The de Havilland DH.88 Comet, a pioneering aircraft of the 1930s, built specifically to contest in the 1934 MacRobertson Air Race from England to Australia, the Comet was not just a racing aircraft but a harbinger of the potential that lay in long-distance air travel.
The inception of the DH.88 Comet can be traced back to the challenge laid down by the MacRobertson Trophy Air Race, part of the Melbourne Centenary celebrations.
This race demanded aircraft to fly from Mildenhall in England to Melbourne, Australia, a daunting task that required covering approximately 11,000 miles. This was at a time when aviation was still in its infancy, and long-distance flights were fraught with danger and uncertainty.
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The Race is On
In 1933, plans were underway for the MacRobertson Air Race, scheduled for October 1934, to mark the centenary of Victoria, Australia. This event, sponsored by Australian confectionery magnate Macpherson Robertson, was set to challenge aviators to fly from England to Melbourne in various stages.
At this time, the latest American monoplane airliners were unmatched by British counterparts. Geoffrey de Havilland, a leading figure in British aviation and the head of the de Havilland aircraft manufacturing company, was keen to ensure Britain’s representation in the race to uphold national pride.
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Despite understanding that the venture was unlikely to break even, the de Havilland company board saw the race as an opportunity to boost their reputation and gain valuable experience in designing fast monoplanes.
Consequently, in January 1934, they proposed the creation of a specialized racing aircraft, named the Comet, capable of reaching speeds of 200 miles per hour. Priced at £5,000 each—a figure only half of its production cost—the offer hinged on securing at least three orders by February 28.
The company successfully received three orders within this timeframe: one from aviator Jim Mollison, who planned to pilot the aircraft with his wife, famed aviator Amy Johnson; another from Arthur Edwards, a hotelier; and a third from Bernard Rubin, a race car driver.
Concept
Despite its design around the MacRobertson race’s unique needs, the Comet didn’t match standard racing aircraft specs. Yet, it was classified as a “Special, sub-division (f), Racing or Record.”
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De Havilland focused on the essential long-range capabilities for the race’s official stages. The initial plan was for a twin-engined, two-seat version of the DH.71 experimental monoplane.
Due to performance concerns, designer A. E. Hagg opted for a more novel approach, choosing a cantilever monoplane with an enclosed cockpit, retractable undercarriage, and flaps. The design included variable-pitch propellers to ensure reasonable take-off speed and satisfactory cruise speed despite the aircraft’s high weight.
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The final design featured a low wing with a high aspect ratio, powered by two specially-tuned Gipsy Six R engines. Constructed mainly from wood, metal was used sparingly for critical stress areas and complex shapes like engine cowlings.
Lifeboat-Building Technique
The aircraft had manually-actuated split flaps and mass-balanced Frise ailerons. To confirm the wing’s viability, a half-scale model was rigorously tested. The exterior underwent a meticulous finish to reduce air friction and boost speed.
Aerodynamic efficiency led to choosing a thin RAF34 wing section. This necessitated a stressed-skin wing construction as the wing couldn’t house deep enough spars for flight loads. Hagg, leveraging his naval architecture background, applied a lifeboat-building technique for the wing, using spruce planking and birch ply ribs. This construction surprised many with its success, enabled by new synthetic bonding resins.
The fuselage, primarily plywood over spruce longerons, depended on its skin for strength. Fuel was stored in three tanks within the fuselage. The cockpit, designed for a pilot and navigator, was positioned to minimize drag, affecting forward visibility.
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The engines, enhanced versions of the Gipsy Six, allowed the aircraft to fly on one engine at altitudes up to 4,000 feet. The manual undercarriage required significant effort to retract.
Flight testing began six weeks before the race, initially with Hamilton-Standard hydromatic propellers. Due to airflow issues, these were replaced with Ratier propellers, which had manually adjustable blades pre-flight and auto-adjusted to high-speed pitch in flight. Modifications also included a new landing light and a slightly raised cockpit for better pilot visibility.
Operational history
The three Comets positioned themselves at the starting line of the race at Mildenhall, a recently developed airfield in Suffolk soon to become part of the RAF.
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G-ACSP, adorned in black and dubbed Black Magic, G-ACSR in green without a name, and G-ACSS in red, known as Grosvenor House, were among the 20 competitors. This diverse group included modern, swift Douglas DC-2 and Boeing 247 airliners as well as vintage Fairey Fox biplanes.
Black Magic G-ACSP
Jim Mollison and his wife Amy, flying G-ACSP Black Magic, were the only Comet crew to be piloted by its owners. They were the first to take off at 6:30 a.m., heading non-stop to Baghdad, the initial mandatory stop, a feat unmatched by any other crew.
Their journey continued to Karachi, where they landed at 4:53 a.m., setting a new record from England to India. However, they faced challenges, including two aborted takeoffs; first, due to a landing gear malfunction and then, a navigational error with an incorrect map.
