De Havilland DH98 Mosquito (1941)
The de Havilland DH.98 Mosquito was a British multi-role combat aircraft with a two-man crew that served during and after the Second World War. It was one of few operational front-line aircraft of the era constructed almost entirely of wood and was nicknamed "The Wooden Wonder". The Mosquito was also known affectionately as the "Mossie" to its crews. Originally conceived as an unarmed fast bomber, the Mosquito was adapted to roles including low to medium-altitude daytime tactical bomber, high-altitude night bomber, pathfinder, day or night fighter, fighter-bomber, intruder, maritime strike aircraft, and fast photo-reconnaissance aircraft. It was also used by the British Overseas Airways Corporation (BOAC) as a fast transport to carry small high-value cargoes to, and from, neutral countries, through enemy-controlled airspace.
When the Mosquito began production in 1941, it was one of the fastest operational aircraft in the world. Entering widespread service in 1942, the Mosquito was a high-speed, high-altitude photo-reconnaissance aircraft, continuing in this role throughout the war. From mid-1942 to mid-1943 Mosquito bombers flew high-speed, medium or low-altitude missions against factories, railways and other pinpoint targets in Germany and German-occupied Europe. From late 1943, Mosquito bombers were formed into the Light Night Strike Force and used as pathfinders for RAF Bomber Command's heavy-bomber raids. They were also used as "nuisance" bombers, often dropping Blockbuster bombs - 4,000 lb (1,812 kg) "cookies" - in high-altitude, high-speed raids that German night fighters were almost powerless to intercept.
As a night fighter, from mid-1942, the Mosquito intercepted Luftwaffe raids on the United Kingdom, notably defeating Operation Steinbock in 1944. Starting in July 1942, Mosquito night-fighter units raided Luftwaffe airfields. As part of 100 Group, it was a night fighter and intruder supporting RAF Bomber Command's heavy bombers and reduced bomber losses during 1944 and 1945. As a fighter-bomber in the Second Tactical Air Force, the Mosquito took part in "special raids", such as the attack on Amiens Prison in early 1944, and in precision attacks against Gestapo or German intelligence and security forces. Second Tactical Air Force Mosquitos supported the British Army during the 1944 Normandy Campaign. From 1943 Mosquitos with RAF Coastal Command strike squadrons attacked Kriegsmarine U-boats (particularly in the 1943 Bay of Biscay, where significant numbers were sunk or damaged) and intercepting transport ship concentrations.
The Mosquito flew with the Royal Air Force (RAF) and other air forces in the European theatre, and the Mediterranean and Italian theatres. The Mosquito was also used by the RAF in the South East Asian theatre, and by the Royal Australian Air Force (RAAF) based in the Halmaheras and Borneo during the Pacific War.
By the early-mid-1930s, de Havilland had a reputation for innovative high-speed aircraft with the DH.88 Comet racer. The later DH.91 Albatross airliner pioneered the composite wood construction that the Mosquito used. The 22-passenger Albatross could cruise at 210 miles per hour (340 km/h) at 11,000 feet (3,400 m), better than the 100 miles per hour (160 km/h) Handley Page H.P.42 and other biplanes it was replacing. The wooden monocoque construction not only saved weight and compensated for the low power of the de Havilland Gipsy Twelve engines used by this aircraft, but simplified production and reduced construction time.
Air Ministry bomber requirements and concepts:
On 8 September 1936, the British Air Ministry issued Specification P.13/36 which called for a twin-engined medium bomber capable of carrying a bomb load of 3,000 pounds (1,400 kg) for 3,000 miles (4,800 km) with a maximum speed of 275 miles per hour (443 km/h) at 15,000 feet (4,600 m); a maximum bomb load of 8,000 pounds (3,600 kg) which could be carried over shorter ranges was also specified. Aviation firms entered heavy designs with new high-powered engines and multiple defensive turrets, leading to the production of the Avro Manchester and Handley Page Halifax.
In May 1937, as a comparison to P.13/36, George Volkert, the chief designer of Handley Page, put forward the concept of a fast unarmed bomber. In 20 pages, Volkert planned an aerodynamically clean medium bomber to carry 3,000 pounds (1,400 kg) of bombs at a cruising speed of 300 miles per hour (480 km/h). There was support in the RAF and Air Ministry; Captain R N Liptrot, Research Director Aircraft 3 (RDA3), appraised Volkert's design, calculating that its top speed would exceed the new Supermarine Spitfire. There were, however, counter-arguments that, although such a design had merit, it would not necessarily be faster than enemy fighters for long. The ministry was also considering using non-strategic materials for aircraft production, which, in 1938, had led to specification B.9/38 and the Armstrong Whitworth Albemarle medium bomber, largely constructed from spruce and plywood attached to a steel-tube frame. The idea of a small, fast bomber gained support at a much earlier stage than sometimes acknowledged though it was unlikely that the Air Ministry envisaged it not using light alloy components.
