Swaroop said:
...for example USA spyed on the MiG-25 and used info to make the F-18 ...
I'm curious why you say this. Besides the fact the the AC have absolutely nothing in common, the US knew virtually nothing about the MiG-25 until late 1976 when Belenko defected to Japan.
The F-18 was a spin-off of the Lightweight Fighter program, which began in 1972. In 1975, General Dynamics won the competition with the YF-16. Northrup's entry, the YF-17, went on to become the F-18.
The first MiG-25 was designed in 1961, and the interceptor variant entered service in 1972,
the same year that the LWF program began. So how did
Northrup use MiG-25 technology in developing the YF-17? And why would they even be interested in such old tech on a new AC?
The MiG-25 was developed as a reconnaissance and interceptor platform to counter to the B-58 Hustler and XB-70 Valkyrie in the late 50's-early 60's. The F-18 was developed as a replacement for the A-4 and F-4, 15 years later. A light fighter and an interceptor are completely different applications.
The only influence the MiG-25 had was to spur the US into developing more advanced AC. The US was in fear of being outpaced in fighter design, so a new generation of fighters was developed to ensure continued US air superiority. But to say that info or tech from the MiG-25 was used in the F-18 makes no sense. The F-18 was
way too advanced for that to be true.