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They departed Karachi at 9:05 p.m. for Allahabad but had to make an unplanned stop in Jabalpur for fuel, using motor car petrol from a local bus company due to the lack of aviation fuel. This led to a seized piston and a ruptured oil line. Continuing on one engine, they reached Allahabad but were forced to withdraw from the race due to the need for complete engine replacements.
Grosvenor House G-ACSS
Arthur Edwards, the managing director of the Grosvenor House Hotel, named his red Comet G-ACSS after the hotel. He chose C. W. A. Scott and Tom Campbell Black as the pilots for the race.
After refueling in Kirkuk, they reached Baghdad shortly after the Mollisons departed, leaving again after just 30 minutes. Skipping Karachi, Scott and Campbell Black flew directly to Allahabad, where they learned they had surpassed the Mollisons, becoming the first to arrive.
Despite battling a severe storm over the Bay of Bengal that required both pilots to control the aircraft together, they safely landed in Singapore, leading the DC-2 by eight hours.
Continuing to Darwin, they faced a power loss in the left engine over the Timor Sea but managed to reach their destination. While mechanics worked on the engine, its designer, Frank Halford, advised from England that they could proceed at reduced power. This advice helped them maintain their lead.
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After another stop for engine repairs in Charleville, they crossed the finish line at Flemington Racecourse at 3:33 p.m. local time on 23 October. Their total race time was 70 hours, 54 minutes, and 18 seconds.
G-ACSR
Bernard Rubin, a renowned motor racing driver, had his Comet, G-ACSR, painted British racing green. Initially planning to fly with Ken Waller, Rubin withdrew last minute due to illness, and Owen Cathcart Jones replaced him.
In Baghdad, they missed the city in the dark, landing near a village as they ran out of fuel. They barely reached Baghdad at dawn with empty tanks. Shortly after takeoff, they discovered a severe oil leak, forcing them to return for repairs.
Further issues on the way to Darwin led them to land in Batavia, where KLM engineers, participants with the DC-2, assisted them. They were the fourth to arrive in Melbourne, clocking in at 108 hours, 13 minutes, and 30 seconds. Cathcart Jones and Waller quickly gathered film from the race’s Australian legs and flew back to Britain the next day, setting a new round-trip record of 13 days, 6 hours, and 43 minutes.
Post Race
Grosvenor House was disassembled and transported back to England, where it was purchased by the Air Ministry. Renamed with the military serial K5084, it was repainted silver with RAF insignia and sent to RAF Martlesham Heath for testing by the Aeroplane and Armament Experimental Establishment. Following several test flights, it was decommissioned due to a rough landing and sold as scrap.
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It was later acquired, refurbished by Essex Aero, equipped with Gipsy Six series II engines, and a pivoting tailwheel. In this updated configuration, it competed in various races and set records, finishing fourth in the 1937 Istres-Damascus-Paris race, twelfth in the King’s Cup Race the following month, and later breaking the round-trip record to the Cape to 15 days and 17 hours.
In March 1938, A. E. Clouston and Victor Ricketts flew it to New Zealand and back, covering 26,450 miles in 10 days, 21 hours, and 22 minutes.
The day after their race, Cathcart Jones and Waller departed in G-ACSR for England. Experiencing engine issues in Allahabad, they encountered the Mollisons, who kindly provided two pistons from Black Magic, aiding their return. Setting a new record for the round trip to England in 13 days, 6 hours, and 43 minutes.
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Later, renamed Reine Astrid to honor the Belgian queen, G-ACSR transported Christmas mail from Brussels to Leopoldville in the Belgian Congo. It was then sold to the French government, reconfigured as a mail plane F-ANPY, and broke the Croydon-Le Bourget record on its delivery flight on July 5, 1935.
It also completed high-speed flights from Paris to Casablanca and Paris to Algiers, named Cité d’Angoulême IV, before being last spotted in an inoperative state in Étampes, France, in 1940.
Black Magic was sold to Portugal for a planned flight from Lisbon to Rio de Janeiro. Re-registered as CS-AAJ and renamed Salazar, it suffered damage during its takeoff attempt for the transatlantic flight at Sintra Air Base. Later, on a flight back from Hatfield, it achieved a record time from London to Lisbon in 5 hours and 17 minutes in July 1937.
Survivors
In 1943, G-ACSS was temporarily requisitioned by the RAF before being transferred to de Havilland. It was later restored to its former glory as Grosvenor House and displayed during the 1951 Festival of Britain. The Shuttleworth Collection at Old Warden became its custodian in 1965, and by 1972, it had been re-registered with its original designation, undergoing a meticulous restoration that culminated in its return to flight in 1987. Today, it is celebrated as one of the most iconic British aircraft still operational.
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After disappearing for over four decades, CS-AAJ Salazar was eventually found in Portugal. It was then transported back to the UK and re-registered as G-ACSP. As of 2020, efforts to restore the aircraft continue, with plans to have it take to the skies once more in its historic Black Magic colors. This restoration is being undertaken by the Comet Racer Project Group at the Amy Johnson Comet Restoration Centre, located at Derby Airfield, aiming to preserve this significant piece of aviation history.
