Aviation Classics 10 de Havilland DH98 Mosquito preivew

The Mosquito B Mk 35,TA634 preserved in the de Havilland Aircraft Museum at Salisbury Hall.

Julian Humphries

Contents 6 Legend understood

40 Flying the supreme Night Fighter

8 Ancestors and evolution

46 American Mosquito Night Fighters

14 Mosquito prototypes and testing 20 The Bombers 26 10,000 Cookies 32 The Fighters, Night Fighters and Fighter Bombers

4 aviationclassics.co.uk

54 The Banff Strike Wing 62 Diver destroyer 66 Alone and unarmed 76 Inside the Mosquito 86 The Trainers

Editor:

88 The Mosquito abroad

Tim Callaway editor@aviationclassics.co.uk Dan Savage Martyn Chorlton, Norm DeWitt, Keith Draycott, Julian Humphries, David Oliver, François Prins, Constance Redgrave, David I Roberts, Clive Rowley, Warren Thompson

Publisher: Contributors:

94 The ball bearing run 100 The story of a Pathfinder

Designers: Reprographics:

Charlotte Pearson Jonathan Schofield

104 Oddball Mosquitos

Group production editor:

Tim Hartley

108 Mosquito variants at a glance

Divisional advertising manager: Tracey Glover-Brown tglover-brown@mortons.co.uk Advertising sales executive: Jamie Moulson jmoulson@mortons.co.uk 01507 529465

118 Mosquito to fly again

Subscription manager:

120 Jay Leno’s Mosquito Merlin

Brand manager:

122 Survivors

Production manager:

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Paul Deacon pdeacon@mortons.co.uk Steve O’Hara sohara@mortons.co.uk Charlotte Park cpark@mortons.co.uk 01507 529549 Craig Lamb clamb@mortons.co.uk

Operations Director: Commercial Director: Business Development Director: Managing Director:

Dan Savage Nigel Hole Terry Clark Brian Hill

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ISBN No 978-1-906167-57-8

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Formation of Mosquito F Mk II fighters of 605 Squadron based at Ford in West Sussex in flight on March 7, 1943. Editors collection

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de Havilland DH.98 Mosquito 5

Another strand of the legend, the people who operated the Mosquito.There are not many memorials to air and ground crew together.This one, appropriately at Salisbury Hall, sums up the last factor of what it is that makes the Mosquito special. Julian Humphries

Legend understood

J

ust so you know, and I make no excuses for this, I have found that this is the hardest page to write in the whole magazine. Summing up an entire edition in a few paragraphs, particularly when you are dealing with such a large subject as this, is difficult without leaving out something important, making it sound glib, or worse still, trite. Consequently, when it came to the Mosquito, information was not the problem. The problem was trying to understand the true nature of a legend, and express it clearly.

A lot of people listen to music when they write. I listen to The Goon Show and Monty Python. There is something about the absurd constructs and lunatic juxtapositions that seem to free the mind. The Gumby Theatre was playing and there, right at the end of the sketch, was inspiration. “Adapted… by putting it on a piece of wood and banging a few nails through it”. Admittedly, the Monty Python boys were talking about Anton Chekhov’s The Cherry Orchard, but they could have been talking about the Mosquito.

Suddenly, I got it. I understood the legend.

Adaptable was what the aircraft was all about, and often those adaptations came about by little more than the Python method, new mission equipment simply screwed, glued or nailed into the slim wooden airframe. This is not to say these adaptations were rushed or ill-considered, but the nature of the airframe lent itself to simple, effective and – most of all – speedy, configuration to many roles.

There were many excellent aircraft built during the Second World War, but only one in 6 aviationclassics.co.uk

this league. A Spitfire would not have made a heavy bomber or a good night-fighter, although it was an excellent fighter, fighterbomber and photo-reconnaissance aircraft. A Lancaster would have not excelled as a fighter.

The only two aircraft that come close are the Ju-88 and P-38 Lightning, but the Lightning did not have the payload of the Mosquito and the Ju-88 lacked its agility as a fighter. Only the Mosquito excelled in every single one of its roles, with the performance each required.

