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風洞研究会議の趣旨のひとつは、航空機の(空力を中心とした)設計問題を幅広く取り上げ、専門家が議論する機会を提供することだろうと思われます。それで今回の話題ですが、知られているようで知られていない飛行船の空力設計を取り上げてみました。, JAXA Special Publication, 宇宙航空研究開発機構特別資料

An innovative concept is proposed for atmospheric entry probe deceleration, wherein one or more deployed rotors (in autorotation or wind-turbine flow states) on the aft end of the probe effect controlled descent. This concept is particularly oriented toward probes intended to land safely on the surface of Venus. Initial work on design trade studies is discussed., To be presented at the International Planetary Probe Workshop (2nd), held at NASA Ames Research Center, Moffett Field, CA on 23-27 Aug 2004.

Segmented rod penetrator concepts created interest in the ballistic performance of high-density, low length-to-diameter (LID) ratio penetrators, but there was a lack of data showing the performance of such thin disks vs. high-obliquity targets. An experimental and computational study was conducted to examine the basic case of a single tungsten heavy alloy disk with an LID of 1/8 impacting a high-obliquity (65 degrees) rolled homogeneous armor steel plate at a nominal velocity of 2 km/s. The study provides valuable insight into the penetration process. Results include depths of penetration and penetration per unit length. Good agreement is seen between the experimental data and the CTH simulation; both show a ricochet phenomenon. Results are also compared to comparable previous studies, and possible explanations for differences are given.

Portland cement concrete is unique among most construction materials in that its properties change substantially from when delivered to the job site to when the final produce made from the concrete is put to use. When delivered, the concrete must exhibit uniformity and workability sufficient to place and consolidate the fresh concrete. After sufficient curing the concrete must have strength and durability. Quality control testing must therefore consider both fresh and hardened properties to evaluate the acceptability of the concrete for its intended application. Standard quality control testing performed at the job site includes slump, air content, unit weight and yield. The information derived from the tests is believed to provide inspectors with an initial indication of the expected short and long term performance of the concrete. The purpose of this research was to investigate the policies and procedures of various agencies for quality control testing at the job site and to determine the influence of one of many important parameters affecting portland concrete, final aggregate gradation, on the test results. Results of this investigation were used to make an assessment of the adequacy of current job site procedures and to develop recommendations for improvement and identify areas requiring further research effort.

This report provides instructions for the development and application of a new compaction control or quality assurance procedure for soils containing gravel-sized particles. The method is based on Density Interference Coefficients which relate the maximum dry density of the total gradation to those of its minus 3/4-in. or minus No. 4 fraction and on Optimum Water Content Factors which relate the optimum water content of the total gradation to those of its minus 3/4-in. or minus No. 4 fraction. Entire families of gradations of earth-rock mixtures such as would typically be obtained from a single borrow source can be represented by single curves of the two parameters versus gravel content. A short-cut method to obtain the curves over the entire range of gravel content of the total materials without large-scale compaction testing of the total materials is described. Instructions are provided as to how to calculate maximum dry density and optimum water content to be associated with the fill density sample from the values of Density Interference Coefficient and Optimum Water Content Factor.

A series of quantitative and qualitative tests were conducted to expand the aerodynamic data base of square cross-section missiles. Quantitative tests included measuring forces and moments acting on square missiles, and measuring flowfield pressures on the leeward side of square missiles at various configurations and orientations in a subsonic wind tunnel. Force and moment data is presented showing the effects of variation in body corner radius, nose and fin shapes, pitch angle, and roll angel. Flowfield pressure and crossflow velocity data are presented for missiles of various pitch angels, roll angles, body corner radii, and fineness ratios (length to width ratio). In addition, flowfield data is shown along the axial length of a square missile. Qualitative tests included photographic tuft grids in the flowfield and photographing oil shear stress patterns on the surface of various missiles. These qualitative photographs are presented for various missile configurations and orientations.

One objective of the Advanced Undersea Vehicle (AUV) program is to design a low drag vehicle. The approach in this investigation is boundary layer control by means of an annular suction slot located on the afterbody. Although wind tunnel data showed significant reduction in propulsive power over conventional shapes, an attempt was made to achieve further reduction by means of forebody shaping. Two methods were used to vary the geometric parameters for this analysis. The direct method, based on the mathematical development of the Series 58 bodies, allows the definition of a shape by a fifth-order polynomial based on the four fundamental parameters of fineness ratio, nose radius of curvature, location of maximum thickness, and prismatic coefficient. The inverse method allows various velocity distributions to define the body shape. The shapes derived by this method have flat velocity distributions and show similar trends to the polynomial shapes (about 3-percent reduction in propulsive power). The range of fineness ratios analyzed was from 1 to 10 at a volume-based Reynolds number of 3.2 million. In the range of 2.5 to 8, fineness ratio did not affect propulsive power more than 6 percent. A maximum improvement of 3 percent as shown by varying the meridian section.

Configuration concepts are presented which have high lift-to-drag ratios and maneuverability achievable by relieving constraints due to carriage, propulsion and subsystem integration. Noncircular body, lifting body, blended wing-body, wing-body and favorable interference concepts are developed using aerodynamic design criteria derived for climb-cruise-intercept missions. The Hypersonic Arbitrary Body Program (HABP) is evaluated for predicting aerodynamic characteristics. Comparisons of wind tunnel data and predictions are presented. Major features such as a spatular nose, flat bottom, high fineness ratio, ramped nose, planar shape, high wing, end plated wing, and interference channel are shown to enhance aerodynamic characteristics. (Author)

Side force measurements, involving ogive-cylinder bodies with systematically varied nose fineness and bluntness ratios, are presented for laminar and turbulent boundary layers. Results indicate that the side force remains small below 25 deg angle of attack and increases to a maximum value at around 35 deg to 40 deg depending on Mach number and geometry. The magnitude of side force increases with increasing fineness ratio, and decreases with large nose blunting. Strong dynamic effects and sensitivity to small geometric variations are evident. In all test conditions the measured side force is significantly reduced when the boundary layer is turbulent.

Tests results showed that drag of test body rose from 0.060 atmospheric pressure at M=0.89 to 0.167 atmospheric pressure at M=1.02, and increased to 0.233 at M=1.19. At near sonic speed, drag or tested wing rose to dobule the value estimated from previous tests. Body drags measureed were higher than those obtained in previous tests of an identical body without wings.

Supersonic rocket-powered, winged, and wingless models were tested to Mach 1.4 to determine effect of nose fineness ratio on total and component drag. Winged models with and without sweepback were tested. Results show that increased nose fineness ratio increased wing-body drag near Mach 1.0 but decreased total drag at higher Mach. Increased fineness ratio decreased drag of wingless bodies. Wing drag values change with installation on different body shapes.

Zero-lift drag data were obtained on a series of fin-stabilized bodies differing only in afterbody shape. Three series of afterbodies (fineness ratios 1.78, 3.00, and 5) with varying ratios of base radius to maximum radius (0, 0.458, 0.700, and 1) were combined with a fineness-ratio-7.13 parabolic nose. Both conical and parabolic afterbodies were tested. The models were launched from the Langley helium gun, and data were obtained for Mach numbers from 0.8 to 1.3 and for Reynolds numbers (based on body length) of about 10 x 10 to the 6th power. The results indicate that a conical angle of about 4.5 deg will give the minimum drag for any fineness ratio less than 6, and that the minimum-drag is approximately 30 to 40 percent of that for a square-base body of fineness ratio 0.