| DH.88 Comet | |
|---|---|
 G-ACSSGrosvenor House at a display by theShuttleworth Collection | |
| General information | |
| Type | Racing aircraft |
| Manufacturer | de Havilland |
| Designer | |
| Status | One airworthy; one in restoration |
| Number built | 5 |
| History | |
| First flight | 8 September1934 |
Thede Havilland DH.88 Comet is a British two-seat, twin-engined aircraft built by thede Havilland Aircraft Company. It was developed specifically to participate in the 1934 England-AustraliaMacRobertson Air Race from theUnited Kingdom toAustralia.
Development of the Comet was seen as both a prestige project and an entry into the use of modern techniques. It was designed to meet the specific requirements of the race. It was the first British aircraft to incorporate in one airframe all the elements of the modern high speed aircraft -stressed-skin construction, cantilever monoplane flying surfaces, retractable undercarriage, landing flaps, variable-pitch propellers and an enclosed cockpit.
Three Comets were produced for the race, all for private owners, at the discounted price of £5,000 per aircraft. The aircraft had a rapid development process, performing itsmaiden flight only six weeks before the race. Comet G-ACSSGrosvenor House eventually won the race. Another two Comets were built after the race. Comets established many aviation records, both during the race and afterwards, and also took part in further races. Three were bought and evaluated by national governments, typically asmail planes. Two Comets,G-ACSS andG-ACSP, survived while a number of full-scale replicas have also been constructed.
During 1933, theMacRobertson Air Race, a multi-stage flight from the United Kingdom to Australia, was being planned for October 1934, to celebrate the 100th anniversary of the AustralianState of Victoria. Sponsored byMacpherson Robertson, an Australian confectionery manufacturer, the race would be flown in stages from England toMelbourne.[1][2]
The new generation ofmonoplane airliners which were then being developed in America had no rival in Britain at the time, soGeoffrey de Havilland, a British aviation pioneer and founder of aircraft manufacturing firmde Havilland, was determined that, for the sake of national prestige, Britain should put up a serious competitor.[3] While the company board recognised that there would be no prospect of recouping the full investment of producing such a machine, they believed that the project would enhance the company's prestige and also provide experience in the development of fast monoplanes.[4]
They therefore announced in January 1934 that, if three orders could be obtained by 28 February, a specialist racer which could achieve a guaranteed speed of 200 miles per hour (320 km/h) to be named theComet would be built and sold for £5,000 each.[5] This price was estimated as being half of the cost of manufacture. Three orders were received by the deadline; one fromJim Mollison, to be flown by him and his wife Amy (better known asAmy Johnson), one fromArthur Edwards, a hotel owner and manager, and the last from motorcar racerBernard Rubin.[6][page needed]
Although designed around the requirements for the MacRobertson race, owing to its unusual requirements the Comet did not fit the standard technical specification for aracing aircraft, nevertheless it was classed as a "Special, sub-division (f), Racing or Record".[7] De Havilland paid special attention to the non-stop range necessary for the long official stages. They initially intended to produce a twin-engined two-seat development of theDH.71 experimental monoplane. However, this would have had inadequate performance so the designer,A. E. Hagg, turned to a more innovative design. This was acantilever monoplane with enclosed cockpit, retractableundercarriage andflaps. In order to achieve take-off at a reasonable speed with a high all-up weight and a satisfactory high-speed cruise, it would be necessary to fit variable-pitch propellers.[3]