The key to the legend, then, is its adaptability, but that key came from skill, dedication and genius. Officialdom was initially very suspicious of the concept, applying an often outmoded understanding of air warfare and aircraft and seeing only problems in an unarmed bomber. Geoffrey de Havilland did understand aircraft, particularly the safety that came with speed and in Eric Bishop he had a chief designer who could give him the performance he needed for the new design.

Even in the face of official rejection, their belief in the concept was unshakeable. This belief was only the beginning of the Mosquito story.

The construction techniques required for the airframe were complex and required great skill, but created a beautifully simple and efficient airframe. The materials were available, being considered non-strategic, and the skills were available as de Havilland had foreseen, there was not much call for pianos and furniture in wartime. These skilled woodworkers took to the task with a will, and the aircraft benefited enormously from their feedback. What resulted from these many layers of skill, dedication and genius was a

lightweight, strong airframe with performance to spare, even from the very beginning. Looking down the inside of the fuselage of a Mosquito, there was also a lot of empty space for equipment.

This last factor was the remaining piece of the legend. You could put what you needed inside the airframe, maintaining its streamlining and therefore performance, and you could put it there with relative ease.

Mounts for cameras, racks for radar equipment, all could be designed and mass produced quickly, then glued or screwed on to the wood internally. Even the bomb bay was extended greatly without real penalty.

Weapons, aerials and drop tanks were the only externally mounted items that ever changed the basic shape. That was the real genius of the Mosquito. There were 7,781 built in 37 versions, but aside from engines and the odd bulge, it actually changed very little. A late model Mosquito could be parked next to the prototype and you still wouldn’t mistake it for anything else. Like the Spitfire and the Mustang, it remained true to its form, because that form was right first time.

Maybe that’s what genius is, the creation of perfection. It certainly is the stuff of legends.

All best, Tim

&

Ancestors Evolution This superb stately hall in Hertfordshire became the centre of the Mosquito stor y, and home to its design team. Before that happened, many manufacturers were to use monocoque wooden construction in a wide variety of aircraft, developing the technique. David I Roberts examines the background to the Mosquito’s construction technique.

Salisbury Hall, near London Colney and just off the M25 at Junction 22. From September 1939 the Hall was the home of the de Havilland design team responsible for the Mosquito, now home to the de Havilland Aircraft Heritage Centre. Julian Humphries

The Albatros D.Va fighter of the First World War featured a compound curved fuselage constructed from plywood panels, giving it a smooth, streamlined form.This one is in the San Diego Air and Space Museum. Constance Redgrave

O

ne day in March, Geoffrey de Havilland sat in the cockpit of an advanced, high-speed military aircraft of his own design, having a streamlined plywood monocoque fuselage, and prepared to take off into the unknown. The year was 1913, the place Farnborough, home of the Royal Aircraft Factory, which de Havilland had joined as a designer and test pilot in December 1910, when it was still the Army Balloon Factory. He had brought with him his second design, which became the F.E.1, and had already collaborated in the creation of the classic B.E.1 and B.E.2. The testing of the new B.S.1, designed in 1912 without a fin, ended in a flat spin and a crash in which de Havilland broke his jaw, but not before a speed of 91.4mph (147kph) had been attained over a measured course. The world’s first single-seat scouting aeroplane, precursor of the fighter, had arrived.

The tough wooden fuselage was taken in for repairs, receiving a new tail unit with fixed upper and lower fins and a less-potent 80hp Gnôme engine replacing the original one of 100hp. Redesignated B.S.2 and then S.E.2 (for Scouting Experimental) the aircraft became known as the ‘Bullet’, which would become a common term for the early scouts and fighters. The monocoque was later replaced by a more conventional fabriccovered rear fuselage, and the machine, now known as the S.E.2a, served operationally with No. 3 Squadron, R.F.C. Armament consisted of the pilot’s revolver and a rifle mounted on the side to clear the propeller. Its successor, the S.E.4, designed

by H P Folland, had and retained a plywood monocoque fuselage, but for the rest of the war, with the exception of the shipboard Parnall Panther and the little-produced

B.A.T. Bantam, the British industry limited its use of plywood to partial covering of fuselages, with few compound-curved parts.

