Le Bristol Brabazon : 1949
aeronewsline :: Accueil :: Histoire :: Aéronefs 1945 à 1955
Page 1 sur 2 • 1, 2
Le Bristol Brabazon : 1949
par Jeannot Mar 06 Avr 2010, 17:58
The Bristol Brabazon - Engineering masterpiece or Great White Elephant
Bristol Brabazon - Type 167
In the dark days of World War 2, a British Cabinet committee met under the chairmanship of Lord Brabazon of Tara. They were to explore and advise upon what Britain's post-war airliner needs would be, a task which at first sight may appear to have been rather optimistic.
Following a 1942 Anglo-American agreement on aircraft production it divided the load of military aircraft construction between Britain and the US. This left Britain unable to develop transport aircraft, which was part of the package assigned to America. So, in something like self-interest, the committee planned for a time when Britain might recover lost ground.
The requirement was for a luxurious aircraft capable of flying from London to New York and able to carry around 100 passengers.
This was a challenge for the time, and would tax the budding designers who, especially at Bristol, were looking for new projects to fill the void left after designing the current fighter-bombers. These aircraft were gaining a name for themselves worldwide. The expertise was there as was the willingness to succeed and the realisation of the workforce that their future could be at stake.
[Vous devez être inscrit et connecté pour voir ce lien]
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mar 06 Avr 2010, 19:11
Design and construction phase
The Brabazon Project team, initially led by Leslie George Frise BSc FRAeS, was among the brightest and best of their time and by 1943 Bristol's war effort was seen to be ending. Aircraft were still being built at Filton and the several Shadow Factories around the region, so the team were eager for new projects.
Frise had done some work on a long range strategic Bomber so when invitations by the government for an airliner came in, the Bristol team were at an advantage. After some consultation BAC were given an order for two prototypes to be followed by a possible ten production aircraft, as long as other war time production was not affected.
Gas turbine engines were very much in their infancy and not at all reliable. However, piston engines had long been developed in Great Britain prior to WW2, and Bristol Aeroplane Company, engine division could be said to be a world leader in air-cooled radials. It was therefore assumed, in 1943, that the aircraft would be piston engined powered.
By November 1944 the design team had decided on a concept shape, the aircraft would have a 177 ft fuselage with a 230 ft wingspan. The successful 18 cylinder Bristol Centaurus would power it. There would be eight engines, four pairs built into the wings and driving eight paired contra-rotating propellers.
[Vous devez être inscrit et connecté pour voir ce lien]
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mar 06 Avr 2010, 19:14
Brabazon seen in the old flight sheds, where the early construction took place. 'Brabazon in naked form'. This image shows the ribs and spars to which the skin would be rivetted. Bristol had pioneered metal construction using the principles of stressed skin to take not only the flight loads but also the static loads when taxying and on the ground. This picture, less than 12 months after VE day shows her as a bare skeleton at night. 24 hour working had ceased with the end of hostilities and people tried hard to regain some normality to life and work. However, due to delays it would not be until September 4th 1949 that the aircraft would make its maiden flight.
Dernière édition par Jeannot le Mar 06 Avr 2010, 19:19, édité 1 fois
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mar 06 Avr 2010, 19:16
NEW CONSTRUCTION TECHNIQUES
Brabazon was a groundbreaker in technology, showing that Bristol was still in the forefront of innovation. She was to have a fully stressed skin construction and be built to the tolerances now the norm in aircraft construction. This method provided for the structure to take greater loading whilst still only of minimal weight.
Brabazon would also have fully powered flying controls, be fully pressurised and have air-conditioning. All this had to be designed and many new skills were being learnt.
These new construction methods would greatly improve the viability of modern passenger aircraft. Fitters would learn new skills to enable them to work too much closer tolerances and begin to understand some of the stresses imposed on an airframe in flight and on the ground.
