The design was originally intended to be a relatively simple upgrade to the F-84 Thunderjet to make it more competitive with the F-86 Sabre, differing largely in the use of a swept-wing and tail.

Looking for a clear performance edge compared to the G models, the engine was upgraded to the much more powerful British Armstrong Siddeley Sapphire built in the United States as the Wright J65.

The larger engine required the fuselage to be stretched into an oval shape and the air intake to be modified.

It finally entered service in November 1954, by which time the Sabre had also undergone many upgrades and the Thunderstreak was relegated to the fighter-bomber role.

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.

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.

The first 275 aircraft, equipped with conventional stabilizer-elevator tailplanes, suffered from accelerated stall pitch-up and poor turning ability at combat speeds.

However, this arrangement permitted placement of cameras in the nose and the design was adopted for the RF-84F Thunderflash reconnaissance version.

Like its predecessor, it also suffered from accelerated stall pitch-up and potential resulting separation of wings from the airplane.

[3] Project Run In completed operational tests in November 1954 and found the aircraft to be to USAF satisfaction and considerably better than the F-84G.

On 9 March 1955, Lt. Col. Robert R. Scott, in a F-84F Thunderstreak, set a three-hour, 44-minute and 53-second record for the 2,446 miles (3,936 km) flight from Los Angeles to New York.

[4] With the appearance of the Republic F-105 Thunderchief, which used wing-root mounted air intakes of a similar design to those fitted on the RF-84F, the photorecon variant Thunderflash became known as the Thud's Mother.

Data from Fighters of the United States Air Force,[71] Combat Aircraft since 1945[72]General characteristics Performance Armament Avionics Communications Equipment Richard Bach, who later wrote the bestseller Jonathan Livingston Seagull, was an ANG F-84F pilot who was once activated for duty in Europe.

His first book, Stranger to the Ground, described in detail what it was like to fly the Thunderstreak in the course of an operational flight at night from England to France in adverse weather.