Next Frontier In Jet Aviation – Russia, USA, Japan and Australia Compete to Master Next Generation Propulsion System


Stealth technology, space rockets and hypersonics could be a thing of the past if a new emerging techno-military race between the United States and Russia is contemplated. The nations’ defense technology developers have identified next-generation propulsion systems that could power future drones, sixth-generation aircraft, missiles, or even entire aircraft.

General Atomics (GA) announced Oct. 4 a “completely disruptive” “hybrid electric propulsion” for its MQ-Next drone concept. This was preceded by Russia’s United Engine Corporation (UEC) declaring research and development (R&D) efforts in “combined electric technology” last July.

And in July this year, the US Defense Advanced Research Projects Agency (DARPA) revealed a high-velocity missile program called ‘Gambit’, powered by a potentially revolutionary spin-detonation (RDE) engine.

HEP systems combine combustion engines with electric motors and batteries and are driven more by environmental concerns of reducing carbon dioxide emissions. Promising fuel savings of 5-30% in commercial aircraft, an HEP ​​has six different subtypes, including various combinations and pairings of batteries, engines, propellers and turbofan and combustion turbojet engines.

RDEs, on the other hand, use the “detonation” (not the “combustion”) of fuel after it is mixed with compressed air as thrust. This allows more thrust with the same amount of fuel, using the “shock waves” of detonation, which travel in a circular path, and fuel and oxidizers are added periodically.

“Hybrid-electric propulsion” and “rotational detonation (RDE) engines” could revolutionize the way air operations are planned and conducted if their expected benefits in range, thrust and speed are realized.

But what would be interesting are the far-reaching tactical and strategic implications of the RDE on US reach, distance, and logistical handicaps ahead of China in the Western Pacific.

Combined hybrid engine projects in the United States and Russia

GA’s MQ-Next, presented as concept art when the company started, has new propulsion that could be “completely disruptive technology,” according to its senior director of advanced programs, Mike Atwood, in a report on Breaking Defense.

“It uses a hybrid electric system where a Tesla Model S and an RQ-170 came together, and you have an all-electric aircraft ‘capable of traveling greater distances,'” Atwood said.

Atwood said they are working on “hybrid electric propulsion…to pioneer a new way to power air-breathing airborne vehicles.” GA Aircraft Systems President Dave Alexander discussed the technical configuration of the HE system, which would consist of a “heavy fuel engine driving very efficient generators and motors (to achieve) fairly low (fan) speeds. .. and efficiency”. He added that it would be difficult to get the fan thrust at low pressure ratios.

The Japanese RDE operating in space, producing thrust

He called the Western Pacific theater a major concern, where the technology, if successful, “would help cover the South China Sea.” Additionally, it is hoped to have other capabilities, such as allowing an aircraft to take off from a small 3,000-foot runway, which also complements the US Air Force’s Agile Combat Deployment (AGE) concept.

Smaller airbases spread across the first and second SCS island chains would make it harder for the Chinese to locate them and present a targeting dilemma. The EurAsian Times reported that US Marine Corps Deputy Commandant Eric Smith admitted that “logistics” was the “ruthless and ruthless challenge in the South China Sea”. Smith had made the remarks during an online interaction with the Stimson Center.

Meanwhile, Russia’s under-development HE systems have been officially classified as a “sixth generation” capability for “combat aircraft”. “Now work is beginning in several promising areas: sixth-generation engine technologies, a combined powertrain and more electric motor technology.

The R&D effort on the sixth-generation demonstration engine technology has been included in United Engine Corporation’s long-term work schedule and our requests for state program funding,” said Mikhail Reznikov, Deputy General Manager. of the UEC, quoted by TASS last year. .

Russia also has a parallel HE development project aimed at civilian aircraft. The Central Institute of Aviation Engines in Baranov announced in February this year “the creation of a range of hybrid power plants and power plants for aircraft with a capacity of one to a hundred seats, including convertible planes and air taxis.

An HE powerplant was tested on February 5 on the Yak-40LL flying test bed. The project then plans to replace the electrical component with a hydrogen fuel cell, multiplying the duration of the flight by 3 to 4.

In the United States, the civilian segment is targeted by Collins Aerospace and Pratt and Whitney, which have announced a collaborative hybrid-electric technology demonstrator program. “Together they are targeting propulsion systems for future advanced air mobility vehicles and – potentially – small and medium-sized regional aircraft,” Aviation Week said.

