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Boeing B-47 Stratojet

Steve Pace

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The only picture I've ever seen of XB-47 number two (46-066) - Life magazine.
 

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aim9xray

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Oddly enough, this aircraft has survived the years and is on display today at the Chanute Air Museum, Rantoul, Illinois... see http://www.aeromuseum.org/aircraft_xb47.html
 

hesham

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Hi,


the Boeing Models, 424,432 and 450-1;


http://coollib.net/b/150691/read
 

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hesham

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We can transfer this topic to Postwar Aircraft Projects section;


From Le FANA 432,here is some Boeing B-47 projects.
 

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hesham

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As I said before,we can transfer this topic to Postwar section,


from Le FANA 431,here is the Boeing Model-413 (which looks like Model-424)
and Model 450-1-1 & Model 450-2-2.
 

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hesham

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GTX said:
That first one looks like a B-29 with jet pods.


My dear GTX,yes,it is,please read the comment.
 

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famvburg

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I have seen a 3 view in an old APR issue and it is very similar to a B-29 with B-45-type nacelles.
 

Cy-27

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The Evolution that led to the B-47

I came across this intriguing wind tunnel model (below) from 1944 of a Boeing Model 432 that I had not come across before, which led to dome digging. All I know about the Boeing Model 432 is that the project arose from a 1943 US Army Air Force (USAAF) requirement for a jet bomber / reconnaissance aircraft that ultimately led to the XB-47.

North American, Convair and Boeing all responded with proposals. The first Boeing proposal, the Model 424, was a modification of a conventional propeller-driven bomber design, a scaled-down version of the Boeing B-29 Superfortress fitted with four TG-180 turbojets.

The US National Advisory Committee for Aeronautics (NACA) performed wind tunnel tests on a model of the design. The NACA wind tunnel tests showed that the model suffered from excessive drag. Boeing engineers then tried a revised design, the Model 432, which had the four engines buried in the forward fuselage. Changing the engine layout didn't really reduce drag all that much. The main benefit of the change was found to be structural advantages. The Boeing engineers turned to the swept-wing of 35 degrees.

Boeing then modified the Model 432 design with swept wings and tail, resulting in the Model 448, which was presented to the USAAF in September 1947.

The Model 448 had the four TG-180s in the forward fuselage as had the Model 432, plus two TG-180s buried in the rear fuselage. Boeing submitted the Model 448 to the USAAF in October 1945, only to have it rejected. The Air Force strongly disliked fitting the engines in the fuselage on safety ground in the event of in-flight fires and the engines were moved back out on the wings.

That led straight back to the drag problem, but the engineering team came up with a clean, elegant solution, with the engines in streamlined pods attached to the wings. This innovation led to the next iteration, the Model 450, which featured two TG-180s in a single pod mounted on a pylon about a third of the way outboard on each wing, plus another engine slung from the wingtip.

The USAAF was very pleased with the refined Model 450 design, and in April 1946 the service ordered two prototypes, to be designated XB-47. Assembly began in June 1946 and the Stratojet flew on into fifties history.

Searching in an Artwork folder I also found some drawings of the designs mentioned above, that led eventually to the Boeing B-47 Stratojet.
 

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The Artist

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aim9xray said:
Oddly enough, this aircraft has survived the years and is on display today at the Chanute Air Museum, Rantoul, Illinois... see http://www.aeromuseum.org/aircraft_xb47.html

The Chanute Air Museum has announced that it will close down on 12/31/2015.

http://www.illinoishomepage.net/story/d/story/chanute-air-museum-closing-for-good/34873/j76_FGQ4SEGr9uO-fnW4-w
 

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The Artist

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I'm not with that museum so I don't know what their plans really are. I have heard, through local conversations, that one or two if the aircraft are likely to go to the James S. McDonnell Air Park at the St Louis Science Center, and a few of the aircraft might (might) go to the Prairie Aviation Museum in Bloomington, Illinois.

In my opinion, based on how they looked the last time I saw them, some of the aircraft like the C-97 might have to be scrapped. Those are aircraft that have been kept outdoors all these years. The B-58 is indoors, so it might be worth moving to some other museum. One of the biggest losses will be that training missile silo deeply imbedded in the floor of the one hangar bay. It is not likely to be moved anywhere.

Again. I'm not with that museum, so I don't know for sure what is going to happen to the collection.
 

Pioneer

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hesham said:
We can transfer this topic to Postwar Aircraft Projects section;


From Le FANA 432,here is some Boeing B-47 projects.

Thank you hesham.
That Gunship has me fascinated indeed :p
Obviously a project in relation to the Vietnam War :(
Had to find out what it said in French ..... alas Google Translate ::)
"Project gunship four TAT-161 ventral turrets in 1966 or 1967. The small drawing diagrams the fuselage section with the ammunition boxes cylindrical above turrets."

Regards
Pioneer
 

Hank58

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The Evolution that led to the B-47

I came across this intriguing wind tunnel model (below) from 1944 of a Boeing Model 432 that I had not come across before, which led to dome digging. All I know about the Boeing Model 432 is that the project arose from a 1943 US Army Air Force (USAAF) requirement for a jet bomber / reconnaissance aircraft that ultimately led to the XB-47.

North American, Convair and Boeing all responded with proposals. The first Boeing proposal, the Model 424, was a modification of a conventional propeller-driven bomber design, a scaled-down version of the Boeing B-29 Superfortress fitted with four TG-180 turbojets.

