Aircraft 101 RCS Modeling [F-35/J-20/Su-57]

[Vendetta]

A blog called Aircraft 101 has published an interesting series of posts over the last year where they have modeled the radar scattering properties of different stealth fighters. Models have been completed for the F-35A, the J-20, and the Su-57, as well as for a clean configuration F-16A. This post offers a comparison between the three stealth fighters. Their simulations only model the effects of aircraft shaping, not the use of radar absorbent materials - so the actual RCS values of each of these fighters would be significantly lower in reality.

Here are a few of the diagrams:

F-35


J-20


Su-57


F-16



Mean RCS figures on different bands (m2)

X-band
1. F-35 (0.09)
2. J-20 (0.28)
3. Su-57 (1.02)
4. F-16 (1.79)

S-band
1. F-35 (0.15)
2. J-20 (0.27)
3. Su-57 (0.59)
4. F-16 (2.00)

L-band
1. F-35 (0.27)
2. J-20 (0.32)
3. Su-57 (0.50)
4. F-16 (1.77)

VHF
1. Su-57 (0.98)
2. J-20 (1.39)
3. F-35 (1.66)
4. F-16 (3.46)






Unfortunately, they have not yet modeled the F-22 (they say the Rafale is next on their list). Several interesting observations here. The F-35 is the best overall performer. Its advantage is most pronounced in the X-band, where it has mean RCS three times smaller than the J-20 and eleven times smaller than the Su-57. Its edge falls off in the S-band to less than two to one against the J-20 and four to one against the Su-57. In the L-band, the J-20 has parity and the Su-57 is behind two to one. The VHF band is an exception; here the F-35 is the worst and the Su-57 is the best.

The J-20 is behind the F-35 but still pretty good. Its mean RCS in the X band is about the same as the F-35's in the L band.

Their model affirms the common belief that the Su-57 lags significantly behind its rivals in stealth. However, it does dispel the popular notion among Indian pundits on Quora that the Su-57 has the same RCS as a 4th generation fighter like the F-16 or the Super Hornet flying in clean configuration. Even without factoring in RAM, the Su-57 is far less observable than a clean F-16 in any bandwith.

The scatter diagrams also make it pretty obvious why all the sixth generation programs are going for tailless designs.

Interesting stuff, I look forward to future entries in their series.