SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 43, ISSUE 13 - JULY 1, 2005

08 AIRCRAFT STABILITY AND CONTROL
Includes flight dynamics, aircraft handling qualities, piloting, flight controls, and autopilots.

For related information see also 05 Aircraft Design, Testing and Performancee and 06 Avionics and Aircraft Instrumentation.

20050177350 Guided Systems Technologies, McDonough, GA USA

Biological Inspired Direct Adaptive Guidance and Control for Autonomous Flight Systems

Corban, J. E.; Gilbert, Cole; Calise, Anthony J.; Tannenbaum, Allen R.; Sep. 2004; 49 pp.; In English Contract(s)/Grant(s): F49620-02-C-0017 Report No.(s): AD-A433221; GST-04-9.1; AFRL-SR-AR-TR-05-0188; No Copyright; Avail: CASI; A03, Hardcopy

The work at Cornell centered on developing experimental methods to characterize flesh fly pursuit evasions, and resulted in the maturation of effective means to capture the 3-D trajectory, as well as body and head orientation. The data was processed at first by hand, and later using image processing algorithms to develop 3-D visualizations at the track, including the head orientation, and ultimately to map the location of the target on the eye during the pursuit. The results provided a means to compare the guidance strategy of the fly with traditional proportional navigation, and to look for inspiration in the development of new guidance laws. Work was also completed to introduce clutter into the encounter. While a much greater understanding of the tracking and guidance strategy of the flesh fly was developed and documented, the work has not yet resulted in the discovery of a better alternative to traditional engineered guidance laws. DTIC

Adaptive Control; Autonomy; Flight Control

20050177639 Academy of Sciences (USSR), Novosibirsk, USSR

Plasma Control of Separated Flows on Bodies of Revolution at High Angles of Attack

Zanine, Boris Y.; Dec. 2004; 61 pp.; In English; Original contains color illustrations Report No.(s): AD-A433660; ISTC-2235P; EOARD-ISTC-01-7036; No Copyright; Avail: Defense Technical Information Center (DTIC)

This report results from a contract tasking Institute of Theoretical and Applied Mechanics as follows: This proposal deals with surface discharge plasmas and other plasma devices to quench stall-slip departure due to 1) asymmetric vortex shedding on conical body nose tips, and 2) augment directional control/ authority. In spite of the extensive work in this area, limited understanding of the underlying basic physical processes near body nose tips as they pertain to symmetry-breaking bifurcations still exist. These deficiencies are evident in the scope of previous experimental, theoretical and CFD studies. It is proposed herein to study and assess the impact of using plasmas on the hydrodynamic stability of key flow singular points. The effort will encompass wind tunnel testing, theoretical analysis, development of prediction methods, and evaluation of potential control techniques. It is envisioned that an important spin-off of this effort will be new yaw departure avoidance and control devices based on high-frequency surface discharges. The team of researchers is well positioned to address this problem. Scientists at the Moscow Institute of Physics and Technology (MIPT) have experience in the flow stability and boundary layer separation as well as the combined asymptotics and numerics needed to perform the theoretical and computational investigations of plasma aerodynamics. The Institute of Theoretical and Applied Mechanics in Novosibirsk (ITAM) will perform the wind tunnel testing. ITAM’s expertise will add their unique capabilities regarding novel experimental techniques such as: spark discharge excitation procedures and special hot wire methods (weakly invasive and ideally suited to assess the boundary layer separation and vortex structure). In addition, Russian personnel expertise will give fresh insights into the attack on the asymmetric vortex problem and surface discharge mechanisms. DTIC

Angle of Attack; Asymmetry; Bodies of Revolution; Plasma Control; Plasmas (Physics); Separated Flow

20050177918 NASA Lewis Research Center, Cleveland, OH, USA

Single-Lever Power Control for General Aviation Aircraft Promises Improved Efficiency and Simplified Pilot Controls

Musgrave, Jeffrey L.; Research and Technology 1996; March 1997; 3 pp.; In English; No Copyright; Avail: CASI; A01, Hardcopy

General aviation research is leading to major advances in internal combustion engine control systems for single-engine, single-pilot aircraft. These advances promise to increase engine performance and fuel efficiency while substantially reducing pilot workload and increasing flight safety. One such advance is a single-lever power control (SLPC) system, a welcome departure from older, less user-friendly, multilever engine control systems. The benefits of using single-lever power controls for general aviation aircraft are improved flight safety through advanced engine diagnostics, simplified powerplant operations, increased time between overhauls, and cost-effective technology (extends fuel burn and reduces overhaul costs). The single-lever concept has proven to be so effective in preliminary studies that general aviation manufacturers are making plans to retrofit current aircraft with the technology and are incorporating it in designs for future aircraft. Derived from text

