Martin Model 316: XB-68 Tactical Bomber

[overscan (PaulMM)]

He is only one person.

 

[KJ_Lesnick]

Skybolt

KJ, the differences were less and less. Originally an attack airplane would have used guns and rockets at a rather low altitude, while light bombers would have used bombs from a medium to high altitude. With the rise in weight carrying capabilities of attack planes and fighter-bombers, the difference waned. During the mid-to-late fifties bombers were supposed to attack fixed targets removed from the front (railway nodes, large airports, harbours), while attack planes would have targeted near the front. Nuclear weapons rendered the picture still more murky: a solitary F-105 with a 100 kton tactical bomb on Kronstadt would have made little different from a B-66 in the same mission...

So basically by the 1950's and 1960's, an attack plane's roles now encompassed the old attack-plane designation, and the light-bomber/tactical-bomber designation?


KJ

 

[Skybolt]

More or less, yes, but using the F- designation (fighter-bomber). Remember that the first USAF A- designation plane was the A-7, and the first newly designed USAF attack planes were the A-9/A-10 couple.... The Navy history is different, the attack role included the bomber role.

 

[Skybolt]

Thanks for the disambiguation

 

[KJ_Lesnick]

Skybolt,

More or less, yes, but using the F- designation (fighter-bomber). Remember that the first USAF A- designation plane was the A-7, and the first newly designed USAF attack planes were the A-9/A-10 couple.... The Navy history is different, the attack role included the bomber role.

Actually the USN did at one time (1930's I think) use the Bomber designation (dive bombers), though they stopped using it though later on and instead went to using the Attack to cover both bomber and attack.

 

[Skybolt]

And TB (Torpedo Bomber) too.

 

[KJ_Lesnick]

And TB (Torpedo Bomber) too.

Good point, but a torpedo bomber is a type of bomber nonetheless


KJ

 

[Skybolt]

I can now knowingly add that (one of) the Douglas contenders to WS-302A was Model 1364. But don't ask me more (really).

 

[Orionblamblam]

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/

 

[OM]

...Finally. The middle and bottom ones I've been curious about since we had that discussion on the B-68 a couple of years back on ssh. Good to see you found something on their layout.

 

[blackkite]

I like Model 316.

 

[Orionblamblam]

Sheesh. Woulda thought this'd generate more chatter. Oh, well. In any event, I've uploaded a much-higher-rez version of the drawing to my blog.

 

[OM]

Sheesh. Woulda thought this'd generate more chatter.

...They're in awe, Scott.

 

[robunos]

They're in awe, Scott.

I'm confused, ???
the top drawing, that you term 'B-68', in your image, you also call 'Model 316' in APR v0n0.
Am i right to assume then , that both the 'B-68', and 'Model 316' images are separate iterations of the same design, the 'Model 316' being the earlier of the two, seeing as there was a SAC for the 'B-68' prepared?
Was there any change in the specification/requirement, that led to the differences in the two designs?

cheers,
Robin.

 

[Orionblamblam]

Am i right to assume then , that both the 'B-68', and 'Model 316' images are separate iterations of the same design,

Very likely, yes. While the available documentation does not spell it out, they are probably Models 316-X and -Y, with X and Y being the different variations. Further variants were wind tunnel tested by NASA, but there's less data for those.

 

[Skybolt]

The "B-68" competition, AKA as WS-302A or TBX has been long in being. The basic configuration changed in development more than once. The final straight wing config, for example, was tested at Langley with a different wingplan, as documentd here in the appropriate topic. So that a configuration of Model 316 was different form the "final" Model 316 is nothing to be surprised. In the Martin Museum there is a drawing of the early Model 316 with corrections done in green and purple pencils describing a straight trailing edge swept wingplan and horizontal tailplanes mounted on the side of the exhausts (if I understand the drawing well). Probably a transitional configuration.

 

[Orionblamblam]

Hey, neat. Martin built a full-scale metal mockup of the B-68/Model 316.

 

[LowObservable]

I have often doodled something that looks a lot like the lower pic, except with podded engines on the aft fuselage... when I get tired of drawing the peroxide-ATR-powered Crusader IV.

 

[Kevin Renner]

Is it just me or do they look more "Russian" than what you would normally see coming out of a US airframe manufacturer?

 

[Skybolt]

A lot of US bombers and heavy fighter designed in the same timeframe had that "look". The high all movable horizontal tail is a trademark of mid-50s Martin design practice. The podded engine was a classic for the timeframe. Apart Martin, Douglas, Boeing, Convair (naturally) and you-name-one used it (even Dassault, for its 4-Atars Mirage-IVB).

 

[ysi_maniac]

This is XB-68 as depicted in Lloyd S Jones' book.