Geoffrey de Havilland had, however, firmly established his credentials as an innovative designer of fast wooden aircraft. It might reasonably be said that the seed sown in 1913 with the B.S.1 would come to fruition with the equally ground-breaking Mosquito in 1940.

Plywood skinning was almost as old as aviation itself. The technology came from boat building; early monoplanes such as the 1910 Martin-Handasyde No.3 and those designed by René Hanriot had elegant shallow fuselages resembling racing rowing boats. The first British monocoque, or more accurately stressed-skin, fuselage belonged to the Handley Page ‘D’ or H.P.4 of 1911. The French Deperdussin company from 1912 produced a superb series of racing monoplanes, the finely streamlined fuselage of which was made by laminating strips of tulip wood over a male mould of circular cross-section, then withdrawing the mould

from the shell. This was a pure monocoque, practical for small racing aircraft, but less so on a larger scale.

Deperdussin had already used diagonally laminated veneer strips for compound-curved underside panels, and the Nieuport firm would develop the technique for the forward fuselage fairings of fighters such as the Ni.17, 27 and 28 (the last two also had a ply covered fin and tailplane), before building the full monocoque Nieuport 29 at the end of the war. The criss-cross technique was perfected by the German firms LFG Roland and Pfalz, who had the idea of building the fuselage skin in two halves, joined along the top and bottom centrelines; the latter company built exquisitely shaped fuselages with integral wing root fillets. A covering of tightly stretched and doped fabric completed the skin. The lightweight interior framework was, however, still built separately. Similar half-fuselage construction and fabric coating would be used to great effect in the Mosquito, albeit with panels of ply rather than diagonal strips. ➤

The forward fuselage and tailplane of the Nieuport 28 were plywood skinned, the fuselage skinning developed from the Deperdussin technique. Constance Redgrave de Havilland DH.98 Mosquito 9

The Lockheed Vega was built using moulded plywood to create its fine lines.This one is a replica of the aircraft flown by Amelia Earhart on the first female solo flight across the Atlantic.

Editor’s Collection

Meanwhile, other German constructors such as Albatros, LVG, Halberstadt and Hannover built simpler compound curved fuselages out of plywood panels, and Fokker essayed a plywood-covered wing on their E.V fighter. Fatal crashes due to faulty manufacture led to its withdrawal; it reemerged with a better built wing as the D.VIII. It had shown, however, that a wooden-skinned wing could be light, aerodynamically clean and efficient, and Fokker would produce such wings for its airliners through the 1920s.

In the US, a process developed by Jack Northrop at the turn of the 1920s for the Loughead brothers involved layering veneer into a two-part female mould with casein glue and inflating a bladder inside to compress it into a pure monocoque shell. The brothers’

company, renamed Lockheed, went on to become the main American producer of plywood-skinned private, transport and racing aircraft until the early 1930s, their customers including Charles Lindbergh and Amelia Earhart.

Plywood techniques

Geoffrey de Havilland, who bought his wartime employer, the Aircraft Manufacturing Company, from its new owners BSA and renamed it for himself, set about supplying the burgeoning airline industry with a succession of types, first adapted from DH.4 and DH.9A bombers, then a range of new designs, all built of wood. The first to have an entirely plywood skinned fuselage was the DH.37 of 1922. The classic Moth series, most

This view of the Comet Racer emphasises its fine lines, and shows the lineage to the Mosquito, both aircraft built for maximum performance. Constance Redgrave 10 aviationclassics.co.uk

with plywood fuselages, were the mainstay of the British subsidised flying club movement, and such was the demand for them that they also came to be produced in Australia, Canada, the US and France.

The plywood forming technique used by DH involved laminating cross-grained sheets of veneer with casein glue over a male mould, then heating it in an oven called an autoclave.

