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At least 271 records · Page 15

Exploratory flight investigation of aircraft response to the wing vortex wake generated by the augmentor wing jet STOL research aircraft

A brief exploratory flight program was conducted at Ames Research Center to investigate the vortex wake hazard of a powered-lift STOL aircraft. The study was made by flying an instrumented Cessna 210 aircraft into the wake of the augmentor wing jet STOL research aircraft at separation distances from 1 to 4 n.mi. Characteristics of the wake were evaluated in terms of the magnitude of the upset of the probing aircraft. Results indicated that within 1 n.mi. separation the wake could cause rolling moments in excess of roll control power and yawing moments equivalent to rudder control power of the probe aircraft. Subjective evaluations by the pilots of the Cessna 210 aircraft, supported by response measurements, indicated that the upset caused by the wake of the STOL aircraft was comparable to that of a DC-9 in the landing configuration.

Jacobsen, R. A.↗

A parametric wing design study for a modern laminar flow wing

The results of a parametric wing design study using a modern laminar flow airfoil designed to exhibit desirable stall characteristics while maintaining high cruise performance are presented. It was found that little is sacrificed in cruise performance when satisfying the stall margin requirements if a taper ratio of 0.65 or greater is used.

Koegler, J. A., Jr.↗

An integrated study of structures, aerodynamics and controls on the forward swept wing X-29A and the oblique wing research aircraft

The results of an integrated study of structures, aerodynamics, and controls using the STARS program on two advanced airplane configurations are presented. Results for the X-29A include finite element modeling, free vibration analyses, unsteady aerodynamic calculations, flutter/divergence analyses, and an aeroservoelastic controls analysis. Good correlation is shown between STARS results and various other verified results. The tasks performed on the Oblique Wing Research Aircraft include finite element modeling and free vibration analyses.

Dawson, Kenneth S.↗

Navier-Stokes prediction of large-amplitude delta-wing roll oscillations characterizing wing rock

High-incidence vortical flow about a 65-deg sweep delta wing undergoing static roll and large-amplitude, high-rate-of-roll oscillations is simulated numerically using the time-dependent, three-dimensional, Reynolds-averaged, Navier-Stokes equations. Turbulent computations are presented for static roll angles up through 42 degrees. The effects of roll angle on the vortex aerodynamics are discussed, and the solution accuracy is evaluated by comparison with experimental data. The effects of grid refinement and zonal boundary condition treatment on solution accuracy are assessed at zero roll angle. Numerical simulation of a forced periodic roll motion is also presented.

Chaderjian, Neal M.↗

On the use of the indicial-function concept in the analysis of unsteady motions of wings and wing-tail combinations

The concept of indicial aerodynamic functions is applied to the analysis of the short-period pitching mode of aircraft. By the use of simple physical relationships associated with the indicial-function relationships concept, quantitative studies are made of the separate effects on the damping in pitch of changes in Mach number, aspect ratio, plan-form shape, and frequency. The concept is further shown to be of value in depicting physically the induced effects on a tail surface which follows in the wake of a starting forward surface. Considerable effort is devoted to the development of theoretical techniques whereby the transient response in lift at the tail to the wing wake may be estimated. Numerical results for several representative cases are presented, and these are analyzed to reassess the importance of the contribution to the rotary damping moment of the interference lift at the tail.

Tobak, Murray↗