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Users manual for 3 computer programs for predicting aerodynamic interference between lifting surfaces and lift and cruise fans in transport-type aircraft
A low frequency unsteady lifting-line theory is developed for a harmonically oscillating wing of large aspect ratio. The wing is assumed to be chordwise rigid but completely flexible in the span direction. The theory is developed by use of the method of matched asymptotic expansions which reduces the problem from a singular integral equation to quadrature. The wing displacements are prescribed and the pressure field, airloads, and unsteady induced downwash are obtained in closed form. The influence of reduced frequency, aspect ratio, planform shape, and mode of oscillation on wing aerodynamics is demonstrated through numerical examples. Compared with lifting-surface theory, computation time is reduced significantly. Using the present theory, the energetic quantities associated with the propulsive performance of a finite wing oscillating in combined pitch and heave are obtained in closed form. Numerical examples are presented for an elliptic wing.
A man-in-the-loop simulation study of the handling qualities of the HL-20 lifting body vehicle has been performed in a fixed-base simulation cockpit. The study was aimed at identifying opportunities to improve the original design of the vehicle from a handling qualities and landing performance perspective. A subsonic aerodynamic model of the HL-20 was used as a baseline, and visual approaches and landings were made at various vehicle lift-to-drag (L/D) ratios. It is concluded that there is a high degree of correlation between maximum L/D ratio and pilot rating. Using the pilot ratings Level 1, flying qualities were found to be possible for configurations with a maximum L/D ratio of 3.8 or higher.
Aerodynamic characteristics of V/STOL transport model powered by lift and rotating cruise fans
Aerodynamic characteristics of V/STOL transport model with wing-mounted lift fans - large-scale wind tunnel investigation
Sharp edge delta wing drag prediction by application of leading edge suction analogy of vortex lift
Aerodynamic characteristics of large-scale model with lift fan mounted in 5 percent thick triangular wing
Conceptual designs of V/STOL lift fan commercial short haul transport aircraft for the 1980-85 time period were studied to determine their technical and economic feasibility. The engine concepts included both integral and remote fans. The scope of the study included definition of the hover control concept for each propulsion system, aircraft design, aircraft mass properties, cruise performance, noise and ride qualities evaluation. Economic evaluating was also studied on a basis of direct operating costs and route structure.
The design and construction of an experimental facility for the investigation of scaling effects in propulsive lift configurations are described. The facility was modeled after an existing full size NASA facility which consisted of a coaxial turbofan jet engine with a rectangular nozzle in a blown surface configuration. The flow field of the model facility was examined with and without a simulated wing surface in place at several locations downstream of the nozzle exit plane. Emphasis was placed on obtaining pressure measurements which were made with static probes and surface pressure ports connected via plastic tubing to condenser microphones for fluctuating measurements. Several pressure spectra were compared with those obtained from the NASA facility, and were used in a preliminary evaluation of scaling laws.
The Personnel Launch System (PLS) is a small transportation system designed to transport people, but no cargo, to and from low-earth orbit. The PLS is being considered as an addition to the manned launch capability of the United States for three main reasons: (1) to assure manned access to space, (2) to achieve a first-stage abort ability, and (3) to reduce operations costs. To those ends, two designs are being considered for the PLS that differ in their lift-to-drag (L/D) ratio. The Lyndon B. Johnson Space Center was assigned the task of examining low L/D capsules with no wings and a parachute landing capability. The Langley Research Center is studying a higher L/D PLS with wings and runway landings. Whichever design is selected, the PLS will act as a complement to the Space Shuttle fleet and will enhance the ability of our Nation to achieve reliable, safe, and cost-effective access to space flight, thus furthering the goals of the U.S. space program and increasing the safety of the human crews manning a future space station.
The NASA Ares Projects are developing the launch vehicles to move the United States and humanity beyond low earth orbit. Ares 1 is a crewed vehicle, and Ares V is a heavy-lift vehicle being designed to send crews and cargo to the Moon. The Ares V design is evolving and maturing toward an authority-to-proceed milestone in 2011. The Ares V vehicle will be considered a national asset, opening new worlds and creating unmatched opportunities for human exploration, science, national security, and space business.
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System identification methods have been applied to rotorcraft to estimate stability derivatives from transient flight control response data. While these applications assumed a linear constant coefficient representation of the rotorcraft, the computer experiments used transient responses in flap-bending and torsion of a rotor blade at high advance ratio which is a rapidly time varying periodic system. It was found that a simple system identification method applying a linear sequential estimator also called least square estimator or equation of motion estimator, is suitable for this periodic system and can be used directly if only the acceleration data are noise polluted. In the case of noise being present also in the state variable data the direct application of the estimator gave poor results.
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