SR-72 Darkstar
Photo taken by Steve Tabor at the Palm Springs Air Museum

In the latest edition of the Top Gun film series, “Top Gun: Maverick,” Tom Cruise glues the audience to their seats as he took the controls of a futuristic aircraft, the SR (Strategic Reconnaissance)-72 Darkstar, and blasts into the night the sky attempting to achieve a speed of Mach 10, ten times the speed of sound, before his commanding officer shuts down this experimental program.

Although the model of the SR-72 appears to be realistic, there is no confirmation that any manufacture in the U.S. has produced a hypersonic aircraft.
Photograph taken by Steve Tabor at the Palm Springs Air Museum

The aircraft used in the film is a model built by Lockheed Martin and includes their Skunk Works decals. It can be found at the Palm Springs Air Museum (PSAM). Despite rumors circulating in the aerospace community credit Lockheed Martin with testing a hypersonic aircraft capable of reaching Mach 6, thus far, no aerospace company has revealed they have produced any aircraft capable of reaching Mach 5, the minimum threshold to be considered a hypersonic aircraft.

Photo taken by Steve Tabor at the Palm Springs Air Museum

The Next Generation of Aerospace

Co-Founders of Hermeus, AJ Piplica, former CEO of Generation Orbit Launch Services (GOLS), Inc., Skyler Shuford, Director of Avionics and Software at GOLS, and Glenn Case, Director of Propulsion and Structures at GOLS, were responsible for the development of U.S. Air Force’s hypersonic research flight vehicle, the X-60A, an experimental underwing launched hypersonic rocket vehicle. But, all three agreed to leave their “high paying jobs” to create a company focused on accelerating the “global human transportation network through the development of hypersonic aircraft.”

The trio believes that the aerospace industry has evolved to the point where too much time and money is spent on the project’s developmental and wind tunnel testing stages, slowing the production and testing of prototype vehicles. According to Piplica, in fiscal 2023, Congress allotted $5.8 billion to the Pentagon to fund approximately 70 hypersonic vehicle programs, but the production of these vehicles has been slowed due to an insufficient number of wind tunnel facilities and other contributing factors.

Piplica believes Hermeus can use its entrepreneurial philosophy of “engineering over science” to reduce the amount of time spent on perfecting systems on paper and as much as possible limiting wind tunnel testing to produce a hypersonic aircraft. The sequential development of their Quarterhorse program allows Hermeus to de-risk the use of the technologies needed produce a hypersonic aircraft.

A modeler carefully crafts a model aircraft to undergo wind tunnel testing.
Photograph courtesy of Hermeus

With the Quarterhorse program, Hermeus produces a sequential series of prototypes, approximately one year apart, Mk 0, Mk 1, Mk 2, and Mk 3. Each version of the Quarterhorse is designed to progressively test the engineering, and technologies that are required in the production of a hypersonic aircraft. The Quarterhorse Mk 0, the first aircraft in the series, was restricted to runway testing of it flight controls and other engineering systems. The Mk 3 will be able to reach a speed of approximately Mach 5 and be capable of being piloted by remote control or auto-pilot.

Taking a Lesson from Aviation Pioneers

Piplica compares the Hermeus process to such 20th century aerospace pioneers, as Lockheed Martin’s Skunk Works founder, Kelly Johnson, and the creative genius of Howard Hughes, who dedicated less time to the development of aircraft and placed greater emphasis on testing their creations. Piplica admires Hughes’ engineering and pioneer spirit that was no more apparent when Hughes crashed his H-1 racer, during its test flight and after the crash landing Hughes told his team, “We can fix her, she’ll go faster.”

A more recent example Piplica points to is the development of SpaceX. Initially, people looked at the high price tag for constructing a rocket and getting it into orbit as something that could not be privately funded. Piplica shares, “SpaceX did it for $90 million, with the Falcon 1. Since that time SpaceX has produced the Dragon, Falcon Heavy and Starship rockets. This allows SpaceX to serve their vision of interplanetary spaceflight while generating revenue through contracts with commercial companies and the National Aeronautics and Space Administration (NASA).”

Chartering Their Own Course

Hermeus goal focuses on producing a commercially successful hypersonic aircraft. During his interview with Forbes, Piplica admits that building such a commercial aircraft of this type faces a number of technical challenges, but he says, “The business challenges are actually the real hard ones. You’re not just going to raise billions of dollars to develop a passenger aircraft.”

