Theodore Theodorsen
Encyclopedia
Theodore Theodorsen was a Norwegian-American theoretical aerodynamicist
noted for his work at NACA
(the forerunner of NASA
) and for his contributions to the study of turbulence
.
, Norway in 1897 to parents Ole Christian Theodorsen, a chief engineer
in the Norwegian
merchant marine, and his wife Andrea Larsen. He was the oldest of six children. At one point Theodore’s father had taken examinations for a merchant marine engineer's license. He was the only applicant who correctly answered a particularly difficult question. To his father’s surprise his then twelve year old son was also able to solve the problem.
At age sixteen, after finishing compulsory schooling, Theodorsen attended gymnasium (equivalent in the USA to senior high school-junior college) in the nearby town of Larvik
. If certain grade levels were attained one would gain a scholarship to university. Norway was then far ahead of most nations in the liberalization of education. Theodorsen's grades were so outstanding that he was admitted to the leading engineering university in Norway, the Norwegian Institute of Technology
in Trondheim
. In those days there were no dormitories; students rented rooms in private homes. Many of the professors in those days were German
or English
, therefore a student at the university had to be familiar with all three languages. Only in mechanical drawing was his grade less than perfect. In those days anyone who achieved perfect grades would receive the honor of an introduction to the King of Norway.
who became a lifelong friend. Onsager also emigrated to the United States and eventually went on to win a Nobel Prize in Chemistry
. Theodorsen, like many Norwegian engineers, decided after some years as an instructor in Norway to emigrate. Jobs for engineers were few and far between in Norway at the time. His wife's family knew a retired Norwegian sea captain who lived in Baltimore
, so that became their American destination. They arrived in the United States on board the SS Stavangerfjord on August 25, 1924.
. Theodorsen took a job working on the third shift as an oiler at the Sparrows Point electrical generating plant located twenty miles from Baltimore. Johns Hopkins University
advertised for an instructor in mechanical engineering. He obtained the position. His English was even then grammatically perfect and only slightly accented. He taught at Johns Hopkins for five years. In 1928, his university friend from Norway, Lars Onsager, came to teach at Johns Hopkins for one semester. It was at that time that Onsager suggested to Theodorsen that he obtain a doctorate
in Physics
.
Theodorsen's thesis dealt with thermodynamic and aerodynamic themes that were to permeate much of his later work, which was developed in two parts: 1) shock waves and explosions and 2) combustion
and detonation
. Through the urging of Dr. Joseph Ames
, president of Johns Hopkins University and Chairman of the Executive Committee of the National Advisory Committee for Aeronautics
(NASA
), Theodorsen came to NACA in 1929 as an associate physicist
.
. This was then the only in-house research arm of NACA and had a highly motivated young staff. The work atmosphere was very informal though competitive, with much open stimulating discussion. However, conditions were rather primitive. For example the library consisted of one small shelf of books. Theodorsen used as his mainstays Hutte Mechanical Engineering Handbook and a set of the 1929 edition of the Handbuch der Physik.
Within a short time Theodorsen was made head of the Physical Research Division, the other research divisions being Engine Research and Aerodynamics
. Langley NACA was then in the process of expanding its experimental facilities to include a Full Scale Wind Tunnel and a Hydrodynamic Towing Basin for testing flying boat hulls. It happened that the proposed location of the towing basin had formerly been a bombing range. One of Theodorsen's first activities was the invention of an instrument for detecting buried metals and on its very first use it located a live bomb.
The ensuing years were highly productive ones for Theodorsen in a great variety of experimental and theoretical areas. As an overview Theodorsen improved thin airfoil theory by introducing the angle of best streamlining, went on to develop the now classical and elegant theory of arbitrary wing sections, performed the first in-house noise research, worked on fire prevention in aircraft and on means of icing removal and prevention, contributed to the theory of open, closed and partially open wind-tunnel test sections, developed the basic theory of aircraft flutter and its verification, made early measurements of skin friction at transonic
and supersonic
speeds, developed the use of freon for experimental aeroelastic work, gave damping properties of structures and expanded general propeller theory. During World War II
Theodorsen was called on for the analysis and troubleshooting of many aircraft problems and to help devise necessary modifications.
