The visual workload of general aviation pilots operating alone in adverse conditions is often high. Airframe-referenced 3D audio systems may improve safety and performance by transferring a portion of this workload to the audio modality. These systems use the aircraft’s axes as a reference to present audio directional cues to the pilot via a headset. This experiment compared the technical performance, workload, and situational awareness of pilots as they performed instrument flight procedures with and without an airframe-referenced 3D audio system. Five pilot participants flew six tasks of each audio condition in a Piper Navajo aircraft modified with a 3D audio system. With the 3D audio system, the pilots showed slightly better technical performance and lower workload, as well as improved situational awareness. However, the improvements from 3D audio were not significant when expanded to the entire pilot population. The lack of statistical significance appeared to be the results of a small pilot sample and better than expected pilot performance in both audio conditions. The most important results of the experiment were the modes of the responses to a situational awareness questionnaire consisting of 26 Likert-type questions. Pilots clearly indicated they preferred flying with the 3D system to flying without it, suggesting the airframe-referenced 3D audio system may have been beneficial in completing flight tasks. Further research should be performed to document the system’s impact on pilot performance, especially at higher levels of workload than were evaluated in this study.

Kinematic equations were developed to describe the dynamic motions of the aircraft piston engine components in terms of time dependent position, velocity, and acceleration relationships. Using the Aeronca E-113 engine as a case study, the brake mean effective pressure (BMEP) rating was used to model the cylinder gas pressure profile. The moments of inertia of the dynamic components including connecting rod, crankshaft, and propeller were measured using a pendulum swing method. Representative values were obtained for inertial and gas pressure forces acting on crankshaft journals, connecting rods, and cylinder walls. The resulting model can help in the design of crankshafts and other dynamically loaded parts to resist failure due to fatigue.

A study was undertaken to assess the effectiveness of the CF188 main landing gear upgrade on reducing Planing Link Mechanism failures. Two main landing gear configurations were studied: the prototype configuration and, for comparison purposes, the current configuration referred to as the baseline. Under this study, the flight test data that was analyzed came from key measurements recorded during maintenance rigging procedures, pilot ground handling quality ratings, and from over 80 landings at different descent rates and aircraft attitudes. Landings consisted of touch and go, full stop, cable overrun and cable engagement. The aircraft that was used through the flight test program had both its main landing gears instrumented. While the prototype configuration had minimal impact on the ground handling characteristics, it demonstrated promising results during maintenance activities as well as loads distribution during landings. The prototype was easier to rig which will allow the use of tighter limits further standardizing the complex maintenance procedure. From both a static and dynamic point of view, the hold down force was significantly increased. Within the scope of this study, it was found that the CF188 main landing gear upgrade will reduce Planing Link Mechanism failures.

The purpose of this thesis was to investigate if it would be possible to integrate a developmental Radar Warning Receiver named “The Puffer” onto a Tier 2 Unmanned Aerial Vehicle, and incorporate the Multifunctional Information Display System/Low Volume Terminal into the UAV‟s ground control station. This integration of systems would become a low cost platform that could provide an Electronic Surveillance and geolocation capability of known mobile threat systems. The results of this investigation showed that the Puffer could be integrated on to the Tier 2 UAV with minor modifications. To control and fully integrate the downlink messages from multiple UAVs plus add the capability to send the information out to other units over Link16 would require a major hardware effort with a sizable software integration effort. While this would be an extensive project, the results could be done at a significant cost saving compared to the manned platforms in use today.

An experimental investigation was performed to analyze the beginning boundary layer produced on the floor of a subsonic wind tunnel and its influence on the flow field about a two-dimensional automotive model. Hot film anemometer measurements were taken in the test section of the wind tunnel operating under various inlet configurations. The use of a splitter plate and modifications to the contour of the inlet to the wind tunnel were then studied to find their affects on the height of the boundary layer in the wind tunnel test section. Finally, a 2-D automotive model was constructed with pressure taps along the centerline of the model. This model was tested in the wind tunnel on the floor of the test section and on top of the splitter plate to resolve any differences created in the data from the different boundary layers created in the test section. The hot film anemometer measurements provided a baseline boundary layer thickness produced in the test section of the wind tunnel. The modifications to the inlet contour of the wind tunnel resulted in a reduction in boundary layer height experienced in the wind tunnel test section. This decrease in boundary layer thickness can attributed to the elimination of the flow disturbance created by the step where the flow straightener and screens mount to the inlet of the wind tunnel. The model data from the test section and splitter plate showed an increase in velocity across the top of the model when placed on the splitter plate that can be partially attributed to the reduced height of the boundary layer created by the splitter plate.