It produced fine, smooth compound-curved nose cones for the series of biplane airliners and air taxis beginning with the DH.84 Dragon and culminating in the DH.90 Dragonfly, which had the entire fuselage of curvaceous moulded plywood, without the fabric-and-stringer fairing of the earlier types.

By the mid-1930s, de Havilland was the only volume producer of wooden aircraft in Britain, or indeed most of the world, the rest of the industry having gone over to metal construction. The main exception was in the Soviet Union, where the 1920s-vintage U-2 biplane, later redesignated Polikarpov Po-2, was being built in large numbers.

In 1934 a very advanced monoplane, the DH.88 Comet, was built to compete in the MacRobertson race from England to Australia. The most up-to-date competitor was a Douglas DC-2 airliner, with all-metal construction and powerful radial engines which no British constructor could hope to match, but de Havilland saw an alternative approach. A very clean, compact wooden airframe powered by two of the company’s existing Gipsy Six engines with modestly increased compression ratio, and equipped with a retractable undercarriage and variable-

Deperdussin began building training and racing aircraft such as this from 1910, now part of the Shuttleworth Collection at Old Warden near Biggleswade in Bedfordshire.

It developed monocoque fuselages on its later aircraft. Constance Redgrave

pitch propellers, would be able to cruise economically at 200mph (321.86kph) and have the necessary range.

DH offered to build the type for £5000 each (equivalent to 10 Gipsy Moths, but well below the development cost) if three were ordered by February 1934. Orders were duly received, and the Comets were completed just six weeks before the start of the race in October. A long, finely shaped fuselage and an exceptionally thin tapered cantilever wing gave the promised performance, and the race was won by C W A Scott and Tom Campbell Black in G-ACSS Grosvenor House in an official time of 71 hours, 18 seconds from Mildenhall to Melbourne, a record which still stands.

Jim and Amy Mollison, first away in GACSP Black Magic, were forced to retire at Allahabad with engine trouble due to bus(!) fuel obtained faute de mieux at Jobbolpore, but G-ACSR flown by Owen Cathcart Jones and Ken Waller arrived fourth with a time of 108 hours 13 minutes and 45 seconds. Their return flight carrying film of the Australian stages of the race set a new record of 10 days, 21 hours and 22 minutes. Grosvenor House established several more longdistance speed records, and is preserved in airworthy condition in the Shuttleworth Collection at Old Warden, Bedfordshire.

Black Magic was sold to a Portuguese owner, who re-registered it as CS-AAJ Salazar. Its best flight in that guise was from London to Lisbon in five hours, 17 minutes in July 1937. It is currently being restored to flying condition, as Black Magic, in Derby. G-

The Shuttleworth Collection’s DH.88 is kept in immaculate condition, its elegant lines and seamless streamlining the product of its moulded plywood construction. Constance Redgrave

ACSR was named Queen Astrid and carried mail from Brussels to the Belgian Congo for Christmas 1934, before being sold to the French government.

Two additional Comets were built: F-ANPZ joined F-ANPY in French air mail service, and G-ADEF, named Boomerang, flown by Tom Campbell Black and JC McArthur, attempted to break the London to Cape Town record.

They established a record of 11 hours 18 minutes to Cairo, but oil problems forced them to abandon the flight to Cape Town.

Mindful of his DH.4, which had been one of the fastest bombers in the First World War, able to outpace most fighters, de Havilland offered a potential light bomber development of the DH.88 to the RAF in 1935, but it was

rejected. Inspired by the success of the DH.88 in the postal rôle, the company turned its attention to a fast four-engined mailplane, the DH.91 Albatross, for which a revolutionary form of plywood was pioneered under the direction of Moth designer Arthur Hagg. The fuselage skin was built of two thin layers of birch ply sandwiching one of 3/8inch balsa wood, previously used only in model aircraft. This allowed a thicker, and thus more rigid, load-bearing skin without added weight, and it could be cold-formed over a male mould with bands of steel clamped over it while the glue set. Slots and recesses in the mould enabled structural members to be pre-installed, considerably shortening construction time. ➤ de Havilland DH.98 Mosquito 11

Inside the narrow cockpit of the DH.88.The second pilot’s feet were on rudder pedals on either side of the pilot’s seat. Constance Redgrave

Like the First World War Roland and Pfalz aircraft, the fuselage was made in two halves, with the extra advantage that the skin had the structure, which also featured balsa filling, already attached. Stronger woods in place of balsa formed the outlines of cut-outs for doors, windows, etc, and the edges along the joints.

