NASA STAR REPORTS_ 08_12_05 - Aircraft Stability And Control

Gardner, James A.; Broadfoot, A. L.; Apr. 2004; 14 pp.; In English Contract(s)/Grant(s): F19628-00-C-0017; Proj-1010 Report No.(s): AD-A434559; AFRL-VS-HA-TR-2004-1149; No Copyright; Avail: CASI; A03, Hardcopy

Activity on this contract is divided between validation and verification testing of FLAASH and its radiative transport engine ‘MODTRAN’, and data collection planning and analysis needed to calibrate and validate flight hyperspectral instruments. Major efforts included the atmospheric compensation code ‘Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes: (FLAASH), the MightySat 11.1 Hyperspectral Interferometer (referred to herein as MS 11.1), the Warfighter-1 Hyperspectral Imager (referred to herein as WF-1), the Noble EYE hyperspectral program, and the COMPASS hyperspectral program. DTIC

Computer Techniques; Flight Instruments; Imagery; Line of Sight; Spectra

20050192638 Georgia Tech Research Inst., Atlanta, GA, USA

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Overview of Circulation Control Pneumatic Aerodynamics: Blown Force and Moment Augmentation and Modification as Applied Primarily to Fixed-Wing Aircraft

Englar, Robert J.; Proceedings of the 2004 NASA/ONR Circulation Control Workshop, Part 1; June 2005, pp. 37-99; In English; See also 20050192624; Original contains color illustrations; No Copyright; Avail: CASI; A04, Hardcopy

The use of tangential jet blowing over highly curved aerodynamic surfaces has been shown to yield very strong flow entrainment and resulting aerodynamic/hydrodynamic force and moment augmentation or modification with few or even no moving surfaces. Known as Circulation Control (CC) aerodynamics, this concept has been shown to augment airfoil lift coefficient by as much as 8000% of the input blowing jet momentum. This paper presents and discusses a wide range of proven CC applications including: lift or down-force augmentation; drag reduction or increase; roll, pitch, and yaw amplification/control; thrust deflection; stability augmentation; boundary layer control; hydrodynamic devices; automotive applications; pneumatic propulsors; and micro aircraft surfaces; but primarily emphasizes the application to fixed-wing aircraft. Author

Aerodynamic Forces; Aircraft Configurations; Airfoils; Boundary Layer Control; Drag Reduction; Fixed Wings; Lateral Control

20050195866 NASA Glenn Research Center, Cleveland, OH, USA

Turbofan Engine Simulated in a Graphical Simulation Environment

Parker, Khary I.; Guo, Ten-Huei; Research and Technology 2003; May 2004; 5 pp.; In English; Original contains black and white illustrations; No Copyright; Avail: CASI; A01, Hardcopy

Recently, there has been an increase in the development of intelligent engine technology with advanced active component control. The computer engine models used in these control studies are component-level models (CLM), models that link individual component models of state space and nonlinear algebraic equations, written in a computer language such as Fortran.

The difficulty faced in performing control studies on Fortran-based models is that Fortran is not supported with control design and analysis tools, so there is no means for implementing real-time control. It is desirable to have a simulation environment that is straightforward, has modular graphical components, and allows easy access to health, control, and engine parameters through a graphical user interface. Such a tool should also provide the ability to convert a control design into real-time code, helping to make it an extremely powerful tool in control and diagnostic system development.

Simulation time management is shown: Mach number versus time, power level angle versus time, altitude versus time, ambient temperature change versus time, afterburner fuel flow versus time, controller and actuator dynamics, collect initial conditions, CAD output, and component-level model: CLM sensor, CAD input, and model output.

The Controls and Dynamics Technologies Branch at the NASA Glenn Research Center has developed and demonstrated a flexible, generic turbofan engine simulation platform that can meet these objectives, known as the Modular Aero-Propulsion System Simulation (MAPSS). MAPSS is a Simulink-based implementation of a Fortran-based, modern high pressure ratio, dual-spool, low-bypass, military-type variable-cycle engine with a digital controller. Simulink (The Mathworks, Natick, MA) is a computer-aided control design and simulation package allows the graphical representation of dynamic systems in a block diagram form. MAPSS is a nonlinear, non-real-time system composed of controller and actuator dynamics (CAD) and component-level model (CLM) modules.

The controller in the CAD module emulates the functionality of a digital controller, which has a typical update rate of 50 Hz. The CLM module simulates the dynamics of the engine components and uses an update rate of 2500 Hz, which is needed to iterate to balance mass and energy among system components. The actuators in the CAD module use the same sampling rate as those in the CLM. Two graphs of normalized spool speed versus time in seconds and one graph of normalized average metal temperature versus time in seconds is shown. MAPSS was validated via open-loop and closed-loop comparisons with the Fortran simulation.

