五毛哭哭，外國網站指 殲20匿蹤與舊4代機差不多

奸20在外國有人指出殲20設計外型有缺陷，他的RCS居然是1~3m2，大概只等同於舊型四代機，發現遠比預期高。
而F22 只有0.0001m2，F117 是0.003m2
這應該會讓軍盲五毛崩潰吧!!

我的英文不好，有興趣英文好的可以翻譯看看!!

- China’s fighter planes are mostly the older 4G J-7s, which were derived from the Russian MIG-21 airframe. So, they probably show the same RCS of about 3m2 best case. Their J-10s have an RCS of 0.5 to 1.5m2. Their newer J-20 fighter has some flaws in its design, so it has an RCS about the same as older 4G fighters (about 1m2 to 3m2).

F-22 has an RCS of 0.0001m2，the same as the size of a bumble bee.
F-117 Nighthawk from the 1980s. It has an RCS of 0.003m2, about the size of a hummingbird

http://mil-embedded.com/guest-blogs/radar-cross-section-the-measure-of-stealth/


Before we get into this, other complications need to be mentioned. The RCS of an aircraft depends on its aspect, the orientation of the target to the radar source. Any aircraft will have a smaller RCS from the front, and show-up bigger from the side or the rear. Looking at the table values, their numbers seem to be based on the frontal aspect, the lowest RCS of the aircraft. Also, some fighter jets have their largest RCS from the rear, due to the exhaust nozzles. And, RCS depends on the wavelength (frequency) of the radar signal and how far away the target is. But we’ll ignore these pesky details for now. Just consider the numbers we use here as the best RCS values for each aircraft. For comparison, an average man has an RCS of about 1m2.

- In my last blog, we talked about Russia’s older 4G MIG-XX, 4.5G SU-34/35, and 5G PAK-FA (T-50) fighter jets. The older 4G MIG platforms have an RCS of 15m2, down to 3m2 for the MIG-21. The SU-34s RCS is 1m2. SU-35s are 1m2 to 3m2, according to web sources. The PAK-FA (T-50) has an RCS of 0.5m2, about the same as a Tomahawk cruise missile. None of those planes are truly stealthy. Most of them are big fat targets to our advanced radars.

- China’s fighter planes are mostly the older 4G J-7s, which were derived from the Russian MIG-21 airframe. So, they probably show the same RCS of about 3m2 best case. Their J-10s have an RCS of 0.5 to 1.5m2. Their newer J-20 fighter has some flaws in its design, so it has an RCS about the same as older 4G fighters (about 1m2 to 3m2). We don’t have much data on their new J-31 (FC-31) fighters, but they did create some rippled exhaust nozzles on their engines that will reduce its rear-aspect reflections. If I had to guess, since the J-31 looks like the offspring of the F-35 and the PAK-FA (T-50), It might have an RCS in the range of 0.5 to 0.1m2, being generous. And, if China is doing so well with their stealth fighter designs, why did they just take delivery of four Russian SU-35s in December 2016? The frontal RCS of their new J-31 is certainly much better than the SU-35, if my guess is accurate, so they must want access to the Russian radar and on-board systems.

- Among the U.S. fighter planes, the 4G F-15 has an RCS of 25m2, not very impressive and bigger than the older Russian MIG fighters. The 4G F16 has an RCS of 5m2, better but still not great. The 4.5G F/A-18 Hornet Navy fighter jet has an RCS of 1m2, about the same as the Russian SU-34/35 and the Chinese J-20. The 5G F-35 has an RCS of 0.005m2, about the size of a golf ball. However, from the rear, it looks much bigger because of the exhaust nozzles, the same problem we saw with the 5G Russian PAK-FA (T-50). For comparison, the 5G F-22 has an RCS of 0.0001m2, about the size of a bumble bee. The U2 and SR-71 spy planes have an RCS of 0.01m2, about the size of a small bird. Our first stealth fighter/bomber was the F-117 Nighthawk from the 1980s. It has an RCS of 0.003m2, about the size of a hummingbird, and those F-117s hit more than 1,600 targets without being molested by Iraqi air defenses during the 1991 Gulf War.