Engineering Papers⌕ Search

Engineering topics

Ayers, T. G.

Publications and source records attributed to Ayers, T. G..

12 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

NACA/NASA supersonic flight research

The use of experimental and testbed vehicles and their contributions to fundamental problem solving and overall vehicle characteristics are presented. A chronological description of aircraft from the first supersonic flight in the X-1 through the development of the F-100 series, the X-15, and the B-1 is given. One of the early significant contributions made was the development of the all-moving stabilizer that solved the problem associated with high-speed tuck and the trim requirements of entry into the supersonic regime. Some wind tunnel/flight drag characteristics studies associated with the B-1 bomber involving flexibility effects and wind tunnel effects are shown. Finally, the evolution of digital systems to enhance maintainability and reliability and to reduce the work load in the cockpit are described.

Ayers, T. G.↗
NASA NTRS1990

The need for a hypersonic demonstrator

The requirement for research aircraft and demonstrator vehicles has been seriously challenged by tight budgets and erroneous impressions that aeronautical technology has matured to a point where the value added by flight research and/or demonstration is not sufficient to offset the costs. While this issue may be debatable with respect to subsonic/transonic speeds, such is not the case for high-speed (supersonic and hypersonic) operation. The aerodynamic performance, weight/payload fractions, and thermodynamic problems are such that small margins of error can be tantamount to the vehicle being unable to reach its design point or so inefficient as to render it useless. This paper addresses some of the critical design considerations and operational constraints which make it mandatory to carry out flight research and develop a demonstrator vehicle in order that the risks be reduced to an acceptable level to assure technology readiness for viable hypersonic flight.

Ayers, T. G.↗
NASA NTRS1982

Review of the 1980 Wind-Tunnel/Flight Correlation Panel

Wind tunnel/flight correlation history from the P-51 to the F-8 supercritical wing is reviewed, showing that researchers continue to be faced with nearly identical discrepancies in predicted versus measured drag. The capabilities of the National Transonic Facility to allow assessment of the effects which have heretofore plagued researchers and aircraft designers are anticipated.

Ayers, T. G.↗
NASA NTRS1981

A review of flight-to-wind tunnel drag correlation

Comparisons are made of wind-tunnel-model and flight drag data for various configurations representing aircraft from the mid-1940s to the 1970s. Discrepancies between model and flight data such as Reynolds number effects, wall interference, and aeroelastic problems are discussed. String support effects and the inability of models to simulate surface deflections for longitudinal trim are also studied. A wind tunnel-to-flight correlation of turbulent friction drag confirms the incompressible Karman-Schoenherr variation of turbulent skin friction with Reynolds number and the T' method for accounting compressibility effects. NASA tested 10 deg cone research indicates that model tests which are affected by tunnel noise may require the lower disturbance level environment available in flight, and it is concluded that new cryogenic facilities will improve the fidelity of model simulations of full-scale flight flow phenomena.

Saltzman, E. J.↗
NASA NTRS1981

Report of the wind tunnel/flight correlation panel

Basic calibration of the tunnel prior to conducting any tests, the areas requiring wind tunnel/flight test correlation for validating the NTF, and recommendations for achieving validation of the NTF are discussed.

Ayers, T. G.↗
NASA NTRS1981

Historical background and design evolution of the transonic aircraft technology supercritical wing

Two dimensional wind tunnel test results obtained for supercritical airfoils indicated that substantial improvements in aircraft performance at high subsonic speeds could be achieved by shaping the airfoil to improve the supercritical flow above the upper surface. Significant increases in the drag divergence Mach number, the maximum lift coefficient for buffer onset, and the Mach number for buffet onset at a given lift coefficient were demonstrated for the supercritical airfoil, as compared with a NACA 6 series airfoil of comparable thickness. These trends were corroborated by results from three dimensional wind tunnel and flight tests. Because these indicated extensions of the buffet boundaries could provide significant improvements in the maneuverability of a fighter airplane, an exploratory wind tunnel investigation was initiated which demonstrated that significant aerodynamic improvements could be achieved from the direct substitution of a supercritical airfoil on a variable wing sweep multimission airplane model.