The resulting design had a low, tapered highaspect ratio wing and was powered by two Gipsy Six R engines, a specially-tuned version of the newGipsy Six. The aircraft was built almost entirely of wood, the use of metal being limited to high-stress components, such as the engine bearers andundercarriage, and to complex curved fairings such as the engine cowlings and wing root fairings. The sheet metal parts used a lightweightmagnesium-aluminiumalloy. Manually-actuatedsplit flaps were fitted beneath the wing's inboard rear sections and lower fuselage, while theFrise ailerons were mass-balanced bylead strips within the aileron'sleading edges.[8] Both therudder andelevators fitted to the conventional tail hadhorn mass balances. In order to validate the wing design, a half-scale model wing was built and tested to destruction.[9] The exterior skin was treated using a time-consuming and repetitive process of painting and rubbing down to produce a highly smooth surface to reduce air friction and increase overall speed.[10]
Aerodynamic efficiency was a design priority and it was therefore decided to use a thin wing ofRAF34 section. This was not thick enough to contain spars of sufficient depth to carry the flight loads, so the wing skin had to carry most of the loading in a "stressed-skin" construction.[11] However, the complex curves required for aerodynamic efficiency could not be manufactured using plywood. Hagg, who also had experience as anaval architect, adapted a construction technique previously used for buildinglifeboats. The majority of the wing was covered using two layers of 2 in (51 mm) widespruce planking laid diagonally across the wing, with the outer layer laid crosswise over the inner. These strips varied in thickness according to the loads they carried, reducing over the span of the wing from 0.5 in (13 mm) at the root to 0.14 in (3.6 mm) towards the tip. It was built as a single assembly around three box-spars located at 21, 40 and 65 percent chord: there was an intermediate spruce stringer between each pair of spars to prevent buckling. The ribs were made of birch ply and spruce. The outboard 6 ft (1.8 m) were skinned with various thicknesses of ply because of the difficulty of machining spruce planking to less than 0.07 in thickness. The leading edge, forward of the front spar, was also ply covered. The centre section was reinforced with two additional layers of 0.07 in (1.8mm) spruce.[12] This method of construction had been made possible only by the recent development of high-strength synthetic bonding resins and its success took many in the industry by surprise.[13]
The fuselage was built principally from plywood over sprucelongerons, while the upper and lower forward section were built up from spruce planking in order to achieve the necessary compound curves. As with the wing, the strength of the structure depended on the skin. Fuel was carried in three fuselage tanks; the two main tanks were in the nose and centre section, in front of the cockpit. A third auxiliary tank, of only 20 gallon capacity, was placed immediately behind the cockpit and could be used to adjust the aircraft'strim. The pilot and navigator were seated intandem in a cockpit set aft of the wing. Although dual flight controls were fitted, only the forward position had a full set of flight instruments. The rear crew member could also see many of the pilot's instruments by craning sideways while seated. The cockpit was set low in order to reduce drag and forward visibility was very poor. The engines were uprated versions of de Havilland's newly developedGipsy Six, race-tuned for optimum performance with a highercompression ratio and with a reduced frontal area; the aircraft could maintain an altitude of up to 4,000 feet (1,200 m) on one engine. The mainundercarriage retracted backwards into the engine nacelles and was operated manually, requiring 14 turns of a large handwheel located on the right hand side of the cockpit.[6][page needed]