The theory of arbitrary airfoils based on conformal mapping developed by Theodorsen, is a model of classical applied mathematics. It should be pointed out that there are two key concepts that made Theodorsen’s approach different from and a clear improvement on the methods that preceded it such as that of von Mises
and von Karman. One was the important use of the complex variable not in the usual form of a polynomial
or power series but in the form of an exponential to power series. The equation led directly to the basic boundary value equation which, as an integral equation, represents an exact solution of the problem in terms of the given airfoil
data. This solution gave the exact pressure distribution around an airfoil of arbitrary shape. Seldom in aeronautics
are solutions “exact”. This is one of the very few. The method has been automated so that complete pressure distributions for a given airfoil section can be obtained in a matter of seconds. The philosophy in Theodorsen’s approach was that an exact formulation is often simpler and preferable to an approximate one and that while approximations are essential in applied mathematics they should be delayed as far as possible.
Another topic that merits discussion is Theodorsen’s work on flutter
. The approach here is again direct and clean, leading to an explicit exact solution as contrasted with previous implicit and approximate results. This exact flutter solution including results for control surfaces has had a keystone role in the development of flutter methods in the United States. It has enabled an engineering feel for the effects of variables and parameters in complex situations and has been available as a model against which approximate solutions can be compared.
Although Theodorsen leaned strongly toward basic theoretical analysis, he usually accompanied his work with experimental verification. He was highly innovative in engineering
and experimental activities where he always sought a theoretical framework or was guided by physical intuition. He was responsible for proposing a wind tunnel for flutter work which employed a mixture of air and freon with variable pressure to greatly increase the scope of research with aeroelastic models throughout the Mach
range and with lower horsepower requirements. The Transonic
Dynamics Wind Tunnel now used exclusively for aeroelastic research is based on the same principles.
Another unique facility due to Theodorsen was the helicopter rotor tower for aerodynamic and noise research. Ideal propeller dynamics was given a definitive treatment in
several reports and a book. Theodorsen was the earliest to obtain reliable skin-friction drag data at subsonic, transonic
and supersonic
speeds.
in 1946 Theodorsen helped to organize and administer the Instituto Tecnológico de Aeronáutica (Aeronautical Institute of Technology) (1947–1950) in Brazil. Then he served as Chief Scientist for the U.S. Air Force (1950–1954) during which time he did important work on the structure of turbulence
. Theodorsen then became the Chief of Research for the Republic Aviation Corporation (manufacturer of the famous P-47 Thunderbolt
fighter plane of World War II, and after the war the F-84 Thunderjet
and the F-105 Thunderchief
) a post from which he retired in 1962 when he became an active consultant to the Sikorsky
Helicopter Corporation where he specialized in ducted propeller work and helicopter rotors.
in a paper honoring Ludwig Prandtl’s 75th birthday. The universality of turbulence from microphenomena to astrophysics
is well known as for example, the hypothesis that the planets have condensed from a gaseous cloud and that the angular momentum of the solar system is a result of the action of viscosity
in the nebula
. Turbulence
remains as the major unsolved domain of fluid mechanics
. Theodorsen identified the main turbulence-creating terms in the equations of motion as (q x curl q . curl curl q); he showed that two-dimensional turbulence cannot exist; that vortex
lines stretching
and bending is the important mechanism and ingredient of turbulence
. He also discussed the hierarchy of vortices (Kolmogorov).
could be obtained without resorting to curved space-time by a modification of Newton's law of universal gravitation
. The paper presents "a successful transformation of the theory of relativity into classical physics... The mathematical entities of the Einstein development have been redefined into rational physical quantities and rearranged in an organized classical framework. Einstein's space-time has been eliminated and replaced by cognitive time." It was published in the Proceedings of the DKNVS Theodorsen Colloquium and on two later occasions.
. They were married in the famous Nidaros Cathedral
, the largest existing medieval church in Scandinavia
. The wedding party was an all-night celebration at the Britannia Hotel with one hundred guests. Their daughter Muriel Gerd-Preutz and sons Theodore Elliott and John Willman were all born in the United States.
In 1976, Dr. Theodorsen was awarded an honorary doctorate degree from the Norwegian University of Science and Technology
in Trondheim. The Royal Norwegian Society of Sciences and Letters
, also held a colloquium in his honor at Trondheim. After a short illness, Dr. Theodorsen died in 1978 at the age of eighty one at his home in Centerport
, Long Island, New York.
