The US Air Force's plan to upgrade its 70-year-old B-52 bombers is billions over budget, watchdog finds

The US has about 76 B-52s in its fleet. US Air Force photo by Airman Ben Selchow The US Air Force's B-52 bomber upgrades are delayed and over budget by billions of dollars. The B-52 Stratofortress has been flying since 1950, and the Air Force hopes to keep it around into the 2050s. The modernization plans include new commercial engines and radars. Cost and scheduling challenges have pushed the US Air Force's B-52 Stratofortress modernization program billions over budget, according to a new…