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In-flight Receptivity Experiments on a 30-degree Swept-wing using Micron-sized Discrete Roughness ElementsCarpenter, Andrew L. 16 January 2010 (has links)
One of the last remaining challenges preventing the laminarization of sweptwings
is the control of unstable crossflow vortices. In low-disturbance environments the
transition from laminar to turbulent flow on the swept-wing initially takes the path of
receptivity, where surface roughness or disturbances in the environment introduce shortwavelength
disturbances into the boundary layer. This is followed by development and
linear growth of stationary crossflow vortices that modify the mean flow, changing the
stability characteristics of the boundary layer. Finally, breakdown to turbulence occurs
over a short length scale due to the high-frequency secondary instability. The receptivity
mechanism is the least understood, yet holds the most promise for providing a laminar
flow control strategy. Results of a 3-year flight test program focused on receptivity
measurements and laminar flow control on a 30-degree swept-wing are presented. A
swept-wing test article was mounted on the port wing of a Cessna O-2A aircraft and
operated at a chord Reynolds number of 6.5 to 7.5 million. Spanwise-periodic, micronsized
discrete roughness elements were applied at the leading edge of the swept-wing in
order to excite the most unstable crossflow wavelength and promote early boundary layer transition. An infrared camera was used to detect boundary-layer transition due to
changes in leading-edge roughness. Combined with the IR camera, a new technique of
calibrating surface-mounted hotfilms was developed for making disturbance-amplitude
measurements downstream of modulated roughness heights. This technique proved to be
effective at measuring disturbance amplitudes and can be applied in future tests where
instrumentation is limited. Furthermore, laminar flow control was performed with
subcritically-spaced roughness. A 100% increase in the region of laminar flow was
achieved for some of the conditions tested here.
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Complete CFD analysis of a Velocity XL-5 RG with flight-test verificationSchouten, Shane Michael 10 October 2008 (has links)
The Texas A&M Flight Research Laboratory (FRL) recently received delivery of its
newest aircraft, the Velocity XL-5 RG. The Velocity can fly faster than the other aircraft
owned by the FRL and does not have a propeller in the front of the aircraft to disrupt the
air flow. These are definite advantages that make the Velocity an attractive addition to
the FRL inventory to be used in boundary-layer stability and transition control. Possible
mounting locations built into the aircraft for future projects include hard points in the
wings and roof of the fuselage. One of the drawbacks of the aircraft is that it has a
canard ahead of the main wing that could disrupt the incoming flow for a wing glove or
research requiring test pieces mounted to the hard point in the wing. Therefore, it is
necessary to understand the influence the canard and the impact of its wake on the wing
of the aircraft before any in-depth aerodynamic research could be completed on the
aircraft.
A combination of in-flight measurements of the canard wake and Computational
Fluid Dynamics (CFD) were used to provide a clear picture of the flowfield around the
aircraft. The first step of the project consisted of making a 3-D CAD model of the
aircraft. This model was then used for the CFD simulations in Fluent. 2-D, 3-D, inviscid,
and viscous simulations were preformed on the aircraft. A pressure rake was designed to
house a 5-hole probe and 18 Pitot probes that extended forward of the main wing to
measure the location and strength of the canard wake at various flight conditions. There
were five primary test points that were recorded at multiple times over the course of three flights. Once all of the data were collected from the flights, the freestream
conditions became the inputs into the final, 3-D CFD simulations on the aircraft.
The good agreement between the CFD results and the in-flight measurements
provided the necessary verification of the CFD model of the aircraft. These results can
be used in the future planning and execution of experiments involving the Velocity XL-5
RG.
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Comparing Packet Fill Strategies in Ethernet-Based Data Acquisition SystemsPenna, Sérgio D. 10 1900 (has links)
ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA / Ethernet-based data acquisition systems are becoming more and more common in the Flight Test Instrumentation environment. Digitized analog sensor output and various other types of digital data is captured and inserted into Ethernet packets using a "packet fill" strategy that in general is under control of the user. This paper discuss and compares two strategies "FILL-TO-TIME" and "FILL-TO- SIZE" for the acquisition of ARINC-429 digital data bus.
