Science Fair Project Encyclopedia
De Havilland DH.88
|de Havilland DH.88 Comet|
|First flight||September 8, 1934|
|Entered service||October 20, 1934|
|Length||29 ft||8.8 m|
|Wingspan||44 ft||13.4 m|
|Height||9 ft||2.7 m|
|Wing area||213 ft²||19.7 m²|
|Empty||3,000 lb||1,360 kg|
|Loaded||5,550 lb||2,520 kg|
|Engine||2 × de Havilland Gipsy Six R|
|Power (each)||225 hp||170 kW|
|Maximum speed||235 mph||378 km/h|
|Range||2,580 miles||4,150 km|
|Ferry range||2,925 miles||4,710 km|
|Service ceiling||19,000 ft||5,790 m|
|Rate of climb||1,200 ft/min||370 m/min|
The de Havilland DH.88 Comet was an aircraft designed for one very specific purpose - to win the 1934 MacRobertson Air Race for Britain. It set many aviation records during the race and afterwards as a pioneer mail-plane.
Despite previous British air racing successes, culminating in 1931 in the outright win of the Schneider Trophy, there was no British plane capable of putting up a challenge over the MacPherson course with its long overland stages. The de Havilland company stepped into the breach by offering to produce a limited run of 200 mph (320 km/h) racers if three were ordered by February, 1934. The sale price of £5,000 each would by no means cover the development costs - de Havilland seem to have been motivated by a mixture of patriotism and an eye to the obvious publicity benefits to the company if one of their planes should win the event.
3 orders were indeed received, and de Havillands set to work. The airframe consisted of a wooden skeleton clad with spruce plywood, with a final fabric covering on the wings. A long streamlined nose held the main fuel tanks, with the low set central two-seat cockpit forming an unbroken line to the tail. The engines were essentially the standard Gipsy Six used on the Express and Dragon Rapide passenger planes, tuned for best performance with a higher compression ratio. The propellors were two-position variable pitch, manually set to fine before takeoff and changed automatically to coarse by a pressure sensor. The main undercarriage retracted upwards and backwards into the engine nacelles. The DH.88 could maintain altitude up to 4,000 ft (1,200 m) on one engine.
De Havillands managed to meet their challenging schedule and testing of the DH.88 began six weeks before the start date of the race. On the day of the race, the three distinctively coloured planes took their places among 17 other entrants ranging from a new Douglas DC-2 airliner to two converted Fairey Fox bombers.
The MacRobertson Race
First to take off at 6.30 am on October 20 were Jim and Amy Mollison in their own G-ACSP Black Magic. They made a faultless journey to Baghdad, and reached Karachi at around 10 am on the second race day, setting a new England-India record. Problems began for the Mollisons when their landing gear failed to retract, and after returning Karachi for repairs they were again delayed by an inability to navigate at night.
Further problems followed when they made an unscheduled refuelling stop at Jobbolpore but found no aviation fuel. Running instead on fuel used by the local bus company, a engine piston seized and an oil line ruptured. They flew on to Allahabad and retired.
The scarlet G-ACSS was the property of Mr.A.O.Edwards and was named Grosvenor House after the hotel which he managed. The crew were Charles W.Scott and Tom Campbell Black . When the Mollisons ran into problems at Karachi, Scott & Campbell Black took over the lead and were first into Allahabad. Despite a severe storm over the Bay of Bengal they reached Singapore safely, 8 hours ahead of the DC-2.
They took off for Darwin, but over the Timor Sea lost power in the port engine when the oil pressure dropped to zero. Repairs at Darwin got them going again, although continuing oil warnings caused them to fly the last two legs with one engine throttled back. Their lead was unassailable despite this, and after the final mandatory stop and more engine work at Charleville they flew on to cross the finish line at Flemington Racecourse at 3.33 pm (local time) on October 23. Their official time was 71 hours 18 seconds.
The third plane G-ACSR had been paid for by racing driver Bernard Rubins and was flown by Owen Cathcart Jones and Ken Waller. They caught up with the Mollisons at Karachi but found they had a serious oil leak and were forced to delay for repairs. They were the fourth plane to reach Melbourne, in a time of 108 h 13 min 45 s.
Cathcart Jones and Waller promptly collected film of the Australian stages of the race at set off to carry it back to Britain. Their return time of 13½ days set a new record.
After the race
G-ACSR, renamed Reine Astrid flew the Christmas mail from Brussels to Leopoldville in the Belgian Congo in 1934. It was then sold to the French government as F-ANPY and set a Croydon-Le Bourget record of 52 minutes on July 5, 1935. It subsequently made Paris-Casablanca and Paris-Algiers high-speed proving flights.
Black Magic was sold to Portugal for a projected flight from Lisbon to Rio de Janeiro. Reregistered CS-AAJ Salazar it made various flights from London to Lisbon, setting a time of 5 h 17 min in July 1937.
Grosvenor House was later fitted with Gypsy Six series II engines and made several race and record attempts under various names. It claimed fourth place in the 1937 Marseilles-Damascus-Paris race, and later the same year lowered the out-and-home record to the Cape to 15 days 17 hours. In March 1938 it made a return trip to New Zealand covering 26,450 miles (42567 km) in 10 days 21 hours 22 minutes.
Two more Comets
A fourth Comet, F-ANPZ, was built for the French government, with a mail compartment in the nose.
The fifth and last Comet named G-ADEF Boomerang was built for Cyril Nicholson, and piloted by Tom Campbell Black (of Grosvenor House fame) and J.C.McArthur in an attempt on the London-Cape Town record. It reached Cairo in a record 11hr 18 min but the Cape Town attempt was abandoned due to oil trouble.
Last resting places
The DH.88 might have been the swan-song for high performance wooden aircraft but for one factor - shortage of metal for aircraft construction during World War II. As it turned out, experience with the DH.88 would be put to use in designing one of the war's finest aircraft - the de Havilland Mosquito.
The clean lines of the DH.88, especially in the striking colours of Grosvenor House, make it a true design classic.
Specifications (variant described)
- Length: m ( ft)
- Wingspan: m ( ft)
- Height: m ( ft)
- Wing area: m² ( ft²)
- Empty: kg ( lb)
- Loaded: kg ( lb)
- Maximum takeoff: kg ( lb)
- Powerplant: Engine type(s), kN (lbf) thrust or
- Powerplant: Engine type(s), kW ( hp)
- Maximum speed: km/h ( mph)
- Range: km ( miles)
- Service ceiling: m ( ft)
- Rate of climb: m/min ( ft/min)
- Wing loading: kg/m² ( lb/ft²)
- Thrust/weight: or
- The MacRobertson Air Race, 1934
- Comet DH88 - fastest from England to Australia
- Black Magic Restoration
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