Rapier entered service in 1971. It was designed to directly hit the target, so it had a tiny 1.4kg warhead and no proximity fuse. Its maximum range and altitude were only slightly better than shoulder launched SAMs. And it was optically guided, so could only be used during the day time and clear weather. Pretty terrible eh? But what can you expect from a light weight, highly mobile system?... except it wasn't highly mobile, it was a towed system that took a long time to set up.

By 1979, they realised it would be a good idea if the Rapier could be fired at targets even if it was dark, foggy or the aircraft were above clouds, so they added a Radar to a 1/3rd of them.

It was used to defend the British army during the Falklands war, but it was a fragile system, and broke down frequently. The Rapier attacked many Argentine aircraft during the Falklands war. And initially it was claimed it achieved 14 kills and 6 probable kills.

But after the war, they looked closely at what was claimed, and decided the real numbers were, 1 confirmed kill, 2 probable kills and 2 possible kills.

Due to its poor performance during 1982, they quickly upgraded the system, and by quickly, I mean 1995. They put in a bigger warhead, and a proximity fuse, and increased its range by 20%

I just don't think it's a very good system