03/31/2009. The private venture Rhino experimental bomber triplane could carry a bomb load of 450 lb (204 kg) stowed beneath the pilots seat, while at the gunner's position a Lewis machine-gun was fitted. The Rhino was powered by a 230 hp B.H.P. six-cylinder water-cooled engine and flew for the first time in late October 1917.
The B.H.P. in the engine designation stood for Beardmore-Halford-Pullinger, the original design was done by Captain (later Major) F.B. Halford, in collaboration with Sir William Beardmore and T.C. Pullinger. The B.H.P. engines were produced in quantity by The Galloway Engine Co., Ltd. of Dumfries, and by The Siddeley-Deasy Motor Co., Ltd. of Coventry.
It was made unlawful in the UK in 1917, under the Defense Regulations, to construct an aeroplane without official authority, to prevent material wastage on aircraft unlikely to be accepted. If a firm wished to venture privately on a promising project, license to construct could be granted and the aircraft numbered in a special 'X' for experimental series, hence the two Rhino's built were assigned the serials X7 and X8. The X-series was abandoned in 1918, after only 25 serials were issued.