Aerodynamics
Aerodynamics is a branch of dynamics concerned with studying the motion of air, particularly when it interacts with a moving object. Aerodynamics is a subfield of fluid dynamics and gas dynamics, with much theory shared between them. Aerodynamics is often used synonymously with gas dynamics, with...
noted for his work at NACA
NACA
- Organizations :* National Advisory Committee for Aeronautics, the forerunner of the U.S. federal agency NASA* National Association for Campus Activities, an organization for programmers of university and college activities...
(the forerunner of NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
) and for his contributions to the study of turbulence
Turbulence
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time...
.
Early years
Dr. Theodore Theodorsen was born in SandefjordSandefjord
is a city and municipality in Vestfold county, Norway. The administrative centre of the municipality is the city of Sandefjord. The municipality of Sandefjord was established on 1 January 1838...
, Norway in 1897 to parents Ole Christian Theodorsen, a chief engineer
Engineer
An engineer is a professional practitioner of engineering, concerned with applying scientific knowledge, mathematics and ingenuity to develop solutions for technical problems. Engineers design materials, structures, machines and systems while considering the limitations imposed by practicality,...
in the Norwegian
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
merchant marine, and his wife Andrea Larsen. He was the oldest of six children. At one point Theodore’s father had taken examinations for a merchant marine engineer's license. He was the only applicant who correctly answered a particularly difficult question. To his father’s surprise his then twelve year old son was also able to solve the problem.
At age sixteen, after finishing compulsory schooling, Theodorsen attended gymnasium (equivalent in the USA to senior high school-junior college) in the nearby town of Larvik
Larvik
is a city and municipality in Vestfold county, Norway. The administrative centre of the municipality is the city of Larvik. Larvik kommune - has about 41 364 inhabitants and covers 530 km2....
. If certain grade levels were attained one would gain a scholarship to university. Norway was then far ahead of most nations in the liberalization of education. Theodorsen's grades were so outstanding that he was admitted to the leading engineering university in Norway, the Norwegian Institute of Technology
Norwegian Institute of Technology
The Norwegian Institute of Technology, known by its Norwegian abbrevation NTH was a science institute in Trondheim, Norway. It was established in 1910, and existed as an independent technical university for 85 years, after which it was merged into the University of Trondheim as an independent...
in Trondheim
Trondheim
Trondheim , historically, Nidaros and Trondhjem, is a city and municipality in Sør-Trøndelag county, Norway. With a population of 173,486, it is the third most populous municipality and city in the country, although the fourth largest metropolitan area. It is the administrative centre of...
. In those days there were no dormitories; students rented rooms in private homes. Many of the professors in those days were German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
or English
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
, therefore a student at the university had to be familiar with all three languages. Only in mechanical drawing was his grade less than perfect. In those days anyone who achieved perfect grades would receive the honor of an introduction to the King of Norway.
Emigration
In 1922 Theodorsen graduated with a masters degree in mechanical engineering and was offered a position at the university as an instructor. It was during that year that one of his students was Lars OnsagerLars Onsager
Lars Onsager was a Norwegian-born American physical chemist and theoretical physicist, winner of the 1968 Nobel Prize in Chemistry.He held the Gibbs Professorship of Theoretical Chemistry at Yale University....
who became a lifelong friend. Onsager also emigrated to the United States and eventually went on to win a Nobel Prize in Chemistry
Nobel Prize in Chemistry
The Nobel Prize in Chemistry is awarded annually by the Royal Swedish Academy of Sciences to scientists in the various fields of chemistry. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895, awarded for outstanding contributions in chemistry, physics, literature,...
. Theodorsen, like many Norwegian engineers, decided after some years as an instructor in Norway to emigrate. Jobs for engineers were few and far between in Norway at the time. His wife's family knew a retired Norwegian sea captain who lived in Baltimore
Baltimore
Baltimore is the largest independent city in the United States and the largest city and cultural center of the US state of Maryland. The city is located in central Maryland along the tidal portion of the Patapsco River, an arm of the Chesapeake Bay. Baltimore is sometimes referred to as Baltimore...
, so that became their American destination. They arrived in the United States on board the SS Stavangerfjord on August 25, 1924.