Realizing Hermeus does not have the necessary financial resources and technology to immediately undertake such an ambitious project, Hermeus received funding from the U.S. Air Force (USAF), Series B start-up financing (utilized to support a company’s next level of growth), and other investors to build a hypersonic aircraft that can be utilized for military purposes. If successful, this undertaking can provide Hermeus with the necessary capital to support its commercial aircraft venture while developing the necessary experience and technology to produce both military and civilian hypersonic aircraft.

The key to Hermeus’ success lies in the teamwork throughout the production of their aircraft. This includes the cooperative effort between engineers and assemblers as the aircraft is assembled on the factory floor.
Photograph courtesy of Hermeus

The Right Place at the Right Time

Fortunately, the void of U.S. hypersonic aircraft in our arsenal and geo-political issues are highly in Hermeus’ favor. Many Pentagon leaders and others involved in our national defense strategies see that this deficiency places our country at a severe disadvantage against our two greatest adversaries, The People’s Republic of China (China) and our long time cold war adversary, the Russian Federation (Russia).

Although the U.S. has produced some hypersonic missiles, and the X-60, a hypersonic flight research vehicle, the only hypersonic aircraft produced in the U.S. was North American Aviation’s (NAA) X-15 rocket plane. Placed into service in 1959, the X-15 was incapable of self-powered take offs. The X-15 was mounted to the underside of a wing of specially fitted B-52 Stratofortress and carried into the sky. Upon reaching the designated altitude, the X-15 was jettisoned and ignited the rocket engine propelling the aircraft into the upper reaches of the earth’s atmosphere into near space, approximately 60,000 miles above sea level. During a test flight in 1964, the X-15 set speed record for a manned aircraft at Mach 6.7. The X-15 program was terminated in 1968.

The X-15 rocket plane was primarily used to prepare the U.S. for the space flight. X-15 pilots were awarded their Astronaut wings for their experiences.
Photo taken by Steve Tabor at the Smithsonian National Air and Space Museum in Washington, D.C.

Currently, China and Russia far exceed the U.S.’s capabilities in the hypersonic aircraft and hypersonic missile race. Hypersonic aircraft and missiles provide a distinct advantage in warfare over ballistic missiles.

After launch, a ballistic missile leaves the earth’s atmosphere and travels through space on a predictable flight path making them visible to conventional radar. The predictability of their flight path allows the adversary to take counter measures before the missile reaches its intended target.

Hypersonic vehicles do not require extensive stealth technology because they are designed to fly in the upper reaches of the earth’s atmosphere using the curvature of the earth to be concealed from the enemy. Once the hypersonic vehicle becomes visible, the vehicle’s speed makes it difficult to destroy or defend against. Unlike a ballistic missile, hypersonic vehicles can be remotely piloted. If mission conditions change, the vehicle can be diverted at any point in the flight to another target. Hypersonic aircraft represent a cost savings over one-time use ballistic missiles because they are designed to take off and land utilizing a runway and returned to service in a short amount of time.

A careful examination of a prototype model before wind tunnel testing begins.
Photograph courtesy of Hermeus

In 2018, Russian President, Vladimir Putin, unveiled an air launched hypersonic missile, Kh-47M2, Dagger. With an approximate range of 300 miles, the missile can reach a speed of Mach 10. Because it uses standard ballistic missile technology it does not represent a significant technological advance, but its speed is unmatched by any conventional ballistic missile.

While in office, former U.S. President, Joseph Biden confirmed the Russian’s use of the weapon against Ukraine while admitting, “It’s almost impossible to stop it. There’s the reason they’re using it.” Chinese analysts cite that it is not a true hypersonic missile because it follows a ballistic trajectory and cannot maneuver at hypersonic speeds.

As far as the Chinese experimentation with hypersonic aircraft, Pentagon officials believe the Chinese have developed significant infrastructure for developing and testing hypersonic flight and are nearing capacity for producing hypersonic aircraft.

In 2021, the Chinese Academy of Science (CAS) reports, there are reports, “A bulky heavy-looking aircraft” flew high and fast over the Gobi Desert reaching a speed of Mach 6.5, approximately 4,987 mph. Based on the description of the aircraft provided by CAS the aircraft tested in the Gobi Desert could be an aircraft capable of carrying cargo and passengers at a speed that would be capable of flying from Beijing to New York in two hours. This information has significant implications regarding national security and commercial uses.

