History of aerodynamics

In 1726 Isaac Newton became one of the first aerodynamicists in the modern sense when he developed a theory of air resistance which was later verified for low flow speeds.

George Cayley developed the concept of the modern fixed-wing aircraft in 1799, and in doing so identified the four fundamental forces of flight - lift, thrust, drag, and weight.

The flight, and the publicity it received, led to more organized collaboration between aviators and aerodynamicists, leading the way to modern aerodynamics.

The fundamental aerodynamics continuity assumption has its origins in Aristotle's Treatise on the Heavens, although Archimedes, working in the 3rd century BC, was the first person to formally assert that a fluid could be treated as a continuum.

In fact, Aristotle paradoxically suggested that the movement of air around a thrown spear both resisted its motion and propelled it forward.

[6] In the 15th century, Leonardo da Vinci published the Codex Leicester, in which he rejected Aristotle's theory and attempted to prove that the only effect of air on a thrown object was to resist its motion,[7] and that air resistance was proportional to flow speed, a false conclusion which was supported by Galileo's 17th century observations of pendulum motion decay.

[3] In addition to his work on drag, da Vinci was the first person to record a number of aerodynamic ideas including correctly describing the circulation of vortices and the continuity principle as applied to channel flow.

[3] The true quadratic dependency of drag on velocity was experimentally proven independently by Edme Mariotte and Christiaan Huygens, both members of the Paris Academy of Sciences, in the late 17th century.

Newton stated that drag was proportional to the dimensions of a body, the density of the fluid, and the square of the air velocity, a relationship which was demonstrated to be correct for low flow speeds, but stood in direct conflict with Galileo's earlier findings.

Drag theories were developed by Jean le Rond d'Alembert,[12] Gustav Kirchhoff,[13] and Lord Rayleigh.

[16] To simulate fluid flow, many experiments involved immersing objects in streams of water or simply dropping them off the top of a tall building.

Working from at least as early as 1796, when he constructed a model helicopter,[18] until his death in 1857, Sir George Cayley is credited as the first person to identify the four aerodynamic forces of flight—weight, lift, drag, and thrust—and the relationships between them.

During this time, the groundwork was laid down for modern day fluid dynamics and aerodynamics, with other less scientifically-inclined enthusiasts testing various flying machines with little success.

[22] In 1889, Charles Renard, a French aeronautical engineer, became the first person to reasonably predict the power needed for sustained flight.

Otto Lilienthal, following the work of Sir George Cayley, was the first person to become highly successful with glider flights.

Octave Chanute's 1893 book, Progress in Flying Machines, outlined all of the known research conducted around the world up to that point.

This first widely publicised flight led to a more organized effort between aviators and scientists, leading the way to modern aerodynamics.

During the time of the first flights, John J. Montgomery,[25] Frederick W. Lanchester,[26] Martin Kutta, and Nikolai Zhukovsky independently created theories that connected circulation of a fluid flow to lift.

Prandtl, a professor at the University of Göttingen, instructed many students who would play important roles in the development of aerodynamics, such as Theodore von Kármán and Max Munk.

These effects, often several of them at a time, made it very difficult for World War II era aircraft to reach speeds much beyond 800 km/h (500 mph).

For instance, the P-38 Lightning with its thick high-lift wing had a particular problem in high-speed dives that led to a nose-down condition subsequently called Mach tuck.

Their research was applied on the MiG-15 and F-86 Sabre and bombers such as the B-47 Stratojet used swept wings which delay the onset of shock waves and reduce drag.

Newton was the first to develop a mathematical model for calculating the speed of sound, but it was not correct until Pierre-Simon Laplace accounted for the molecular behavior of gases and introduced the heat capacity ratio.

Macquorn Rankine and Pierre Henri Hugoniot independently developed the theory for flow properties before and after a shock wave.

[29] Theodore von Kármán and Hugh Latimer Dryden introduced the term transonic to describe flow speeds around Mach 1 where drag increases rapidly.

On September 30, 1935, a Volta Congress was held in Rome on the topic of high velocity flight and the possibility of breaking the sound barrier.

[30] Participants included Theodore von Kármán, Ludwig Prandtl, Jakob Ackeret, Eastman Jacobs, Adolf Busemann, Geoffrey Ingram Taylor, Gaetano Arturo Crocco, and Enrico Pistolesi.

Nevertheless, there are still important problems in basic aerodynamic theory, such as in predicting transition to turbulence, and the existence and uniqueness of solutions to the Navier-Stokes equations.