Johns Hopkins University
For some time there were few job prospects in BaltimoreBaltimore
Baltimore is the largest independent city in the United States and the largest city and cultural center of the US state of Maryland. The city is located in central Maryland along the tidal portion of the Patapsco River, an arm of the Chesapeake Bay. Baltimore is sometimes referred to as Baltimore...
. Theodorsen took a job working on the third shift as an oiler at the Sparrows Point electrical generating plant located twenty miles from Baltimore. Johns Hopkins University
Johns Hopkins University
The Johns Hopkins University, commonly referred to as Johns Hopkins, JHU, or simply Hopkins, is a private research university based in Baltimore, Maryland, United States...
advertised for an instructor in mechanical engineering. He obtained the position. His English was even then grammatically perfect and only slightly accented. He taught at Johns Hopkins for five years. In 1928, his university friend from Norway, Lars Onsager, came to teach at Johns Hopkins for one semester. It was at that time that Onsager suggested to Theodorsen that he obtain a doctorate
Doctorate
A doctorate is an academic degree or professional degree that in most countries refers to a class of degrees which qualify the holder to teach in a specific field, A doctorate is an academic degree or professional degree that in most countries refers to a class of degrees which qualify the holder...
in Physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
.
Theodorsen's thesis dealt with thermodynamic and aerodynamic themes that were to permeate much of his later work, which was developed in two parts: 1) shock waves and explosions and 2) combustion
Combustion
Combustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species. The release of heat can result in the production of light in the form of either glowing or a flame...
and detonation
Detonation
Detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases...
. Through the urging of Dr. Joseph Ames
Joseph Sweetman Ames
Joseph Sweetman Ames was a physics professor at Johns Hopkins University, provost of the university from 1926 until 1929, and university president from 1929 until 1935.He was born at Manchester, Vermont...
, president of Johns Hopkins University and Chairman of the Executive Committee of the National Advisory Committee for Aeronautics
National Advisory Committee for Aeronautics
The National Advisory Committee for Aeronautics was a U.S. federal agency founded on March 3, 1915 to undertake, promote, and institutionalize aeronautical research. On October 1, 1958 the agency was dissolved, and its assets and personnel transferred to the newly created National Aeronautics and...
(NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
), Theodorsen came to NACA in 1929 as an associate physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
.
National Advisory Committee for Aeronautics
The NACA facility was located adjoining the Langley Air Force Base near Hampton, VirginiaHampton, Virginia
Hampton is an independent city that is not part of any county in Southeast Virginia. Its population is 137,436. As one of the seven major cities that compose the Hampton Roads metropolitan area, it is on the southeastern end of the Virginia Peninsula. Located on the Hampton Roads Beltway, it hosts...
. This was then the only in-house research arm of NACA and had a highly motivated young staff. The work atmosphere was very informal though competitive, with much open stimulating discussion. However, conditions were rather primitive. For example the library consisted of one small shelf of books. Theodorsen used as his mainstays Hutte Mechanical Engineering Handbook and a set of the 1929 edition of the Handbuch der Physik.
Within a short time Theodorsen was made head of the Physical Research Division, the other research divisions being Engine Research and Aerodynamics
Aerodynamics
Aerodynamics is a branch of dynamics concerned with studying the motion of air, particularly when it interacts with a moving object. Aerodynamics is a subfield of fluid dynamics and gas dynamics, with much theory shared between them. Aerodynamics is often used synonymously with gas dynamics, with...
. Langley NACA was then in the process of expanding its experimental facilities to include a Full Scale Wind Tunnel and a Hydrodynamic Towing Basin for testing flying boat hulls. It happened that the proposed location of the towing basin had formerly been a bombing range. One of Theodorsen's first activities was the invention of an instrument for detecting buried metals and on its very first use it located a live bomb.