Once design of the DH.98 had started, de Havilland built mock-ups, the most detailed at Salisbury Hall, in the hangar where E0234 was being built. Initially, this was designed with the crew enclosed in the fuselage behind a transparent nose (similar to the Bristol Blenheim or Heinkel He 111H), but this was quickly altered to a more solid nose with a more conventional canopy.
The construction of the prototype began in March 1940, but work was cancelled again after the Battle of Dunkirk, when Lord Beaverbrook, as Minister of Aircraft Production, decided there was no production capacity for aircraft like the DH.98, which was not expected to be in service until early 1941. Although Lord Beaverbrook told Air Vice-Marshal Freeman that work on the project had better stop, he did not issue a specific instruction, and Freeman ignored the request. In June 1940, however, Lord Beaverbrook and the Air Staff ordered that production was to focus on five existing types, namely the Supermarine Spitfire, Hawker Hurricane, Vickers Wellington, Armstrong-Whitworth Whitley and the Bristol Blenheim. Work on the DH.98 prototype stopped, and it seemed that the project would be shut down when the design team were denied the materials with which to build their prototype.
The Mosquito was only reinstated as a priority in July 1940, after de Havilland's General Manager L.C.L Murray, promised Lord Beaverbrook 50 Mosquitoes by December 1941, and this, only after Beaverbrook was satisfied that Mosquito production would not hinder de Havilland's primary work of producing Tiger Moth and Oxford trainers and repairing Hurricanes as well as the licence manufacture of Merlin engines. In promising Beaverbrook 50 Mosquitoes by the end of 1941, de Havilland was taking a gamble, because it was unlikely that 50 Mosquitos could be built in such a limited time; as it transpired only 20 Mosquitos were built in 1941, but the other 30 were delivered by mid-March 1942.
During the Battle of Britain, nearly a third of de Havilland's factory time was lost because the workers took cover in the factory's bomb shelters. Nevertheless, work on the prototype went quickly, such that E0234 was rolled out on 19 November 1940.
In the aftermath of the Battle of Britain, the original order was changed to 20 bomber variants and 30 fighters. It was still uncertain whether the fighter version should have dual or single controls, or should carry a turret, so three prototypes were eventually built: W4052, W4053 and W4073. The latter, both turret armed, were later disarmed, to become the prototypes for the T.III trainer. This caused some delays as half-built wing components had to be strengthened for the expected higher combat load requirements. The nose sections also had to be altered, omitting the clear perspex bomb-aimer's position, to solid noses designed to house four .303 machine guns and their ammunition.
The Mosquito was a fast, twin-engined aircraft with shoulder-mounted wings. The most-produced variant, designated the FB Mk VI (Fighter-bomber Mark 6), was powered by two Merlin Mk 23 or Mk 25 engines driving three-bladed de Havilland hydromatic propellers. The typical fixed armament for an FB Mk VI was four Browning .303 machine guns and four 20 mm Hispano cannon while the offensive load consisted of up to 2,000 pounds (910 kg) of bombs, or eight RP-3 unguided rockets.
The oval-section fuselage was a frameless monocoque shell built in two halves being formed to shape by band clamps over a mahogany or concrete mould, each holding one half of the fuselage, split vertically. The shell halves were made of sheets of Ecuadorean balsawood sandwiched between sheets of Canadian birch, but in areas needing extra strength— such as along cut-outs— stronger woods replaced the balsa filler; the overall thickness of the birch and balsa sandwich skin was only 7⁄16 inch (11 mm). This sandwich skin was so stiff that no internal reinforcement was necessary from the wing's rear spar to the tail bearing bulkhead. The join was along the vertical centre line. This split construction greatly aided the assembly of the internal equipment as it allowed the technicians easy access to the fuselage interior. While the glue in the plywood skin dried, carpenters cut a sawtooth joint into the edges of the fuselage shells, while other workers installed the controls and cabling on the inside wall. When the glue completely dried, the two halves were glued and screwed together. The fuselage was strengthened internally by seven bulkheads made up of two plywood skins parted by spruce blocks, which formed the basis on each half for the outer shell. Each bulkhead was a repeat of the spruce design for the fuselage halves; a balsa sheet sandwich between two plywood sheets/skins. Bulkhead number seven carried the fittings and loads for the tailplane and rudder, The type of glue originally used was Casein, which was later replaced by "Aerolite", a synthetic urea-formaldehyde, which was more durable. Many other types of screws and flanges (made of various woods) also held the structure together.