The US National Advisory Committee for Aeronautics (NACA) performed wind tunnel tests on a model of the design. The NACA wind tunnel tests showed that the model suffered from excessive drag. Boeing engineers then tried a revised design, the Model 432, which had the four engines buried in the forward fuselage. Changing the engine layout didn't really reduce drag all that much. The main benefit of the change was found to be structural advantages. The Boeing engineers turned to the swept-wing of 35 degrees.

Boeing then modified the Model 432 design with swept wings and tail, resulting in the Model 448, which was presented to the USAAF in September 1947.

The Model 448 had the four TG-180s in the forward fuselage as had the Model 432, plus two TG-180s buried in the rear fuselage. Boeing submitted the Model 448 to the USAAF in October 1945, only to have it rejected. The Air Force strongly disliked fitting the engines in the fuselage on safety ground in the event of in-flight fires and the engines were moved back out on the wings.

That led straight back to the drag problem, but the engineering team came up with a clean, elegant solution, with the engines in streamlined pods attached to the wings. This innovation led to the next iteration, the Model 450, which featured two TG-180s in a single pod mounted on a pylon about a third of the way outboard on each wing, plus another engine slung from the wingtip.

The USAAF was very pleased with the refined Model 450 design, and in April 1946 the service ordered two prototypes, to be designated XB-47. Assembly began in June 1946 and the Stratojet flew on into fifties history.

Searching in an Artwork folder I also found some drawings of the designs mentioned above, that led eventually to the Boeing B-47 Stratojet.
Yikes! That Model 432 is ugly. Goes right into the "fugly" category. I cannot believe it had any structural advantages over layouts with wing-mounted engines. Medium to high aspect ratio wings are wing-bending-moment critical (hence few spars, with the loads primarily carried in the wing skins, and the skins get thick). Moving the engines out on the wing puts their mass outboard and greatly reduce wing-bending moments (and correspondingly wing skin thickness and weight). That's the "span loading" concept.
 

apparition13

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Yikes! That Model 432 is ugly. Goes right into the "fugly" category. I cannot believe it had any structural advantages over layouts with wing-mounted engines. Medium to high aspect ratio wings are wing-bending-moment critical (hence few spars, with the loads primarily carried in the wing skins, and the skins get thick). Moving the engines out on the wing puts their mass outboard and greatly reduce wing-bending moments (and correspondingly wing skin thickness and weight). That's the "span loading" concept.
Looks a bit like an amphibian, as does the 448. I think Convair had an amphibian or sea plane with a similar design.
 

taildragger

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The Evolution that led to the B-47

I came across this intriguing wind tunnel model (below) from 1944 of a Boeing Model 432 that I had not come across before, which led to dome digging. All I know about the Boeing Model 432 is that the project arose from a 1943 US Army Air Force (USAAF) requirement for a jet bomber / reconnaissance aircraft that ultimately led to the XB-47.

North American, Convair and Boeing all responded with proposals. The first Boeing proposal, the Model 424, was a modification of a conventional propeller-driven bomber design, a scaled-down version of the Boeing B-29 Superfortress fitted with four TG-180 turbojets.

The US National Advisory Committee for Aeronautics (NACA) performed wind tunnel tests on a model of the design. The NACA wind tunnel tests showed that the model suffered from excessive drag. Boeing engineers then tried a revised design, the Model 432, which had the four engines buried in the forward fuselage. Changing the engine layout didn't really reduce drag all that much. The main benefit of the change was found to be structural advantages. The Boeing engineers turned to the swept-wing of 35 degrees.

Boeing then modified the Model 432 design with swept wings and tail, resulting in the Model 448, which was presented to the USAAF in September 1947.

The Model 448 had the four TG-180s in the forward fuselage as had the Model 432, plus two TG-180s buried in the rear fuselage. Boeing submitted the Model 448 to the USAAF in October 1945, only to have it rejected. The Air Force strongly disliked fitting the engines in the fuselage on safety ground in the event of in-flight fires and the engines were moved back out on the wings.

That led straight back to the drag problem, but the engineering team came up with a clean, elegant solution, with the engines in streamlined pods attached to the wings. This innovation led to the next iteration, the Model 450, which featured two TG-180s in a single pod mounted on a pylon about a third of the way outboard on each wing, plus another engine slung from the wingtip.

The USAAF was very pleased with the refined Model 450 design, and in April 1946 the service ordered two prototypes, to be designated XB-47. Assembly began in June 1946 and the Stratojet flew on into fifties history.

Searching in an Artwork folder I also found some drawings of the designs mentioned above, that led eventually to the Boeing B-47 Stratojet.
Yikes! That Model 432 is ugly. Goes right into the "fugly" category. I cannot believe it had any structural advantages over layouts with wing-mounted engines. Medium to high aspect ratio wings are wing-bending-moment critical (hence few spars, with the loads primarily carried in the wing skins, and the skins get thick). Moving the engines out on the wing puts their mass outboard and greatly reduce wing-bending moments (and correspondingly wing skin thickness and weight). That's the "span loading" concept.
I've read that a major reason for the underestimation of the B-47's performance was an overestimation of the drag produced by externally mounted jet engines due to experience with piston engine nacelles and a misunderstanding of how much of their drag was due to intake and exhaust of cooling air. This probably contributed to the British enthusiasm for buried engines also.
 
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