radiator, upper fuselage decking, fin and rudder. The fourth prototype was selected as the production standard. Series production commenced in October 1917, with 121 Dolphins delivered by the end of the year. Operational history The Dolphin Mk I became operational with Nos. 19 and 79 Squadrons in February 1918 and Nos. 87 and 23 Squadrons in March. The Dolphin's debut was marred by several incidents in which British and Belgian pilots attacked the new aircraft, mistaking it for a German type. For the next few weeks, Dolphin pilots accordingly exercised caution near other Allied aircraft. New pilots also voiced concern over the Dolphin's wing arrangement, fearing serious injury to the head and neck in the event of a crash. Early aircraft were often fitted with improvised crash pylons consisting of steel tubes over the cockpit to protect the pilot's head. Experience showed that fears of pilot injury from overturning were largely unfounded. Crash pylons disappeared from frontline aircraft, though they were often retained on trainers. Night-flying Dolphins of No. 141 Squadron, a Home Defence unit, had metal loops fitted above the inner set of interplane struts. Despite early problems, the Dolphin proved successful and generally popular with pilots. The aircraft was fast, manoeuvrable, and easy to fly, though a sharp stall was noted. In his memoir Sagittarius Rising, Cecil Lewis described a mock dogfight between his S.E.5 and a Dolphin: "The Dolphin had a better performance than I realised. He was up in a climbing turn and on my tail in a flash. I half rolled out of the way, he was still there. I sat in a tight climbing spiral, he sat in a tighter one. I tried to climb above him, he climbed faster. Every dodge I have ever learned I tried on him; but he just sat there on my tail, for all the world as if I had just been towing him behind me." When functioning properly, the Dolphin's Hispano-Suiza engine afforded excellent performance at high altitude. Accordingly, the Dolphin was often sent against German reconnaissance aircraft such as the Rumpler C.VII, which in its specialized Rubild photo-reconnaissance version routinely operated at altitudes above . No. 87 Squadron explored the use of equipment to supply pilots with oxygen at high altitude but the experiment was abandoned after trials showed that the oxygen tanks exploded when struck by gunfire. Four Royal Air Force squadrons operated the Dolphin