Their designs have taken advantage of recent developments of technology, and their designers have had the opportunity to analyze the successes and failures of earlier versions of similar tools of war.

For various reasons, however, the U.S. Air Force still uses some aircraft that might be 50 or even 60 years old.

The oldest aircraft in the Air Force is the Boeing KC-135 Stratotanker, an aerial refueling plane manufactured between 1955 and 1965.

The average age of the 30 examples still in active inventory was 60.6 years as of 2021.

An example is the F-35 Joint Strike Fighter. The Defense Department spends about $133 million for each of these. In the federal government's 2021 fiscal year, the F-35 program cost $1.7 billion.

The F-35 program budget request for fiscal 2023 is $11 billion. Put briefly, the Air Force sees the F-35 as its workhorse fighter for the future.

Congress and the Defense Department have run into a roadblock with the F-35, however. It does not work as well as expected.

The Air Force hit similar hurdles with the B-2 Spirit stealth bomber, which made its first flight in 1989 and was officially introduced in 1997.

Unfortunately, overruns put the cost per aircraft, including development, engineering, and testing, at over $2 billion, according to the General Accounting Office.