The first point: patent applications need to disclose technology. Whether it is a patent in any field or not, as long as you apply for a patent, you need to disclose the technology. The openness of technology means that all countries in the world know the production technology of this fighter, so the safety of this fighter will be greatly threatened. Some hostile countries may manufacture corresponding confrontational fighters according to these technologies. Countries are very secretive about military weapons technology. The technology we can see is only the simple data published by various countries, and the real core technology is beyond the reach of ordinary people. This is why some countries can produce five generations of fighters, some countries can only produce three generations of fighters, and some countries can't even produce fighters.
The second point: the restriction of patent application is of little significance. There are countless treaties and regulations in the world, but in the face of absolute interests, no country will fully abide by them. Take the current Iranian nuclear issue as an example. According to international regulations, Iran cannot produce nuclear weapons. However, Iran still insists on producing nuclear weapons, and even if American warplanes are deployed at home, they are unwilling to give up easily. If, after the publication of the patented technology for fighter production, other countries produce the same fighter, or other countries make minor improvements in technology to produce a new fighter, there is nothing the patentee can do.
Imagine that if the United States announces the technology of the F22 fighter, countries that have the conditions to produce this fighter will spare no effort to produce it. Although the United States is strong enough, it is impossible to offend the world for a fighter plane. Once this happens, it will only go away. Therefore, no country will easily announce its world-leading military technology, let alone apply for so-called patents.
In fact, military weapons are all collected? Technical fee? Although the fighter plane does not apply for patent, when it is sold to other countries, the exporting country will sell some technologies together, and it will cost a certain technical fee. Because the export of technology is not open, the inventor country of weapons can still maintain its technological advantage over most countries, and can also ask for a large sum of money when exporting technology, and the risk it bears is far lower than applying for a patent.