For the United States Air Force (USAF), the ambitious B-21 Raider program, valued at USD 203 billion, represents a significant strategic pivot.
This cutting-edge long-range stealth bomber is set to succeed the aging fleet of B-1 Lancers and B-2 Spirit bombers, thereby enhancing the U.S. military’s capacity for both conventional and nuclear strike operations.
The USAF has pledged to procure no fewer than 100 B-21 Raiders, with some analysts advocating for a fleet size of between 145 and 200 aircraft to address contemporary geopolitical challenges posed by nations like China and Russia.
While the overall program expenditure is estimated at US$203 billion in Fiscal Year 2019 dollars, the singular development costs for the stealth bomber are projected to exceed US$25.1 billion.
Currently, Northrop Grumman has successfully deliveredtwo flight-test aircraft, with trials in progress at Edwards Air Force Base in California.
In a surprising turn, a research paper disseminated in China asserts that a newly invented aerospace simulation tool has identified several structural flaws in the B-21 Raider’s design, potentially hindering its aerodynamic stability.
This sophisticated stealth aircraft design software, named ‘PADJ-X’, has been characterized as an “all-in-one” system, underscoring its interdisciplinary methodology in aircraft design and simulation testing.
Unveiled last month in a paper that graced the pages of the peer-reviewed Acta Aeronautica et Astronautica Sinica, the software employs adjoint optimization technology to amalgamate multiple engineering disciplines into a cohesive optimization framework.
China’s Bold Assertions Regarding the B-21 Raider
The publication posits that PADJ-X may represent the inaugural fully integrated, multidisciplinary platform for stealth aircraft design, utilizing an algorithmic technique that enables the simultaneous testing and adjustment of thousands of design parameters, effectively minimizing computational expenses.
In contrast, conventional methodologies relying on repetitive trials are often cumbersome and yield only marginal enhancements.
The research collective, spearheaded by Huang Jiangtao from the China Aerodynamics Research and Development Centre, applied the PADJ-X software to scrutinize the B-21’s configuration.
They concluded that the stealth bomber, currently in the flight testing phase, may disappoint in terms of aerodynamic and stability performance.
The researchers claimed to have employed 288 parameters to simulate a B-21 layout, though specifics regarding the data used remained undisclosed.
According to their findings, aerodynamic optimization purportedly enhanced the aircraft’s lift-to-drag ratio by approximately 15% and significantly mitigated shock-wave effects.
Furthermore, the paper reported an improvement in the pitching moment from 0.07 to -0.001, indicating a more stable flight. When this value approaches zero, the aircraft can maintain level flight without necessitating pilot intervention, thereby augmenting natural trim capability and fuel efficiency.
The study asserted that the enhanced lift and diminished wave drag of the optimized B-21 design imply a promising increase in operational range, as noted by Huang.
“The exigencies of future combat scenarios necessitate higher integrated performance from aircraft designs, compelling a deeper interdisciplinary approach,” Huang stated.
“PADJ-X, distinguished by its comprehensive intellectual property rights, integrates five principal disciplines: aerodynamics, propulsion, electromagnetics, infrared signature, and sonic boom.
This enables holistic optimization of aircraft aerodynamic configurations,” reported the South China Morning Post, attributing it to the paper.
Additionally, the research team conducted simulations on the U.S. Navy’s X-47B stealth drone, which was terminated in 2015 but remains classified, much like the B-21. B-21 Raider
The research claimed that the PADJ-X model reduced the drag coefficient by approximately 10% and brought down the average forward Radar Cross Section (RCS) from 13.55 square meters (44 sq ft) to a mere 1.33 square meters, along with slight improvements in intake performance.
This remarkable enhancement in the drone’s stealth capabilities was attributed to the PADJ-X model’s proficiency in multidisciplinary coordination, adeptly balancing drag reduction with radar reflection minimization, according to the publication.