Much internal equipment was easily installed before the halves were joined. The thin wings had more conventional plywood skin, like that of the DH.88, and the whole airframe had a stretched and doped covering of fabric. The result was surely one of the most beautiful aircraft ever built; its svelte lines gave it a cruising speed of 210mph (338kph) on the 2100hp of its four Gipsy 12 engines, and a range of 1040 miles (1673.7km).

The first Albatross flew in May 1937, and seven were built for Imperial Airways, two as mail carriers and five as 22-passenger airliners. Imperial Airways became BOAC in 1940, and the two mailplanes were impressed into the RAF, to be operated by 271 Squadron.

Sadly, none survived the war, the last two being scrapped in 1943 after accidents and enemy bombing had claimed the other five.

Air Ministry Specification 13/36, issued in September 1936, was for a twin-engined bomber able to carry 3000lb (1360kg) of bombs over a range of 3000 miles (4828km) at a maximum speed of 275mph (442.6kph), and a load of 8000lb (3629kg) over a shorter range. de Havilland was sure this could be met by a lightweight, streamlined wooden aircraft, but the Air Ministry at the time preferred to concentrate on all-metal bombers with multiple defensive turrets; Specification 13/36 eventually resulted in the Avro Manchester and the Handley Page Halifax. de Havilland’s proposals were rejected, but the

firm persisted, offering in 1938 a twin RollsRoyce Merlin engined development of the Albatross, with a crew of six and three turrets, which would carry a 6000lb (2720kg) bomb load to Berlin, cruising at 268mph (431.3kph) at 22,500 feet (6858m), with a maximum speed of 300mph (508kph).

Geoffrey de Havilland gained an ally in Air Marshal Wilfred Freeman, the Air Council’s member for research and development, who had been convinced by de Havilland’s argument that, pound for pound, wood was as strong as steel or duralumin, and that the fast, lightly armed bomber concept was worth pursuing. Handley Page was also considering the idea, and the Ministry was beginning to favour the use of non-strategic materials; one outcome was the Armstrong Whitworth Albemarle, which had wooden structure and skin on a frame of steel tubing.

Geoffrey Havilland was given official backing to pursue his ideas further.

By late July 1938, the de Havilland team had concluded that S.13/36 could not be met with a twin-Merlin bomber that was both fast and heavily armed. After considering their new Flamingo airliner, a departure into all-metal construction, as a basis for a bomber, the DH team decided a radical new approach was needed – an unarmed, highly manoeuvrable Merlin-powered twin built of wood and able to outrun fighters, thus having no need of defensive armament. A crew of two would suffice, and the simplicity of the design would permit rapid production. Additionally, it would use the skills of thousands of woodworkers in the furniture industry, who might otherwise have been redundant in wartime. The concept that was to become the Mosquito had arrived.

■ Words: David I Roberts

The moulds to build the DH.91 Albatross were made of mahogany.The moulds for the Mosquito, and here, the later Hornet fighter, were made of easily mass produced concrete.

The slots in the concrete were for structural members to be inserted before the plywood skin was strapped over the mould to shape it. Julian Humphries

The DH.91 Albatross of 1937 was one of the most elegant aircraft ever built, and was intended as a high speed mailplane and transport aircraft. Editor’s Collection

The Shuttleworth Collection’s airworthy DH.88 Comet Racer. This is the actual aircraft that won the MacRobertson Race from England to Australia, Mildenhall to Melbourne, in 1934. Constance Redgrave