Engineering topics

Abel, Irving

Publications and source records attributed to Abel, Irving.

5 records

NASA NTRS1997

Research and Applications in Aeroelasticity and Structural Dynamics at the NASA Langley Research Center

An overview of recently completed programs in aeroelasticity and structural dynamics research at the NASA Langley Research Center is presented. Methods used to perform flutter clearance studies in the wind-tunnel on a high performance fighter are discussed. Recent advances in the use of smart structures and controls to solve aeroelastic problems, including flutter and gust response are presented. An aeroelastic models program designed to support an advanced high speed civil transport is described. An extension to transonic small disturbance theory that better predicts flows involving separation and reattachment is presented. The results of a research study to determine the effects of flexibility on the taxi and takeoff characteristics of a high speed civil transport are presented. The use of photogrammetric methods aboard Space Shuttle to measure spacecraft dynamic response is discussed. Issues associated with the jitter response of multi-payload spacecraft are discussed. Finally a Space Shuttle flight experiment that studied the control of flexible spacecraft is described.

Abel, Irving↗

NASA NTRS1992

Research and applications in structural dynamics and aeroelasticity

Results of some recently completed research programs in aeroelasticity and structural dynamics at the NASA Langley Research Center are presented. It is shown that multifunctional active controls can be used to control flutter and loads on future advanced fighter configurations. A description and early results of an experimental program are presented in order to provide a well documented data base for validating unsteady aerodynamic codes. It is shown that the degradation in aeroelastic behavior due to thermal effects on a hypersonic vehicle can be offset by the use of active controls. The feasibility of using adaptive materials to control flutter is demonstrated experimentally. A description of the latest unstructured grid methods for use in advanced computational unsteady aerodynamic codes is presented. A program to improve the ability of FEMs to predict rotorcraft vibrational characteristics is described. The use of aeroelastic tailoring to improve the performance of tilt rotor vehicles is examined.

Abel, Irving↗

NASA NTRS1989

Overview of Dynamics Integration Research (DIR) program at Langley Research Center

Research goals and objectives for an ongoing activity at Langley Research Center (LaRC) are described. The activity is aimed principally at dynamics optimization for aircraft. The effort involves active participation by the Flight Systems, Structures, and Electronics directorates at LaRC. The Functional Integration Technology (FIT) team has been pursuing related goals since 1985. A prime goal has been the integration and optimization of vehicle dynamics through collaboration at the basic principles or equation level. Some significant technical progress has been accomplished since then and is reflected here. An augmentation for this activity, Dynamics Integration Research (DIR), has been proposed to NASA Headquarters and is being considered for funding in FY 1990 or FY 1991.

Sliwa, Steven M.↗

NASA NTRS1988

Filling the expertise gap

Aeroelasticity, structures, and stability-and-control specialists can work in concerted fashion during the early design phases of future aircraft to achieve active control of naturally unstable configurations. In order to take full advantage of active control, attention must be given by designers to control-law synthesis, and to tools for the efficient synthesis and analysis of complex flexible-aircraft control systems. Analysts must consider interfaces among unsteady aerodynamics, structures, and control theory, as explored by the theory of analytic continuation for unsteady aerodynamics.

Abel, Irving↗

NASA NTRS1988

Research and applications in aeroservoelasticity at the NASA Langley Research Center

A review of analytical methods used to analyze flexible vehicles with active controls is presented. Methods used to approximate and correct unsteady aerodynamic forces used in the analysis are discussed. Recent advances in the application of optimal methods to digital control law synthesis are presented. The use of active controls in an integrated design process is also discussed. Finally, the results of recent wind-tunnel studies aimed at demonstrating active control concepts and validating the analytical methods are presented.

Abel, Irving↗