The ensuing years were highly productive ones for Theodorsen in a great variety of experimental and theoretical areas. As an overview Theodorsen improved thin airfoil theory by introducing the angle of best streamlining, went on to develop the now classical and elegant theory of arbitrary wing sections, performed the first in-house noise research, worked on fire prevention in aircraft and on means of icing removal and prevention, contributed to the theory of open, closed and partially open wind-tunnel test sections, developed the basic theory of aircraft flutter and its verification, made early measurements of skin friction at transonic
Transonic
Transonic speed is an aeronautics term referring to the condition of flight in which a range of velocities of airflow exist surrounding and flowing past an air vehicle or an airfoil that are concurrently below, at, and above the speed of sound in the range of Mach 0.8 to 1.2, i.e. 600–900 mph...
and supersonic
Supersonic
Supersonic speed is a rate of travel of an object that exceeds the speed of sound . For objects traveling in dry air of a temperature of 20 °C this speed is approximately 343 m/s, 1,125 ft/s, 768 mph or 1,235 km/h. Speeds greater than five times the speed of sound are often...
speeds, developed the use of freon for experimental aeroelastic work, gave damping properties of structures and expanded general propeller theory. During World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
Theodorsen was called on for the analysis and troubleshooting of many aircraft problems and to help devise necessary modifications.
Expanding on Significant Themes
Theodorsen was an innovative practical engineer at a time in which most of his contemporary theoretical aerodynamists were located at educational institutions and thus were not involved in practical engineering solutions. Theodorsen’s work is especially significant in that it still plays an important role in current research and technology.The theory of arbitrary airfoils based on conformal mapping developed by Theodorsen, is a model of classical applied mathematics. It should be pointed out that there are two key concepts that made Theodorsen’s approach different from and a clear improvement on the methods that preceded it such as that of von Mises
Von Mises
von Mises may refer to:* Ludwig von Mises Institute* von Mises distribution, named after Richard von Mises* von Mises yield criterion, named after Richard von Mises- People :* Dr...
and von Karman. One was the important use of the complex variable not in the usual form of a polynomial
Polynomial
In mathematics, a polynomial is an expression of finite length constructed from variables and constants, using only the operations of addition, subtraction, multiplication, and non-negative integer exponents...
or power series but in the form of an exponential to power series. The equation led directly to the basic boundary value equation which, as an integral equation, represents an exact solution of the problem in terms of the given airfoil
Airfoil
An airfoil or aerofoil is the shape of a wing or blade or sail as seen in cross-section....
data. This solution gave the exact pressure distribution around an airfoil of arbitrary shape. Seldom in aeronautics
Aeronautics
Aeronautics is the science involved with the study, design, and manufacturing of airflight-capable machines, or the techniques of operating aircraft and rocketry within the atmosphere...
are solutions “exact”. This is one of the very few. The method has been automated so that complete pressure distributions for a given airfoil section can be obtained in a matter of seconds. The philosophy in Theodorsen’s approach was that an exact formulation is often simpler and preferable to an approximate one and that while approximations are essential in applied mathematics they should be delayed as far as possible.
Another topic that merits discussion is Theodorsen’s work on flutter
Aeroelasticity
Aeroelasticity is the science which studies the interactions among inertial, elastic, and aerodynamic forces. It was defined by Arthur Collar in 1947 as "the study of the mutual interaction that takes place within the triangle of the inertial, elastic, and aerodynamic forces acting on structural...
. The approach here is again direct and clean, leading to an explicit exact solution as contrasted with previous implicit and approximate results. This exact flutter solution including results for control surfaces has had a keystone role in the development of flutter methods in the United States. It has enabled an engineering feel for the effects of variables and parameters in complex situations and has been available as a model against which approximate solutions can be compared.
Although Theodorsen leaned strongly toward basic theoretical analysis, he usually accompanied his work with experimental verification. He was highly innovative in engineering
Engineering
Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...
and experimental activities where he always sought a theoretical framework or was guided by physical intuition. He was responsible for proposing a wind tunnel for flutter work which employed a mixture of air and freon with variable pressure to greatly increase the scope of research with aeroelastic models throughout the Mach
Mach number
Mach number is the speed of an object moving through air, or any other fluid substance, divided by the speed of sound as it is in that substance for its particular physical conditions, including those of temperature and pressure...
range and with lower horsepower requirements. The Transonic
Transonic
Transonic speed is an aeronautics term referring to the condition of flight in which a range of velocities of airflow exist surrounding and flowing past an air vehicle or an airfoil that are concurrently below, at, and above the speed of sound in the range of Mach 0.8 to 1.2, i.e. 600–900 mph...
Dynamics Wind Tunnel now used exclusively for aeroelastic research is based on the same principles.
