[alanscheckenbach]

Coming at this from a slightly different angle.

Up to a point, at the time, the military didn't care how much these aircraft cost on a per unit basis. Generally, the price of victory is never too high in terms of money.

Don't forget that the US, far more than any other country, had additional industrial capacity for war production. This meant that they had the ability to produce a wide variety of equipment, without putting undue strain on any particular section their industry (This is often important in terms of aero engines). Hence we see the production of many different types within classes of aircraft.

As weapons platforms, the military didn't, and still doesn't really care what kind of engine or radio an aircraft carries, but are vitally interested in whether the machine does the job they want it to. If it doesn't or only misses by a little bit, it gets reassigned to a different role that it is more suited to, especially when something better in terms of specialisation or technology comes along.

I see the P47 - P51 situation in this light. The P47 did a good job before the P51 and continued to do so after the P51 arrived on the scene. After the P51 proved its superior range, the P47 tended to be tasked with ground attack, still doing a very good job, arguably better than the P51 in that role.

From a miliatary view, these aircraft are just tools and as a commander, you employ them in the best way you can. Sometimes you just have to use a screwdriver as a chisel to get the job done. And in the same fashion, if you find a tool that does the same job better, or one that can do more jobs than the other one and so saves resources or time, you use that, discarding the old one, even if the new tool cost more.....