Post by Diarist on Sept 14, 2014 18:26:20 GMT 1
The de Havilland DH.88 Comet is a twin-engined British aircraft designed for the 1934 MacRobertson Air Race. Three examples took part in the race and one of them won it. The type set many aviation records during the race and afterwards, as a pioneer mail plane. The modern features and clean lines of the DH.88, especially in the striking colours of Grosvenor House, the race winner, make it a true design classic.
Design and development
The MacRobertson International Air Race, a race between London and Melbourne to be held in October 1934 to celebrate the 100th anniversary of the State of Victoria, was announced in 1933. Despite previous British air racing successes, culminating in 1931 in the outright winning of the Schneider Trophy, there was no British aeroplane capable of putting up a challenge over the MacRobertson course with its long overland stages. In January 1934, the de Havilland company stepped into the breach when it offered to design a 200 mph (322 km/h) aircraft to compete in the race and produce a limited run if three were ordered by February 1934. The sale price of £5,000 each would by no means cover the development costs.
Three orders were indeed received, and de Havilland set to work. The airframe consists of a wooden skeleton clad with spruce plywood, with a final fabric covering on the wings. A long streamlined nose holds the main fuel tanks, with the low-set and fully glazed central two-seat cockpit faired into an unbroken line to the tail. The wings are of a thin cantilever monoplane design for high-speed flight, and as such would require stressed-skin construction to achieve sufficient strength. While other designers are turning to metal to provide this extra strength, de Havilland took the unusual approach of increasing the strength of all-wood construction. De Havilland achieved the skin profile using many thin, shaped pieces set side by side, and then overlaid in the manner of plywood. This was made possible only by the recent development of high-strength synthetic bonding resins and its success took many in the industry by surprise.
The engines are uprated versions of the standard Gipsy Six, being tuned for best performance with a higher compression ratio. The DH.88 can maintain altitude up to 4,000 ft (1,200 m) on one engine. The propellers are two-position variable pitch, manually set to fine before takeoff using a bicycle pump and changed automatically to coarse by a pressure sensor. The main undercarriage retracts upwards and backwards into the engine nacelles, while the tailskid does not retract. Later examples and rebuilds will feature a castoring tail wheel.
Landing flaps are placed slightly forward of the inboard wing trailing edge and continue in to the aircraft centre line. The forward fuselage is occupied by two large fuel tanks, with a third small tank located behind the cockpit.
With de Havilland managing to meet the challenging production schedule, testing of the DH.88 began six weeks before the start date of the race.
de Havilland has proposed a high-speed bomber version of the DH.88 to the RAF.
Source: Wikipedia - en.wikipedia.org/wiki/De_Havilland_DH.88
Design and development
The MacRobertson International Air Race, a race between London and Melbourne to be held in October 1934 to celebrate the 100th anniversary of the State of Victoria, was announced in 1933. Despite previous British air racing successes, culminating in 1931 in the outright winning of the Schneider Trophy, there was no British aeroplane capable of putting up a challenge over the MacRobertson course with its long overland stages. In January 1934, the de Havilland company stepped into the breach when it offered to design a 200 mph (322 km/h) aircraft to compete in the race and produce a limited run if three were ordered by February 1934. The sale price of £5,000 each would by no means cover the development costs.
Three orders were indeed received, and de Havilland set to work. The airframe consists of a wooden skeleton clad with spruce plywood, with a final fabric covering on the wings. A long streamlined nose holds the main fuel tanks, with the low-set and fully glazed central two-seat cockpit faired into an unbroken line to the tail. The wings are of a thin cantilever monoplane design for high-speed flight, and as such would require stressed-skin construction to achieve sufficient strength. While other designers are turning to metal to provide this extra strength, de Havilland took the unusual approach of increasing the strength of all-wood construction. De Havilland achieved the skin profile using many thin, shaped pieces set side by side, and then overlaid in the manner of plywood. This was made possible only by the recent development of high-strength synthetic bonding resins and its success took many in the industry by surprise.
The engines are uprated versions of the standard Gipsy Six, being tuned for best performance with a higher compression ratio. The DH.88 can maintain altitude up to 4,000 ft (1,200 m) on one engine. The propellers are two-position variable pitch, manually set to fine before takeoff using a bicycle pump and changed automatically to coarse by a pressure sensor. The main undercarriage retracts upwards and backwards into the engine nacelles, while the tailskid does not retract. Later examples and rebuilds will feature a castoring tail wheel.
Landing flaps are placed slightly forward of the inboard wing trailing edge and continue in to the aircraft centre line. The forward fuselage is occupied by two large fuel tanks, with a third small tank located behind the cockpit.
With de Havilland managing to meet the challenging production schedule, testing of the DH.88 began six weeks before the start date of the race.
de Havilland has proposed a high-speed bomber version of the DH.88 to the RAF.
Source: Wikipedia - en.wikipedia.org/wiki/De_Havilland_DH.88