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Vibration Induced Stress And Accelerated Life Analyses Of An Aerospace StructureOzsoy, Serhan 01 February 2006 (has links) (PDF)
Fatigue failure of metallic structures operating under dynamic loading is a
common occurrence in engineering applications. It is difficult to estimate the
response of complicated systems analytically, due to structure& / #8217 / s dynamic
characteristics and varying loadings. Therefore, experimental, numerical or a
combination of both methods are used for fatigue evaluations. Fatigue failure can
occur on systems and platforms as well as components to be mounted on the
platform.
In this thesis, a helicopter& / #8217 / s Missile Warning Sensor - Cowling assembly is
analyzed. Analytical, numerical and experimental approaches are used wherever
necessary to perform stress and fatigue analyses. Operational flight tests are used
for obtaining the loading history at the analyzed location by using sensors.
Operational vibration profiles are created by synthesizing the data (LMS Mission
Synthesis). Numerical fatigue analysis of the assembly is done for determining the
natural modes and the critical locations on the assembly by using a finite element
model (MSC Fatigue). In addition, numerical multiaxial PSD analysis is
performed for relating the experimental results (Ansys). Residual stresses due to
riveting are determined (MSC Marc) and included in experimental analysis as
mean stresses. Bolt analysis is performed analytically (Hexagon) for keeping the
v
assembly stresses in safe levels while mounting the experimental prototype to the
test fixture.
Fatigue tests for determining the accelerated life parameters are done by an
electromagnetic shaker and stress data is collected. Afterwards, fatigue test is
performed for determining whether the assembly satisfies the required operational
life. Resonance test is performed at the frequency in which the critical location is
at resonance, since there was no failure observed after fatigue testing. A failure is
obtained during resonance test. At the end of the study, an analytical equation is
brought up which relates accelerated life test durations with equivalent alternating
stresses. Therefore, optimization of the accelerated life test duration can be done,
especially in military applications, by avoiding the maximum stress level to reach
or exceed the yield limit.
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Determining the role of a candidate gene in Drososphila muscle developmentMaity, Chaitali. January 2006 (has links)
Thesis (M.S.)--Miami University, Dept. of Zoology, 2006. / Title from first page of PDF document. Includes bibliographical references (p. 56-61).
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A resource allocation system for heterogeneous autonomous vehiclesKaddouh, Bilal January 2017 (has links)
This research aims to understand the different requirements of civilian multiple autonomous vehicle systems in order to propose an adequate solution for the resource allocation problem. A new classification of unmanned system applications is presented with focus on unmanned aerial vehicles (UAVs). The main resource allocation systems requirements in each category are presented and discussed. A novel dynamic resource allocation model is introduced for efficient sharing of services provided by ad hoc assemblies of heterogeneous autonomous vehicles. A key contribution is the provision of capability to dynamically select sensors and platforms within constraints imposed by time dependencies, refuelling, and transportation services. The resource allocation problem is modelled as a connected network of nodes and formulated as an Integer Linear Program (ILP). Solution fitness is prioritized over computation time. Simulation results of an illustrative scenario are used to demonstrate the ability of the model to plan for sensor selection, refuelling, collaboration and cooperation between heterogeneous resources. Prioritization of operational cost leads to missions that use cheaper resources but take longer to complete. Prioritization of completion time leads to shorter missions at the expense of increased overall resource cost. Missions can be successfully re-planned through dynamic reallocation of new requests during a mission. Monte Carlo studies on systems of increasing complexity show that good solutions can be obtained using low time resolutions, with small time windows at a relatively low computational cost. In comparison with other approaches, the developed ILP model provides provably optimal solutions at the expense of longer computation time. Flight test procedures were developed for performing low cost experiments on a small scale, using commercial off the shelf equipment, with ability to infer conclusions on the large-scale implementation. Flight test experiments were developed and performed that assessed the performance of the developed ILP model and successfully demonstrated its main capabilities.
