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A Study In Drag Reduction Of Close Formation Flight Accounting For Flight Control Trim Positions And Dissimilar Formations
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Book Synopsis A Study in Drag Reduction of Close Formation Flight Accounting for Flight Control Trim Positions and Dissimilar Formations by : Michael T. Morgan
Download or read book A Study in Drag Reduction of Close Formation Flight Accounting for Flight Control Trim Positions and Dissimilar Formations written by Michael T. Morgan and published by . This book was released on 2005 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Aircraft Drag Reduction Through Extended Formation Flight by : Simeon Andrew Ning
Download or read book Aircraft Drag Reduction Through Extended Formation Flight written by Simeon Andrew Ning and published by Stanford University. This book was released on 2011 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Formation flight has the potential to significantly reduce the fuel consumption of long range flights, even with existing aircraft. This research explores a safer approach to formation flying of transport aircraft, which we term extended formation flight. Extended formations take advantage of the persistence of cruise wakes and extend the streamwise separation between the aircraft by at least five wingspans. Classical aerodynamic theory suggests that the total induced drag of the formation should not change as the streamwise separation is increased, but the large separation distances of extended formation flight violate the simple assumptions of these theorems. At large distances, considerations such as wake rollup, atmospheric effects on circulation decay, and vortex motion become important to consider. We first examine the wake rollup process in the context of extended formations and develop an appropriate physics-based model. Using this model, this dissertation addresses three aspects of formation flight: longitudinally extended formations, compressibility effects, and formations of heterogeneous aircraft. Uncertainty analysis is used to investigate the induced drag savings of extended formations in the presence of variation in atmospheric properties, limitations of positioning accuracy, and uncertainty in model parameters. Next, the methodology is integrated with an Euler solver to assess the impact of compressibility while flying in formation. Finally, we examine the important considerations for optimally arranging formations of non-identical aircraft.
Book Synopsis Modeling, Analysis, and Control of Close Formation Flight by : Qingrui Zhang
Download or read book Modeling, Analysis, and Control of Close Formation Flight written by Qingrui Zhang and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Close formation flight is extensively investigated from the perspectives of dynamic modeling, aerodynamic analysis, and control design. A lifting-line based aerodynamic model is presented to describe the aerodynamic coupling between two aircraft in close formation. The introduced aerodynamic model is validated via the comparison with a single horseshoe vortex-based model, a vortex lattice method-based model, and experimental results. Comprehensive analysis is thereafter conducted to investigate the drag reduction variations with respect to different relative positions, angles of attack, sideslip angles, and leader-to-follower wing span ratios. The analysis indicates that the drag reduction performance of close formation flight is sensitive to the formation position accuracy. Additionally, basic requirements are formulated for close formation flight control. In terms of the proposed aerodynamic model, a linear robust adaptive formation controller is developed specifically for close formation at level and straight flight. The proposed robust adaptive controller shows dramatic increase in both transient performance and robustness against model uncertainties and disturbances. The nonlinear robust close formation control problem is thereafter studied under a leader-following architecture. Nonlinear robust close formation controllers with different considerations are proposed based on a command filtered backstepping method and an uncertainty and disturbance estimation technique. The proposed nonlinear robust formation controllers could accommodate more complex flight scenarios, for instance, different flight maneuvers and close formation of more than three aircraft. With the increase of the number of aircraft in close formation, a leader-following formation controller might become less and less efficient. Regarding the efficiency degradation issue of leader-following formation controllers, two cooperative control algorithms are introduced, which exhibit better tracking performance for close formation of a large number of aircraft. Extensive simulations are carried out to validate the effectiveness of all proposed close formation control algorithms.
