New Position

Today I started my new position as the Senior Scientific Technical Manager (SSTM) for Hypersonics at the US Navy’s Naval Air Warfare Center (NAWCAD).

Framework for Analytical Solutions of the Navier-Stokes Equations for Hyperbolic Boundary Value Problems in the Aerodynamic Near-Field

Abstract: A framework to create new specific analytical solutions of the equations of motion for hyperbolic boundary value problems is presented. The method relies on a closed-form integral equation for mass density, involving a term that combines sources, geometry, ambient values, and radiation. Products of the density integral result in new more complicated solutions. The density field is used to recover the field variables in the near-field through far-field relative to the aerodynamic body. The aerodynamic body is modeled as a product and combination of generalized functions. Thus, resultant analytical solutions are also a combination of generalized functions. Derivations of time-dependent analytical solutions and example predictions are presented in one and two spacial domains. Cases examined for Euler equations include moving shock waves, oblique shock waves, Prandtl-Meyer expansions, and fields from more complicated bodies. A discussion of limitations and future directions of the methodology is included. The methodology, in a more complicated form, is used primarily for hypersonic sonic boom prediction.

Paper Link [PDF]

Academic Odyssey to Ithaca

Today marks the conclusion of my professorship at the University of Florida. Odysseus’s journey from the Ilion Wars (Trojan Wars) back to Ithaca was an odyssey that defined much of his lifetime. Though separated from his love, it was the journey that made his love meaningful.

Approximately eight and a half years ago, I began as a professor and also created a photographic memoir to document my journey at the University of Florida, titled Academic Odyssey. The memoir was short-lived; however, my tenure was not. Over this period, I earned tenure by working six to seven days a week for six consecutive years.

I had the privilege of working with some of the best students from around the world. I taught thousands of undergraduate students, guided and graduated several Ph.D. students, and collaborated with them to publish journal articles and conference papers. Through these efforts, I helped them develop their research and professional skills, guided by the theme of Technical Excellence originally taught to me by Dr. Charlie Harris of NASA Langley.

Collectively, I delivered approximately 500 lectures, seminars, and classes. These experiences deepened my appreciation for the written word, the English language, and the art of delivering an excellent lecture.

When I began as an assistant professor on the tenure track in 2016, I believed I understood what a professor, student, teacher, leader, university, and scholar were. Over time, I learned at length what it means to produce high-quality research. I engaged with department chairs, deans of leading international universities, colleagues at the University of Florida and abroad, undergraduate students, and distinguished emeritus professors. I also made lifelong friends.

More importantly, I learned who I am. I found my core values as a person. I witnessed others falter when put to moral and ethical tests.

Now, I find myself returning to foundational questions, which I did not understand before: What is a university? What is a student? What is a professor? What is a scholar?

Book Collecting

I have known men to hazard their fortunes, go long journeys halfway about the world, forget friendship, even lie, cheat, and steal, all for the gain of a book. – A.S.W. Rosenbach, Books, and Bidders

The Three Pillars of Rocketry Culminating in Human Spaceflight

Below is an article that is upcoming in the NASA Alumni newsletter without images.

“The Earth is the cradle of humanity, but one cannot live in the cradle forever.” – Konstantin Tsiolkovsky

Modern rocketry began with foundational work by pioneers such as Tsiolkovsky, Oberth, Goddard, and the American Rocket Society. Their theoretical and experimental advances led to the V-2 program and ultimately enabled NASA’s Apollo missions to the moon through Dr. von Braun.

Born in September 1857 in the village of Izhevskoye, Russia, Tsiolkovsky was the fifth child in a family of Polish descent. A bout of scarlet fever at the age of ten left him with significant hearing loss, limiting his formal education. Undeterred, he became an autodidact. The imaginative works of Jules Verne, “From the Earth to the Moon,” ignited his fascination with space travel. Tsiolkovsky was a schoolteacher.

In 1883, Tsiolkovsky came up with an idea for reactive propulsion with the principle that a vehicle could propel itself by expelling part of its mass at high-speed in the opposite direction. He created the fundamental equation of rocket motion, now known as the Tsiolkovsky Rocket Equation, which is taught today to freshman in aerospace internationally.