The preceding plots show the normalized results of a closed-loop comparison looking at three states of the model: low-pressure spool speed, high-pressure spool speed, and the average metal temperature measured from the combustor to the high-pressure turbine. In steady state, the error between the simulations is less than 1 percent. During a transient, the difference between the simulations is due to a correction in MAPSS that prevents the gas flow in the bypass duct inlet from flowing forward instead of toward the aft end, which occurs in the Fortran simulation. A comparison between MAPSS and the Fortran model of the bypass duct inlet flow for power lever angles greater than 35 degrees is shown. Author

Active Control; Graphical User Interface; Computerized Simulation; Turbofan Engines

20050195891 West Virginia Univ., Morgantown, WV USA

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Development of Formation Flight Control Algorithms Using 3 YF-22 Flying Models

Napolitano, Marcello R.; Apr. 2005; 223 pp.; In English Contract(s)/Grant(s): F49620-01-1-0373 Report No.(s): AD-A434499; AFRL-SR-AR-TR-05-0164; No Copyright; Avail: CASI; A10, Hardcopy

The main objective of this project was to provide a flight demonstration of formation control using UAV research aircraft models. This document will describe the efforts leading to the design, construction, and flight testing of formation control laws using three YF-22 research UAVs designed, built, and instrumented at West Virginia University (WVU). In the selected formation configuration, a radio control (R/C) pilot maintains ground control of the ‘leader’ aircraft while two autonomous ‘follower’ aircraft are required to maintain a pre-defined position and orientation with respect to the ‘leader’ aircraft. The report is organized as follows. First, a description of the aircraft test-bed construction and on-board payload systems will be provided. The following sections will describe the overall design of the formation control laws. Specifically, this design was based on a set of inner and outer loop control laws using a NLDI (non Linear Dynamic Inversion) approach. The implementation of the controller design featured a mathematical model obtained directly from flight data through a PID (Parameter Identification) study. Additional sections will provide a description of the on-board flight control software and simulation work prior to the flight testing activities. A final section will describe the results from an extensive flight testing program. The flight testing activities were articulated in several flight testing of 2-aircraft and 3-aircraft formations. DTIC

Algorithms; Computer Programs; Flight Control; Flight Tests; Formation Flying

20050196208

High Confidence Reconfigurable Distributed Control

Hickey, Jason; Hauser, John; Murray, Richard; Apr. 2005; 44 pp.; In English Contract(s)/Grant(s): F33615-98-C-3613; Proj-A04H Report No.(s): AD-A435114; AFRL-VA-WP-TR-2005-3041; No Copyright; Avail: Defense Technical Information Center (DTIC)

The Caltech/Colorado SEC project developed and tested two major advances in software enabled control: optimizationbased control using real-time trajectory generation and logical programming environments for formal analysis of distributed control systems. These two activities, funded under the OCC and HSCC tasks of the SEC, were integrated and tested on the industry-led demonstration using the F-15 and T-33 flight tests. DTIC

Active Control; Computer Programs; Distributed Parameter Systems; Flight Control; Liquid Phase Epitaxy; Programming Environments

20050196256 Stanford Univ., Stanford, CA USA

Software Enabled Control. Design of Hierarchical, Hybrid Systems

Tomlin, Claire J.; Jan. 2005; 37 pp.; In English Contract(s)/Grant(s): F33615-99-C-3014; Proj-A04H Report No.(s): AD-A435200; AFRL-VA-WP-TR-2005-3053; No Copyright; Avail: Defense Technical Information Center (DTIC)

The objective of this effort is to develop a hybrid control theory for multiple UAVs. Specifically, to develop: A) A hybrid interface between discrete and continuous systems, B) A coordination algorithm for UAVs with distributed sensors. Application areas are air traffic control and satellite formation flight. 1) Real time hybrid system analysis and controller design, 2) Distributed sensing systems, and 3) Asynchronous control theory. Hybrid design (1) is based on solving a constrained optimization problem. This is solved using LMIs with ellipsoidal bounding. The discrete modes use a theorem proven to validate that the modes transition correctly. Distributed sensing (2) is based on precision control of formations of UAVs or satellites with SAR or optical interferometry. Coordinated video ad motion is used to estimate position and resolve conflicts. Asynchronous theory (3) is needed for an effective distributed control architecture. Data is time stamped and weighed with value over time. DTIC

Air Traffýc Control; Artificial Satellites; Computer Programs; Formation Flying; Pilotless Aircraft

20050196629 Naval Surface Warfare Center, Bethesda, MD, USA

Selected Topics Related to Operational Applications of Circulation Control

Rogers, Ernest O.; Abramson, Jane; Proceedings of the 2004 NASA/ONR Circulation Control Workshop, Part 2; June 2005, pp. 743-770; In English; See also 20050196628; Original contains color and black and white illustrations; No Copyright; Avail: CASI; A03, Hardcopy

