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aeronewsline :: Accueil :: Histoire :: Aéronefs 1945 à 1955
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Re: Boeing B-52 Stratofortress
par Peewee Jeu 15 Avr 2010, 15:55
The outright cancellation of the Boeing contract on 11 December 1947 was staved off by a plea from its president [Vous devez être inscrit et connecté pour voir ce lien], and in January 1948 Boeing was instructed to thoroughly explore recent technological innovations, including [Vous devez être inscrit et connecté pour voir ce lien] and the [Vous devez être inscrit et connecté pour voir ce lien].
Noting stability and control problems [Vous devez être inscrit et connecté pour voir ce lien] was experiencing with their [Vous devez être inscrit et connecté pour voir ce lien] and [Vous devez être inscrit et connecté pour voir ce lien] flying wing bombers, Boeing insisted on a conventional aircraft, and in April 1948 presented a US$30 million (1948 dollars) proposal for design, construction, and testing of two Model 464-35 prototypes.
Noting stability and control problems [Vous devez être inscrit et connecté pour voir ce lien] was experiencing with their [Vous devez être inscrit et connecté pour voir ce lien] and [Vous devez être inscrit et connecté pour voir ce lien] flying wing bombers, Boeing insisted on a conventional aircraft, and in April 1948 presented a US$30 million (1948 dollars) proposal for design, construction, and testing of two Model 464-35 prototypes.
Peewee- CLUB
- Messages : 761
Re: Boeing B-52 Stratofortress
par Peewee Jeu 15 Avr 2010, 15:57
Further revisions of specifications during 1948 resulted in an aircraft with a top speed of 513 miles per hour
(445 kn, 825 km/h) at 35,000 feet (10,700 m), a range of 6,909 miles (6,005 nmi, 11,125 km), and a 280,000 pounds (125,000 kg) gross weight which included 10,000 pounds (4500 kg) of bombs and 19,875 US gallons (75,225 L) of fuel.
(445 kn, 825 km/h) at 35,000 feet (10,700 m), a range of 6,909 miles (6,005 nmi, 11,125 km), and a 280,000 pounds (125,000 kg) gross weight which included 10,000 pounds (4500 kg) of bombs and 19,875 US gallons (75,225 L) of fuel.
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- Messages : 761
Re: Boeing B-52 Stratofortress
par Peewee Jeu 15 Avr 2010, 16:00
Pre-production
In May 1948 AMC asked Boeing to incorporate the previously discarded, but now more fuel-efficient, jet engine into the design.
This resulted in Boeing developing yet another revision — in July 1948, Model 464-40 substituted [Vous devez être inscrit et connecté pour voir ce lien] for the turboprops.
Nevertheless, on 21 October 1948, Boeing was told to create an entirely new aircraft using [Vous devez être inscrit et connecté pour voir ce lien] turbojets.
In May 1948 AMC asked Boeing to incorporate the previously discarded, but now more fuel-efficient, jet engine into the design.
This resulted in Boeing developing yet another revision — in July 1948, Model 464-40 substituted [Vous devez être inscrit et connecté pour voir ce lien] for the turboprops.
Nevertheless, on 21 October 1948, Boeing was told to create an entirely new aircraft using [Vous devez être inscrit et connecté pour voir ce lien] turbojets.
Peewee- CLUB
- Messages : 761
Re: Boeing B-52 Stratofortress
par Peewee Jeu 15 Avr 2010, 16:01
On 25 October, Boeing engineers produced a proposal and a hand-carved model of 464-49.
The new design built upon the basic layout of the [Vous devez être inscrit et connecté pour voir ce lien] with 35° [Vous devez être inscrit et connecté pour voir ce lien], eight engines paired in four underwing pods, and bicycle landing gear with wingtip outrigger wheels.
A notable feature of the landing gear was the ability to pivot the main landing gear up to 20° from the aircraft centerline to increase safety during [Vous devez être inscrit et connecté pour voir ce lien].
The new design built upon the basic layout of the [Vous devez être inscrit et connecté pour voir ce lien] with 35° [Vous devez être inscrit et connecté pour voir ce lien], eight engines paired in four underwing pods, and bicycle landing gear with wingtip outrigger wheels.
A notable feature of the landing gear was the ability to pivot the main landing gear up to 20° from the aircraft centerline to increase safety during [Vous devez être inscrit et connecté pour voir ce lien].
Peewee- CLUB
- Messages : 761
Re: Boeing B-52 Stratofortress
par Peewee Jeu 15 Avr 2010, 16:03
The aircraft was projected to exceed all design specifications.
Although the full-size mock-up inspection in April 1949 was generally favorable, range again became a concern since the J40s and the early model J57s had excessive fuel consumption.
Although the full-size mock-up inspection in April 1949 was generally favorable, range again became a concern since the J40s and the early model J57s had excessive fuel consumption.
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- Messages : 761
Re: Boeing B-52 Stratofortress
par Peewee Jeu 15 Avr 2010, 16:05
Despite talk of another revision of specifications or even a full design competition among aircraft manufacturers, General LeMay, now in charge of Strategic Air Command, insisted that performance should not be compromised due to delays in engine development.
