The Sunbeam 350HP is an aero-engined car built by the Sunbeam company in 1922, the first of several land speed record breaking cars with aircraft engines.
The car was fitted with a 18.3-litre V12 Sunbeam Manitou aero engine. In aircraft trim this produced 300 hp, raised to 350 hp here after a major re-design. A 4-speed transmission drove the differential-less rear axle, with a shaft drive rather than the hazardous chains of other cars. Brakes were crude, as was usual in the period, with a foot brake acting on the transmission and a hand brake on the rear drums. Suspension was also typical, with half-elliptic springs all round.
The 350HP was first raced at Brooklands in 1920 by Harry Hawker. In October Rene Thomas set a new record at the Gaillon hill climb.
In May 1922 Kenelm Lee Guinness set three records with it: the Brooklands lap record at 123.30 mph (198.43 km/h), then the land speed record over a mile at 129.17 mph (207.88 km/h) and over a kilometre at 133.75 mph (215.25 km/h) – this was the last land speed record to be set on the Brooklands track.
Malcolm Campbell drove the borrowed car at the Saltburn Speed Trials on 17 June 1922 and broke his first speed record at 138.08 mph (222.22 km/h). However the manual stopwatch timing system was not accepted for an official record.
Campbell persuaded Coatalen to sell the Sunbeam to him, painted it blue and renamed it 'Blue Bird', already the fourth Blue Bird. 23 June 1923 saw Campbell at Fanø, Denmark, recording another record-breaking speed of 137.72 mph (221.64 km/h) over the flying kilometre. This time the record was not officially accepted as the timing equipment was not of the approved type.
Over the winter of 1923–1924 the car was sent to the aircraft maker Boulton Paul at Norwich, for wind tunnel tests. They streamlined the car with a narrow radiator cowl at the nose and a long tapered tail. The rear wheels were also fitted with disk covers. Engine compression was raised by new pistons.
Campbell returned to Fanø in the summer, but the beach was in poor condition and crowd control of the spectators was poor. On the first run both rear tyres were ripped off Blue Bird and narrowly missed the crowd. Campbell protested to the officials about safety standards and declined to take any responsibility for anything else. Sadly, this time a front tyre came off and killed a boy in the crowd.
The car was taken to Pendine Sands in South Wales and saw a more successful result with the first of Campbell's nine records. The record was achieved on 24 September 1924, with a speed of 146.16 mph (235.23 km/h) and an officially sanctioned time. After this he put the car up for sale for £1,500, but decided to keep it for a further attempt on hearing that Parry-Thomas was also planning a record attempt with 'Babs'. Blue Bird returned to Pendine in 1925, and on 21 July it raised this record to 150.766 mph (242.628 km/h), the first time a car had exceeded 150 mph (240 km/h). The best run over the mile had reached 152.833 mph (245.961 km/h), a figure that appeared in contemporary motoring adverts for oil and sparkplugs. To commemorate this achievement Campbell had commemorative models of Blue Bird made.