Ludwig Prandtl

Ludwig Prandtl (4 February 1875 – 15 August 1953) was a German fluid dynamicist, physicist and aerospace scientist. He was a pioneer in the development of rigorous systematic mathematical analyses which he used for underlying the science of aerodynamics, which have come to form the basis of the applied science of aeronautical engineering. In the 1920s he developed the mathematical basis for the fundamental principles of subsonic aerodynamics in particular; and in general up to and including transonic velocities. His studies identified the boundary layer, thin-airfoils, and lifting-line theories. The Prandtl number was named after him.
Early years.
Prandtl was born in Freising, near Munich, in 1875. His mother suffered from a lengthy illness and, as a result, Ludwig spent more time with his father, a professor of engineering. His father also encouraged him to observe nature and think about his observations.
He entered the Technische Hochschule Munich in 1894 and graduated with a Ph.D. under guidance of Professor August Foeppl in six years. His work at Munich had been in solid mechanics, and his first job was as an engineer designing factory equipment. There, he entered the field of fluid mechanics where he had to design a suction device. After carrying out some experiments, he came up with a new device that worked well and used less power than the one it replaced.
Later years.
In 1901 Prandtl became a professor of fluid mechanics at the technical school in Hannover, later the Technical University Hannover and now the University of Hannover. It was here that he developed many of his most important theories. On August 8th 1904, he delivered a groundbreaking paper, "Über Flüssigkeitsbewegung bei sehr kleiner Reibung" ("On the Motion of Fluids in Very Little Friction"), at the Third International Mathematics Congress in Heidelberg. In this paper, he described the boundary layer and its importance for drag and streamlining. The paper also described flow separation as a result of the boundary layer, clearly explaining the concept of stall for the first time. Several of his students made attempts at closed-form solutions, but failed, and in the end the approximation contained in his original paper remains in widespread use.
The effect of the paper was so great that Prandtl became director of the Institute for Technical Physics at the University of Göttingen later in the year. Over the next decades he developed it into a powerhouse of aerodynamics, leading the world until the end of World War II. In 1925 the university spun off his research arm to create the Kaiser Wilhelm Institute for Flow Research (now the Max Planck Institute for Dynamics and Self-Organization).
Following earlier leads by Frederick Lanchester from 1902–1907, Prandtl worked with Albert Betz and Max Munk on the problem of a useful mathematical tool for examining lift from "real world" wings. The results were published in 1918–1919, known as the Lanchester–Prandtl wing theory. He also made specific additions to study cambered airfoils, like those on World War I aircraft, and published a simplified thin-airfoil theory for these designs. This work led to the realization that on any wing of finite length, wing-tip effects became very important to the overall performance and characterization of the wing. Considerable work was included on the nature of induced drag and wingtip vortices, which had previously been ignored. Prandtl showed that an elliptical spanwise lift distribution the most efficient, giving the minimum induced drag for the given span. These tools enabled aircraft designers to make meaningful theoretical studies of their aircraft before they were built.
Prandtl later extended his theory to describe a bell-like lift distribution, obtained by washing out the wing tips until negative lift was obtained, which gave the minimum induced drag for any given aircraft weight, also suggesting that adverse yaw forces could be countered solely by wing tip aerodynamics, but this new theory was largely ignored. In the 21st century the American engineer Al Bowers has confirmed the idea, calling his experimental wing the PRANDTL-D.
Prandtl and his student Theodor Meyer developed the first theories of supersonic shock waves and flow in 1908. The Prandtl–Meyer expansion fans allowed for the construction of supersonic wind tunnels. He had little time to work on the problem further until the 1920s, when he worked with Adolf Busemann and created a method for designing a supersonic nozzle in 1929. Today, all supersonic wind tunnels and rocket nozzles are designed using the same method. A full development of supersonics would have to wait for the work of Theodore von Kármán, a student of Prandtl at Göttingen.
In 1922 Prandtl, together with Richard von Mises, founded the GAMM (the International Association of Applied Mathematics and Mechanics). and was its chairman from 1922 until 1933. Until 1945 he also worked closely with the RLM.
Other work examined the problem of compressibility at high subsonic speeds, known as the Prandtl–Glauert correction. This became very useful during World War II as aircraft began approaching supersonic speeds for the first time. He also worked on meteorology, plasticity and structural mechanics.

Dark Colony

Dark Colony is a real-time strategy video game developed by Alternative Reality Technologies and published by Strategic Simulations. The game was released for Microsoft Windows and Mac OS in September 1997.
Overview.
The game is set on a fictional Mars colony - the so-called "Dark Colony" - in the year 2137. Humans have discovered a "remarkable energy source" by the name of Petra-7 on the red planet. Figuring they'd rather not choke on the atmosphere of Mars whilst mining Petra-7, the Humans begin terraforming the planet. At the start of the game the project has produced jungles and deserts habitable by people. All seems to be going well, until the Taar show up. The Taar are aliens from a scattered and dying race looking for a new homeworld, and Mars seems to be good fit. Before they can move in though, they seek to get rid of the humans.
The game consists of two campaigns where players can either play as the humans, commanding a colonization force from Pan Luma Industries (one of the Earth corporations along with Aerogen and Stratus who are in charge of the Mars project) whose goal is to defend against and defeat the alien threat, or as the Taar, where players have to defeat the human presence on Mars and claim it as their own.
Balance.
Both the human and alien armies have almost entirely mirrored units that differ mostly in appearance. The few differences between races are that the range of the heavy assault units is bigger by 1 for humans in exchange for speed, the range of alien sniper units is bigger by 1, and alien defense turrets have less range and less damage. However, there are two aspects to the gameplay that can sway the tide of battle: effective use of artifacts and day/night cycle.
"Dark Colony" is one of the first RTS to add day/night cycle as a tactical consideration, as the Taar see much better during night time and also deal a little more damage and Humans see much better during day time while dealing some more damage in daylight.
Dark Colony: The Council Wars.
"Dark Colony: The Council Wars" is an expansion pack to the 1997 video game Dark Colony, published on January 8, 1998.
New things players can find are crashed flying saucers, Taar fortress markings, and a revisit of Area 51, featuring rattlesnakes. Apart from that, familiar terrain types have a slightly different appearance, and new ambient sounds.
Gameplay involves eradicating humans as you play the alien Taar, or to destroy aliens as a human player.