Two-dimensional aerodynamic characteristics of three rotorcraft airfoils at Mach numbers from 0.35 to 0.90

Three airfoils designed for helicopter rotor application were investigated in the Langley 6- by 28-inch Transonic Tunnel to determine the two dimensional aerodynamic characteristics at Mach numbers from 0.34 to 0.88 and respective Reynolds numbers from about 4.4 x 10(6) power to 9.5 x 10(6) power. The airfoils have thickness-to-chord ratios of 0.08, 0.10, and 0.12. Trailing-edge reflex was applied to minimize pitching moment. The maximum normal-force coefficient of the RC(3)-12 airfoil is from 0.1 to 0.2 higher, depending on Mach number M, than that of the NACA 0012 airfoil tested in the same facility. The maximum normal-force coefficient of the RC(3)-10 is about equal to that of the NACA 0012 at Mach numbers to 0.40 and is higher than that of the NACA 0012 at Mach numbers above 0.40. The maximum normal force coefficient of the RC(3)-08 is about 0.19 lower than that of the NACA 0012 at a Mach number of 0.35 and about 0.05 lower at a Mach number of 0.54. The drag divergence Mach number of the RC(3)-08 airfoil at normal-force coefficients below 0.1 was indicated to be greater than the maximum test Mach number of 0.88. At zero lift, the drag-divergence Mach numbers of the RC(3)-12 and the RC(3)-10 are about 0.77 and 0.82, respectively

Aerodynamic characteristics of three helicopter rotor airfoil sections at Reynolds number from model scale to full scale at Mach numbers from 0.35 to 0.90

An investigation was conducted in the Langely 6 by 28 inch transonic tunnel to determine the two dimensional aerodynamic characteristics of three helicopter rotor airfoils at Reynolds numbers from typical model scale to full scale at Mach numbers from about 0.35 to 0.90. The model scale Reynolds numbers ranged from about 700,00 to 1,500,000 and the full scale Reynolds numbers ranged from about 3,000,000 to 6,600,000. The airfoils tested were the NACA 0012 (0 deg Tab), the SC 1095 R8, and the SC 1095. Both the SC 1095 and the SC 1095 R8 airfoils had trailing edge tabs. The results of this investigation indicate that Reynolds number effects can be significant on the maximum normal force coefficient and all drag related parameters; namely, drag at zero normal force, maximum normal force drag ratio, and drag divergence Mach number. The increments in these parameters at a given Mach number owing to the model scale to full scale Reynolds number change are different for each of the airfoils

Experimental investigation of three helicopter rotor airfoils designed analytically

Three helicopter rotor airfoils designed analytically were investigated in a wind tunnel at Mach numbers from about 0.30 to 0.90 and Reynolds from about 0.8 to 2.3 x 10 to the 6th power. The airfoils had thickness-to-chord ratios of 0.08, 0.10, and 0.12 with maximum thickness at 40 percent chord. The camber distribution of each section was the same with maximum camber at 35 percent chord. The 10-percent-thick airfoil was also investigated at Reynolds numbers from 4.8 to 9.4 x 10 to the 6th power. The drag divergence Mach number of the 10-percent-thick airfoil is about 0.83 at a normal-force coefficient of 0 and about 0.72 at a normal-force coefficient of 0.6 at Reynolds numbers near 9 x 10 to the 6th power. The maximum normal-force coefficient is slightly less than that of the NACA 0012 airfoil tested in the same facility. The results indicate that a qualitative evaluation of the drag divergence can be made at normal-force coefficients up to the onset of boundary-layer separation by analytically predicting the onset of sonic flow at the airfoil crest. The qualitative results are conservative with respect to experimental values with the experimental drag divergence Mach number up to 0.05 higher than that indicated by analysis

Low speed aerodynamic characteristics of NACA 6716 and NACA 4416 airfoils with 35 percent-chord single-slotted flaps