In 1903, Tsiolkovsky published his seminal work, “Exploration of Outer Space by Means of Rocket Devices,” in the Russian magazine Science Review (Nauchnoye Obozreniye). He proposed the use of liquid hydrogen and oxygen as rocket propellants. He envisioned multi-stage rockets, space stations, airlocks for spacewalks, and colonization of the solar system. His thoughts were unrecognized and remained within a small circle in Russia.

In 1919, his contributions were formally acknowledged when he was elected to the Socialist Academy, the precursor to the USSR Academy of Sciences. His research inspired Sergei Korolev, the chief designer of the Soviet space program, who was almost entirely unknown in history until much later.

“To boldly go where no man has gone before.” – Hermann Oberth

Hermann Oberth, held a place alongside Russia’s Konstantin Tsiolkovsky and the United States’ Robert H. Goddard. Born on July 25, 1894, in Hermannstadt, Transylvania (Romania), Oberth was captivated by space from an early age, drawing inspiration from Jules Verne’s science fiction, notably “From the Earth to the Moon” and “Around the Moon.” Oberth proposed liquid-fueled rockets as a means for long-range missiles to the German War Department. His ideas were dismissed.

In 1922, Oberth formalized his concepts in his doctoral dissertation, “Die Rakete zu den Planetenräumen” (“By Rocket into Planetary Space”), which the University of Heidelberg rejected as speculative. Oberth self-published in 1923. His research demonstrated that rockets could reach space, detailed the feasibility of liquid propellants, oxygen and hydrogen, proposed multi-stage rockets for increased velocities, and identified navigation and life support problems.

To advance Oberth’s vision, the Verein für Raumschiffahrt (VfR), (German Society for Space Travel), was established in 1927. The VfR began conducting experimental rocket tests in 1929. The society attracted notable members, including Wernher von Braun, a young engineering student who became Oberth’s assistant and protégé.

Oberth’s mentorship influenced von Braun, who later directed Germany’s rocket development efforts during World War II. Leveraging Oberth’s theories, Germany developed the V-2 rocket, the world’s first long-range guided ballistic missile. They knew of the work of Tsiolkovsky and Goddard in America.

“The dream of yesterday is the hope of today and the reality of tomorrow.” – Robert H. Goddard

Born on October 5, 1882, in Worcester, Massachusetts, Dr. Robert H. Goddard’s life shared similarities with Konstantin Tsiolkovsky. Like Tsiolkovsky, he was an avid physicist and mathematician, convinced that rockets were the key to space flight, and he worked in obscurity for most of his life. However, there was a significant difference between them: while Tsiolkovsky’s contributions were purely theoretical, Goddard transformed theory into practice by developing the world’s first liquid-fueled rocket that worked.

Goddard was educated in Worcester, graduating from South High School in 1904, obtaining a bachelor’s degree from Worcester Polytechnic Institute in 1908, and earning a doctorate in physics from Clark University in 1911. He became a professor of physics at Clark University, where he began to apply science and engineering to space flight. He determined that liquid hydrogen and liquid oxygen would be highly efficient rocket propellants. In July 1914, he was granted patents on rocket combustion chambers, nozzles, propellant feed systems, and multistage rockets.

While Dr. Robert H. Goddard was advancing rocketry through private experiments, another group of American enthusiasts independently pursued space exploration. Formed in the early 1930s, the American Rocket Society (ARS) emerged as an organization that envisioned the potential of rockets and tested them.

The ARS was part of the American Interplanetary Society (AIS). Established in New York City by science fiction enthusiasts and amateur scientists David Lasser, G. Edward Pendray, and H. Winfield Secor. AIS members engaged in experimental rocketry, designing and testing rockets to while creating a network of for space exploration. In 1934, AIS became the American Rocket Society.

In 1963, recognizing the need for a unified professional body to represent the aerospace industry, the ARS merged with the Institute of the Aerospace Sciences to form the American Institute of Aeronautics and Astronautics (AIAA).

The combined contributions of Tsiolkovsky, Oberth, Goddard, and the ARS laid the groundwork for modern rocketry, leading to the V-2 and subsequent space initiatives at NACA and NASA. Tsiolkovsky’s mathematical models defined spaceflight’s theoretical foundation, while Goddard’s liquid-fueled engines launched American programs. In Germany, Oberth turned speculative science into reality, mentoring Dr. Wernher von Braun, who would drive the V-2 program and later the U.S. space program.

