Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 44 for “"forward flight"”.
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Analysis of a quadrotor in forward flight
… valid when flying at high speed or in prolonged forward flight as the aerodynamics can no longer be ignored. This results in a highly nonlinear system with both aerodynamics and rigid body dynamics affecting the dynamics. In this thesis, a model of a quadrotor that takes into account both …
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Performance Analysis of a Coaxial Helicopter in Hover and Forward Flight
<p>The performance of a coaxial rotor system has been analyzed by establishing a proper basis of comparison between a conventional single rotor and coaxial rotor. An attempt has also been made to better understand the complicated aerodynamic interactions associated with coaxial rotor wakes by using …
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Rotor Blade Flap-Lag Stability and Response in Forward Flight in Turbulent Flows
… flap-lag motion of a helicopter rotor blade in forward flight is investigated. By assuming white noise turbulence and applying a special case of the stochastic averaging procedure, equations are developed which describe the stochastic first and second moments of the perturbations in flap and …
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Investigating Forward Flight Multirotor Wind Tunnel Testing in a 3-By 4-Foot Wind Tunnel
<p>Investigation of complex multirotor aerodynamic phenomena via wind tunnel experimentation is becoming extremely important with the rapid progress in advanced distributed propulsion VTOL concepts. Much of this experimentation is being performed in large, highly advanced tunnels. However, the …
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An Experimental Investigation of Ground Effect on a Quad Tilt Rotor in Hover and Low Speed Forward Flight
… the QTR was tested in hover and very low speed forward flight. Fixed-pitch propellers were used to model the rotors. In order to avoid the boundary layer problems associated with wind tunnel testing of rotorcraft IGE, a unique moving setup was developed for testing in forward flight. The effect …
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Effects of Duct Lip Shaping and Various Control Devices on the Hover and Forward Flight Performance of Ducted Fan UAVs
… a small leading edge radius performed best in forward flight and crosswind conditions, while the performance of a lip with a large leading edge radius was enhanced in static conditions. Through tuft flow visualization and static pressure measurements it was determined that the reason for the …
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Integral twist actuation of helicolpter rotor blades for vibration reduction
… vibration reduction of helicopter rotors during forward flight is investigated. The twist deformation is obtained using embedded anisotropic piezocomposite actuators. An analytical framework is developed to examine integrally-twisted blades and their aeroelastic response during different flight …
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CFD analysis and design of a low-twist, hovering rotor equipped with trailing-edge flaps
… effects on the advancing blade in forward flight. The twisted blade gives rise to negative incidence at the blade tip, which accelerates shock formation on the lower surface. The current work looks to evaluate the implementation of a low twist rotor for improved forward flight …
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Aerodynamic analysis of groove based vortex trap configuration on the retreating helicopter blade
… on the retreating side of the rotor disc in forward flight conditions. One of the codes used to implement the method is the Blade Element Theory Code using Prouty‟s dataset. The code aids in the analysis of the aerodynamic characteristics of the helicopter main rotor blade. To validate the …
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Coaxial contrarotating twin rotor aerodynamics
… been developed to model the wake of a CCTR in forward flight. Comparisons between theory and experimental results from model and full scale rotors are shown over a variety of hovering and forward flight conditions. Both wake models have been written in Fortran IV computer language with a …
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Design and manufacturing of a VTOL Micro Aerial Vehicle
… miniature aerial vehicles capable of autonomous flight. Such vehicles could perform reconnaissance missions in environments that are unsafe to humans. Their small size minimizes their chance of being detected in hostile areas and allows them mobility not afforded by typical full size vehicles and …
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AEROMECHANICS OF A DOUBLE ANHEDRAL TIP COMPOSITE ROTOR: EXPERIMENT AND MODELING
… dynamics and aeromechanics in hover and forward flight. The local center of gravity offset at the tip appeared to make the blade softer. No performance gain was predicted in hover, however, the static flap, lag, and torsion moments at the root all decreased due to the vertical center of …
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ROBUST CONTROL OF AN EVTOL THROUGH TRANSITION WITH A GAIN SCHEDULING LQR CONTROLLER
… into control of the eVTOLs to ensure safe flight through the transition from hover to forward flight. This paper proposes a control strategy using the transition dynamics in a gain scheduling LQR attitude controller to robustly control the vehicle at any point throughout transition. The …
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Systematic investigation of models of helicopter with a slung load
… of the dynamic stability of such a system in forward flight, in a turbulent atmosphere, is suggested. Configurations in which the load is suspended by multiple tethers should be examined, using better models than in the past, to determine the merits of such suspension schemes.
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Effect of tip-speed ratio on induced velocities near a lifting rotor
… flow in the vicinity of a lifting rotor in forward flight has been conducted. The analysis is based upon an asymmetric wake which is a logical extension of that used for previous investigations. Equations for the induced velocities at an arbitrary point in space are presented in a form …
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Measurement and Prediction of Rotor Noise Sources for sUAS in Outdoor and Laboratory Environments
… footprint of a hexacopter in hover and low speed forward flight, comparison of aerodynamic performance and noise of eVTOL rotors operating in multiple facilities, and analysis of the noise associated with an outrunner brushless DC motor. Empirical and low-order models are used to predict …
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The Static Thrust Characterization of the Quatra Aerrow Q100XL Engine for Flight Performance Prediction of the 1/3-scaled Cessna 172P Model
… is to predict the thrust as a function of forward flight velocity required for the one-third-scaled Cessna 172P. This model was designed to verify scaling laws. Therefore, it is important that it be aerodynamically scaled and that it have similar thrust characteristic as that of the full …
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Micro air vehicle control design : a comparison of classical and dynamic inversion techniques
… successfully implemented in hover, climb, and forward flight simulations. A dynamic inversion routine was then applied to the inner-loop control, providing improved inner-loop performance compared to the classical approach for nominal flight conditions. Finally, the two approaches were compared …
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