Saving Time and Money

With the urgency of the matter and lacking the budget to spend on facilities and development, Hermeus focuses on using their engineering talents to produce a hypersonic aircraft. Each progression of their prototypes utilizes previously proven engineering, technologies, and materials. The prototypes produced by Hermeus will be powered by “off the shelf” jet engines, the General Electric J-85 jet engine, capable of producing 5,000 lbs. of thrust, and the Pratt & Whitney F100 jet engine, capable of producing 30,000 lbs. of thrust. The landing gear used on Northrop Grumman’s F-5 Tiger and General Dynamics’ F-16 Falcon, has been adapted for use on the Quarterhorse prototypes. Instead of using tool and dies to produce aircraft structures, Hermeus utilizes 2D and 3D printers to produce a variety of parts and structures. Lastly, Hermeus carefully monitors the amount spent on wind tunnel testing.

The Pratt & Whitney F100 jet engine (left) and the General Electric J-85 jet engine (right)
Photograph courtesy of Hermeus

The friction involved in hypersonic flight causes extreme spikes in temperatures on the aircraft’s external surfaces and internal systems. Co-founder, Skyler Shuford states, “Mach 5 is the technology cliff for hypersonic aircraft.” By not exceeding Mach 5, the aircraft can utilized a ramjet engine versus a more complex scramjet engine. The primary structure of the aircraft uses existing and previously tested metallic materials. It is important to note that metallic materials were previously used in the construction of the U.S.’s fastest aircraft, Lockheed Martin’s SR-71 Blackbird, Mach 3+, and the NAA X-15.

Although USAF retired the SR 71 in 1998, it continues to hold the record for the world’s fastest aircraft.
Photograph taken by Steve Tabor at the Smithsonian National Air and Space Museum in Washington, D.C.

Shuford stresses, “Hypersonic aircraft cause us to think differently about the lifespan of an aircraft. Traditionally we think about “flight hours” regarding the maintenance of the airframe or engines. When it comes to hypersonic aircraft, variations in extreme temperatures caused by the transitions during the various stages of flight cause extreme stresses on the structure.” Instead of thinking in terms of the number of flight hours,, the life span of a hypersonic aircraft is determined by the number of times the aircraft cycles between subsonic, supersonic and hypersonic flight.

Another key aspect in their production process is that assemblers and engineers work together on the production floor as they assemble an aircraft allowing personnel to confidentially modify or adjust parts and structures quickly without extended production delays.

Combining Tested and True with New Theory to Create New Technologies

The goal of achieving hypersonic flight lies in the aircraft’s powerplant. Currently, there is no “off the shelf” hypersonic powerplant in production. To overcome this obstacle, All of the Hermeus prototypes incorporate “off the shelf” jet turbine engine into their design. But, jet turbine engines have their limitations because they produce their power by drawing air into the compressor. The compressor mixes the air with fuel and burns the mixture in the combustor before expelling it through a turbine and a nozzle.

In its regular configuration, the F100 jet engine produces temperatures reaching 1,832°F as it reaches a top speed of Mach 2. Any attempts at increasing its speed further increases the engine’s internal temperatures causing irreversible engine damage. But, for the purpose of hypersonic flight, engineers must have the F100 jet engine reach a speed of nearly Mach 3 in order to ignite the second component of the aircraft’s powerplant, the ramjet engine.

Testing of the F100 jet engine at the Hermeus facility in Florida.
Photograph courtesy of Hermeus

Previously, engineers at the Japanese Aerospace Exploration Agency (JAXA), conducted research to significantly increase the speed on jet turbine engines without raising the internal temperatures of the engine. As a result of their research, the engineers at JAXA developed a precooler, similar to a car’s radiator, which uses hydrogen in place of antifreeze, the precooler is installed near the intake of the F100 jet engine. The precooler reduces the temperature of the incoming air from 1,832°F to 570°F allowing the engine to safely reach speeds of Mach 3.

Hermeus engineers test the Pratt & Whitney F100 jet engine after installing the precooler allowing the engine to produce enough power to ignite the ramjet engine.
Photograph courtesy of Hermeus

Once engineers were able to have the F100 reach Mach 3, they needed to develop a way to divert the power from the F100 to ramjet while ensuring the engines can safely and smoothly cycle through the stages of subsonic flight, supersonic flight, and hypersonic flight.

Hermeus engineers resolved this challenge by designing and building their proprietary Chimera bypass. The Chimera bypass safely and consistently diverts the air traveling at nearly Mach 3 from F100 jet engine to the ramjet engine where it ignites and powers the aircraft to Mach 5.

Upper graphic displays engine air flow during flight below Mach 3. The bottom graphic shows the Chimera bypass directing the Mach 3+ air flow to the ramjet engine.
Graphic courtesy of Hermeus

This breakthrough technology was completed in 21 months at a cost of $18 million. Testing was conducted at the Notre Dame Turbomachinery Laboratory utilizing heated air to simulate high-Mach temperatures and pressures.

