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Technical Paper

Recent Transonic Airfoil Developments and Some Business Aircraft Implications

Significant advances in transonic airfoil technology have occurred during the last decade in Europe and in the United States. Some of this new technology, available in the open literature, could be applied to business aircraft. The phenomenological differences between the flow characteristics of the newer transonic airfoils and the conventional NASA-type airfoils are described. In particular, supercritical flow generation and recompression without shock-wave, boundary-layer interaction sufficiently strong to destroy the airfoil aerodynamic efficiency are emphasized. One deterrent to the use of improved transonic airfoils is the sophisticated design methodology required to transform an airfoil into a successful three-dimensional wing. Some techniques for designing compatible wings and fuselages, where a large percentage of their surfaces is covered with supercritical flow, are described.
Technical Paper

The Significance of Advanced Structural Fabrication Techniques on Aircraft Lightning Protection

The basic electromagnetic shielding of conventional riveted aluminum aircraft construction provides inherent protection to the aircraft systems and occupants against the hazards of lightning discharges. The increased use of adhesively bonded construction techniques on structures of future aircraft indicates a potential reduction in the basic electrical continuity of the airframe. The significance of the conductivity reduction on aircraft lightning protection will be evaluated for various proposed construction techniques, including: bonded honeycomb skin panels, bonded skin joints, bonded basic structure, and different types of monocoque construction. The discussion examines related problems that have been encountered in designing protection for aluminum aircraft.
Technical Paper

A General Three-Dimensional Potential-Flow Method Applied to V/STOL Aerodynamics

This paper describes a numerical method for solving three-dimensional incompressible flow problems and its use in predicting the aerodynamic characteristics of V/STOL aircraft. Arbitrary configuration and inlet geometry, fan inflow distributions, thrust vectoring, jet entrainment, angles of yaw, and flight speeds from hover through transition can be treated. Potential-flow solutions are obtained with the method of influence coefficients, using source and doublet panels distributed on the boundary surfaces. The results include pressure distributions, lift, induced drag and side force, and moments. Theoretical solutions are presented for clean lifting wings and for a NASA fan-in-wing model. Comparisons with the experimental NASA data demonstrate the validity of the approach and uncover the importance of viscous effects, fan inflow distribution, and jet entrainment.
Technical Paper

New Developments in Fluidics for Aircraft High-Pressure Hydraulic System Applications

The new technology of hydraulic fluidics has been applied to the control of aircraft hydraulic systems in three areas: hydraulic circuit damage isolation, control column artificial feel computation, and the sequencing of landing gear motion. Successful development is demonstrated, and hydraulic fluidics are shown to produce considerable improvements to hardware in specific instances.
Technical Paper

Future Airplane Hydraulic Distribution System Design Developments and Testing Criteria

The latest tubing, fitting, and flexible line designs as well as the testing techniques presently used on production airplane hydraulic distribution systems are reviewed in this paper. Designs and materials that are being considered for future airplanes as well as their advantages are presented here in terms of weight and cost. Other major trade parameters such as reliability and maintainability are also considered along with the most significant of all distribution system areas requiring improvement-the installation criteria and techniques. Advanced tensile, impulse, and flexure testing techniques are evaluated and compared with actual airplane combined load environments encountered by hydraulic systems on large jet aircraft.