Download or read book Cathrine Zernichow written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Analytical Study of T-38 Drag Reduction in Tight Formation Flight by :
Download or read book An Analytical Study of T-38 Drag Reduction in Tight Formation Flight written by and published by . This book was released on 2002 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis explores the benefits of flying in a tight formation, mimicking the natural behavior of migratory birds such as geese. The first phase of the research was to determine an optimal position for the wingman of a tight formation flight of T-38 Talon aircraft using the HASC95 vortex lattice code. A second wingman was then added to determine the benefit derived by increasing formation size. The second wingman was predicted to derive an even greater induced drag benefit than the first wingman for T-38s operating at Mach 0.54 at a 10,000-foot altitude. The predicted values were 17.5% savings for the second wingman versus 15% for the first wingman. The flight test phase flew two and three-ship formations to validate the computational work. The results of the two-ship flight tests showed with 80% confidence that the wingman saved fuel in the predicted optimal position (86% wingspan lateral spacing). This position yielded actual fuel savings of 8.8% 5.0% versus the predicted 15%. The other lateral positions did not show a statistically significant fuel savings. The flight test team felt that the three-ship formation data was inconclusive due to the difficulty of trying to fly a stable position as the third aircraft in the formation without station-keeping ability.
Book Synopsis An Analytical Study of T-38 Drag Reduction in Tight Formation Flight by : Eugene H. Wagner
Download or read book An Analytical Study of T-38 Drag Reduction in Tight Formation Flight written by Eugene H. Wagner and published by . This book was released on 2002-03-01 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis explores the benefits of flying in a tight formation, mimicking the natural behavior of migratory birds such as geese. The first phase of the research was to determine an optimal position for the wingman of a tight formation flight of T-38 Talon aircraft using the HASC95 vortex lattice code. A second wingman was then added to determine the benefit derived by increasing formation size. The second wingman was predicted to derive an even greater induced drag benefit than the first wingman for T-38s operating at Mach 0.54 at a 10,000-foot altitude. The predicted values were 17.5% savings for the second wingman versus 15% for the first wingman. The flight test phase flew two and three-ship formations to validate the computational work. The results of the two-ship flight tests showed with 80% confidence that the wingman saved fuel in the predicted optimal position (86% wingspan lateral spacing). This position yielded actual fuel savings of 8.8% 5.0% versus the predicted 15%. The other lateral positions did not show a statistically significant fuel savings. The flight test team felt that the three-ship formation data was inconclusive due to the difficulty of trying to fly a stable position as the third aircraft in the formation without station-keeping ability.
Book Synopsis Evaluating and Augmenting Fuel-saving Benefits Obtained in Aircraft Formation Flight by : Wendy Awele Okolo
Download or read book Evaluating and Augmenting Fuel-saving Benefits Obtained in Aircraft Formation Flight written by Wendy Awele Okolo and published by . This book was released on 2015 with total page 235 pages. Available in PDF, EPUB and Kindle. Book excerpt: When an aircraft flies, it generates wake vortices, which induce a non-uniform wind distribution in its wake. A trail aircraft, placed in the wake of a lead's aircraft vortices experiences this non-uniform wind distribution with varying directions and magnitudes, depending on the location within the wake. It has been demonstrated that there is a "sweet spot" within the wake of a leader in which a trail can experience upwash which leads to reduced drag. Through this mechanism, aircraft can save significant amounts of fuel by flying at the sweet spot of the lead aircraft's wake. This dissertation provides two metrics of obtaining the sweet spot and evaluating the benefits to the trail aircraft at the sweet spot: a static and a dynamic study. The static study, similar to wind tunnel tests in which aircraft are statically placed in formation without trimming, investigates the induced aerodynamic forces and moments on the trail aircraft as it varies its position within the wake of the lead aircraft, and assigns the relative location of maximum lift-to-drag ratio as the static sweet spot. The dynamic study, similar to flight tests which account for trim, analyzes the control surface deflection and thrusts for the trail aircraft as it varies its position within the lead's wake and assigns the location of minimum thrust as the dynamic sweet spot. The static and dynamic analyses are applied to aircraft formations with different relative sizes and varying configurations of trail aircraft such as a flying-wing and a conventional aircraft. Results indicate that sweet spot locations and associated bene ts are dependent on the weight of the leader and the relative sizes of the aircraft pair in the formation. This dissertation then augments the fuel-savings by investigating alternate lateral trimming methods to reduce the need for drag-inducing control effector deflections required at the static sweet spot. Internal fuel transfer and differential thrusting are employed to increase the thrust saved at the static sweet spot, making it comparable to the dynamic sweet spot. Formation simulations of extended durations are also studied to understand the impact of significant weight variations in the leader on the formation benefits. In longduration flights, the lead and trail aircraft weights decrease due to fuel burn. Since the upwash generated by the leader decreases with lift and weight as fuel is burned, the magnitudes of the non-uniform wind induced and thus bene ts for the trail decrease. This decrease is investigated for a 6.5-hour formation simulation. Although there is a reduction in the benefits with time, the overall benefits of flying in formation is significant enough to motivate formations of such long durations. Finally, the feasibility of formation flying is also considered from a perspective of comfort levels for passengers or aircrew in the trail aircraft. Using international standards for likely reactions of a person subjected to discomforts characterized by vibrations, it is shown that there is no additional detrimental degradation of comfort levels for a person onboard a trail aircraft in formation as compared to a solo flight.
