First flight of the Supermarine Type 300 serial K5054 was on the morning of March 5, 1936 by pilot Captain Joseph 'Mutt' Summers. After testing various types of propellers, it eventually reached a top speed of 349mph at 18,000 feet, 2,400 feet per minute climb rate at sea level, 8 min 12 sec to 20,000 ft, weight 5,321 lbs. It was officially named 'Spitfire' by June 10, 1936 after a request by Supermarine or such name on March 10.