The fuselage construction joints were made from balsa wood and plywood strips with the spruce multi-ply being connected by a balsa V joint, along with the interior frame. The spruce would be reinforced by plywood strips at the point where the two halves joined to form the V-joint. Located on top of the joint the plywood formed the outer skin. During the joining of the two halves ("boxing up"), two laminated wooden clamps would be used in the after portion of the fuselage to act as support. A covering of doped Madapolam (a fine plain woven cotton) fabric was stretched tightly over the shell and a coat of silver dope was applied, after which the exterior camouflage was applied. The fuselage had a large ventral section cut-out, which was braced during construction, to allow it to be lowered onto the wing centre-section. Once the wing was secured the lower panels were replaced, and the bomb bay or armament doors fitted.
The all-wood wing was built as a one-piece structure and was not divided into separate construction sections. It was made up of two main spars, spruce and plywood compression ribs, stringers, and a plywood covering. The outer plywood skin was covered and doped like the fuselage. The wing was installed into the roots by means of four large attachment points. The engine radiators were fitted in the inner wing, just outboard of the fuselage on either side. These gave less drag. The radiators themselves were split into three sections: an oil cooler section outboard, the middle section forming the coolant radiator and the inboard section serving the cabin heater. The wing contained metal framed and skinned ailerons, but the flaps were made of wood and were hydraulically controlled. The nacelles were mostly wood, although, for strength, the engine mounts were all metal as were the undercarriage parts. Engine mounts of welded steel tube were added, along with simple landing gear oleos filled with rubber blocks. Wood was used to carry only in-plane loads, with metal fittings used for all triaxially loaded components such as landing gear, engine mounts, control surface mounting brackets, and the wing-to-fuselage junction. The outer leading wing edge had to be brought 22 inches (56 cm) further forward to accommodate this design. The main tail unit was all wood built. The control surfaces, the rudder and elevator, were aluminium framed and fabric covered. The total weight of metal castings and forgings used in the aircraft was only 280 lb (130 kg).
In November 1944, several crashes occurred in the Far East. At first, it was thought these were as a result of wing structure failures. The casein glue, it was said, cracked when exposed to extreme heat and/or monsoon conditions. This caused the upper surfaces to "lift" from the main spar. An investigating team led by Major Hereward de Havilland travelled to India and produced a report in early December 1944 stating that "the accidents were not caused by the deterioration of the glue but by shrinkage of the airframe during the wet monsoon season". However a later inquiry by Cabot & Myers definitely attributed the accidents to faulty manufacture and this was confirmed by a further investigation team by the Ministry of Aircraft Production at Defford which found faults in six different Marks of Mosquito (all built at de Havilland's Hatfield and Leavesden plants) which showed similar defects, and none of the aircraft had been exposed to monsoon conditions or termite attack; thus it was concluded that there were construction defects found at the two plants. It was found that the "Standard of glueing...left much to be desired”. Records at the time showed that accidents caused by "loss of control" were three times more frequent on Mosquitoes than on any other type of aircraft. The Air Ministry forestalled any loss of confidence in the Mosquito by holding to Major de Havilland's initial investigation in India that the accidents were caused "largely by climate" To solve the problem, a sheet of plywood was set along the span of the wing to seal the entire length of the skin joint along the main spar.
Information regarding the de Havilland DH98 Mosquito has been taken from excerpts contained on Wikipedia
Aston Martin Ulster Roadster (1936)
In 1927 Aston Martin was taken over by race driver A. C. Bertelli. He designed a 1.5-litre, SOHC engine which would eventually power the LeMans-racing Ulster. Thoughout the years the engine was devloped to include dry sump lubrication.
The Aston Martin Ulster stands as one of the most respected pre-war racecars. It was largely based on the Mark II which came before it.
The Ulster had a breif two year race program. During this time they dominated the British Tourist Trophy at Goodwood. In 1934, Ulsters took first, second and third place. The best LeMans result was achieved in 1935. Chassis LM20 raced to third overall which put it first in the 1101 to 1500cc class.
After the race efforts, Aston Martin readied a production version of the LeMans cars. Twenty-One of these cars were built of which all are accounted for today.
Aston Martin Ulster information used from:
In the 1980's a small number (7) replicas of the Aston Martin Ulster Roadster were manufactured as a kit car:
Fergus Mosquito (Aston Martin Ulster replica)
Kop Hill Climb - 25th September 2011
Fergus Mosquito - an Aston Martin Ulster replica.
Only seven were made in Kingsbridge, Devon, in the 1980s, using donor Morris Marina B-series engines and other parts.
UIJ233 is the best of the 7 replicas.
These two models, the de Havilland DH98 Mosquito aircraft and the Aston Martin Ulster Roadster of 1936 have been created in Lego miniland scale for Flickr LUGNuts' 79th Build Challenge, - 'LUGNuts goes Wingnuts" - featuring automotive vehicles named after, inspired by or related to aircraft.