The challenging production schedule meant that flight tests of the DH.88 began just six weeks prior to the start of the race.Hamilton-Standard hydromaticvariable-pitch propellers were initially fitted.[14] During testing, the propeller blade roots were found to interfere unacceptably with the airflow into the engine. Instead, a French two-positionpneumatically actuatedRatier type was substituted. Its blades were manually set to fine pitch before takeoff using abicycle pump, and in flight they were repositioned automatically to coarse (high-speed) pitch via a pressure sensor. A drawback was that the propellers could not be reset to fine pitch except on the ground. Other changes included the installation of a large landing light fitted in the nose, and a higher cockpit profile to give the pilot marginally improved visibility.[15]
All three Comets lined up for the start of the race atMildenhall, a newly established airfield inSuffolk shortly to be handed over to the RAF. G-ACSP was painted black and namedBlack Magic, G-ACSR was green and unnamed and G-ACSS was red and namedGrosvenor House. The three aircraft took their places among 17 other entrants, which ranged from new high-speedDouglas DC-2 andBoeing 247 airliners to oldFairey Fox biplanes.[16]
G-ACSP was the only Comet to be flown by its owner. Jim Mollison and his wife Amy and were the first to start[a], taking off at At 6:30 a.m. G-ACSP, namedBlack Magic.[17] to begin a non-stop flight to the first compulsory staging point atBaghdad, the only crew who flew this leg non-stop.[16][18] Their next stop was atKarachi, landing at 4:53 a.m, and setting a new England-India record.[18] They made two unsuccessful attempts to depart, returning after the first when their landing gear failed to retract, and after the second on discovering that they had the wrong map. They finally left Karachi at 9:05 p.m. forAllahabad. After drifting off course, they made an unscheduled stop atJabalpur to refuel and determine their position. Since there was no aviation fuel available, they had to use motor car petrol provided by a local bus company; apiston seized and an oil line ruptured. They flew on to Allahabad on one engine but, by now needing completely new engines, were forced to retire.[19]
Arthur Edwards named his red Comet G-ACSS after theGrosvenor House Hotel, of which he was the managing director. He engagedC. W. A. Scott andTom Campbell Black to fly it in the race.[20]
Having landed atKirkuk to refuel, they arrived at Baghdad after the Mollisons had left but took off again after a half-hour turnaround. Scott and Campbell Black missed out Karachi and flew non-stop to Allahabad where they were told they were the first to arrive, having overtaken the Mollisons. Despite a severe storm over theBay of Bengal, in which both pilots had to wrestle with the controls together, they reachedSingapore safely, eight hours ahead of the DC-2.[citation needed]
They took off forDarwin, losing power in the port engine over theTimor Sea but struggled on to Darwin.[21] While mechanics were working on the engine its designer,Frank Halford, saw a news placard back in England and telephoned through to Darwin. Talking it over he concluded that, despite the warning indicator, they should be able to fly on at reduced power. Despite the setback their lead was now unassailable and after the final mandatory stop and more engine work atCharleville they flew on to cross the finish line atFlemington Racecourse at 3.33 p.m. (local time) on 23 October.[citation needed] Their official time was 70 hours 54 minutes 18 seconds.[22]
The third Comet, G-ACSR, had been painted inBritish racing green byBernard Rubin who was a successful motor race driver. He had intended to fly it himself along withKen Waller but had to pull out at the last minute due to ill health and instead engaged Owen Cathcart Jones to take his place.[20]
On reaching Baghdad, they overshot in the dark, landing by a village when they ran low on fuel. Leaving at first light, they just made it to Baghdad on empty tanks. On taking off again they found that they had a serious oil leak and had to return for repairs.[23] More trouble was encountered on the Darwin leg so they landed atBatavia,[24]where engineers employed by KLM, who had entered the DC-2, made repairs for them.[citation needed] They were the fourth aircraft to reachMelbourne, in a time of 108 hours 13 minutes 30 seconds. Cathcart Jones and Waller promptly collected film of theAustralian stages of the race and set off the next day to carry it back to Britain. Their return time of 13 days 6 hr 43 min set a new record for a flight to Australia and back.[25]
