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Two-dimensional and three-dimensional leading edge ice shapes for a finite wing model computed with the NASA Glenn LEWICE 2.0 and LEWICE3D Version 2 ice accretion codes are compared with experimental data from icing tunnel tests. The wing model had 28° leading edge sweep angle, 1.52-m (60-in) semispan and an airfoil section representative of business jet wings. Experimental wing leading edge ice shapes were obtained at the NASA Glenn Icing Research Tunnel (IRT) for six icing conditions. Tests conditions included angles of attack of 4° and 6°, airspeeds ranging from 67.06 m/s (150 mph) to 111.76 m/s (250 mph), static air temperatures in the range of -11.28°C (11.7°F) to -2.78°C (27°F), liquid water contents of 0.46 g/m₃, 0.51 g/m₃, and 0.68 g/m₃, and median volumetric diameters of 14.5 μm and 20 μm.

The architecture and training of artificial neural networks are briefly described. Five applications of these networks to design and analysis problems are presented; three in aerodynamics and two in flight dynamics. The aerodynamics cases are those of a harmonically oscillating airfoil, a pitching delta wing, and airfoil design. The flight dynamic examples involve control of a super maneuver and a decoupled control case. It is demonstrated that highly nonlinear aerodynamic cases can be generalized with sufficient accuracy for design purposes. It is shown that although neural networks generalize well on the aerodynamic problems, they appear lacking comparable robustness in modeling dynamic systems. It is also shown that generalization appears to become weak outside of the training domain.

This paper compares the environmental durability of currently used as well as some of the potential aircraft aluminum alloy skin materials. A simple test was developed to evaluate the environmental durability by simultaneous application of fatigue loads and aerated salt water attack. Alclad alloys showed excellent resistance to corrosion fatigue. On the other hand, 7475 alloy and new potential material 6013 alloy experienced inter-granular corrosion at the fatigue crack origin area. The test results also indicated the significance of corrosion preventive coatings to increase the age of aircraft.

The aerodynamic properties of a forward-swept wing were tested at low Reynolds numbers. The investigation was performed in a low-speed wind tunnel using a reflection plane model. Tunnel balance, model pressure taps, and flow visualization results were utilized to characterize the wing behavior over a range of Reynolds numbers from 0.25 × 106 - 0.75 × 106. In addition, the experimental data is compared to results obtained using a recently developed computer program known as WING3D. This modified Non-Planar Vortex Lattice Method program can calculate total wing lift and surface pressure distributions. The forward-swept wing has good aerodynamic qualities; in addition, the flow, on the outboard sections of the wing, remains attached beyond stall. The comparison of WING3D and experimental surface pressure distributions is good.

An investigation was performed to evaluate a novel and inexpensive wind tunnel model mount for dynamic aerodynamic testing. A computer analysis code was developed to identify the dimensions of the control surface needed to produce a desired pitching motion for a delta wing. The code was then used to design and build a dynamic model apparatus that was evaluated in a low speed wind tunnel at Wichita State University. The dynamic model mount and control were evaluated for a variety of motions, including constant pitch rate ramps, constant frequency oscillations and impulse or step inputs. Results from the ramp and oscillation test indicated the system is very responsive and capable of a wide range of motion.

A new class of aerodynamic control devices have recently been designed specifically for wind turbine applications. These new controls were tested to evaluate their effectiveness in modulating wind turbine power output and for slowing or stopping a wind turbine in high wind or loss of generator situations. While these control devices were developed specifically for wind turbine applications, there exists the possibility that alternate aviation uses exist. In particular, these trailing-edge control devices were evaluated for reducing aircraft landing distances, generating rapid rates of descent, deep stall or spin recovery and for high angle of attack control.

Two new concept of flexible fixture subsystem (FFS) for aircraft wing spar assembly are introduced in this paper. The advantages and characteristics of FFS are discussed and compared with the current assembly method and fixtures. The objective of FFS is to replace the dedicated tooling and be able to quickly reconfigure itself for new types of spars. The fixture enables a family of spars to be mounted and assembled in the same tooling. Left- and right-hand side spars, varying lofts(spar cap angles), height, and depths are all accommodated on the same tool, within its envelop.

The effect of Gurney flaps on a NACA 0011 airfoil was investigated. Gurney flaps provide a substantial increase in lift while the penalty in drag is small. With the Gurney flap, the airfoil pressure distribution shows increased suction on the upper surface and higher pressure on the lower surface compared to the clean airfoil. This change in pressure is most profound on the lower surface just in front of the Gurney flap. Since separation occurs on the upper surface upon stall, this higher pressure condition on the lower surface continues into the post-stall regime. Thus, the NACA 0011 airfoil with Gurney flaps generates lift coefficients greater than one even under post-stall conditions.

Separated flows and subsequent formation of shear layers are important fluid processes which play a dominant role in numerous engineering applications. Prediction of this fluid process is an important element in the design and analysis of highspeed vehicles and, ultimately, in the performance and trajectory analysis. The prediction methodology used in the current study includes the numerical solution of the Navier-Stokes equations on a multi-block grid system. Several turbulence models are used to investigate their performance for compressible, turbulent, separated and shear layer flows. The computational results are compared to available experimental data.

An experimental investigation on the effects of Gurney flaps on a reflection plane model was conducted. Two sizes of Gurney flaps were tested on a series of configurations which included a tapered wing (with a NLF-0215 airfoil section), a fuselage, a nacelle, and their permutations. The tests were conducted at a Reynolds number of 1.0 million based on mean chord. Results indicated that lift and drag were increased upon using the Gurney flaps; lift to drag and lift squared to drag ratios were also increased. In particular, the lift to drag ratio for the complete “airplane” was almost the same with or without a small Gurney flap. Pitching moment became more negative (nose-down) with the Gurney flap, and positive (nose-up) with the addition of the fuselage.

The present scenario of increasing the production rates in drilling demands high speed drilling while at the same time maintaining the quality of the drilled holes. Of the many factors that affect the high-speed drilling process, such as speed, feed rate, material of drill and work piece, and drill geometry this study attempts only to study the effect of drill geometry in high-speed drilling of aluminum sheet metal. In the Experiments conducted, different speeds, feed rates and drill bits of varying geometry are utilized in order to study their effects on hole quality as it relates to hole diameter and burr formation. Also the variation of thrust and torque with increase in speed over a speed range of 6,000 to 30,000 rpm has been studied.