Ayers, T. G.↗
NASA NTRS1977

Transonic wind-tunnel investigation of the maneuver potential of the NASA supercritical wing concept, phase 1

An investigation was conducted in the NASA Langley 8-foot transonic pressure tunnel at Mach numbers from 0.60 to 0.975 with a variable-wing-sweep airplane model in order to evaluate a series of wings designed to demonstrate the maneuver potential of the supercritical airfoil concept. Both conventional and supercritical wing designs for several planform configurations were investigated with wing sweep angles from 16.0 deg to 72.5 deg, depending on Mach number and wing configuration. The supercritical wing configuration showed significant improvements over the conventional configurations in drag-divergence Mach number and in drag level at transonic maneuver conditions.

Hallissy, J. B.↗
NASA NTRS1973

A Wind-Tunnel Investigation of the Application of the NASA Supercritical Airfoil to a Variable-Wing-Sweep Fighter Airplane

An investigation was conducted in the Langley 8 foot transonic pressure tunnel and the Langley Unitary Plan wind tunnel to evaluate the effectiveness of three variations of the NASA supercritical airfoil as applied to a model of a variable wing sweep fighter airplane. Wing panels incorporating conventional NACA 64A series airfoil with 0.20 and 0.40 camber were used as bases of reference for this evaluation. Static force and moment measurements were obtained for wing leading edge sweep angles of 26, 33, 39, and 72.5 degrees. Fluctuating wing root bending moment data were obtained at subsonic speeds to determine buffet characteristics. Subsonic data were also obtained for determining the effects of wing transition location and spoiler deflection. Limited lateral directional data are included for the conventional 0.20 cambered wing and the supercritical wing.

Ayers, T. G.↗
NASA NTRS1972

Supercritical aerodynamics - Worthwhile over a range of speeds.

Supercritical flow exists whenever a high enough forward speed causes local flow over a lifting surface or body to exceed the sonic or critical value. The principal difference between conventional subsonic aerodynamic technology and supercritical technology lies in the cross-sectional profile of lifting surfaces. The characteristics of the supercritical airfoil suggests three potential benefits from applications to civil aircraft. For aircraft designed to operate at moderate subsonic speeds the supercritical airfoil may permit the reduction of structural weight. Supercritical technology would have a second application in permitting efficient high subsonic speed cruise by delaying the transonic drag rise. Another advantage of the thick supercritical wing shows up at low speeds.

Ayers, T. G.↗
NASA NTRS1972

The NASA Advanced Transport Technology Program.

Review of an advanced technology program initiated by NASA to expedite the development and application of advanced technologies to the next generation of subsonic CTOL jet transports. The major technical elements of this program include airframe and engine system studies for identifying technology needs, technology development for providing the necessary base in those areas of the aeronautical disciplines offering significant payoffs, and exploratory flight vehicles for validating advanced concepts and demonstrating specific benefits associated with civil applications. The possible benefits and application of the NASA-developed supercritical aerodynamic technology are discussed in some detail. Early experimental aerodynamic results obtained from wind tunnel and flight investigations are included.

Ayers, T. G.↗
NASA NTRS1969

Effect of wing-transition location and slotted and unslotted flaps on aerodynamic characteristics of a fighter model at high subsonic speeds

An investigation was conducted in the Langley 8 foot transonic pressure tunnel to determine the effects of wing transition location and of slotted and unslotted full span flaps on the longitudinal aerodynamic characteristics of a 1/15 scale model of a variable wing sweep tactical fighter model. Tests were at Mach numbers from 0.70 to 0.85 for a wing leading edge sweep of 26 deg.

Ayers, T. G.↗