An investigation was conducted in a low-turbulence pressure tunnel to determine the two-dimensional lift and pitching-moment characteristics of an NACA 6716 and an NACA 4416 airfoil with 35-percent-chord single-slotted flaps. Both models were tested with flaps deflected from 0 deg to 45 deg, at angles of attack from minus 6 deg to several degrees past stall, at Reynolds numbers from 3.0 million to 13.8 million, and primarily at a Mach number of 0.23. Tests were also made to determine the effect of several slot entry shapes on performance

A novel linear direct drive system for textile winding applications

The paper describes the specification, modelling, magnetic design, thermal characteristics and control of a novel, high acceleration (up to 82g) brushless PM linear actuator with Halbach array, for textile package winding applications. Experimental results demonstrate the realisation of the actuator and induced performance advantages afforded to the phase lead, closed-loop position control scheme

What is the Law?

It is intended that this title shall demand an analysis of the field of study in which the lawyer or jurist works and a determination of its essential and contributing elements. The purpose of the article is to sketch briefly a partial answer which will be instructive and helpful to the student who faces the problem as I faced it some ten years ago. I do not expect that anything new will be found in these ideas. I imagine that all of them must have been expressed many times before. Some of them are common­place. None is esoteric. Probably the value of what I shall say will lie in focusing the attention on facts which commonly influence thought and action, but seldom are brought before the footlights of consciousness, comprehended, and properly correlated. At the outset I wish to free my discussion from a cloud which would dim whatever clarity it might otherwise possess. In all philosophical debate there is much that is only a wrangle over language and its meanings. This is true of the literature of jurisprudence. It is not easy to keep a controversy concerning a hazy topic of substance from stumbling into the ditch of merely verbal disputes. It requires unprejudiced, receptive, and discriminating habits of thought to understand opposing statements as the maker understood them, to get fully and in proper relief his point of view, and then to criticise, not his expression, but his perception and comprehension of facts. The flexibility of language and the uncommonness of clear, adequate exposition increase the difficulty. It is comparatively easy to attach an unintended meaning to expression in honesty and with plausibility which will open it to criticism. The ensuing dispute frequently will rage interminably over matters of language without either party realizing that this is the only issue. Such differences between myself and my reader I hibernioally desire to remove before they occur. It will be necessary in the course of this article to mention various legal meanings of the word law; but this definition of the word is only for the purpose of facilitating the communication of my ideas. Therefore I shall not quarrel with anyone who chooses to evolve different meanings or to object to some or all of mine. All I ask on this matter is that my language be interpreted in accordance with my discussion of its meanings. The reader may make mental reservations of his own definitions and usage. I do not regard such differences as important ones and I am not concerned to war over them. My purpose is not to define the word law, but to focus your attention on each of several sorts of elements which exist in the field of legal study and their essential differences and correlations. My language and its definition are merely means to this end. Do not let your criticism of the means prevent the full accomplishment of the end

A Comparative Study of Teacher Opinion With Respect to the Mathematics Program in Grades Seven, Eight, and Nine in the Schools of Utah and California

To live intelligently in our rapidly changing society, every member of our society needs to acquire knowledge and skills in the field of mathematics, not only in specialized fields, but in all areas of everyday living

Chamber 10 and more!

https://mds.marshall.edu/music_perf/1222/thumbnail.jp

Professor Kales and Common Law Remainders

In an article in Vol. 22 of the Law Quarterly Review, Professor Albert M. Kales presents a reclassification of future interests in land, the salient feature of which is an attempt to overthrow the conventional conception of a contingent remainder as a future estate given, not presently, but on condition precedent, and to substitute an entirely new conception of his own. This effort, by its boldness and novelty commands something more than a mere passing mention. It is my purpose, first to present as briefly as is consistent with clearness what I conceive to be the common law theory of estates in land and the nature of remainders, vested and contingent; and then to discuss Professor Kales\u27 article with like brevity and attempt to show how and why he has wandered from what I conceive to be the beaten path, trodden by our law-makers