The ambitious fighter designed for simplicity that became an entirely new machine

Countries & Cities · Published 12 October 2026 · Updated 25 October 2026 Swipe more like this →

In short: Engineers intended the F-84F Thunderstreak to be a low-cost upgrade to the existing Thunderjet. Instead, massive production delays, engine swaps, and structural redesigns transformed a simple modification into an expensive, complex, and often unpredictable new aircraft.

The F-84F project began with the goal of achieving 55 percent tooling commonality with the straight-wing F-84 Thunderjet. However, the reality of production was far more turbulent. While the design was meant to be a simple evolution, the need for a more powerful engine led to the adoption of the British Armstrong Siddeley Sapphire, built in the US as the Wright J65. This larger engine required a vertically stretched, oval-shaped fuselage and a modified air intake. By the time production was underway, only 15 percent of the original tools could actually be reused.

The aircraft's development was plagued by technical instability. Initial versions experienced rapid pitch-up during stalls and inadequate manoeuvrability during combat, leading to the Block 25's adoption of a single-piece, hydraulic stabilator. Performance was further hampered by the engine installation; because the J65 was installed at an angle, the aircraft lost approximately 700 pounds-force, or 10 percent, of its total thrust. On hot days, this necessitated a massive 7,500-foot runway roll for takeoff.

Despite these flaws, the Thunderstreak saw extensive global service. It was utilized by numerous NATO allies, including the Belgian, French, West German, and Italian Air Forces. While its time as a front-line fighter was brief, with active duty phaseout beginning as early as 1958, it remained a significant presence in secondary roles and the Air National Guard until the early 1970s. The aircraft's legacy includes notable feats, such as Lt. Col. Robert R. Scott's 1955 record-breaking flight from Los Angeles to New York.

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