Another unique facility due to Theodorsen was the helicopter rotor tower for aerodynamic and noise research. Ideal propeller dynamics was given a definitive treatment in
several reports and a book. Theodorsen was the earliest to obtain reliable skin-friction drag data at subsonic, transonic
Transonic
Transonic speed is an aeronautics term referring to the condition of flight in which a range of velocities of airflow exist surrounding and flowing past an air vehicle or an airfoil that are concurrently below, at, and above the speed of sound in the range of Mach 0.8 to 1.2, i.e. 600–900 mph...
and supersonic
Supersonic
Supersonic speed is a rate of travel of an object that exceeds the speed of sound . For objects traveling in dry air of a temperature of 20 °C this speed is approximately 343 m/s, 1,125 ft/s, 768 mph or 1,235 km/h. Speeds greater than five times the speed of sound are often...
speeds.
Later years
After leaving NACANACA
- Organizations :* National Advisory Committee for Aeronautics, the forerunner of the U.S. federal agency NASA* National Association for Campus Activities, an organization for programmers of university and college activities...
in 1946 Theodorsen helped to organize and administer the Instituto Tecnológico de Aeronáutica (Aeronautical Institute of Technology) (1947–1950) in Brazil. Then he served as Chief Scientist for the U.S. Air Force (1950–1954) during which time he did important work on the structure of turbulence
Turbulence
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time...
. Theodorsen then became the Chief of Research for the Republic Aviation Corporation (manufacturer of the famous P-47 Thunderbolt
P-47 Thunderbolt
Republic Aviation's P-47 Thunderbolt, also known as the "Jug", was the largest, heaviest, and most expensive fighter aircraft in history to be powered by a single reciprocating engine. It was heavily armed with eight .50-caliber machine guns, four per wing. When fully loaded, the P-47 weighed up to...
fighter plane of World War II, and after the war the F-84 Thunderjet
F-84 Thunderjet
The Republic F-84 Thunderjet was an American turbojet fighter-bomber aircraft. Originating as a 1944 United States Army Air Forces proposal for a "day fighter", the F-84 flew in 1946...
and the F-105 Thunderchief
F-105 Thunderchief
The Republic F-105 Thunderchief, was a supersonic fighter-bomber used by the United States Air Force. The Mach 2 capable F-105 conducted the majority of strike bombing missions during the early years of the Vietnam War; it has the dubious distinction of being the only US aircraft to have been...
) a post from which he retired in 1962 when he became an active consultant to the Sikorsky
Sikorsky Aircraft
The Sikorsky Aircraft Corporation is an American aircraft manufacturer based in Stratford, Connecticut. Its parent company is United Technologies Corporation.-History:...
Helicopter Corporation where he specialized in ducted propeller work and helicopter rotors.
Turbulence Theory
A significant development was his contribution to the structure of turbulenceTurbulence
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time...
in a paper honoring Ludwig Prandtl’s 75th birthday. The universality of turbulence from microphenomena to astrophysics
Astrophysics
Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior...
is well known as for example, the hypothesis that the planets have condensed from a gaseous cloud and that the angular momentum of the solar system is a result of the action of viscosity
Viscosity
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...
in the nebula
Nebula
A nebula is an interstellar cloud of dust, hydrogen gas, helium gas and other ionized gases...
. Turbulence
Turbulence
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time...
remains as the major unsolved domain of fluid mechanics
Fluid mechanics
Fluid mechanics is the study of fluids and the forces on them. Fluid mechanics can be divided into fluid statics, the study of fluids at rest; fluid kinematics, the study of fluids in motion; and fluid dynamics, the study of the effect of forces on fluid motion...
. Theodorsen identified the main turbulence-creating terms in the equations of motion as (q x curl q . curl curl q); he showed that two-dimensional turbulence cannot exist; that vortex
Vortex
A vortex is a spinning, often turbulent,flow of fluid. Any spiral motion with closed streamlines is vortex flow. The motion of the fluid swirling rapidly around a center is called a vortex...
lines stretching
Vortex stretching
In fluid dynamics, vortex stretching is the lengthening of vortices in three-dimensional fluid flow, associated with a corresponding increase of the component of vorticity in the stretching direction—due to the conservation of angular momentum....
and bending is the important mechanism and ingredient of turbulence
Turbulence
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time...
. He also discussed the hierarchy of vortices (Kolmogorov).