In a final attempt to increase the range, Boeing created the larger 464-67, stating that once in production, the range could be further increased in subsequent modifications.
In a final attempt to increase the range, Boeing created the larger 464-67, stating that once in production, the range could be further increased in subsequent modifications.
Peewee- CLUB
- Messages : 761
Re: Boeing B-52 Stratofortress
par Peewee Jeu 15 Avr 2010, 22:27
Following several direct interventions by LeMay, on 14 February 1951 Boeing was awarded a production contract for 13
B-52As and 17 detachable [Vous devez être inscrit et connecté pour voir ce lien].
The last major design change, also at the insistence of General LeMay, was a switch from the B-47 style tandem seating to a more conventional side-by-side cockpit which increased the effectiveness of the copilot and reduced crew fatigue.
Both XB-52 prototypes featured the original tandem seating arrangement with a framed bubble-type canopy.
B-52As and 17 detachable [Vous devez être inscrit et connecté pour voir ce lien].
The last major design change, also at the insistence of General LeMay, was a switch from the B-47 style tandem seating to a more conventional side-by-side cockpit which increased the effectiveness of the copilot and reduced crew fatigue.
Both XB-52 prototypes featured the original tandem seating arrangement with a framed bubble-type canopy.
Peewee- CLUB
- Messages : 761
Re: Boeing B-52 Stratofortress
par Peewee Jeu 15 Avr 2010, 22:32
The YB-52, the second XB-52 modified with more operational equipment, first flew on 15 April 1952,[Vous devez être inscrit et connecté pour voir ce lien] a 2 hour 21 minute flight from [Vous devez être inscrit et connecté pour voir ce lien] in [Vous devez être inscrit et connecté pour voir ce lien] to [Vous devez être inscrit et connecté pour voir ce lien] with Boeing test pilot [Vous devez être inscrit et connecté pour voir ce lien] and Air Force Lieutenant Colonel [Vous devez être inscrit et connecté pour voir ce lien].
The XB-52 followed on 2 October 1952.
The thorough development, including 670 days in the [Vous devez être inscrit et connecté pour voir ce lien] and 130 days of aerodynamic and aeroelastic testing, paid off with smooth flight testing.
Encouraged, the Air Force increased its order to 282 B-52s.
The XB-52 followed on 2 October 1952.
The thorough development, including 670 days in the [Vous devez être inscrit et connecté pour voir ce lien] and 130 days of aerodynamic and aeroelastic testing, paid off with smooth flight testing.
Encouraged, the Air Force increased its order to 282 B-52s.
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Re: Boeing B-52 Stratofortress
par Peewee Jeu 15 Avr 2010, 22:36
First production
Only three of the 13 B-52As ordered were built. All were returned to Boeing, and used in their test program.
On 9 June 1952 the February 1951 contract was updated to order the aircraft under new specifications.
The final 10, the first aircraft to enter active service, were completed as B-52Bs.
Only three of the 13 B-52As ordered were built. All were returned to Boeing, and used in their test program.
On 9 June 1952 the February 1951 contract was updated to order the aircraft under new specifications.
The final 10, the first aircraft to enter active service, were completed as B-52Bs.
Peewee- CLUB
- Messages : 761
Re: Boeing B-52 Stratofortress
par Peewee Jeu 15 Avr 2010, 22:42
Design
Upgrades and modifications
In November 1959, SAC initiated the Big Four modification program (also known as Modification 1000) for all operational B-52s except early B models. The program was completed by 1963.
The four modifications were:
Upgrades and modifications
In November 1959, SAC initiated the Big Four modification program (also known as Modification 1000) for all operational B-52s except early B models. The program was completed by 1963.
The four modifications were:
- Ability to perform all-weather, low-altitude (below 500 feet or 150 m) interdiction as a response to advancements in [Vous devez être inscrit et connecté pour voir ce lien]'s missile defenses. The low-altitude flights were estimated to accelerate structural fatigue by at least a factor of eight, requiring costly repairs to extend service life.
- Ability to launch [Vous devez être inscrit et connecté pour voir ce lien] standoff nuclear missiles
- Ability to launch [Vous devez être inscrit et connecté pour voir ce lien] decoys
- An advanced [Vous devez être inscrit et connecté pour voir ce lien] (ECM) suite
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Re: Boeing B-52 Stratofortress
par Peewee Jeu 15 Avr 2010, 22:45
The ability to carry up to 20 [Vous devez être inscrit et connecté pour voir ce lien] nuclear missiles was added to G and H models starting in 1971.
Fuel leaks due to deteriorating [Vous devez être inscrit et connecté pour voir ce lien] continued to plague all variants of the B-52.
To this end, the aircraft were subjected to Blue Band (1957), Hard Shell (1958), and finally QuickClip (1958) programs.
The latter fitted safety straps which prevented catastrophic loss of fuel in case of clamp failure.
Fuel leaks due to deteriorating [Vous devez être inscrit et connecté pour voir ce lien] continued to plague all variants of the B-52.
To this end, the aircraft were subjected to Blue Band (1957), Hard Shell (1958), and finally QuickClip (1958) programs.
The latter fitted safety straps which prevented catastrophic loss of fuel in case of clamp failure.
Peewee- CLUB
- Messages : 761
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