[Vous devez être inscrit et connecté pour voir ce lien]
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mar 06 Avr 2010, 19:20
The Bristol Brabazon now with her 'skin' fitted. She would be one of the first fully pressurised passenger aircraft and amonsgt first with fully powered flying controls. With her dorsal fin fitted, Brabazon gets ready for her move to the new Assembly Hall in September 1947. However, following the war years and the sharing of information, much of the work in designing these new systems was eagerly picked up by the Americans and there manufacturing base, which had not suffered through the vageries of war, was able to design, test and produce the modern jet aircraft, Boeing 707 and Douglas DC8, that spelt oblivion for the likes of the Brabazon
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mar 06 Avr 2010, 19:22
October 1947, Brabazon arrives at her new home, the vast Assembly Hall purpose built alongside the lengthened and widened runway built especially for the aircraft and also a symbol of Great Britains pride in a project which allowed a whole village to be demolished and its people moved to ensure it came to fruition.
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mar 06 Avr 2010, 19:24
Brabazon in her new Assembly Hall gets her wings, all 230 feet of them. These halls were part of the whole project for Brabazon, which had not only included constructing them but widening and lengthening the runway. It also entailed uprooting and re-housing a community and cutting through a recently opened bypass
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mar 06 Avr 2010, 21:44
First of the Modern Airliners
Brabazon was also going to be the first modern aircraft to be designed with pressurisation in mind. This system would allow the aircraft to fly at a greater altitude. This would make the engines more fuel-efficient. The cabin being pressurised would maintain a much lower altitude for passenger comfort.
To accompany this the aircraft would have temperature-controlled air-conditioning, and set the pattern for all future passenger aircraft. The system would aim for a cabin altitude no higher than 8000 feet and a cabin temperature between 18C - 24C. This was deemed to be the most comfortable.
To achieve this, new equipment was needed, new controls to monitor its performance and new skills for flight engineers to learn. The aircraft was to be 100% powered flying controls, therefore needing hydraulic servos to operate control surfaces. Hydraulic systems had to convert right amount of pilot input whilst feeding back enough 'feel' to enable the pilot to fly competently.
[Vous devez être inscrit et connecté pour voir ce lien]
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mar 06 Avr 2010, 21:53
The Engine Configuration - 8 Centaurus Sleeve Valve engines
To achieve the necessary reduction in drag and also achieve the design criteria, i.e. non-stop across the Atlantic with 100 passengers, a serious rethink was needed. Bristol had done some initial design work for the aborted Type 159 long-range bomber. This had been a 100 ton bomber with a range up to 5000 miles.
Analysis of the current designs showed that conventional wing mounted engines accounted for 30% of the overall drag, although only 5% was needed for cooling. It became clear to the design team that power plants completely submerged in the wing were thus likely to reduce total drag by 25%, if technically feasible.
The wing would have to be at least as thick as the height of the engine, and coupling several engines side by side to a single airscrew would leave the outer wing free from interference and available for fuel storage. By using this method the larger range required could be easily achieved
[Vous devez être inscrit et connecté pour voir ce lien]
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mar 06 Avr 2010, 21:54
This picture shows how the internally wing mounted Centaurus engines were mounted. Each engine drives through a coupling to a tractor propellor. They were designed as contra-rotating to counteract anti-torque. They also acted as reversing airscrews to assist in breaking on landing.
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mar 06 Avr 2010, 21:56
The external wing mounted test bed, built to test the coupled Centaurus engines as fitted in the Brabazon. This was used for exhaustive endurance testing of the engines in the proposed configuration. The Centaurus engines were producing nearly 3000 shp but by this time the gar turbine was making them obsolete for large aircraft
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mar 06 Avr 2010, 22:00
The testing Phase
At around 150,000 lbs all up weight the Brabazon was sight to see, particularly by onlookers more used to single seat or small fighter/bombers. When the Mk1 rolled out of her purpose built assembly sheds, most of the factory was there to witness the occasion. This, in 1947/48 was the hope of the factory, with the war over work was scarce and the workforce were banking on its success.
The aircraft carried out extensive testing before her, very late maiden flight in 1949. She was programmed to fly first in 1947 but it was two years later before she finally took to the air. This delay would cost her dearly for it allowed the American manufacturers to get ahead. The Boeing 707 and Douglas DC8 would leave her behind.