Theory of Relativity
Although Theodorsen's life work was in aerodynamics, and he published numerous books and papers in that field, he had other interests. In particular, he wrote a paper, Relativity and Classical Physics which sought to show that the results of Einstein's theory of general relativityGeneral relativity
General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...
could be obtained without resorting to curved space-time by a modification of Newton's law of universal gravitation
Newton's law of universal gravitation
Newton's law of universal gravitation states that every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them...
. The paper presents "a successful transformation of the theory of relativity into classical physics... The mathematical entities of the Einstein development have been redefined into rational physical quantities and rearranged in an organized classical framework. Einstein's space-time has been eliminated and replaced by cognitive time." It was published in the Proceedings of the DKNVS Theodorsen Colloquium and on two later occasions.
Personal life
In 1922 Theodorsen married Johanne Magdelene Hoem. Her family was a well known respected family in TrondheimTrondheim
Trondheim , historically, Nidaros and Trondhjem, is a city and municipality in Sør-Trøndelag county, Norway. With a population of 173,486, it is the third most populous municipality and city in the country, although the fourth largest metropolitan area. It is the administrative centre of...
. They were married in the famous Nidaros Cathedral
Nidaros Cathedral
Nidaros Cathedral is a Church of Norway cathedral located in the city of Trondheim in Sør-Trøndelag county, Norway. It was the cathedral of the Roman Catholic Archdiocese of Nidaros from its establishment in 1152 until its abolition in 1537. Since the Reformation, it has been the cathedral of the...
, the largest existing medieval church in Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...
. The wedding party was an all-night celebration at the Britannia Hotel with one hundred guests. Their daughter Muriel Gerd-Preutz and sons Theodore Elliott and John Willman were all born in the United States.
In 1976, Dr. Theodorsen was awarded an honorary doctorate degree from the Norwegian University of Science and Technology
Norwegian University of Science and Technology
The Norwegian University of Science and Technology , commonly known as NTNU, is located in Trondheim. NTNU is the second largest of the eight universities in Norway, and, as its name suggests, has the main national responsibility for higher education in engineering and technology...
in Trondheim. The Royal Norwegian Society of Sciences and Letters
Royal Norwegian Society of Sciences and Letters
The Royal Norwegian Society of Sciences and Letters is a learned society based in Trondheim, Norway.-History:DKNVS was founded in 1760 by bishop of Nidaros Johan Ernst Gunnerus, headmaster at the Trondheim Cathedral School Gerhard Schøning and Councillor of State Peter Frederik Suhm under the name...
, also held a colloquium in his honor at Trondheim. After a short illness, Dr. Theodorsen died in 1978 at the age of eighty one at his home in Centerport
Centerport, New York
Centerport is a hamlet in Suffolk County, New York on the notably affluent North Shore of Long Island. Formerly known as Little Cow Harbor about 1700, Centreport in 1836, and then the present Centerport after 1895...
, Long Island, New York.
Selected works
- The Theory of Wind-Tunnel Wall Interference (1931)
- A new principle of sound frequency analysis (1931)
- The prevention of ice formation on gasoline tank vents (1931)
- General Potential Theory of Arbitrary Wing Sections (1932)
- Experimental Verification of the Theory of Wind-Tunnel Boundary Interference (1934)
- General theory of aerodynamic instability and the mechanism of flutter (1935)
- Characteristics of six propellers including the high-speed range (1937)
- Nonstationary flow about a wing-aileron-tab combination including aerodynamic balance (1942)
- Extension of The Chaplygin Proofs on the Existence of Compressible Flow Solutions to the Supersonic Region (1946)
- Theory of Propellers (1948)
- The Structure of Turbulence (1954)
- Theory of Static Propellers and Helicopter Rotors (1968)
Sources
- Dowell, Earl H.(editor) A Modern view and appreciation of the works of Theodore Theodorsen, physicist and engineer (American Institute of Aeronautics and Astronautics: 1992) ISBN 0-930403-85-1
- Anderson, John David A History of Aerodynamics and its impact on Flying Machines (Cambridge University Press. 1999) ISBN 0-521669-55-3
- Hansen, James R. (editor) The Wind and Beyond: A Documentary Journey into the History of Aerodynamics in America (National Aeronautics and Space Administration. 2003) ISBN 0-756743-14-1
- Jones, R. T. (compiler) Classical Aerodynamic Theory (University Press of the Pacific. 2005) ISBN 1-410224-89-9