The Martin Handasyde No.3 was an early British single-seat monoplane design, built in partnership by H.P. Martin and George Handasyde. Only one was built.
The Martin-Handasyde No.3 bore a strong resemblance to the Antoinette monoplanes, with a slender wood-covered triangular fuselage, and tapered wings which were braced by mid-span kingposts. Lateral control was by wing-warping and the angle of incidence of the wings varied from 5° at the wing root to zero at the tip. The undercarriage consisted of a pair of wheels on a cross-axle supplemented by a forward-projecting curved skid. It was initially powered by a 60hp Antoinette V-8 engine. This was later changed for a 40hp J.A.P.It was first flown at Brooklands by H.P. Martin during November 1910, and was flown throughout 1912 by Graham Gilmour, who was eventually killed in the aircraft when it suffered a mid-air structural failure over Richmond Park on 17 February 1912.
A two-seater version of the aircraft, the Martin Handasyde 4B, also called the Dragonfly, with a wingspan of 37feet was built for Thomas Sopwith and was displayed at the 1911 Aero Show at Olympia.