One has to remember that by late 40's standards the Brabazon was a remarkable aircraft. Tolerances were so tight that it was said one coat of paint would mean forfeiting one passenger. She is still the biggest aircraft ever to have been built in Britain and had a longer wingspan than any modern airliner
[Vous devez être inscrit et connecté pour voir ce lien]
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mar 06 Avr 2010, 22:10
Being towed to the engine run test area, nacelle doors open, note steam train passing power station behind. The sound of eight Centaurus engines on song must have been a delight to an aviation engineers ears. To the local housewives a pain in the neck. There were three stages of the power plant ground testing.
Phase 1 - Vibration testing of the propellor shafts and employed dummy propellors and electric motors to simulate the engines.
Phase 2 - Involved a test rig with two Centaurus engines geared together in order to test the gearbox and adjacently mounted engines.
Phase 3 - Involved a complete replica of the power plant complete with accessories mounted within a wing section.
The twin Centaurus power unit completed its ARB type test in June 1948, after more than 1200 hours of development running which had started in 1946.
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mar 06 Avr 2010, 22:13
Brabazon Flight test programme
Think of the biggest plane you've ever seen. OK? Probably a Boeing 747,jumbo jet. Imagine yourself over fifty years ago when the biggest aircraft you had seen was probably a Lancaster Bomber. Visualise that 747, got it clearly in mind! Now imagine an aircraft more than twice as big, four times as heavy and able to fly three times as far. That was how the Bristol Brabazon struck people in 1949. To small boys it was awesome.In 1949, some two years late, the Type 167, Bristol Brabazon was ready for its maiden flight and its test programme. The maiden flight was scheduled for September 4th of that year. The factory, the local population and the nation eagerly awaited the great lift off. This aircraft would see Great Britain as the world leader in modern aircraft design and technology. The crew were selected with Test pilot Bill Pegg given the honour of being the first to 'lift' the big bird into the air.
[Vous devez être inscrit et connecté pour voir ce lien]
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mar 06 Avr 2010, 22:15
The Brabazon test flight crew leave the aircraft following its successful maiden flight in September 1949. This was a press release picture and clearly shows the joy the crew felt at this time. The aircraft had taxied back to the apron in front of the huge purpose built Assembly Halls.
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mer 07 Avr 2010, 05:49
Test flying the Brabazon
Since early morning on Sunday September 4th 1949 crowds had been gathering at all the vantage points around the airfield as well as the enclosures set up on the airfield for factory personnel and families. Over 10,000 were there to watch A J (Bill) Pegg complete his morning taxi tests. He was a consummate professional and he ensured everything was in order.
By 10.00 am Bill Pegg had completed taxi tests along the runway, all the levels were rechecked and the aircraft was cleared to fly.
On the next taxi run Bill Pegg decided to go, and the greatest aeroplane ever produced in Britain, became airborne. "Good God - it works!" he is claimed to have said. This followed some of the remarks from commentators alarmed at the escalating costs, then at around £11,000,000, saying it was too big and would never fly.
The aircraft needed only a quarter of the 2750-yard extended runway before lifting off for an initial flight of only 27 minutes. The co-pilot, and the only other pilot to captain a Brabazon was Walter Gibb, smiled. The crowds on the ground cheered and the story was transmitted around the globe on what was one of the first uses of live outside broadcasting after the war.
In an era devoid of good news, such was the value of this aircraft, that the Queen was introduced to the crew and all the newspapers ran stories about the event. Some 250 newspaper reporters and photographers, broadcasting television and newsreel staff men were on hand, more than had ever before assembled in Bristol for a single event
The BBC broadcast the event simultaneosly in eight languages, such was the impact of this new aircraft on the world stage. Filton would get used to this phenomenum.
[Vous devez être inscrit et connecté pour voir ce lien]
Dernière édition par Jeannot le Mer 07 Avr 2010, 10:00, édité 1 fois
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Re: Le Bristol Brabazon : 1949
par Jeannot Mer 07 Avr 2010, 05:52
A super-imposed image of the Brabazon, made to look as if the aircraft is in flight. This picture was put togther in early 1949 and was an example of newspaper and factory 'spin' by showing what the pride of Bristol and Britain's aviation was proposing for its post war development.
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Jeannot- Membre
- Messages : 10002
Localisation : Vexin 78
Page 1 sur 2 • 1, 2
aeronewsline :: Accueil :: Histoire :: Aéronefs 1945 à 1955
|
|