The first prototype (serial number "72-1569") was rolled out at Hawthorne on 4 April 1974; its first flight at Edwards AFB came on 9 June with Henry "Hank" Chouteau at the controls flying for 61 minutes reaching an altitude of 18,000 feet and a maximum speed of 610 miles per hour. Chouteau afterwards remarked that, "When our designers said that in the YF-17 they were going to give the airplane back to the pilot, they meant it. It's a fighter pilot's fighter." The second YF-17 (s/n "72-1570") first flew on 21 August. Through 1974, the YF-17 competed against the General Dynamics YF-16. The two YF-17 prototypes flew 288 test flights, totaling 345.5 hours. The YF-17 attained a top speed of Mach 1.95, a peak load factor of 9.4 "g", and a maximum altitude of over . It demonstrated a maximum angle of attack of 68 degrees at 28 kts IAS.