The family of hybrid-electric aircraft planned by Collins Aerospace

American Rotary Detonation Engines (RDE)

But the RDE promises to transform civil aviation, military, missiles and even naval surface transport if it unfolds as its developers envisioned. Developed in the United States, RDEs power DARPA’s “Gambit” high-speed missile, which was revealed in July this year.

RDEs are similar to pulse detonation engines (PDEs), exploiting ‘detonation’ instead of a ‘deflagration’ of the fuel and oxidizer/compressed air mixture to extract more energy, reducing the load from fuel and offering greater autonomy. The deflagration is therefore only a rapid combustion of fuel which reaches subsonic speeds, while the detonations are supersonic.

An RDE takes this phenomenon to the next level, using the powerful detonation shock wave instead of letting it exit the longer exhaust tube.

Fuel and oxidizers are added into the circular channel through small holes, the mixture of which causes detonation. The circling “detonation shock wave” strikes and ignites (or “detonates”) another mixture of fuel and oxidizer, and the cycle continues. The self-sustaining process thus produces continuous combustion rather than pulsating combustion.

That’s the tricky part of detonation engines, Dr. Prahlada, a former Defense Research and Development Organization (DRDO) missile scientist, told the EurAsian Times. “It should continue to produce a steady push for an extended period of time, even if it performs as expected,” Prahlada added.

In May 2020, joint researchers from the University of Central Florida (UCF) and the Air Force Research Laboratory (AFRL) presented a working laboratory model of a copper test bed from 3 inch powered by hydrogen-oxygen propellant.

Kareem Ahmed, an assistant professor in UCF’s Department of Mechanical and Aerospace Engineering, said the trick is to properly regulate the amount of propellant fuel injected into the channel so that the detonation of the strike doesn’t deflagrate or burn. not slowly.

DARPA’s “Proposers’ Day” notice on July 18 of this year invited information on RDE projects from defense majors, directly alluding to the Western Pacific region as the priority of the Gambit program.

“The goal of the Gambit program is to develop and demonstrate a novel Rotary Detonation Engine (RDE) propulsion system that enables a supersonic, low-cost, mass-produced long-range weapon for air-to-ground strike in an anti-access/area denial (A2AD) environment,” the advisory reads.

Benefits of space travel

A continuous combustion engine that uses less fuel and can gradually increase thrust will be a boon to space exploration. Space agencies have long sought to reduce reliance on heavy and bulky rocket boosters, which would be a liability when shuttling between Earth, Moon and Mars becomes a regular affair.

Japan’s Nagoya University, Keio University, Muroran Institute of Technology (MIT), and Japan Aerospace Exploration Agency (JAXA) successfully demonstrated an RDE and PDE on July 27, 2021. was successfully exploited in space,” Nagoya University said.

Japan’s experience was even more original. It used methane as fuel, reducing dependence on rocket fuels derived from fossil fuels like petroleum. Methane is abundantly and readily available from the decomposition of organic matter in food, agricultural and kitchen waste.

Australia is also not far behind, with a research consortium led by the Royal Melbourne Institute of Technology (RMIT), the University of Sydney and Germany’s Universitat der Bundeswehr testing its RDE in February 2021.

Aims to “enable high-speed flight and space launch services” from “Australian soil and business opportunities for the Australian space industry”.

The pursuit of India’s ‘detonated’ detonation engine

Explaining how the scientific community has been hearing about detonation engines for nearly 10 years, Prahlada spoke about India’s own two-decade-old project.

“The Terminal Ballistics Research Laboratory (TBRL) in Delhi and a few other academic institutions tried to develop a detonation engine. But even the lab version was not functional,” Prahlada revealed.

Prahlada doubts that he will be realized as a successful mover in the future. “Even if it is, the production process will take a very long time,” he says.

Prahlada is right, at least in the Indian context. Engines (reactors, rockets, turbines and even marine engines) are a complex amalgamation of electrical, electronic, mechanical, metallurgical and chemical sciences. Extremely complex and precision parts/components are developed by an ecosystem of hundreds, sometimes thousands, of other companies, both public and private.

Finding such suppliers, sharing specifications for those parts (which may require specialized tools and machinery to produce), and streamlining the supply chain takes years. Indian industry, unfortunately, lacks the advanced high-tech manufacturing orientation of the West and now even China.

When asked if he thinks another push from the government with massive funds for R&D could revive the project, Prahlada senses the administration’s reluctance due to our history of defense research and our current needs.

“I don’t think the government will have the time and energy for new engines. It will focus on all-electric or all-hydrogen engines (fuel cell). We struggled with a gas turbine engine (Kaveri) for two decades,” observes Prahlada.


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