Grosvenor House was dismantled and shipped back to England. It was later bought by theAir Ministry, given the military serial K5084, painted silver overall with RAF markings and flown toRAF Martlesham Heath for evaluation by theAeroplane and Armament Experimental Establishment. It made several flights before being written off in a heavy landing and sold for scrap. It was subsequently sold on, rebuilt byEssex Aero and fitted with Gipsy Six series II engines and a castoring tailwheel. In this form it made several race and record attempts under various names. It claimed fourth place in the 1937Istres-Damascus-Paris race and 12th in theKing's Cup the next month. Later in the same year it lowered the out-and-home record to the Cape to 5 days 17 hours. In March 1938,A. E. Clouston andVictor Ricketts made a return trip toNew Zealand covering 26,450 mi (42,570 km) in 10 days 21 hours 22 minutes.[26][27]
The day after they finished the race, Cathcart Jones and Waller took off in G-ACSR for the return journey. Suffering engine trouble at Allahabad, they found the Mollisons still there and were generously given two good pistons fromBlack Magic to allow them to continue. Arriving back in England they had set a new round-trip record of 13 days, 6 hours and 43 minutes. That December, now namedReine Astrid in honour of theBelgian queen, G-ACSR flew the Christmas mail fromBrussels toLeopoldville in theBelgian Congo.[6][page needed] It was then sold to the French government and modified as mail plane F-ANPY, its delivery flight setting aCroydon-Le Bourget record on 5 July 1935. It subsequently madeParis–Casablanca and Paris—Algiers high-speed proving flights with the nameCité d'Angoulême IV. Formerly believed destroyed alongside F-ANPZ, F-ANPY was last seen in an unflyable condition atÉtampes inFrance in 1940.[28]
Black Magic was sold toPortugal for a projected flight fromLisbon toRio de Janeiro. Re-registered CS-AAJ and renamedSalazar it was damaged on its attempted takeoff atSintra Air Base for the Atlantic crossing. On a later return flight from Hatfield it made a record flight from London toLisbon, setting a time of 5 hours 17 minutes in July 1937.[29]
Following theFrench government's acquisition of F-ANPY (see above), they ordered a fourth Comet, F-ANPZ, with a mail compartment in the nose. It was later taken on charge by the French Air Force before being destroyed in a hangar fire atIstres inFrance in June 1940.[28]
The fifth and last Comet, registered G-ADEF and namedBoomerang, was built for Cyril Nicholson. It was piloted by Tom Campbell Black and J. C. McArthur in an attempt on the London-Cape Town record. It reachedCairo in a record 11 hr, 18 min, but the next leg of the journey was cut short due to oil trouble while in flight overSudan.[30] On 21 September 1935, Campbell Black and McArthur took off in "Boomerang" from Hatfield in another attempt at the Cape record. The aircraft crashed while flying over Sudan on 22 September 1935 due to propeller problems, the crew escaping by parachute.[31]
The de Havilland Comets set many record times for long-distance flights during the 1930s, both during races and on special record-breaking flights. Some flights set multiple point-to-point records.
| Date | Aircraft | Crew | Route | Distance | Time | Notes |
|---|---|---|---|---|---|---|
| 20–21 October 1934 | G-ACSP | Jim Mollison andAmy Mollison | England–Karachi | During theMacRobertson air race | ||
| 20–23 October 1934 | G-ACSS | C. W. A. Scott andTom Campbell Black | England–Australia | 11,000 mi (18,000 km) | 70 hr 55 min | Winner of theMacRobertson air race |
| 20 Oct–2 Nov 1934 | G-ACSR | Owen Cathcart Jones andKen Waller | England–Australia–England | 22,000 mi (35,000 km) | 13 days 6 hr 43 min | First leg during theMacRobertson air race |
| 20 December 1934 | G-ACSR | Ken Waller andMaurice Franchhomme | Brussels–Belgian Congo–Brussels | 882 mi (1,419 km) | 44 hr 40 min | Intermediate records set along the way. |