A new combination of methods used to solve the transient, two-dimensional inverse heat conduction problem (IHCP) is presented in this thesis. A simple implicit in time with space marching approach is used in combination with digital filtering for regularization. Results are presented for both one-dimensional and two-dimensional problems. As much as 10% measurement error is added to the data to simulate experimental results. One-dimensional results with “perfect” data suggested that refining the spatial and temporal meshes improved the accuracy of the inverse solution. However, the nodal Fourier number was found to have no effect on accuracy. Further investigation into the effect of the Fourier number on the inverse solution led to the discovery of a precisely defined stability criterion, which is presented for the one-dimensional problem. The digital filter was proven to be a highly effective regularization method for both the one-dimensional and two-dimensional cases. The Gauss low pass filter employed a cutoff frequency as the regularization parameter, which has an exact definition with physical significance. No trial and error method of choosing a regularization parameter was necessary. Temperature and heat flux data were given at the sensor sites, noise was added to the data, filtered, and used as input data to the inverse code. The prediction error resulting from the use of “perfect” data suggested a bias (over-prediction). With this bias removed from the noisy, filtered results, the inverse solution was accurate to 2% for the 1D case and 3% for the 2D case. The dramatic reduction of error through an inverse process was striking, since the inverse problem is well-known to magnify measurement errors. An additional case using only one line of temperature data and no heat flux data was used as alternate approach to the inverse problem. The new strategy relies on a recently developed integral relationship between the heating rate and the heat flux, which is valid on the half-space. The relationship allows for the heat flux to be found at the sensor site using only temperature and heating rate data. This data could be experimentally obtained using one line of thermocouples combined with numerical differentiation to obtain the heating rate; no heat flux gauges or second series of thermocouples are necessary. This thesis is the first to take advantage of heat flux – heating rate relationship. Results from this method with a measurement error of 5% predicted a surface heat flux error of only 5%.

During the cure of polymer matrix composites, induced stresses develop due to shrinkage of the matrix material. Consequences of this can lead to shifting of the reinforcement, adversely affecting final properties of the material, or the induced stresses can alter the final geometry of the part. With the use of a new closed loop feedback program developed, residual stresses built up during cure were minimized. Experiments were performed using the EPON 828 resin with two types of reinforcement, carbon and glass fiber. The residual stress built up during the optimized cure cycle was compared with that produced during the lPanufacturer recommended 2-step cure cycle and isothermal cure cycles. Results for both fibers show a large reduction in stresses endured during cure for the optimized cure compared to typical stresses seen under isothermal and standard cure cycles. Static and dynamic testing were done on specimens and showed that the modulus and the glass transition temperatures of cured specimens were not significantly affected by the optimized cure cycles. Results also show that optimized cure cycles were of shorter duration compared to the standard cure cycles.

The setup of the converging jets is commonly used in the manufacture of meltblown fibers. This requires forced airflow through small channels angled toward each other until meeting at the exit of the die. The emerging air jets impinge while molten polymer is extruded and becomes entrained in the air flow to be collected downstream as a thin cooled fiber. The experimental analysis of converging free jets was examined to reveal characteristics of the flow field. A hot-film anemometer was used to gather and analyze the corresponding data for two separate meltblown fiber dies. These were examined and compared to each other as well as previous computational fluid dynamics studies of similar setups. A traverse system was used to position the anemometer probe while measurements of the mean velocity and turbulence intensity were obtained at varying positions throughout the flow fields. This data was analyzed and compared to existing studies and theoretical prediction and was found to agree with existing computer models by showing three distinct regions: the first zone where each emerging jet maintains individual velocity profiles; a second mixing zone of maximum turbulence and an intermediate velocity profile; and a third zone where the individual jets are no longer present and the velocity profile becomes characteristic of a theoretical single emerging jet of similar mass flow rate.

Optimum stacking sequence design of composite sandwich panel using genetic algorithms

Experimental evaluation of erosive burning in composite propellants - effect of binder