance was considered in terms of total deflection. Two concepts are presented as potential 3D-printed morphing-wing mechanisms. The Airfoil Recambering Compliant System (ARCS) is presented as a solution for a wing using continuous trailing-edge technology. The Kinetic Internal Nexus Compliant System (KINCS) is presented as a solution for a wing using discontinuous trailing-edge technology. The final KINCS design used for a prototype flying-wing aircraft is presented

Stick-Fixed Maneuver Points in Roll, Pitch, and Yaw and Associated Handling Qualities

The stick-fixed pitch maneuver point is an important measure of aircraft longitudinal dynamic response and handling quality characteristics, and includes effects of both aerodynamic and inertia properties of the aircraft about the pitch axis. In the present work, the existence of stick-fixed roll and yaw maneuver points is demonstrated, which are determined from the lateral forces, moments, and inertial properties of the aircraft. These stick-fixed roll and yaw maneuver points are directly related to the predicted lateral handling qualities. Example results are included for several aircraft that demonstrate the importance of this parameter when predicting the dynamic response of the aircraft. A better understanding of stick-fixed roll, pitch, and yaw maneuver points can inform aircraft design during early stages to ensure adequate handling qualities for both longitudinal and lateral modes

On the History and Semantics of Burble in Aerodynamic Theory

The term burble has been in use in aerodynamic theory for over a century. While burble may be unfamiliar to most contemporary aerodynamicists, the word has a rich history based in aerodynamic theory and experimentation. The present paper outlines the fluidity of burble\u27s meaning over time. From analyzing subsonic flow over an airfoil, to the implementation of stochastic turbulence in aircraft carrier landing simulations, the term burble has had a significant impact on the study of aerodynamics. The term burble has fallen out of use in aerodynamic engineering circles. Why did this happen? And what can be learned from the decline in use of the term burble

Evaluation of First-Order Actuator Dynamics and Linear Controller for a Bio-Inspired Rotating Empennage Fighter Aircraft

This paper considers the problem of stabilizing a bio-inspired fighter aircraft variant at its Air Combat Maneuver Condition. The aircraft equations of motion are linearized, and an infinite-horizon linear quadratic regulator design is conducted for this aircraft. Included in the dynamics are first-order actuator models, which have the effect of slowing actuator responses. This is particularly important for the bio-inspired variant because it requires rotation of the empennage, which has relatively large inertia. The bio-inspired variant open-loop system is unstable in the short period and Dutch roll modes, which is mitigated in the closed-loop system. Monte Carlo simulation responses to initial condition dispersions, aerodynamic model errors, and atmospheric turbulence are presented for the controlled aircraft system. These simulations demonstrate the robust properties of the presented control design. Discussion is dedicated to control designs neglecting input from throttle and the rotating tail, and corresponding successes. Whereas the bio-inspired variant aircraft can be successfully controlled without rotating tail input, effects from neglecting throttle input show throttle should be included, but perhaps in an alternate loop such as a speed controller

3D simulations of turbulent mixing in a simplified slab-divertor geometry

Three-dimensional simulations of plasma turbulence have been run using the STORM module of BOUT  + + in a simple slab geometry aimed at representing a single, isolated tokamak divertor leg. Turbulence is driven primarily by the Kelvin-Helmholtz mechanism due to the sheared ExB flow that forms around the separatrix due to strong radial gradients in the sheath potential which arise from strong radial gradients in the electron temperature. The turbulence forms a mixing layer around the separatrix which spreads heat and particles into the private-flux region. The resulting spread of the electron heat flux is within the experimental range measured on MAST. An effective thermal transport coefficient which is approximately 10% of the Bohm value is measured from the simulations. When a transport coefficient of this magnitude is used in a diffusive axisymmetric simulation, the time-averaged radial profiles share similar features to the full turbulence simulation

A cost-effectiveness analysis of provider and community interventions to improve the treatment of uncomplicated malaria in Nigeria: study protocol for a randomized controlled trial.

BACKGROUND: There is mounting evidence of poor adherence by health service personnel to clinical guidelines for malaria following a symptomatic diagnosis. In response to this, the World Health Organization (WHO) recommends that in all settings clinical suspicion of malaria should be confirmed by parasitological diagnosis using microscopy or Rapid Diagnostic Test (RDT). The Government of Nigeria plans to introduce RDTs in public health facilities over the coming year. In this context, we will evaluate the effectiveness and cost-effectiveness of two interventions designed to support the roll-out of RDTs and improve the rational use of ACTs. It is feared that without supporting interventions, non-adherence will remain a serious impediment to implementing malaria treatment guidelines. METHODS/DESIGN: A three-arm stratified cluster randomized trial is used to compare the effectiveness and cost-effectiveness of: (1) provider malaria training intervention versus expected standard practice in malaria diagnosis and treatment; (2) provider malaria training intervention plus school-based intervention versus expected standard practice; and (3) the combined provider plus school-based intervention versus provider intervention alone. RDTs will be introduced in all arms of the trial. The primary outcome is the proportion of patients attending facilities that report a fever or suspected malaria and receive treatment according to malaria guidelines. This will be measured by surveying patients (or caregivers) as they exit primary health centers, pharmacies, and patent medicine dealers. Cost-effectiveness will be presented in terms of the primary outcome and a range of secondary outcomes, including changes in provider and community knowledge. Costs will be estimated from both a societal and provider perspective using standard economic evaluation methodologies. TRIAL REGISTRATION: Clinicaltrials.gov NCT01350752