The topics are: 1. Techniques for exploring new CC application ideas: 3D panel-methods (inviscid), usage and validation modeling of rotary devices. Checklists: initial concept examination; slot flow power accounting 2. Assorted items: Lift: behavior under conditions of very low or negative Vjet. Drag: the airfoil measurement correction term. 3. Recommendations of tasks to support future applications. Derived from text

Airfoils; Automatic Control; Lift Drag Ratio

20050196634 Office of Naval Research, Arlington, VA, USA

Circulation Control: Issues for Naval Applications

Joslin, Ronald D.; Proceedings of the 2004 NASA/ONR Circulation Control Workshop, Part 2; June 2005, pp. 553-575; In English; See also 20050196628; Original contains color illustrations; No Copyright; Avail: CASI; A03, Hardcopy

The application, investigation, and modeling of circulation control are the focus of this workshop and resulting proceedings. Most of the papers in this workshop either experimentally observe performance gains using circulation control or attempt to predict such performance gains with computational fluid dynamics. This paper will highlight the successful implementation of circulation control for some naval aircraft demonstrations. Issues are then raised for the potential application of circulation control for undersea platforms. Author

Computational Fluid Dynamics; Military Aircraft; Circulation Control Airfoils; Circulation Control Rotors

20050196636 Vortex Dynamics Pty. Ltd., Australia

Commercial Applications of Circulation Control

Day, Terence R.; Proceedings of the 2004 NASA/ONR Circulation Control Workshop, Part 2; June 2005, pp. 934-946; In English; See also 20050196628; Original contains color and black and white illustrations; No Copyright; Avail: CASI; A03, Hardcopy

Commercial applications include: wind turbines, orbital pumps, jetfan coanda vacuum cleaner, jetfan driven coanda ceiling fan, and jetfan as a water pump. Derived from text

Coanda Effect; Wind Turbines; Pumps; Sprayers; Vacuum

20050196640 Manchester Univ., UK

The Use of Circulation Control for Flight Control

Frith, Steven; Wood, Norman; Proceedings of the 2004 NASA/ONR Circulation Control Workshop, Part 2; June 2005, pp. 675-688; In English; See also 20050196628; Original contains color and black and white illustrations; No Copyright; Avail: CASI; A03, Hardcopy

The objectives of this project are: (a) To investigate various trailing edge configurations with a view to optimizing the circulation control system on a delta wing; (b) To determine whether the leading edge vortex contributes to the circulation control characteristics; and (c) To extend circulation control as a flight control device as well as providing high lift. Author

Control Equipment; Delta Wings; Flight Control; Vortices

20050196642 Pennsylvania State Univ., State College, PA, USA

Simulation of Steady Circulation Control for the General Aviation Circulation Control (GACC) Wing

Baker, Warren J.; Paterson, Eric G.; Proceedings of the 2004 NASA/ONR Circulation Control Workshop, Part 2; June 2005, pp. 791-811; In English; See also 20050196628; Original contains color and black and white illustrations Contract(s)/Grant(s): N00014-03-1-0122; No Copyright; Avail: CASI; A03, Hardcopy

The aerodynamic characteristics of the General Aviation Circulation Control (GACC) airfoil have been investigated using non time-accurate, 2D, Reynolds-averaged Navier- Stokes simulations with a blended k-omega/k-epsilon turbulence model. An initial study has been completed to determine the most efficient and accurate method to model the jet flow introduction. Convergence histories show that modeling the jet at the jet orifice, instead of including a plenum decreases computational runtime by a factor of 4, while obtaining accurate results as compared to experiment. A 3-point grid study with the square root of 2 refinement was completed for the computational domain without the plenum. Monotonic convergence was not achieved for the grid study, as the convergence rate of (Deltax(sup 2)) was not consistent with a second order scheme. Results for the fine grid show good agreement of surface pressure over the leading 95% of the foil for a given blowing coefficient. Along the aft 5% of the airfoil, CFDSHIP under predicts the magnitude of both the maxima and minima of surface pressure, located at the two jet-slot exits. Mean lift values agree very well with experiment and previous RANS simulations, but RANS results predict a source of unsteadiness not seen in experiment. This source of unsteadiness may be related to using a large domain approach instead of including the tunnel walls in the computational domain. At larger values of C(sub mu), where no experimental data has been obtained, CFDSHIP simulations differ from previous RANS efforts. The near wall spacing for the coarse and medium grids was insufficient to properly capture the physics of the coanda jet, more specifically, the location of the jet separation. Results for the fine grid RANS simulations are encouraging, and as more data from experiment is obtained, more definitive conclusions may be made. Author

