@july
"But Boyd did not believe the performance specs and had no fear of the aircraft. He jostled the T-6; he pushed it and horsed it around the sky. He flung the airplane up against the outside edges of the performance envelope and then beyond. If the book said the aircraft should never exceed 260 mph, Boyd pushed it to 265 or 270 or 280. He knew intuitively by the sound of the aircraft when it was approaching not the book limits but the true limits, which, for those bold enough to search for them, always are slightly greater. Test pilots do the same thing, but most of them are engineers and highly skilled pilots tuned to a razor edge of proficiency. Few student pilots are so bold."
- John Boyd: The Fighter Pilot Who Changed the Art of War by Robert Coram