Brennan Helicopter

Louis Brennan became interested in helicopters in the 1910s. In 1916 he submitted a patent application entitled "Improvements Relating to Aerial Navigation", with that being granted to him on 10 December 1918. From 1919 to 1926 he was engaged by the Air Ministry at the Royal Aircraft Establishment, Farnborough to develop the helicopter. Though not formally named, the craft is referred to as the Brennan Helicopter. As originally built, the helicopter featured a two-bladed rotor, and was powered by a centrally located Bentley engine which drove four-bladed pusher propellers on each blade. A pyramidal structure acted as the mount for the engine and the blades and rotated, as a single unit, around a vertical axle. Sited below that structure was a small streamlined fuselage, containing the pilot, and an undercarriage that consisted of four landing pads mounted outboard on struts. Directional control was meant to be achieved by ailerons incorporated into the outboard end of each blade. ==Operational history==

The first tethered flights took place, inside a hangar at Farnborough, in December 1921. Stability and control tests showed that use of the ailerons on the blades was insufficient. The craft was then modified to address those issues, with a pair of smaller, auxiliary, blades being added to the rotor. Outdoor testing commenced in May 1924, and continued till 1926. During that two year time period, the helicopter made 70 flights, consisting mostly of short hovers and transitions to horizontal flight. Flights averaged about 3 minutes in duration, with one traversing about . The helicopter's stability and control issues were never resolved. One test flight in October 1925 ended when a rotor blade touched the ground, causing considerable damage. The project was discontinued in 1926 when the Air Ministry withdrew funding, with them preferring to focus further rotary wing activities on craft like the Cierva autogiro. ==Specifications==