Book Synopsis Aircraft Drag Reduction Through Extended Formation Flight by : Simeon Andrew Ning
Download or read book Aircraft Drag Reduction Through Extended Formation Flight written by Simeon Andrew Ning and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Formation flight has the potential to significantly reduce the fuel consumption of long range flights, even with existing aircraft. This research explores a safer approach to formation flying of transport aircraft, which we term extended formation flight. Extended formations take advantage of the persistence of cruise wakes and extend the streamwise separation between the aircraft by at least five wingspans. Classical aerodynamic theory suggests that the total induced drag of the formation should not change as the streamwise separation is increased, but the large separation distances of extended formation flight violate the simple assumptions of these theorems. At large distances, considerations such as wake rollup, atmospheric effects on circulation decay, and vortex motion become important to consider. We first examine the wake rollup process in the context of extended formations and develop an appropriate physics-based model. Using this model, this dissertation addresses three aspects of formation flight: longitudinally extended formations, compressibility effects, and formations of heterogeneous aircraft. Uncertainty analysis is used to investigate the induced drag savings of extended formations in the presence of variation in atmospheric properties, limitations of positioning accuracy, and uncertainty in model parameters. Next, the methodology is integrated with an Euler solver to assess the impact of compressibility while flying in formation. Finally, we examine the important considerations for optimally arranging formations of non-identical aircraft.
Book Synopsis Aerodynamic Drag Reduction Technologies by : Peter Thiede
Download or read book Aerodynamic Drag Reduction Technologies written by Peter Thiede and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: ------------------------------------------------------------ This volume contains the Proceedings of the CEAS/DragNet European Drag Reduction Conference held on 19-21 June 2000 in Potsdam, Germany. This conference, succeeding the European Fora on Laminar Flow Technology 1992 and 1996, was initiated by the European Drag Reduction Network (DragNet) and organised by DGLR under the auspice of CEAS. The conference addressed the recent advances in all areas of drag reduction research, development, validation and demonstration including laminar flow technology, adaptive wing concepts, turbulent and induced drag reduction, separation control and supersonic flow aspects. This volume which comprises more than 40 conference papers is of particular interest to engineers, scientists and students working in the aeronautics industry, research establishments or academia.
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781721993598 Total Pages :30 pages Book Rating :4.9/5 (935 download)
Book Synopsis A Closed-Form Trim Solution Yielding Minimum Trim Drag for Airplanes with Multiple Longitudinal-Control Effectors by : National Aeronautics and Space Administration (NASA)
Download or read book A Closed-Form Trim Solution Yielding Minimum Trim Drag for Airplanes with Multiple Longitudinal-Control Effectors written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-27 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Airplane designs are currently being proposed with a multitude of lifting and control devices. Because of the redundancy in ways to generate moments and forces, there are a variety of strategies for trimming each airplane. A linear optimum trim solution (LOTS) is derived using a Lagrange formulation. LOTS enables the rapid calculation of the longitudinal load distribution resulting in the minimum trim drag in level, steady-state flight for airplanes with a mixture of three or more aerodynamic surfaces and propulsive control effectors. Comparisons of the trim drags obtained using LOTS, a direct constrained optimization method, and several ad hoc methods are presented for vortex-lattice representations of a three-surface airplane and two-surface airplane with thrust vectoring. These comparisons show that LOTS accurately predicts the results obtained from the nonlinear optimization and that the optimum methods result in trim drag reductions of up to 80 percent compared to the ad hoc methods. Goodrich, Kenneth H. and Sliwa, Steven M. and Lallman, Frederick J. Langley Research Center RTOP 505-66-01-02...