The Apollo moon landings ultimately rested on the foundational work of these pioneers from the U.S., Germany, and Russia. From this historical viewpoint, the outcome was truly an international effort for the benefit of all mankind.

References

  • Tsiolkovsky, K. S. (1903). Exploration of outer space by means of rocket devices. The Science Review, 5.
  • Kosmodemyansky, A. (2000). Konstantin Tsiolkovsky: His life and work. The Minerva Group.
  • Siddiqi, A. A. (2000). Challenge to Apollo: the Soviet Union and the space race, 1945-1974 (Vol. 4408). National Aeronautics and Space Administration, NASA History Division, Office of Policy and Plans.
  • Lasser, D. (1931). The Conquest of Space. Penguin Press.
  • Springer, A. (2001). The development of an aerospace society – The AIAA at 70. In 39th Aerospace Sciences Meeting and Exhibit (p. 177).
  • Oberth, H. (1984). Die Rakete zu den Planetenräumen. Oldenbourg Wissenschaftsverlag.
  • Anderson, M. (Ed.). (2012). Pioneers in Astronomy and Space Exploration. Britannica Educational Publishing.
  • Neufeld, M. J. (1995). The rocket and the Reich: Peenemünde and the coming of the ballistic missile era. Simon and Schuster.

Research Notes on The American Rocket Society

“The dream of yesterday is the hope of today and the reality of tomorrow.” – Robert H. Goddard

While Dr. Robert H. Goddard was advancing rocketry through private experiments, another group of American enthusiasts independently pursued space exploration. Formed in the early 1930s, the American Rocket Society (ARS) emerged as an organization that not only envisioned the potential of rockets, but also built and tested them, laying groundwork for America’s future in space.

The ARS story began with the founding of the American Interplanetary Society (AIS) in 1930. Established in New York City by science fiction enthusiasts and amateur scientists David Lasser, G. Edward Pendray, and H. Winfield Secor, AIS aimed to promote interplanetary travel and advance rocketry as the flight-vehicle to achieve it. Initially, the society dedicated itself to educating the public about the possibilities of space travel, publishing materials that both informed and inspired. Also, AIS members engaged in experimental rocketry, designing and testing rockets to validate theoretical concepts while creating a network of like-minded individuals passionate about space exploration. In 1934, AIS became the American Rocket Society.

On May 14, 1933, the ARS launched its first liquid-fueled rocket from Marine Park in Staten Island, New York. This rocket, powered by liquid oxygen and gasoline, reached an altitude of 250 feet, marking one of the earliest successful liquid-propelled rocket launches in the United States. ARS experiments contributed to significant advancements in rocket technology, particularly in liquid propulsion systems, structural design for stability, and instrumentation for measuring flight performance.

Throughout the 1930s, the ARS was a hub for rocket research and development in the United States. Operating without government funding, the society relied on resources of its members, who conducted numerous tests and shared findings openly. The ARS evolved into a group of visionaries; its regular meetings and publications fostered collaboration on projects, facilitated the exchange of experimental results, and offered lectures that created public interest in rocketry.

With the onset of World War II, the United States redirected focus toward military technology. ARS members’ expertise became highly valued, leading many to join government and private projects. As a result, the society’s experimental activities were gradually absorbed into larger national initiatives. After the war, ARS shifted its focus back to peaceful applications of rocketry and space exploration. It resumed publication of the prestigious ARS Journal, which became a leading publication for aerospace engineering. This journal played a role in establishing industry standards in rocket design and testing.

In 1963, recognizing the need for a unified professional body to represent the aerospace industry, the American Rocket Society merged with the Institute of the Aerospace Sciences to form the American Institute of Aeronautics and Astronautics (AIAA).

References

  • Lasser, D. (1931). The Conquest of Space. Penguin Press.
  • Springer, A. (2001). The development of an aerospace society – The AIAA at 70. In 39th Aerospace Sciences Meeting and Exhibit (p. 177).