Circulation Control Airfoils; General Aviation Aircraft; Aerodynamic Characteristics; Reynolds Averaging; Coanda Effect; Blowing

20050196644 West Virginia Univ., WV, USA

Experimental and Computational Investigation into the Use of the Coanda Effect on the Bell A821201 Airfoil

Angle, Gerald M., II; Huebsch, Wade W.; Smith, James E.; Proceedings of the 2004 NASA/ONR Circulation Control Workshop, Part 2; June 2005, pp. 889-910; In English; See also 20050196628; Original contains color and black and white illustrations; No Copyright; Avail: CASI; A03, Hardcopy

Tilt-rotor aircraft, e.g. the V-22 ‘Osprey’, experience a unique flow scenario in the vertical flight / hover mode. While hovering, this aircraft impinges its rotor wash upon the main wing, limiting the available lift performance. Circulation control (CC) techniques, such as blowing slots using the Coanda effect, can reduce the down-force felt on the main wing, thus recovering part of the lost lift. Leading and trailing edge blowing slots have been added to experimental and computational models of the V-22 main wing to induce the Coanda effect over the curved leading edge and to align the flow with the trailing-edge flap, in the operationally deployed position of 67 degrees. The overall goal is to reduce the size of the wake region below the main wing and thus reduce the downwash force. Initial experimental results show approximately a 10% reduction in download, while the computational fluid dynamics (CFD) analysis indicates a potential 35% reduction could be achieved. Optimal conditions are currently under investigation. Author

Airfoils; Coanda Effect; Tilt Rotor Aircraft; Trailing Edge Flaps; Vertical Flight; Hovering; V-22 Aircraft; Control Systems Design

20050196645 Naval Surface Warfare Center, Bethesda, MD, USA

Exploratory Investigations of Circulation Control Technology: Overview for Period 1987-2003 at NSWCCD

Imber, Robin; Proceedings of the 2004 NASA/ONR Circulation Control Workshop, Part 2; June 2005, pp. 577-602; In English; See also 20050196628; Original contains color and black and white illustrations; No Copyright; Avail: CASI; A03, Hardcopy

This presentation covers six of the major CC exploratory investigations that have taken place since the last CC workshop that was held in 1986. The 2-D dual slotted airfoil was designed and tested in 1987 by Jane Abramson. Test documentation can be found in NSWCCD-50-TR-2004/030. The airfoil was the first CC model designed at Carderock to incorporate both upper and lower trailing edge blowing slots. The dual slots provide the ability to produce lift in either direction. The fundamental design objective was to increase the control range so that force control in both directions was available. This plot shows lift coefficient vs. C(sub mu) and reveals that the goal of doubling the control range was met. An unexpected finding was that the performance of the lower slot, in terms of measured lift augmentation, was noticeably better than the upper slot. Derived from text

Aerodynamic Coeffýcients; Circulation Control Airfoils; Circulation Control Rotors; Lift; Trailing Edges

20050196721 NASA Dryden Flight Research Center, Edwards, CA, USA

Selected Flight Test Results for Online Learning Neural Network-Based Flight Control System

Williams-Hayes, Peggy S.; December 30, 2004; 17 pp.; In English; AIAA 1st Intelligent Systems Technical Conference, 20-23 Sep. 2004, Chicago, IL, USA Contract(s)/Grant(s): WU 711-60-00-SE-80 Report No.(s): NASA/TM-2004-212857; H-2575; No Copyright; Avail: CASI; A03, Hardcopy

The NASA F-15 Intelligent Flight Control System project team developed a series of flight control concepts designed to demonstrate neural network-based adaptive controller benefits, with the objective to develop and flight-test control systems using neural network technology to optimize aircraft performance under nominal conditions and stabilize the aircraft under failure conditions. This report presents flight-test results for an adaptive controller using stability and control derivative values from an online learning neural network. A dynamic cell structure neural network is used in conjunction with a real-time parameter identification algorithm to estimate aerodynamic stability and control derivative increments to baseline aerodynamic derivatives in flight. This open-loop flight test set was performed in preparation for a future phase in which the learning neural network and parameter identification algorithm output would provide the flight controller with aerodynamic stability and control derivative updates in near real time. Two flight maneuvers are analyzed - pitch frequency sweep and automated flight-test maneuver designed to optimally excite the parameter identification algorithm in all axes. Frequency responses generated from flight data are compared to those obtained from nonlinear simulation runs. Flight data examination shows that addition of flight-identified aerodynamic derivative increments into the simulation improved aircraft pitch handling qualities. Author

F-15 Aircraft; Automatic Flight Control; Aircraft Control; Neural Nets; Flight Tests

Source: NASA.

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