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Proposta conceitual de excitador de \"flutter\" alternativo para ensaios em vôo / Conceptual purpose of an alternative flutter exciter for flight testingJorge Henrique Bidinotto 19 October 2007 (has links)
Os novos materiais utilizados nas estruturas de aeronaves, mais leves e flexíveis, tornam estas estruturas mais sujeitas a fenômenos aeroelásticos, sendo que o mais sério deles é o flutter, que deve ser cuidadosamente investigado com uma boa campanha de ensaios em vôo durante o desenvolvimento e certificação da aeronave. Este trabalho propõe um projeto conceitual de um excitador de flutter que atenda às necessidades dos ensaios, tentando resolver problemas encontrados nos modelos utilizados comumente. Para isso, é feita uma revisão da literatura pertinente, apresentando conceitos de ensaios em vôo e do fenômeno em questão, além de apresentar um histórico dos ensaios e modelos de excitadores utilizados ao longo da história. Em seguida, são apresentados alguns conceitos de excitadores, que são dimensionados e analisados segundo suas vantagens e desvantagens para finalmente escolher o modelo mais pertinente visando no futuro um projeto detalhado, construção e testes em túnel de vento. / The ultimate materials used in aircraft structures, lighter and more flexibles, make these structures more susceptible to aeroelastic phenomena including flutter, the most dangerous of all. This kind of phenomena must be carefully investigated with satisfactory flight test campaigns during the aircraft development and certification. This work proposes a flutter exciter conceptual design that attends the test necessities, trying to solve problems found in the models used actually. So, a bibliographic revision is done, presenting flight test concepts and the studied phenomena, regarding a flight test history and the exciter models used through the years. Finally, some exciter concepts are presented, dimensioned and analyzed considering their advantages and disadvantages in order to choose the most pertinent model, considering, in a near future, the detailed design, manufacturing and wind tunnel tests.
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Flight Testing Small, Electric Powered Unmanned Aerial VehiclesOstler, Jon N. 17 March 2006 (has links) (PDF)
Flight testing methods are developed to find the drag polar for small UAVs powered by electric motors with fixed-pitch propellers. Wind tunnel testing was used to characterize the propeller-motor efficiency. The drag polar was constructed using data from flight tests. The proposed methods were implemented for a small UAV. A drag polar was found for this aircraft with CDo equal to 0.021, K1 equal to 0.229, and K2 equal to -0.056. This drag polar was then used to find the following performance parameters; maximum velocity, minimum velocity, velocity for maximum range, velocity for maximum endurance, maximum rate of climb, maximum climb angle, minimum turn radius, maximum turn rate, and maximum bank angle. Applications in UAV control and mission planning are also proposed.
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Common Flight Test Module for Multiple Harsh EnvironmentsHILL, BRIAN JAMES 28 August 2008 (has links)
No description available.
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INTERACTIVE ANALYSIS AND DISPLAY SYSTEM (IADS)Mattingly, Patrick, Suszek, Eileen, Bretz, James 10 1900 (has links)
International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The Interactive Analysis and Display System (IADS) provides the test engineer with enhanced test-data
processing, management and display capabilities necessary to perform critical data monitoring
in near real-time during a test mission. The IADS provides enhanced situational awareness through
a display capability designed to increase the confidence of the engineer in making clearance
decisions within a Mission Control Room (MCR) environment. The engineer achieves this
confidence level through IADS’ real-time display capability (every data point) and simultaneous
near real-time processing capability consisting of both time and frequency domain analyses. The
system displays real-time data while performing interactive and automated near real-time analyses;
alerting the engineer when displayed data exceed predefined threshold limits.
The IADS provides a post-test capability at the engineer’s project area desktop, with a user interface
common with the real-time system. The IADS promotes teamwork by allowing engineers to share
data and test results during a mission and in the post-test environment. The IADS was originally
developed for the government’s premier flight test programs. IADS has set the standard for MCR
advancements in data acquisition and monitoring and is currently being integrated into all the
existing MCR disciplines.
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