The Experts below are selected from a list of 138 Experts worldwide ranked by ideXlab platform
Rick Lind - One of the best experts on this subject based on the ideXlab platform.
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Flight dynamics of a pterosaur-inspired aircraft utilizing a variable-placement vertical tail
Bioinspiration & Biomimetics, 2011Co-Authors: Brian Roberts, Rick Lind, Sankar ChatterjeeAbstract:Mission performance for small aircraft is often dependent on the turn radius. Various biologically inspired concepts have demonstrated that performance can be improved by morphing the wings in a manner similar to birds and bats; however, the morphing of the vertical tail has received less attention since neither birds nor bats have an appreciable vertical tail. This paper investigates a design that incorporates the morphing of the vertical tail based on the cranial crest of a pterosaur. The aerodynamics demonstrate a reduction in the turn radius of 14% when placing the tail over the nose in comparison to a traditional aft-placed vertical tail. The flight dynamics associated with this configuration has unique characteristics such as a Dutch-Roll Mode with excessive Roll motion and a skid divergence that replaces the Roll convergence.
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Roll Control for a Micro Air Vehicle Using Active Wing Morphing
AIAA Guidance Navigation and Control Conference and Exhibit, 2003Co-Authors: Helen Garcia, Mujahid Abdulrahim, Rick LindAbstract:Relatively small aircraft have recently been receiving considerable attention in the flight test community. In particular, aircraft denoted by DARPA as a micro air vehicle, MAV, are being designed with wing span less than 6 in to operate at airspeeds less than 25 mph. Such aircraft are envisioned as expendable platforms for surveillance and data collection that can operate in dangerous or confined spaces. The University of Florida has been extremely active in the field of MAV design and testing. The team led by Dr. Peter Ifju is especially accomplished in that they have won various aspects of the Micro Aerial Vehicle Competition, sponsored by the International Society of Structural and Multidisciplinary Optimization, each year from 1999 to 2002. His team has designed, built, and flown many unique designs ranging from 2 ft to 4 in wing span that are remotely piloted using vision feedback to a ground station. Most of the MAVs currently being flown at the University of Florida have a similarity; namely, these aircraft are demonstrably difficult to fly. Such difficulty is somewhat expected given that the aircraft are highly agile and maneuverable but must be flown remotely. The team is currently investigating methods of active control for the MAV that would allow autonomous operation and greatly extend the applications for which such vehicles may be considered. The use of innovative control effectors is an area being explored as an enabling technology for designing a stability augmentation system. The current generation ofMAV uses traditional effectors, specifically an elevator and rudder, whose positions are commanded by the remote pilot. The elevator presents adequate effectiveness for longitudinal control but the rudder presents some difficulty for lateral-directional control. Basically, the rudder mainly excites the Dutch Roll Mode so steering and gust rejection are really accomplished using the coupled Roll and yaw motion resulting from Dutch Roll dynamics. Such an approach is obviously not optimal but traditional ailerons are not feasible on this type of aircraft. The concept of morphing presents several opportunities for enabling control of a MAV. Morphing is particularly appealing for twisting the wing and enabling Roll control. Wing twist is actually used on the current MAV but in a passive sense. Essentially, the wing deforms under loading in flight to produce a passive washout that helps smooth the flight path. Such a concept can be extended to allow greater twists that are actively commanded to generate large Roll moments.
L I Rui - One of the best experts on this subject based on the ideXlab platform.
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Coordinated Stability Based Trajectory Tracking Control Law Design of Reconnaissance and Attack UAV
Control Conference (CCC) 2011 30th Chinese, 2011Co-Authors: S H I Yingjng, L I RuiAbstract:Trajectory tracking problem of reconnaissance and attack UAV is considered in this paper. Arch circle is introduced before the turning point of the flight route to keep good reconnaissance and attack purpose. Trim, small disturbance and linearization techniques are applied to the ontology Mode of the UAV. By analyzing the dynamical character of pitching Mode, Rolling Mode and Dutch Roll Mode, the integrated guidance and control (IGC) system design method is used for UAV to accomplish reconnaissance and attack task. For longitudinal control law design, height feedback is used as guidance loop and pitching angle and pitching angular velocity replace control loop, while for lateral-directional control law design, coordinated stability based method is used, where interface signal is introduced to aileron and rudder channel. The six freedom simulations are given to demonstrate the efficiency of the proposed method.
Ronglin Li - One of the best experts on this subject based on the ideXlab platform.