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722917272 Total Pages :34 pages Book Rating :4.9/5 (172 download)
Book Synopsis Trim Drag Reduction Concepts for Horizontal Takeoff Single-Stage-To-Orbit Vehicles by : National Aeronautics and Space Administration (NASA)
Download or read book Trim Drag Reduction Concepts for Horizontal Takeoff Single-Stage-To-Orbit Vehicles written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-15 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of a study to investigate concepts for minimizing trim drag of horizontal takeoff single-stage-to-orbit (SSTO) vehicles are presented. A generic hypersonic airbreathing conical configuration was used as the subject aircraft. The investigation indicates that extreme forward migration of the aerodynamic center as the vehicle accelerates to orbital velocities causes severe aerodynamic instability and trim moments that must be counteracted. Adequate stability can be provided by active control of elevons and rudder, but use of elevons to produce trim moments results in excessive trim drag and fuel consumption. To alleviate this problem, two solution concepts are examined. Active control of the center of gravity (COG) location to track the aerodynamic center decreases trim moment requirements, reduces elevon deflections, and leads to significant fuel savings. Active control of the direction of the thrust vector produces required trim moments, reduces elevon deflections, and also results in significant fuel savings. It is concluded that the combination of active flight control to provide stabilization, (COG) position control to minimize trim moment requirements, and thrust vectoring to generate required trim moments has the potential to significantly reduce fuel consumption during ascent to orbit of horizontal takeoff SSTO vehicles. Shaughnessy, John D. and Gregory, Irene M. Langley Research Center RTOP 505-64-40-01...
Book Synopsis Close Formation Flight Control by : Andrew W. Proud (CAPT, USAF.)
Download or read book Close Formation Flight Control written by Andrew W. Proud (CAPT, USAF.) and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Bulletin of the Atomic Scientists by :
Download or read book Bulletin of the Atomic Scientists written by and published by . This book was released on 1961-05 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Bulletin of the Atomic Scientists is the premier public resource on scientific and technological developments that impact global security. Founded by Manhattan Project Scientists, the Bulletin's iconic "Doomsday Clock" stimulates solutions for a safer world.
Book Synopsis A Closed-form Trim Solution Yielding Minimum Trim Drag for Airplanes with Multiple Longitudinal-control Effectors by : Kenneth H. Goodrich
Download or read book A Closed-form Trim Solution Yielding Minimum Trim Drag for Airplanes with Multiple Longitudinal-control Effectors written by Kenneth H. Goodrich and published by . This book was released on 1989 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Three Dimensional Formation Flight Control by : James K. Hall
Download or read book Three Dimensional Formation Flight Control written by James K. Hall and published by . This book was released on 2000-03-01 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: Automating the control of an aircraft flying in formation necessitates the extension of the theory of formation flight control to allow for three dimensional maneuvers. The formation was modeled as a two-aircraft, leader and wingspan, formation. Both aircraft has its own three dimensional, rotating and translating, Cartesian axes system, with special attention being given to the motion of the leader in relation to the wingspan. The controller operated using the equations of motion expressed in the rotating reference frame of the wing aircraft. The control system has seven states, three inputs and three disturbance signals to model the dynamics of the formation in three dimensional space. The control law employed was the feedback of the difference between in actual separation distance and the commanded separation distance to affect changes in thrust, lift, and roll rate. The control system incorporated proportional, integral, and derivative control elements, each with separate gains, to achieve and maintain the specified formation geometry despite various maneuvers flown by the leader. Simulated maneuvers included: an initial displacement of the wingspan away from the formation geometry, and changes in the leader's velocity, altitude, and heading. For each maneuver, the controller performance was sufficient to maintain the commanded formation geometry.
Book Synopsis Proceedings of the NASA·Industry·University General Aviation Drag Reduction Workshop by : Jan Roskam
Download or read book Proceedings of the NASA·Industry·University General Aviation Drag Reduction Workshop written by Jan Roskam and published by . This book was released on 1984 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Viscous Drag Reduction by : C. Sinclair Wells
Download or read book Viscous Drag Reduction written by C. Sinclair Wells and published by . This book was released on 2014-09-01 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt:
