Smooth test flight proves ‘new concept’ human-drone design for China’s next-gen fighter

A new aircraft combining a stealth fighter with two drones that can break away in a flash is the latest weapon in China’s arsenal

Science

Stephen Chenin Beijing

Published: 10:00am, 28 Jun 2024

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At an airport on the southern edge of the Mu Us Desert in Ningxia, northwest China, engineers and scientists conduct a test flight on a jet plane that the world has never seen.

According to some recently disclosed design drawings, this mysterious fighter aircraft, powered by a dual-inlet turbojet engine, has a blended wing body design with sweeping delta wings, a hallmark of high-speed stealth fighters.

And what happens during the flight is nothing short of extraordinary: a segment of each of the wings detaches from the fighter, metamorphosing into two “flying wing” drones propelled by electric ducted fans.

Immediately after the drones’ separation, however, the fighter experiences a tremor, a consequence of the abrupt wing area reduction and gravity centre shift that significantly alters its aerodynamic profile.

Nevertheless, the aircraft and the drones quickly resume stable flight, showing the effectiveness of the aerodynamic design and automatic control algorithms.

The successful test flight proves a “new concept” for the Chinese Air Force’s next generation fighter jet, according to Du Xin, a senior engineer with the Aerospace Technology Institute of the China Aerodynamics Research and Development Centre (CARDC), which has been sanctioned by the US.

“It represents an advanced mode of manned/unmanned collaborative combat, where multiple aircraft with different functions are integrated for coordinated flight,” Du and his colleagues wrote in a peer-reviewed paper published on May 29 in the Chinese academic journal Advances in Aeronautical Science and Engineering.

“This can effectively address issues such as speed mismatch and range incompatibility between manned and unmanned aircraft, achieving complementary advantages.”

Designs of the next-generation stealth fighter shows the two drones attached to the rear edge of the plane’s delta wings. Photo: China Aerodynamics Research and Development Centre

Yang Wei, chief designer of the J-20 aircraft, has said several times in recent years that China is developing a new generation of stealth fighters that will focus on fighting alongside drones.

The J-20 is China’s most potent stealth fighter, and the Chinese air force is in the process of testing its two-seat variant, which will enable one pilot to dedicate their focus to drone interaction.

But most drones cannot match the speed and range of crewed fighters.

Yang said a distinctive feature of China’s next-generation fighter was its unexpected shape-changing capability.

“Future aircraft may be like the transformers in science fiction movies,” Yang told state broadcaster CCTV in 2020.

In 2022, he also said: “In the near future, we will soon see the J-30 and J-40 [as the successors to the J-20].”

The idea of combining different aircraft for flight is not new.

German scientists pioneered such tests during World War II. Then in the 1950s the US Air Force made a bold attempt to affix two fighter jets to the wingtips of a bomber. While this improved wing length augmented the bomber’s range, it also generated strong, unexpected wingtip vortices.

Tragically, during a test flight on April 24, 1953, an F-84 fighter jet attached to a B-29 bomber’s wingtip flipped and collided, claiming the lives of one fighter pilot and all five bomber crew members.

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But instead of the affixed aircraft being on the wingtips, Du’s team adopted a so-called “rear edge docking layout”.

“The main aircraft connects to the leading edges of two sub-aircraft wings via a retractable separation mechanism at the main wing’s trailing edge,” they wrote in the paper.

This layout allows the aircraft to become more stable during flight, but “the centre of gravity and focus of the host can undergo drastic shifts before and after detachment, posing a profound challenge to the formulation of the control law”.

Du’s team disclosed a new algorithm in their paper – which can accurately analyse various disturbances, including wind changes – that occur during separation.

Both the jet aircraft and the drones use the FCC-100 flight control computer developed by Northwestern Polytechnical University. This computer can perform complex calculations in a short time and provide highly reliable control instructions.

Northwestern Polytechnical University is an important institution for researching cutting-edge aircraft in China. Last year, the Chinese government accused US intelligence agencies of repeated attempts to infiltrate the university’s computer network to obtain confidential technical information.

The project team also employs high-performance components such as rapidly responding rudders, enabling immediate execution of computer instructions.

“During separation, the combined aircraft can overcome significant airflow disturbances, achieving safe and smooth separation of the host and sub-aircraft, with the entire process being controllable,” Du’s team wrote.

“It is ready for real-life applications.”

The date of the test flight remains classified.

The test flight of the mystery stealth fighter was conducted at an airport in Ningxia, northwest China. Photo: China Aerodynamics Research and Development Centre (CARDC)

Chinese scientists are also testing other new technologies that may be used in the next generation of fighters, such as replacing physical rudders with airflow and plasma stealth equipment.

Other countries are developing similar technologies. In 2020, the US Air Force tested a prototype of the Next Generation Air Dominance (NGAD) programme. This initiative aims to develop successors to the F-22 and F-35 fighters.

“We’ve already built and flown a full-scale flight demonstrator in the real world, and we broke records in doing it,” Will Roper, former assistant secretary of the Air Force for acquisition, technology and logistics, told Defence News in 2020.

“We are ready to go and build the next-generation aircraft in a way that has never happened before,” he added, but did not provide any details about the plane.

But recently, high-level officials in the US Air Force said that the NGAD programme was not progressing as smoothly as planned.

Budget constraints have forced them to “take another look” at spending plans for the NGAD fighter, US Air Force secretary Frank Kendall told Aviation Week this month.

The next generation of US fighter jets will be manufactured either by Boeing or Lockheed Martin. However, Boeing has recently encountered a series of crises, while Lockheed Martin has been unable to deliver F-35 fighter jets to the US Air Force for nearly a year due to supply chain and technical difficulties.

Some American military experts believe that the US military may suspend the development of a new generation fighter jet in the coming years and instead focus on upgrading existing F-22 and F-35 squadrons.