6 May 1941: Just eight months after a prototype for a new single-engine fighter was ordered by the U.S. Army Air Forces, test pilot Lowery Lawson Brabham took off from the Republic Aviation Corporation factory airfield at Farmingdale, New York, and flew the prototype XP-47B Thunderbolt, serial number 40-3051, to Mitchel Field, New York. 
During the flight, oil which had collected in the exhaust duct began burning. There was so much smoke that Brabham considered bailing out. He stayed with the prototype, though, and when he arrived at Mitchel Field, he exclaimed, “I think we’ve hit the jackpot!”
Thank you Bryan R. Swopes, This Day in Aviation History c. 2018 for allowing me to use your information. https://www.thisdayinaviation.com/6-1941/