James V. Carroll

Bio: James V. Carroll is an academic researcher. The author has contributed to research in topics: Catastrophe theory & Stall (fluid mechanics). The author has an hindex of 5, co-authored 8 publications receiving 331 citations.

Bifurcation Analysis of Nonlinear Aircraft Dynamics

Abstract: A new approach is presented for analyzing nonlinear and high-a dynamic behavior and stability of aircraft. This approach involves the application of bifurcation analysis and catastrophe theory methodology to specific phenomena such as stall, departure, spin entry, flat and steep spin, nose slice, and wing rock. Quantitative results of a global nature are presented, using numerical techniques based on parametric continuation. It is shown how our methodology provides a complete representation of the aircraft equilibrium and bifurcation surfaces in the state-control space, using a rigid body model with aerodynamic controls. Also presented is a particularly useful extension of continuation methods to the detection and stability analysis of stable attracting orbits (limit cycles). The use of this methodology for understanding high-a phenomena, especially spin-related behavior, is discussed. RENDS in fighter aircraft design over the past few decades have resulted in configuration s noted for their high speed and performance capability. The cost of achieving this capability has been a drastic, often fatal loss of positive control of the aircraft as the pilot operates at or near the extremes of the flight envelope. This is especially true for aircraft motion at high angles of attack (a), where large deviations both in the state and control variables limits the application of the usual linearized analysis techniques. There is a conspicuous lack of techniques for analyzing global stability and large maneuver response of aircraft. While certain phenomena (e.g., roll coupling) have been analyzed in an isolated manner, there exists a clear need for a unified approach to analyze systematically global aircraft behavior at high a.

Global Stability and Control Analysis of Aircraft at High Angles-of-Attack.

Abstract: : High angle-of-attack phenomena have been of interest to aerodynamicists, aircraft designers, pilots and control system analysts ever since the advent of modern high performance aircraft. Due to the concentration of inertia along the fuselage, the modern jet fighters are highly susceptible to poststall departures and spin. In spite of extensive design effort, modern aircraft still inadvertently enter spins which sometimes result in loss of life and/or property. Extensive wind-tunnel testing and radio-controlled flight testing has been done over the last 20 years to gain a better understanding of the dynamic instabilities at high angles-of-attack. A basic problem has existed in interpreting these data and in making predictions of aircraft dynamic behavior so as to achieve close agreement with flight test data. Most of the work on this project involved a study of the second aircraft model, the F-4. A detailed description of modeling this aircraft, correlation time history runs, and a high angle-of-attack analysis utilizing equilibrium and bifurcation surfaces, is included in this report. The equilibrium spin regimes were found to be rather insensitive to aerosurface control deflections, a result consistent with observed performance. Studies were conducted as well in the stall/post-stall/spin entry regime, a control synthesis approach was initiated, and thrust effects were analyzed.

Bifurcation analysis of aircraft high angle-of-attack flight dynamics

Abstract: A new approach is presented for analyzing nonlinear and high-a dynamic behavior and stability of aircraft. This approach involves the application of bifurcation analysis and catastrophe theory methodology (BACTM) to s pecific phenomena such as stall, departure, spin entry, flat and steep s pin, nose slice, and wing rock. Quantitative results of a global nature are presented, using numerical techniques based on parametric continuation. It is shown how BACTM provides a complete representation of the aircraft equilibrium and bifurcation surfaces in the s tate-control space, u sing a rigid body model and aerosurface controls. Also presented is a particularly useful extension of continuation methods to the d etection and stability analysis of stable a ttracting orbits (limit cycles). The use of BACTM for understanding high-a phenomena, especially spin-related behavior, is discussed.

A study of the application of singular perturbation theory

Abstract: A hierarchical real time algorithm for optimal three dimensional control of aircraft is described Systematic methods are developed for real time computation of nonlinear feedback controls by means of singular perturbation theory The results are applied to a six state, three control variable, point mass model of an F-4 aircraft Nonlinear feedback laws are presented for computing the optimal control of throttle, bank angle, and angle of attack Real Time capability is assessed on a TI 9900 microcomputer The breakdown of the singular perturbation approximation near the terminal point is examined Continuation methods are examined to obtain exact optimal trajectories starting from the singular perturbation solutions

Applications of Singular Perturbation Techniques to Control Problems

Abstract: This paper discusses typical applications of singular perturbation techniques to control problems in the last fifteen years. The first three sections are devoted to the standard model and its time-scale, stability and controllability properties. The next two sections deal with linear-quadratic optimal control and one with cheap (near-singular) control. Then the composite control and trajectory optimization are considered in two sections, and stochastic control in one section. The last section returns to the problem of modeling, this time in the context of large scale systems. The bibliography contains more than 250 titles.

A locally parameterized continuation process

Abstract: The design of a package of continuation procedures called PITCON to handle the following tasks is described' (1) follow numerically any a priori specified curve on an equilibrium manifold; (2) on such a curve determine the exact location of target points where a given variable has a specified value; and (3) on such a curve identify and compute exactly the (simple) limit points where stability may be lost. The process is based on the local parametenzatmn wh]ch uses an estimate of the curvature to control the chome of parameter varmble. Categorms and Subject Descriptors. G 1.5 [Numerical Analysis]Roots of Nonlinear Equations-tteratwe methods, systems of equattons General Terms" Algorithms, Design Addltmnal