According to a report from China’s “Ordnance Science and Technology” magazine on August 24, prior to July 15, the State Intellectual Property Administration of China announced the results of the 21st China Patent Awards. And the appearance design patent of J-20’s “lifting body side strip canard wing layout” won the gold prize of China Patent Award.
The report quoted equipment expert from the Chinese Air Force – Fu Qianshao as saying that J-20 uses a lift body fuselage, canards, sidebars, wings, rear side rails, camber double ventral fins, and camber full-motion double vertical tails based on vortex control technology. If the design level is high and properly controlled, it will produce huge lift gains and drag reduction effects. And its lift coefficient is about 2.1 to 2.2, ranking the first in the world.
Fu Qianshao said that the conventionally deployed US F-22 fighter has a lift coefficient reported to be about 1.7 and a supersonic cruise zero-lift drag coefficient of about 0.035. China has used a high-precision scaled-down model for wind tunnel tests, and the measured data are similar to the reported numbers, proving that the lift and drag coefficients of J-20 are significantly better than those of the F-22.
According to the report, in the conventional layout, when tail flatting maneuver the aircraft to raise its head, it has to deflect downward to generate negative lift and press down the tails, which belongs to the loading rudder surface. However, after the aircraft has a positive angle of attack, it will partially offset the negative angle of attack for the flat tails, reducing its efficiency.
However, J-20 has a mid-to-late canard layout, with large canard wing areas and long distances from the wings, with a side strip transition in the middle, which can use the multi-vortex interference generated by different aerodynamic surfaces to improve the lift and drag characteristics of the aircraft, thereby improved its control torque.
In addition, J-20 has larger rear side rails, double camber ventral fins, and full-moving double vertical tails with a larger camber angle. At high angles of attack, the side rails of the rear aircraft can provide certain pitch stability and head-down moment; the camber double ventral fins are located in a low position and are not easily affected by wing turbulence, and can provide certain lateral stability and head-down moment; and due to the large effective rudder surface area, full-motion camber double vertical tails can also play a part in flatting tails.