Utilizing publicly accessible information concerning the B-21 Raider and the X-47B stealth drone, the Chinese scientists input data into the PADJ-X system, allowing the algorithm to conduct simulations aimed at uncovering potential design vulnerabilities.
This system is touted as a technological breakthrough, capable of managing stealth shaping, drag, and control characteristics within a unified framework, in stark contrast to traditional software applications utilized by the U.S., France, and Germany, which typically rely on disparate simulation cycles.
Several research institutions have been actively employing adjoint optimization platforms for decades, including NASA’s FUN3D framework developed in the 1990s, Germany’s aerospace research center’s FLOWer and TAU solvers, and France’s ONERA, which has developed tools based on the elsA solver.
Notably, the paper asserts that these existing systems do not cover as extensive a spectrum as PADJ-X, and often necessitate manual adjustments throughout the optimization process across different disciplines.
Furthermore, the authors contend that PADJ-X could expedite aircraft development, diminish the necessity for wind tunnel evaluations, reduce prototyping expenses, and empower future unmanned and piloted aircraft to achieve greater ranges and improved performance.
Such claims are impressive, particularly the assertion that the PADJ-X platform has uncovered vulnerabilities within the B-21 Raider’s design, indicating that optimizations proposed by the system can markedly enhance the stealth bomber’s lift-to-drag ratio by approximately 15% while simultaneously refining its pitching moment.
With the U.S. investing substantial resources over the years, exceeding US$25 billion, in the development of the B-21 Raider, it raises the question: could a civil software tool unveil vulnerabilities in its structural design? Image for Representation: B-21
Assessing the Validity of China’s Assertions
While the aforementioned research paper merits scrutiny, its grandiose claims ought to be approached with skepticism for a variety of reasons.
Primarily, as the research team acknowledges, the conclusions were derived from theoretical models and publicly inferred designs rather than classified design data.
Both the B-21 Raider and the U.S. Navy’s X-47B stealth drone are classified programs, and detailed information concerning their internal capabilities or external design features remains undisclosed.
Consequently, the PADJ-X simulations concerning the B-21 Raider and X-47B are fundamentally based on publicly accessible configurations and estimations, devoid of classified U.S. data.
The input data for the PADJ-X platform was presumably sourced from approximations derived from images and videos, alongside conjectures regarding materials, coatings, and internal systems.
Identified vulnerabilities can thus be deemed speculative rather than grounded in empirical aircraft performance data.
The paper openly concedes that, owing to the classified nature of the B-21 and X-47B parameters, it remains uncertain whether PADJ-X results can fulfill specific mission requirements or tactical objectives of the U.S. military.
Simulations conducted without comprehensive data cannot yield precise forecasts regarding operational effectiveness.
Moreover, the U.S. has been harnessing such adjunct optimization software for multiple decades, as the authors concede.
The research team posits that PADJ-X distinguishes itself from traditional frameworks by integrating various engineering disciplines into a singular software application, as opposed to executing distinct optimization simulations.
However, it is noteworthy that Western software solutions have matured over decades through AI incorporation and real-world validation, frequently circumventing the need for manual adjustments, contrary to their claims.
Furthermore, the complexities associated with stealth design are recognized challenges that U.S. engineers have addressed since the inception of the F-117 and B-2 programs. The B-21’s flying-wing architecture represents an evolution of proven technologies, and its ongoing test flights indicate stability.
Any deficiencies must have already been accounted for and rectified during extensive simulations, wind-tunnel assessments, and real-world flight trials.
Additionally, China has a history of making grand claims regarding its systems and technologies, which frequently underperform in practical scenarios.
For instance, claims surrounding China’s JY-27 “anti-stealth” radars, purportedly designed to neutralize stealth, have not held up under scrutiny, as evidenced by their lack of success during recent operations in Venezuela, where they failed to detect U.S. Air Force missions despite approximately 150 sorties.
Given these constraints, the research paper warrants careful examination and should not be divorced from the broader context of geopolitical and technological competition between the United States and China.
Source link: Eurasiantimes.com.
