Bristol Hydro no.120

British and Colonial Aeroplane Company

Industry	Aerospace
Founded	1910
Headquarters	Bristol , United Kingdom

The Hydro no.120 was a two-seat, single-engine biplane seaplane featuring a single central float, designed in Romania. Constructed by Bristol in 1913, it was destroyed during its maiden flight.

Development

In January 1912, Romanian aeronautical engineer Henri Coandă joined the British and Colonial Aeroplane Company, later known as Bristol. By January of the following year, he had created a two-seat, single-engine biplane equipped with a single float. Initially developed as a private project, the aircraft was subsequently acquired by the Admiralty pending successful acceptance trials. However, the aircraft did not survive long enough to participate in these evaluations. At the time, it lacked an official Bristol type designation and, being a pre-First World War design, was not assigned a retrospective Type number in 1923. Consequently, it is commonly identified by its Bristol construction number, 120, or simply as the Hydro no.120.

The design featured a single-bay biplane wing arrangement with both wings unswept and unstaggered. The fuselage had a circular cross-section and was positioned between the wings with a gap beneath and distinctive framed struts above at the centre section. The observer’s cockpit was situated within these frames, while the pilot's seat was located at the trailing edge of the upper wing. Power was provided by an 80 hp (60 kW) Gnome rotary engine, enclosed within a closely fitted aluminium cowling. The fuselage tapered towards the tail assembly, which reflected Coandă’s characteristic style: a nearly semicircular fixed horizontal stabiliser with a single elevator and a balanced rudder lacking a fixed fin. The aircraft rested on one broad mahogany float manufactured by Oscar Gnosspelius, equipped with two water rudders at its rear for directional control. Additionally, two streamlined cylindrical wingtip floats ensured lateral stability.

The operational life of No. 120 was notably short. After several days conducting water trials at Cowes, the original Gnosspelius float absorbed water and became excessively heavy. It was subsequently replaced with a lighter float constructed using Consuta techniques by Saunders and Company of Cowes. On 15 April 1913, pilot Harry Busteed successfully took off; however, overheating of the tightly cowled engine caused power loss. This led to a severe emergency landing that destroyed the float and resulted in the loss of the aircraft itself—though fortunately, the pilot survived unharmed.