Research Notes on Hermann Oberth

“To boldly go where no man has gone before.” – Hermann Oberth

Hermann Oberth’s theoretical breakthroughs transformed rocketry from speculative fiction into science, thus influencing the development of modern space exploration. His mentorship of Wernher von Braun and contributions to the V-2 rocket program set foundational principles that shape the field.

Germany’s major figure in early rocketry, Oberth held a place alongside Russia’s Konstantin Tsiolkovsky and the United States’ Robert H. Goddard. Born on July 25, 1894, in Hermannstadt, Transylvania (now Sibiu, Romania), Oberth was captivated by space from an early age, drawing inspiration from Jules Verne’s science fiction, notably “From the Earth to the Moon” and “Around the Moon.” Initially pursuing medicine in Munich, he served as a medic in World War I, during which he developed an interest in rocketry. Oberth proposed liquid-fueled rockets as a means for long-range missiles to the German War Department, though his ideas were dismissed.

In 1922, Oberth formalized his concepts in his doctoral dissertation, “Die Rakete zu den Planetenräumen” (“By Rocket into Planetary Space”), which the University of Heidelberg rejected as speculative. Undeterred, Oberth self-published in 1923. His research demonstrated that rockets could reach outer space, detailed the feasibility of liquid propellants – liquid oxygen and hydrogen, proposed multi-stage rockets for increased velocities, and addressed challenges in space navigation and life support.

To advance Oberth’s vision, the Verein für Raumschiffahrt (VfR), or German Society for Space Travel, was established in 1927. The VfR, drawing scientists and engineers eager to make space travel a reality, began conducting experimental rocket tests by 1929. The society attracted notable members, including Wernher von Braun, a young engineering student who became Oberth’s assistant and protégé, as well as Rudolf Nebel, a pivotal figure in early rocketry. The VfR’s activities inspired similar organizations globally, including the American Rocket Society.

Oberth’s mentorship influenced von Braun, who later directed Germany’s rocket development efforts during World War II. Together, Oberth and von Braun worked on liquid-fueled rockets to achieve high-altitudes, accelerating Germany’s rocketry program. Leveraging Oberth’s theories, Germany developed the V-2 rocket, the world’s first long-range guided ballistic missile.

The legacy of Oberth’s work is clear: the V-2’s technology became the blueprint for postwar rocketry. In the United States, von Braun’s Saturn V rocket launched the Apollo missions to the Moon. In the Soviet Union, captured V-2 technology supported early rocket development. All modern rockets trace their lineage to the V-2 and to Oberth’s pioneering contributions.

References

  • Anderson, M. (Ed.). (2012). Pioneers in Astronomy and Space Exploration. Britannica Educational Publishing.
  • Oberth, H. (1984). Die Rakete zu den Planetenräumen. Oldenbourg Wissenschaftsverlag.
  • Neufeld, M. J. (1995). The rocket and the Reich: Peenemünde and the coming of the ballistic missile era. Simon and Schuster.

A Possible High-Re Liquid He Experiment

I wrote about this experiment and discussed it with funding agencies long ago and just wanted to post the idea.

I am exploring the possibility of conducting high-Reynolds number turbulence experiments. One experiment would involve constructing a large isolated vessel filled with liquid helium to create fully developed, spatially localized high-Re flow through transient forcing mechanisms. The forcing would be induced either by localized heating using multiple femtosecond lasers or by mechanical grid motion. The experiment will focus on capturing the acoustic radiation produced by turbulence, which is deterministically linked to the flow-field. A total of 2500 microphones would be strategically embedded within the containment vessel’s walls to measure the acoustic signatures without disturbing the flow as intrusive methods contaminate the data. Additionally, sapphire windows will be integrated into the vessel to enable high-speed CCD cameras to track tracer particles introduced into the flow. These particles will be activated by a 5-kHz femtosecond laser system, capturing the temporal and spatial resolution.

The collected data will be used to reconstruct the turbulent field variables as a function of space and time. This reconstruction will be based on the theory of isotropic homogeneous turbulence and radiation, a framework I previously published. The method provides the foundation for predicting noise generated by homogeneous isotropic turbulence and is directly applicable to the proposed experiment. By combining predicted statistical models with time-dependent data and advanced beamforming techniques—specifically, those contained within the Acoular open-source code—the aim is to achieve a three-dimensional, time-dependent reconstruction of the turbulent field.