In recognition of this breakthrough technology, in November 2024, Aviation Week’s 67th Annual Laureate Award was presented to Hermeus for their work on developing and completing their initial tests of the full-scale precooler with a Pratt & Whitney F100-229 engine, paving the way for flight tests of a low cost, reusable, air-breathing hypersonic aircraft.

The ramjet engine is ignited during testing.
Photograph courtesy of Hermeus

Remote Flight Operations

Plans call for the Quarterhorse prototypes and the final version of the hypersonic aircraft, Darkhorse, are designed to be remotely flown aircraft in a similar way to the drones currently in use in civilian and military aviation. Advanced prototypes and the final production aircraft will incorporate manual flight and auto-flight capabilities.

The remotely controlled aircraft allows the pilot to remain at a control desk while the vehicle streaks across the sky.
Photograph courtesy of Hermeus

Integrating the complex flight systems and software systems requires hours of collaboration between the program’s engineers and mission pilots. Former USAF test pilot and Peninsula resident, Jeremy Vanderhal, is part of that collaboration effort. Vanderhal relies on his years of flying F-15 Eagles and F-16 Fighting Falcons to translate a “pilot’s feel” for the aircraft into engineering commands and functions of each aircraft. This is not new technology, but tailoring these systems into a new aircraft is critical in order to maintain its stability and flyability.

Vanderhal inspects the Mk 1’s wing surface prior to its test flight.
Photograph courtesy of Hermeus

Adding to equation is the aircraft’s delta wing configuration which is necessary due to sonic the shockwave formed at the nose of the aircraft, but the delta wing aircraft tend to have their noses pull up during flight. Both manual and auto-pilot flight systems must be programed to address this tendency.

Obviously, an aircraft of this complexity demands redundant fly-by-wire systems that provide flawless transitions from manual flight to auto-flight as well as the transitions from subsonic flight through supersonic flight to hypersonic flight.

Test Flights

The flight readiness tests as well as all of Quarterhorse test flights are conducted at Edwards Air Force Base. Vanderhal explains careful planning goes into every aspect of a test of the Quarterhorse. Designing a flight profile focuses on addressing the aircraft’s functions and performance as well as insuring there is no foreseeable risk of harm to persons and property. Vanderhal explains. “Each runway run up or test flight involves fast speeds and a heavy weight aircraft generating a great amount of kinetic energy and managing the risks is of the utmost importance.”

Hermeus prototype testing is underway. The Hermeus team has set a goal of advancing its prototype testing by producing one aircraft per year, an industry pace that has not been utilized in more than 50 years. The vehicle, Quarterhorse Mk 0, is a non-flying prototype that completed its runway testing in November 2023. Its ground testing targeted the aircraft’s response to remote pilot controls while under power. Vanderhal indicates that the test was successful, clearing the pathway for the prototype testing of the Mk 1.

The Mk 0 undergoes its high speed runway testing of its controllability and other engineering systems.
Photograph courtesy of Hermeus

The first subsonic flight of the Mk 1 recently took place at Edwards Air Force Base. The primary focus of the flight test includes proving the capabilities of the aircraft to perform high speed take off and landing. Additionally, the test flight validates the aircraft’s design and performance including the vehicle’s propulsion, fuel systems, hydraulics, thermal management, avionics, flight software, telemetry, flight termination, and control and command.

The sleek design of the Mk 1 along with the enhanced F100 jet engine allows the aircraft to achieve high supersonic flight.

Photograph courtesy of Hermeus

Following the flight, Shuford stated, “The real-world flight data from Mk 1 provides significant technical value that we’re rolling into our next aircraft. Moreover, the team has accomplished this milestone on a challenging timeline while operating within the overall aerospace ecosystem — all to support rebuilding America’s lost capability to quickly develop brand-new, full-scale jets.”

Following the success of the Mk 1 missions, Hermeus will progress to the Quarterhorse Mk 2. The Mk 2 prototype is approximately the same size as the F-16 Fighting Falcon and fitted with the F100 Pratt & Whitney jet engine and a ramjet engine enabling the aircraft to reach and tests its abilities during hypersonic flight.

The Quarterhorse Mk 2 chassis is under construction while Hermeus begins successful testing of its Mk 1.
Photograph courtesy of Hermeus

Current designs for the Mk 2 show the aircraft is equipped with a shock cone, commonly referred to a “spike.” The spike is similar to the spikes on both engines of a SR-71. The spike is capable of moving forward and backward to adjust the angle of the supersonic shockwave entering the engine inlet ensuring that the airflow into the engine is appropriate throughout the flight regardless of the aircraft’s speed. The Mk 2 is scheduled to fly later this year.