| 26 February 1935 | CS-AAJ | Carlos Bleck andCosta Macedo | London–Lisbon | 1,010 mi (1,630 km) | 6 hr 30 min | [32] |
| 11 April 1935 | F-ANPY | Hugh Buckingham and Martin Sharp | Croydon–Le Bourget | 205 mi (330 km)[33] | 56 min | namedCité d'Angoulême IV[32] |
| 5 July 1935 | F-ANPZ | Hubert Broad | Croydon–Le Bourget | 205 mi (330 km)[33] | 50 min | [32] |
| 1–2 August 1935 | F-ANPY | Jean Mermoz andLéo Gimié[32] | Paris–Casablanca–Dakar | 2,990 mi (4,810 km) | 15 hr 41 min | Faster on the return. |
| September 1935 | F-ANPY | Jean Mermoz andLéo Gimié | Paris–Algiers | 8 hr 38 min | [32] | |
| July 1937 | CS-AAJ | Costa Macedo | London–Lisbon | 1,010 mi (1,630 km) | 5 hr 27 min | Breaking its previous record |
| 14–16 November 1937 | G-ACSS | A.E. Clouston andBetty Kirby-Green | London–Cape Town | 7,200 mi (11,600 km) | 45 hr 2 min | NamedTheBurberry. |
| 18–20 November 1937 | G-ACSS | A.E. Clouston andBetty Kirby-Green | Cape Town–London | 7,200 mi (11,600 km) | 57 hr 23 min | Return trip. |
| 15–20 March 1938 | G-ACSS | A.E. Clouston andVictor Ricketts | London–New Zealand | 13,179 mi (21,210 km) | 104 hr 20 min | NamedAustralian Anniversary. |
| 20–26 March 1938 | G-ACSS | A.E. Clouston andVictor Ricketts | New Zealand–London | 13,179 mi (21,210 km) | 140 hr 12 min | Return leg, completing the first round trip. |
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G-ACSS was requisitioned for the RAF once again in 1943 but soon passed on to de Havilland. Restored for static display asGrosvenor House, it was put on show for the 1951Festival of Britain. TheShuttleworth Collection atOld Warden acquired it in 1965 and then in 1972 re-registered it under its original identity for restoration to flying condition, finally achieved in 1987. It is regarded as "one of the most significant British aircraft still flying."[34]
CS-AAJSalazar was rediscovered in Portugal after being lost for more than 40 years. It was brought back to the UK and re-registered once again as G-ACSP. As of 2020 restoration continues by the Comet Racer Project Group at the Amy Johnson Comet Restoration Centre,Derby Airfield. The objective is for G-ACSP to fly again in its original livery asBlack Magic.[19][35]
N88XD is a full-scale flying replica Comet. Built in 1993 for Thomas W. Wathen of Santa Barbara, CA by Bill Turner of Repeat Aircraft atFlabob Airport inRubidoux, California, it wears the livery of G-ACSSGrosvenor House.[36]
A replica, originally started by George Lemay in Canada, was acquired by theCroydon Aircraft Company based atOld Mandeville Airfield, near Gore, New Zealand, where it is currently[when?] still under construction.[37]
G-RCSR is a reproduction Comet based on the original construction drawings, being built by Ken Fern in parallel with the restoration ofBlack Magic at Derby.[38]
Portugal
United Kingdom
Data fromDe Havilland Aircraft since 1909,[39]
General characteristics
Performance
The MacRobertson Air Race was an event of world-wide importance and did much to drive aeroplane design forward.[42][43] The triumph of the Comet and its high-speed design marked a milestone in aviation.[44]
The Comet Hotel, Hatfield was begun the year before the race, as one of the first modernist inns in England.[45] Located close to the de Havilland factory, when it was finished it was named after the Comet Racer. War artistEric Kennington was commissioned to create a 9 feet (2.7 m) carved column in its car park, which was erected in 1936.[46] On its top is mounted a famous model of the Comet, currently[when?] in the livery ofGrosvenor House.[47]
Full-scale but non-flying replicas ofGrosvenor House andBlack Magic were constructed for the 1990 TV two-part Australian-produced dramatisationHalf a World Away, which was also released on DVD asThe Great Air Race. The G-ACSS replica was taxi-able and has since been restored in the livery of G-ACSR and is on static display at theDe Havilland Aircraft Museum,Salisbury Hall, UK.[48]
Comets have also appeared in fiction, seeAircraft in fiction#de Havilland DH.88 Comet.
Aircraft of comparable role, configuration, and era