Combustion Control; Internal Combustion Engines; Levers; Engine Control

20050180663 NASA Lewis Research Center, Cleveland, OH, USA, NASA Dryden Flight Research Center, Edwards, CA, USA, Pratt and Whitney Aircraft, USA, Boeing Phantom Works, USA

Distortion Tolerant Control Demonstrated in Flight

DeLaat, John C.; Research and Technology 1997; April 1998; 3 pp.; In English; No Copyright; Avail: CASI; A01, Hardcopy

Future aircraft turbine engines, both commercial and military, will have to be able to successfully accommodate expected increased levels of steady-state and dynamic engine-face distortion. Advanced tactical aircraft are likely to use thrust vectoring for enhanced aircraft maneuverability.As a result, the engines will see more extreme aircraft angle-of-attack alpha and sideslip beta levels than currently encountered with present-day aircraft. Also, the mixed-compression inlets needed for the High Speed Civil Transport (HSCT) will likely encounter disturbances similar to those seen by tactical aircraft, in addition to planar pulse, inlet buzz, and high distortion levels at low flight speed and off-design operation. The current approach of incorporating sufficient component design stall margin to tolerate these expected levels of distortion would result in significant performance penalties. The objective of NASA’s High Stability Engine Control (HISTEC) program is to design, develop, and flight demonstrate an advanced, high-stability, integrated engine control system that uses measurement-based real-time estimates of distortion to enhance engine stability. The resulting distortion tolerant control adjusts the stall margin requirement online in real-time. This reduces the design stall margin requirement, with a corresponding increase in performance and decrease in fuel burn. Derived from text

Aircraft Engines; Aircraft Control; Turbojet Engine Control; Engine Monitoring Instruments

20050181469 NASA Langley Research Center, Hampton, VA, USA

A Fast-Time Simulation Environment for Airborne Merging and Spacing Research

Bussink, Frank J. L.; Doble, Nathan A.; Barmore, Bryan E.; Singer, Sharon; [2005]; 9 pp.; In English; 23rd Digital Avionics Systems Conference, 24-28 Oct. 2004, Salt Lake City, UT, USA; Original contains color and black and white illustrations Contract(s)/Grant(s): 23-727-01-10; No Copyright; Avail: CASI; A02, Hardcopy

As part of NASA’s Distributed Air/Ground Traffic Management (DAG-TM) effort, NASA Langley Research Center is developing concepts and algorithms for merging multiple aircraft arrival streams and precisely spacing aircraft over the runway threshold. An airborne tool has been created for this purpose, called Airborne Merging and Spacing for Terminal Arrivals (AMSTAR). To evaluate the performance ofAMSTAR and complement human-in-the-loop experiments, a simulation environment has been developed that enables fast-time studies of AMSTAR operations. The environment is based on TMX, a multiple aircraft desktop simulation program created by the Netherlands National Aerospace Laboratory (NLR). This paper reviews the AMSTAR concept, discusses the integration of the AMSTAR algorithm into TMX and the enhancements added to TMX to support fast-time AMSTAR studies, and presents initial simulation results. Author

Aircraft Approach Spacing; Simulation; Algorithms; Air Traffýc Control

20050182046 Kentucky Univ., Lexington, KY, USA

Unsteady Aerodynamic Response of a Linear Cascade of Airfoils in Separated Flow

Capece, Vincent R.; Ford, Christopher; Bone, Christopher; Li, Rui; September 30, 2004; 108 pp.; In English Contract(s)/Grant(s): NAG3-2695; No Copyright; Avail: CASI; A06, Hardcopy

The overall objective of this research program was to investigate methods to modify the leading edge separation region, which could lead to an improvement in aeroelastic stability of advanced airfoil designs. The airfoil section used is representative of current low aspect ratio fan blade tip sections. The experimental potion of this study investigated separated zone boundary layer from removal through suction slots. Suction applied to a cavity in the vicinity of the separation onset point was found to be the most effective location. The computational study looked into the influence of front camber on flutter stability. To assess the influence of the change in airfoil shape on stability the work-per-cycle was evaluated for torsion mode oscillations. It was shown that the front camberline shape can be an important factor for stabilizing the predicted work-per-cycle and reducing the predicted extent of the separation zone. In addition, data analysis procedures are discussed for reducing data acquired in experiments that involve periodic unsteady data. This work was conducted in support of experiments being conducted in the NASA Glenn Research Center Transonic Flutter Cascade. The spectral block averaging method is presented. This method is shown to be able to account for variations in airfoil oscillation frequency that can occur in experiments that force oscillate the airfoils to simulate flutter. Author

Aeroelasticity; Airfoil Oscillations; Airfoil Profiles; Boundary Layer Separation; Transonic Flutter; Unsteady Aerodynamics

Source: NASA.