The MK 2 equipped with an enhanced F100 jet engine and ramjet engine will be capable of reaching speeds five times faster than the speed of sound.
Photograph courtesy of Hermeus

Moving Ahead with Production

Once successful prototype testing is concluded, Hermeus is hopeful to move ahead with the production of the Darkhorse Uncrewed Aerial System (UAS), a military aircraft capable of hypersonic flight. Once the Darkhorse enters the USAF arsenal, it is unclear as to the exact use of the vehicle, but it appears the aircraft will be used for defensive and national security missions.

Capable of reaching Mach 5 flight, Hermeus is hoping to add the Darkhorse to the U.S. Air Force arsenal within the next decade.
Photograph courtesy of Hermeus

Vanderhal shares at this point in time, the aircraft is considered a civilian aircraft, and the Federal Aviation Administration (FAA) is responsible to certify the aircraft’s air worthiness. Vanderhal points out the only problem with this is, “Prior to this program, the FAA did not have any flight worthy certification program for ‘heavy weight remotely operated aircraft.’’ Eventually, the FAA was able to establish a new set of standards and Hermeus’ staff is anxiously awaiting receiving full certification for their aircraft.

Time is Money

Looking into the not too distant future, Hermeus is riding on their success from Quarterhorse and Darkhorse program, Hermeus will be able to move toward producing the first hypersonic commercial aircraft, the Halcyon. Capable of reaching Mach 5, the Halcyon could complete a trip from New York to London in approximately 90 minutes, saving almost six hours, over a typical commercial flight.

This photograph was taken prior to the Museum of Flight’s construction of their Aviation Pavillion in 2015. The Pavillion is large enough to provide indoor storage for the Concorde and other aircraft in the Museum’s collection.
Photo taken by Steve Tabor at The Museum of Flight, Seattle, Washington

The supersonic transport Concorde G-BOAG carried approximately 100 passengers and was capable of reaching a speed of twice the speed of sound, Mach 2. The Concorde was able to fly from New York to London in approximately three hours. Cooperatively, 20 aircraft were produce by British Aerospace and the French manufacturer, Aérospatiale. The aircraft remained in service from 1973 to 2003.

Hermeus realizes that hypersonic trans-Atlantic flights do not fit the pocketbooks and needs of many travelers. However, Piplica and Hermeus believe that frequent 1st class and business class passengers would place a higher value on their time with clients over time spent in transit, and would opt for a seat on the aircraft. Anticipating a limited number of passengers, the Halcyon will be about the same size as a large business jet, seating approximately 20 passengers and capable of offering nearly 125 trans-oceanic routes.

Approximately the same size of a large private jet, the Halcyon will be capable of carrying 20 passengers at a speed of Mach 5.
Photograph courtesy of Hermeus

Piplica states, “Historically, accelerating transportation networks has resulted in massive social and economic growth.” Piplica estimates that Halcyon could increase global gross domestic product (GDP) by $4 trillion per year.

There is no doubt that the demands in our daily lives set a much faster pace than ever before. As for the aviation industry, it seems to be traveling at a hypersonic pace.

More on Hermeus

Hermeus has spread its operations across the U.S. They maintain an office in Washington D.C. to allow proximity to the Department of Defense leadership and key policy makers. The Factory, Hermeus headquarters, is in Atlanta, GA. The 110,000 sq. ft. houses primary engineering, manufacturing, and operations teams. The High Enthalpy Air-breathing Test (HEAT) facility in Jacksonville, FL, houses testing facilities for the engines and propulsion subsystems including the Pratt & Whitney F-100 engine and the proprietary hypersonic Chimera engine. The Shop in Los Angeles, CA houses hardcore engineering and analysis work. Additionally, the facility is used for smaller, highly complex component and subassembly builds.

For more information visit:

www.hermeus.com

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Steve Tabor

This South Bay native’s photographic journey began after receiving his first 35 mm film camera upon earning his Bachelor of Arts degree. As a classroom teacher he used photography to share the world and his experiences with his students. Steve began his photography career photographing coastal landscapes and marine life. His experiences have led him to include portraits and group photography, special event photography as well as live performance and athletics in his portfolio. As a contributor and photojournalist, he has published stories about the people, places and events in and around the Palos Verdes Peninsula and beyond.

Interested in seeing more of Steve’s work, visit website at: www.stevetaborimages.com

Hermeus Accelerating Towards Aviation History at a Hypersonic Rate By Photographer and Contributor Steve Tabor

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