Although The Guinness Book of Records recorded the XF-84H as the fastest propeller-driven aircraft ever built, with a design top speed of  (Mach 0.9) and  (Mach 0.83) during tests, this claim has been disputed.
Despite Guinness World Records listing the XF-84H as the fastest propeller-driven plane ever made, with speeds reaching (Mach 0.9) and (Mach 0.83) in tests, this record has been challenged.