The second YF-84F prototype was completed with wing-root air intakes.
Note the unique articulation of the canopy, which is mounted on a pair of hydraulic rams and a lever arm, allowing it to automatically pivot up and backwards behind the cockpit. RF-84F Thunderflash, the reconnaissance version of the F-84F. As a result, the F-84F was not declared operational until. A number of aircraft were also retrofitted with spoilers for improved high-speed control. Beginning with Block 25, the problem was improved upon by the introduction of a hydraulically powered one-piece stabilator. The first 275 aircraft, equipped with conventional stabilizer-elevator tailplanes, suffered from accelerated stall pitch-up and poor turning ability at combat speeds. The aircraft was considered not ready for operational deployment due to control and stability problems. It had a different canopy which opened up and back instead of sliding to the rear (a unique design, the canopy was mounted on a pair of hydraulic rams and a pivoted lever arm that allowed it to lift up and backwards while remaining almost level with the fuselage, instead of the more common simple hinged canopy), as well as airbrakes on the sides of the fuselage instead of the bottom of the aircraft.
When the first production F-84F finally flew on 22 November 1952, it differed from the service test aircraft. The YJ65-W-1 engine was considered obsolete and the improved J65-W-3 did not become available until 1954. At the time, only three presses in the United States could manufacture these, and priority was given to the Boeing B-47 Stratojet bomber over the F-84. To make matters worse, the F-84F utilized press-forged wing spars and ribs. Although tooling commonality with the Thunderjet was supposed to be 55 percent, in reality only fifteen percent of tools could be reused. Production delays with the F-84F forced the USAF to order a number of straight-wing F-84Gs as an interim measure. To accommodate the larger engine, YF-84Fs with a British-built Sapphire as well as production F-84Fs with the J65 had a vertically stretched fuselage, with the air intake attaining an oval cross-section. In the meantime, the USAF, hoping for improved high-altitude performance from a more powerful engine, arranged for the British Armstrong Siddeley Sapphire turbojet engine to be built in the United States as the Wright J65. The standard F-84F reverted to the original nose intake due to a loss of thrust from the wing root intakes. Note the early style wing root jet intakes, which were eventually only retained on the RF-84F, due to the need to fit cameras in the nose. The F-84 designation was retained because the fighter was expected to be a low-cost improvement of the straight-wing Thunderjet with over 55 percent commonality in tooling. Nonetheless, it was ordered into production in July 1950 as the F-84F Thunderstreak. Although the airplane was capable of 602 knots (693 mph, 1,115 km/h), the performance gain over the F-84E was considered minor. The last production F-84E was fitted with a swept tail, a new wing with 38.5 degrees of leading edge sweep and 3.5 degrees of anhedral, and a J35-A-25 engine producing 5,300 pound-force (23.58 kN) of thrust. In 1948, a swept wing version of the F-84 was created with the hope of bringing performance to the level of the F-86.