||The SE (Scout Experimental) -5a was one of the most successful British fighters of the First World War. The most recent of a series of designs stretching back to 1911, the SE-5 was fast, rugged and easy to fly, and first entered service in April 1917. It featured a distinctive square nose, mounting a prominent radiator, as well as two machine-guns - one mounted in the fuselage, and synchronized to fire through the propeller, and the other atop the second wing, and capable of firing straight ahead or at an oblique angle. The design was slightly modified, and a more powerful engine fitted to it, in May 1917, resulting in a variation that became known as the SE-5a. This aircraft entered service in June and retained its combat superiority over German fighters until mid-1918. 2 Squadron AFC was first equipped with the SE-5a in December 1917, and 16 SE-5a pilots became aces before the war's end. In all, 2,700 SE-5/5a aircraft were manufactured during the war, and another 2,500 were produced before production ceased in 1919. The SE-5a was one of the aircraft equipping the RAAF when it was formed in 1921, and 35 examples of the type remained in service until 1928.