Engineering topics
Dryden, Hugh L.
Publications and source records attributed to Dryden, Hugh L..
The National and International Significance of the Lunar Exploration Program
No abstract available
Atoms and Space
The stated subject of this paper is so broad that it might include everything from the study of the infinitely small recesses of the atom to the vast infinity of galactic space. We will therefore begin by limiting the scope of the subject to a discussion of three questions: --- (1) What are the potentialities of the use of nuclear energy in the exploration of space? --- (2) What uses of nuclear energy in space exploration are expected in the next decade? - - - (3) What is likely to be the impact of space exploration on the development of other applications of nuclear energy? We will discuss these questions in relation to the space activities of the United States as set forth in the National Aeronautics and Space Act of 1958 and in the programs of the National Aeronautics and Space Administration, the agency established by Congress to carry out the policy established in that Act that activities in space should be devoted to peaceful purposes for the benefit of all mankind. Such activities include at present the exploration of space to gain greater knowledge and understanding of the earth and its atmosphere, the moon, planets, and the universe; the application of available knowledge to develop capabilities for other activities in space for the benefit of mankind; and the beginning of the exploration of space by man himself.
Global Aspects of the Exploration of Space
The interest of man in outer space began long ago among uncivilized peoples to whom the face of the sky was clock and almanac; the celestial bodies, objects of worship. Exploration was at first by visual observation, later aided by armillary spheres and quadrants, and still later by more precise measuring instruments, telescopes, and spectroscopes. The information obtained was that borne by the light that was transmitted from the distant celestial object through the atmosphere to the observing instrument on the ground. In recent years the light waves have been supplemented by radio waves as carriers of information from the stars and planets. Men of many nations have contributed through the centuries to the exploration of space by the methods of astronomy. The history of advances in astronomical knowledge and technique includes the records of Chinese, Babylonians, Greeks, Arabians, and of nearly every nation of the modern world. International cooperation was early recognized as essential and beneficial; the countless number of the stars and the vastness of space present mankind with a truly global task. The picture of the universe obtained by the astronomers early stirred the imagination of men to speculate about the existence of life elsewhere in the universe, about means of communication with distant stars, and in the last centuries about the possibility of the travel of man to the moon and planets. Some sought to apply the science and engineering of their day to describe the vehicles to be used. For example, Jules Verne published in 1865 in "From the Earth to the Moon" a description of a gun-launched projectile carrying passengers to orbit the moon. Today we have taken the first steps to bring this inspired vision to reality. The exploration of space by unmanned vehicles carrying scientific apparatus began on October 4, 1957; exploration by man will follow in due course.
Fifty Years of Boundary-Layer Theory and Experiment
The year 1954 marked the 50th anniversary of the Prandtl boundary-layer theory from which we may date the beginning of man's understanding of the dynamics of real fluids. A backward look at this aspect of the history of the last 50 years may be instructive. This paper (1) attempts to compress the events of those 50 years into a few thousand words, to tell in this brief space the interesting story of the development of a new concept, its slow acceptance and growth, its spread from group to group within its country of origin, and its diffusion to other countries of the world. The original brief paper of Prandtl (2) was presented at the Third International Mathematical Congress at Heidelberg in 1904 and published in the following year. It was an attempt to explain the d'Alembert paradox, namely, that the neglect of the small friction of air in the theory resulted in the prediction of zero resistance to motion. Prandtl set himself the task of computing the motion of a fluid of small friction, so small that its effect could be neglected everywhere except where large velocity differences were present or a cumulative effect of friction occurred This led to the concept of boundary layer, or transition layer, near the wall of a body immersed in a fluid stream in which the velocity rises from zero to the free-stream value. It is interesting that Prandtl used the term Grenzsehicht (boundary layer) only once and the term Ubergangsschicht (transition layer) seven times in the brief article. Later writers also used Reibungsschicht (friction layer), but most writers today use Grenzschicht (boundary layer).