The primary focus will be on analyzing the intermittency and bursting phenomena that are characteristic of high-Re turbulence. These events generate strong acoustic impulses, which will be captured at a frequency of 180 kHz by the microphone array. The goal is to process this data to find the mechanisms behind these bursts and to create a high-fidelity database that could potentially be used to validate direct numerical simulations (DNS) in the future.

The experiment’s design addresses the limitations of previous liquid helium experiments, such as those conducted at Florida State and Minnesota, where intrusive measurement techniques altered the flow-field. By using acoustic measurements as a non-intrusive method, the experiment will capture the unique “fingerprint” of turbulence without affecting the flow itself. Each turbulent field radiates its own unique acoustic signature.

The expected outcomes include:

  • A comprehensive database of a high-Re number turbulent field with documented intermittent bursts and associated scaling.
  • New insights into the universal nature of small-scale turbulence within a high-Re field.
  • A better understanding of the hierarchical structure and nature of turbulence.

I think that such an experiment would take five years to conduct.

Research Notes on Konstantin Tsiolkovsky

“The Earth is the cradle of humanity, but one cannot live in the cradle forever.” – Konstantin Tsiolkovsky

In 1903, Tsiolkovsky wrote an article called, “Exploration of outer space by means of rocket devices,” in The Science Review.

Born in September 1857 in the village of Izhevskoye, Russia, Tsiolkovsky was the fifth child in a family of Polish descent. A bout of scarlet fever at the age of ten left him with significant hearing loss, limiting his formal education. Undeterred, he became an autodidact, immersing himself in physics and mathematics. The imaginative works of Jules Verne, especially “From the Earth to the Moon”, ignited his fascination with space travel. In 1876, Tsiolkovsky began his career as a schoolteacher in Borovsk, where he started crafting aeronautical experiments. In 1882, he moved to the town of Kaluga, dedicating his life to teaching and scientific inquiry. Working in virtual obscurity and without institutional support, he went into creating theory of space flight.

1883, Tsiolkovsky came up with an idea for reactive propulsion with the principle that a vehicle could propel itself by expelling part of its mass at high speed in the opposite direction. This insight was revolutionary, laying groundwork for modern rocket science. He mathematically derived the fundamental equation of rocket motion, now known as the Tsiolkovsky Rocket Equation, is the final total mass (after propellant is expended). This equation describes how rockets achieve velocity change, factoring in the expulsion of mass (still taught today by some historically minded faculty).

In 1903, Tsiolkovsky published his seminal work, “Exploration of Outer Space by Means of Rocket Devices”, in the Russian magazine Science Review (Nauchnoye Obozreniye) (see ref). He proposed the use of liquid hydrogen and liquid oxygen as rocket propellants. He envisioned multi-stage rockets, space stations, airlocks for spacewalks, and colonization of the Solar System (though not the originator of these ideas). Despite his new theories, Tsiolkovsky did not have resources to create experimental research or practical applications. His thoughts were unrecognized and remained in a small circle within Russia.

In 1919, his contributions were formally acknowledged when he was elected to the Socialist Academy, the precursor to the USSR Academy of Sciences. He was granted a government pension, allowing him to focus on research. His research inspired a new generation of engineers and scientists, including Sergei Korolev, the chief designer of Soviet space program (who was not known outside the Soviet Union for a long time and there are wonderful documentaries online about Korolev).

Suggest reading the biography by Kosmodemyansky, A. (2000), “Konstantin Tsiolkovsky: His life and work,” 2000.

References

  • Tsiolkovsky, K. S. (1903). Exploration of outer space by means of rocket devices. The Science Review, 5. (primary ref).
  • https://www.nasa.gov/history/sputnik/
  • Siddiqi, A. A. (2000). Challenge to Apollo: the Soviet Union and the space race, 1945-1974 (Vol. 4408). National Aeronautics and Space Administration, NASA History Division, Office of Policy and Plans.
  • Kosmodemyansky, A. (2000). Konstantin Tsiolkovsky: His life and work. The Minerva Group.