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Coordinated stability based trajectory tracking control law design of reconnaissance and attack UAV
Proceedings of the 30th Chinese Control Conference CCC 2011, 2011Co-Authors: Y Shi, Ronglin LiAbstract:Trajectory tracking problem of reconnaissance and attack UAV is considered in this paper. Arch circle is introduced before the turning point of the flight route to keep good reconnaissance and attack purpose. Trim, small disturbance and linearization techniques are applied to the ontology Mode of the UAV. By analyzing the dynamical character of pitching Mode, Rolling Mode and Dutch Roll Mode, the integrated guidance and control (IGC) system design method is used for UAV to accomplish reconnaissance and attack task. For longitudinal control law design, height feedback is used as guidance loop and pitching angle and pitching angular velocity replace control loop, while for lateral-directional control law design, coordinated stability based method is used, where interface signal is introduced to aileron and rudder channel. The six freedom simulations are given to demonstrate the efficiency of the proposed method. © 2011 Chinese Assoc of Automati.
Sankar Chatterjee - One of the best experts on this subject based on the ideXlab platform.
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Flight dynamics of a pterosaur-inspired aircraft utilizing a variable-placement vertical tail
Bioinspiration & Biomimetics, 2011Co-Authors: Brian Roberts, Rick Lind, Sankar ChatterjeeAbstract:Mission performance for small aircraft is often dependent on the turn radius. Various biologically inspired concepts have demonstrated that performance can be improved by morphing the wings in a manner similar to birds and bats; however, the morphing of the vertical tail has received less attention since neither birds nor bats have an appreciable vertical tail. This paper investigates a design that incorporates the morphing of the vertical tail based on the cranial crest of a pterosaur. The aerodynamics demonstrate a reduction in the turn radius of 14% when placing the tail over the nose in comparison to a traditional aft-placed vertical tail. The flight dynamics associated with this configuration has unique characteristics such as a Dutch-Roll Mode with excessive Roll motion and a skid divergence that replaces the Roll convergence.
D. Thomson - One of the best experts on this subject based on the ideXlab platform.
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Examining the stability derivatives of a compound helicopter
Aeronautical Journal, 2017Co-Authors: K. Ferguson, D. ThomsonAbstract:© Royal Aeronautical Society 2016. Some helicopter manufacturers are exploring the compound helicopter design as it could potentially satisfy the new emerging requirements placed on the next generation of rotorcraft. It is well understood that the main benefit of the compound helicopter is its ability to reach speeds that significantly surpass the conventional helicopter. However, it is possible that the introduction of compounding may lead to a vehicle with significantly different flight characteristics when compared to a conventional helicopter. One method to examine the flight dynamics of an aircraft is to create a linearised mathematical Model of the aircraft and to investigate the stability derivatives of the vehicle. The aim of this paper is to examine the stability derivatives of a compound helicopter through a comparison with a conventional helicopter. By taking this approach, some stability, handling qualities and design issues associated with the compound helicopter can be identified. The paper features a conventional helicopter and a compound helicopter. The conventional helicopter is a standard design, featuring a main rotor and a tail-rotor. The compound helicopter configuration features both lift and thrust compounding. The wing offloads the main rotor at high speeds, whereas two propellers provide additional propulsive thrust as well as yaw control. The results highlight that the bare airframe compound helicopter would require a larger tailplane surface to ensure acceptable longitudinal handling qualities in forward flight. In addition, without increasing the size of the bare airframe compound helicopter's vertical fin, the Dutch Roll Mode satisfies the ADS-33 level 1 handling qualities category for the majority of the flight envelope.
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Examining the stability derivatives of a compound helicopter
Aeronautical Journal, 2016Co-Authors: K. Ferguson, D. ThomsonAbstract:Some helicopter manufacturers are exploring the compound helicopter design as it could potentially satisfy the new emerging requirements placed on the next generation of rotorcraft. It is well understood that the main benefit of the compound helicopter is its ability to reach speeds that significantly surpass the conventional helicopter. However, it is possible that the introduction of compounding may lead to a vehicle with significantly different flight characteristics when compared to a conventional helicopter. One method to examine the flight dynamics of an aircraft is to create a linearised mathematical Model of the aircraft and to investigate the stability derivatives of the vehicle. The aim of this paper is to examine the stability derivatives of a compound helicopter through a comparison with a conventional helicopter. By taking this approach, some stability, handling qualities and design issues associated with the compound helicopter can be identified. The paper features a conventional helicopter and a compound helicopter. The conventional helicopter is a standard design, featuring a main rotor and a tail-rotor. The compound helicopter configuration features both lift and thrust compounding. The wing offloads the main rotor at high speeds, whereas two propellers provide additional propulsive thrust as well as yaw control. The results highlight that the bare airframe compound helicopter would require a larger tailplane surface to ensure acceptable longitudinal handling qualities in forward flight. In addition, without increasing the size of the bare airframe compound helicopter’s vertical fin, the Dutch Roll Mode satisfies the ADS-33 level 1 handling qualities category for the majority of the flight envelope.
