The DAS apertures can be seen very clearly now.
Radar Cross Section (RCS) performance:
A Preliminary Assessment of Specular Radar Cross Section Performance in the Chengdu J-20 Prototype | Ausairpower | APA-2011-03
This study has explored the specular Radar Cross Section of the Chengdu J-20 prototype aircraft shaping design. Simulations using a Physical Optics simulation algorithm were performed for frequencies of 150 MHz, 600 MHz, 1.2 GHz, 3.0 GHz, 6.0 GHz, 8.0 GHz, 12.0 GHz, 16.0 GHz and 28 GHz without an absorbent coating, and for frequencies of 1.2 GHz, 3.0 GHz, 6.0 GHz, 8.0 GHz, 12.0 GHz, 16.0 GHz with an absorbent coating, covering all angular aspects of the airframe. In addition, the performance of a range of Chinese developed radar absorbers was modelled, based on a reasonable survey of unclassified Chinese research publications in the area. None of the surveyed materials were found to be suitable for use as impedance matched specular radar absorbers. Modelling has determined, that if the production J-20 retains the axisymmetric nozzles and smoothly area ruled sides, the aircraft could at best deliver robust Very Low Observable performance in the nose aspect angular sector. Conversely, if the production J-20 introduces a rectangular faceted nozzle design, and refinements to fuselage side shaping, the design would present very good potential for robust Very Low Observable performance in the S-band and above, for the nose and tail aspect angular sectors, with good performance in the beam aspect angular sector. This study has therefore established through Physical Optics simulation across nine radio-frequency bands, that no fundamental obstacles exist in the shaping design of the J-20 prototype precluding its development into a genuine Very Low Observable design.