I have been assessing this project in order to make a model. It is confusing because:
It is shorter than a F-105.
Having 3 J79s burning fuel, its range cannot be outstanding. On the other hand, this extra power would allow a bigger fuselage, full of fuel.
Could it carry tanks and weapons externally mounted? a combo pack a la Hustler?
Another possibility would be small canard surfaces a la XB-70.

Please, discuss about the issue.

 

[Skybolt]

The answer is simple: it is not the XB-68. No submissions to the TBX competition were like that (Douglas, NAA, Martin and Boeing). What is it ? Who knowns ?

 

[Stargazer]

Hey, neat. Martin built a full-scale metal mockup of the B-68/Model 316.

Did I miss something? Where did you read about this in the topic? Or did you get that piece of info from elsewhere? I'd love to know more about it!

As for the trijet delta aircraft designs that were long thought to be the XB-68 — and provided they are Martin designd indeed (which remains to be seen) — I would think more of some kind of interceptor than a bomber, really. Perhaps something to do with the LRI-X competition?

Possible candidates from the Martin list of models (I restricted the list to bombers and fighters):

- Model 276 fighter bomber
- Model 281 short-range bombing recon aircraft
- Model 286 Strategic Air Command (SAC) bomber, WS-110A competitor
- Model 288 fighter bomber
- Model 319 TAC interceptor/bomber
- Model 327 fighter bomber
- Model 328 fighter bomber
- Model 350 Strategic Air Command (SAC) bomber
- Model 351 Tactical Air Command (TAC) bomber

 

[Skybolt]

Unfortunately, documentation on none of those designs has survived in the shreds of the Martin archive that are stored in the GMAM. Possibly the only exception is the Model 286 WS-110 tentative submitall, of which I published some time ago an art (in the WS-110 thread), but actually it is only a guess (there is no caption on the two slightly different copies of the art I have). I know that another type of search is very imminent, but it is very difficult to anticipate the results, if any.

 

[Stargazer]

That is, until someone comes up with a factory model like the Comanche, which surfaced recently against all odds... Let's keep hope! You never know what some people keep in their vaults...

 

[Steve Pace]

Here's two interesting images re Martin's proposed XB-68 Tactical Bomber; Model 316.

Credit Glenn L. Martin Air Museum

 

[Stargazer]

;D I LOVE THIS FORUM!!!

 

[flateric]

yep, this is harvester day
thank you, Mr.Pace!

 

[overscan (PaulMM)]

Ta daaa

 

[Pioneer]

Nice find with the XB-68 mock-up XB-70 Guy!

I never knew the program had got this far


Regards
Pioneer

 

[blackkite]

Wow!! Air intake shape is unique.

 

[Michel Van]

Here's two interesting images re Martin's proposed XB-68 Tactical Bomber; Model 316.

Credit Glenn L. Martin Air Museum

Wat, is chrismass allready now ???

 

[Steve Pace]

Here's another goody....

 

[Overkiller]

Oh boy, it's Christmas, New Year, Easter and my birthday rolled into one!

Fantastic stuff!

 

[sferrin]

SWEET! I love original artwork!

 

[Stargazer]

The XB-68 program is definitely no mystery anymore, and it's thanks to all of you guys. Thank you so much for the treat!

 

[Skybolt]

The XB-68 program is definitely no mystery anymore, and it's thanks to all of you guys. Thank you so much for the treat!

oh, really ? So, show me the other competitors, say the NAA one, a bautiful design, with a Vigilante flavouir but sleeker and even more elegant, in my opinion. Or the three different Douglas submissions.... or the too-late Boeing one (no, not the patent of the early configuration, the definitive one...). I've seen them, so it is all really relative. And what about the three-engined delta Lloyd Jones published a lot of time ago ? Mysteries are not finished until they are finished....
The above mentioned, will be clarified somewhat by next book from Tony, BTW. Except the last one.

 

[Stargazer]

The XB-68 program is definitely no mystery anymore, and it's thanks to all of you guys. Thank you so much for the treat!

oh, really ? So, show me the other competitors, say the NAA one, a bautiful design, with a Vigilante flavouir but sleeker and even more elegant, in my opinion. Or the three different Douglas submissions.... or the too-late Boeing one (no, not the patent of the early configuration, the definitive one...). I've seen them, so it is all really relative. And what about the three-engined delta Lloyd Jones published a lot of time ago ? Mysteries are not finished until they are finished....

Okay, don't overreact. I was talking about Martin's entry, the winning one and the only one elected to be designated XB-68. Of course if you're talking about the whole WS-302A program, sure there is plenty we don't know about. Also I make a distinction between saying that something is "no longer a mystery" and that it "holds no mysteries anymore"! So bear with me, Skybolt, of course there will always be people more knowledgeable than us, and secrets to be dug out, but for an aircraft that we knew virtually nothing about months ago, I think we have definitely got some place!

 

[Skybolt]

Not overreacting, only having fun...
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....

 

[Sundog]

Not overreacting, only having fun...
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....

You're such a tease!

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.