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Martin Model 316: XB-68 Tactical Bomber

sferrin

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Skybolt said:
Not overreacting, only having fun... :D
And, seriously, that piece of story is really in the dark. Talking about the Martin WS-302A, I have reason to believe that the Model 316 wasn't the end of the line, that there were further evolution, both inside and outside the TBX and WS-302A frame, before the entire Supersonic Tactical Bomber concept was shelved in favour of low altitude souped up Fighter Bombers or Strike Aircrafts, which happened only in 1959, when General Lauris Norstad, SHAPE, decided that the long range theater nuclear strike mission would have been left to missiles, and this was the origin of MMRBM, and the rest taken up by strike aircrafts (SDR-17 and later TFX). BTW, the Super Hustler concept, in the ZEL mode, was intended as a highly supersonic tactical bomber for theater operation. In a certain Convair document a Super Hustler is even shown with Luftwaffe markings....
Ahem,. . . is that Convair document available anywhere? ;D
 

RyanCrierie

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Sundog said:
I can't wait to see the books with all of this new info. I only wish Tony's books had larger images of the designs when using actual blueprints, instead of the small, barely legible pictures that end up in the books.
The problem is, that much of these blueprints are by this point, badly faded, or have had the ink rub off on them after 50~ years in archives. Take into account there is only so much time and money available for Tony to redraw these things in better formats; and you can see how a lot of stuff is of lower quality.
 

overscan (PaulMM)

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Using a photoediting package (GIMP in this case, but it works in most packages) I used "Curves" (or Levels) function to greatly increase contrast in the image, this makes the grey parts of the drawing go to white or black. I played with the curve until most of the grey was white, but the blacks of the drawing were still largely in place. This gave a good clean drawing on most of the image, but the bottom right hand had quite a lot of grey/black noise present. I selected this section only, repeated the curves operation, and this got rid of more. I then used the selection tool to select remaining areas containing noise and deleted those areas. Took about 20 minutes altogether.
 

hesham

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Orionblamblam said:
A scale drawing of the B-68 (top), the Model 316 Tac Bomber (middle) and 302 Long Range Interceptor (bottom). The B-68 drawing was redrawn from Standard Aircraft Characteristics drawings, which are kinda small, so precision is not possible (source grade: 3). However, the 316 was redrawn from diagrams scanned at the Martin archive, and the 302 was redrawn from large-format drawings which I eventually got scans of (source grade for both: 5).

The Model 316 had two afterburning J-67's. The 302 had four afterburning J-67s, eight Falcon missiles and 48 rockets. Fuselage length of the 302 was 1200 inches, fuselage length of the 316, 1131 inches.

Source grading primer: http://www.secretprojects.co.uk/forum/index.php/topic,2849.0/highlight,source+grading.html

Higher-rez version of this drawing will be posted at my blog in a while, when I'm no longer tuckered: http://up-ship.com/blog/
Hi,

the Martin M-302 with 45 swept wing degree.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930090123_1993090123.pdf
 

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hesham

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Hi,


here is a good view to Martin XB-68 its early drawing.
 

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Stargazer2006

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hesham said:
here is a good view to Martin XB-68 its early drawing.
No hesham. This particular project doesn't look anywhere near the Martin proposals we know of, so I'd be careful before asserting something like that. I think it has been discussed here before, this particular design appears in the Lloyd S. Jones book as a would-be "XB-68" but there has never been any evidence so far that this was an actual Martin design for it (unless some new evidence has emerged, which I haven't heard of). All reliable sources show the XB-68 to be along the lines of the Models 302 and 316 designs. Of course I'll be glad to be proved wrong, if...
 

hesham

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You're absolutely right my dear Skyblazer,


I meant a hypothetical design to XB-68,sorry.
 

blackkite

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Hi! NACA RESEARCH MEMORANDUM
"Investigation of the aerodynamic characteristics of a model of a supersonic bomber configuration with a swept and an unswept wing at Mach numbers from 1.79 to 2.67"

https://digital.library.unt.edu/ark:/67531/metadc64207/m1/1/
 

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sat_dxer

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That Douglas trapezoidal wing model reminds one of the various Tsybin variants
 

JFC Fuller

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And, seriously, that piece of story is really in the dark. Talking about the Martin WS-302A, I have reason to believe that the Model 316 wasn't the end of the line, that there were further evolution, both inside and outside the TBX and WS-302A frame, before the entire Supersonic Tactical Bomber concept was shelved in favour of low altitude souped up Fighter Bombers or Strike Aircrafts, which happened only in 1959, when General Lauris Norstad, SHAPE, decided that the long range theater nuclear strike mission would have been left to missiles, and this was the origin of MMRBM, and the rest taken up by strike aircrafts (SDR-17 and later TFX). BTW, the Super Hustler concept, in the ZEL mode, was intended as a highly supersonic tactical bomber for theater operation. In a certain Convair document a Super Hustler is even shown with Luftwaffe markings....
Congress was informed in the December 31st 1956 programming report that the TBX/WS-202A program was to be deleted (along with the F-108/LRIX/WS-202A and C-132), the Martin XB-68 was subsequently cancelled on the 3rd January 1957 for broadly the reasons you outlined. A development contract was given to Martin in April 1952 with the intention that it replace the B-66 Destroyer in the all-weather bomber role in the 1958-63 timeframe. The XB-68 was at the Phase II contract (prototype construction phase) stage when it was cancelled suggesting the 1952 contract was analogous to a Phase I contract (engineering and mock-up). Rather like with the F-105, the presence of competing designs at certain points suggests periodic attempts to open up competition, or at least the appearance of competition to motivate the original contractor.

Ten years later, B-66s were using their K-5 bombing systems to provide an all-weather bomb aiming capability for USAF tactical fighters over Vietnam, thus demonstrating a continued need for the nav-attack system even if a stainless-steel, mach-2, high altitude bomber with a bomb bay designed for a large nuclear weapon was probably not the ideal platform.
 
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