Recently, at a flight test site located somewhere in the northwest of China, an aircraft strikingly similar to the Su-34 soared into the sky. What’s baffling isn’t just the aircraft’s resemblance but also the primitive engine it carried beneath its fuselage. This engine is designed to propel the “Su-34” through persistent explosions.
This peculiar test marks a groundbreaking advancement in domestically produced aviation engines: the inaugural flight of the Chinese FB-1 detonation engine. This indicates that China’s detonation engine has progressed from theoretical research to practical application, laying a firm foundation for its large-scale use in the future.
Detonation engines are a new concept pursued by various countries and regions in this century. Such engines promise higher efficiency, lower fuel consumption, a simpler structure, lighter weight, and are more apt for hypersonic flight, hence holding significant potential.
Conventional jet engines, like turbojets and turbofans, are categorized as constant pressure engines. Air must be compressed before entering the combustion chamber, and the compressors, when running at high speeds, face increased aerodynamic loads and erosion, limiting the engine’s rotational speed. This limitation caps the top speed of aircraft equipped with conventional jet engines, making it challenging to exceed four times the speed of sound.
Due to technical complexities, manufacturing costs, and logistical support considerations, the speed of modern aircraft is generally capped below 2.5 times the speed of sound, with only a few specialized designs surpassing this limit.
A detonation engine, as its name suggests, relies on explosions instead of burning within its combustion chamber. The explosions result in high temperatures and pressures, negating the need for compressors, simplifying the engine’s design, reducing its size and weight—both vital advantages for aviation.
Explosions ensure more efficient energy utilization from the fuel, decreasing consumption. The international aviation engine industry estimates that detonation engines offer approximately 20% better fuel efficiency than current engines.
While the advantages are evident, detonation engines are still considered novel due to their design and control complexities. Controlling the energy from the continuous explosions without damaging the engine itself remains a significant challenge. This has led to the introduction of rotating detonation engines.
These engines can operate continuously. As fuel mixes with air and ignites in the combustion chamber, a detonation wave forms at the chamber’s base, rotating perpendicularly to the fuel injection direction. The intense pressure from the wave temporarily halts fuel injection. This cycle of explosion, pressure drop, and subsequent fuel injection repeats, propelling the aircraft forward.
The absence of rotating components in detonation engines makes their structure relatively “simple” compared to current turbofan engines. This allows for a broader operating range, especially for hypersonic flights. Combined with other aviation engines, they can further expand the flight envelope.
Since the turn of the century, the U.S. has heavily invested in detonation engines, aiming to dominate this emerging domain. Given the technical achievements revealed, NASA leads in this field, having verified rotating detonation mechanisms and ignition tests, achieving a thrust level of about 1,000 pounds or approximately 454 kilograms.
By 2020, the U.S. Air Force awarded three key R&D contracts for rotating detonation engines to major aviation engine manufacturers, aiming for practical engines by 2025-2030. Rumors suggest the U.S. has started incorporating detonation engines into cruise missiles and other precision-guided munitions. Other nations like Russia, France, and Japan have also initiated research and development in this domain.
China began its detonation engine research quite some time ago, yielding significant results, with several technical patents filed. The recent unveiling of the domestic detonation engine’s development came from the domestic commercial aviation company, the Thrust-to-Weight Engine Company, with the FB-1 being their first independently developed detonation engine.
The flight testing phase of the FB-1 suggests the company has mastered the R&D and manufacturing techniques for detonation engines. Their continuous efforts could soon see the deployment of these engines on missiles or hypersonic drones.
According to the Thrust-to-Weight Engine Company’s data, their tested detonation engine achieves thrust levels of about 1,000 newtons, roughly equivalent to 100 kilograms. This could potentially power aircrafts weighing around 500 kilograms.
Interestingly, the aircraft chosen for testing the domestic detonation engine bears a resemblance to Russia’s Su-34 fighter-bomber. It might be a scale model utilized to validate aerodynamic features of the Su-34, which has several commendable design elements. China’s quest for an alternative to its JH-7 “Flying Leopard” fighter-bomber included considering the Su-34, but the People’s Liberation Army opted for the multirole J-16 instead of pursuing specialized fighter-bombers.
Using the Su-34 scale model for detonation engine validation might just be a coincidence regarding size and take-off weight.
The landscape of modern aviation engine development is ushering in a transformative era filled with innovative concepts. By capitalizing on these opportunities and achieving key technological breakthroughs, it’s possible to catch up with and even surpass the capabilities of leading nations, bridging the current gap in aviation engine technology.
In the realm of new energy, China established an early presence in the electric vehicle sector, navigating around challenges that developed nations faced in the traditional automotive arena. The progress in electric vehicles places China prominently on the global stage. It’s anticipated that, given the dedication of aviation engine developers in the country, a comparable ascent can be witnessed in the domain of next-generation aviation engines, potentially setting new benchmarks.
