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Martin XB-16 and XB-16A bomber projects (Model 145)

Stargazer2006

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This started off as an aside in the Douglas XB-19 thread, and was taking just too much importance, so I prefer to create a dedicated post to these designs. Why "these"? Because the Martin B-16 bomber project consisted of two very different designs, both studied under the Model 145 inhouse designation. According to hesham, the first design was Model 145A while the second one was 145B. I haven't been able to verify this, but it does make sense as it is not only coherent with Martin's designation system of the time, but also with the fact that the earlier design is described everywhere as Model 145A.

The first of these designs, the Model 145A, was entered in the same competition as the Boeing XBLR-1/XB-15, the Douglas XBLR-2/XB-19 and the Sikorsky XBLR-3 (the only known aircraft in the short-lived "BLR-for Bomber, Long Range" class). One source apparently suggested that the Martin 145A was to have been the XBLR-4 but there doesn't seem to be evidence to back this up for now. Its configuration was generally similar to its competitors, being a very large, four-engined long-range monoplane bomber. The only major difference in general design was the use of a twin fin instead of the single dorsal fin chosen by the other three competitors.

Here is what the Lloyd S. Jones's book U.S. Bombers (Aero, 1974) has to say about the Model 145A:

Late in 1934, the Martin Company laid down a proposal for a fast, long-range, heavy bomber, the Martin Model 145-A, and received the Air Corps designation XB-16. Though conforming to the new concept of large bombardment types and utilizing four engines, the XB-16 design deviated from the bulky, air-cooled radials now receiving wide acceptance. Four 1,000 hp Allison V-1710 liquid cooled engines were buried entirely in the wings driving 12 foot 3 inch propellers via extension shafts. The inboard nacelles were enlarged to accomodate the dual five foot tires of the landing gear. Estimated top speed, with supercharging, at 20,000 feet was 237 mph. Service ceiling was placed at 22,500 feet with a rate of climb of 740 feet per minute. A landing speed of 60 mph was anticipated by the use of the Fowler type flaps of 360 square feet which spanned 80 feet.
Defensive armament was to be carried in plexiglas nose and tail enclosures and retractable dorsal and ventral turrets. A bomb load of 12,180 pounds was to be transported 3,200 miles, and flight endurance with 4,238 gallons of fuel was 42 hours. A crew of ten was to have operated the aircraft.
© Aero Publishers 1974

SaturnCanuck has exposed a very interesting theory that the B-15 and B-16 designations actually pre-dated the BLR-class, and that the B-15 merely retrieved its initial designation in the end. Two elements seem to validate this theory: (a) if the Martin 145A never got a BLR designation and it was in competition with the Boeing 294 and the BLR designators came first, then why not give it a BLR designation? and (b) if all four designs were entered at the same time and only later reassigned as B-types, why didn't the Douglas DS-167C get the B-17 designator? And if B-17 and B-18 had already been allocated by then, it can only mean that the B-15 and B-16 designations pre-date the BLR interlude.

Besides, Jones's book says the following about the Boeing design, which confirms the above:

On June 1935, the proposal was given the designation XB-15 (...) For a short time during construction [the Boeing XB-15] was classed in a new group of experimental long range bombers as the XBLR-1.
© Aero Publishers 1974

Building on these sources and elements, we can elaborate the following chronology:

1°) Boeing and Martin are the first to propose a design and get the B-15 and B-16 designations in 1934.
2°) Someone comes up with the notion that this is a new category of bombers and should therefore belong to a separate list; the B-15 becomes the BLR-1.
3°) The Martin bomber gets the brush, so it doesn't get a BLR designation.
4°) In the meantime, Douglas and Sikorsky submit their own entries, and receive BLR-2 and BLR-3.
5°) Sikorsky's design is eliminated.
6°) Douglas wins over Boeing, but the Army Air Corps decides to get both designs built in prototype form and evaluate them.
7°) As it appears clearly that the bomber mission is evolving, the existence of a separate BLR class doesn't seem such a good idea after all; the BLR-1 returns to B-15 status; the BLR-2 receives the next available B-designation, namely B-19.
8°) Not being detered, Martin designers go back to the drawing board and come up in 1935 with the totally different Model 145B, a large twin-boom bomber with four tractor and two pusher engines. The Air Corps allocates the designation XB-16A (thus reusing the old B-16 slot used for the 1934 design).

Here is what U.S. Bombers has to say about the Model 145B:

Continued development of the original XB-16 design in 1935 led to a grotesque giant featuring a huge 4,256 square foot wing to which two thin tail booms were attached. An unusual podded, nacelle type fuselage housing the payload and crew of ten was suspended beneath the wing. Six buried Allison V-1710-3 engines were located in a unique four tractor, two pusher arrangement driving their propellers through extension shafts. Maximum speed anticipated was 256 mph, cruising at 140 mph, with a range of 3,300 miles. Bomb load was 2,500 pounds. Fuel tanks were to have a 7,435 gallon capacity.
It is interesting to note the first appearance of the tricycle type landing gear on this projected design. The large diameter main tires were partially exposed when the gear retracted into the wing. Estimated landing speed was 77 mph.
Wing span of this XB-16 configuration was to be 173 feet, the twin rudders extending to 114 feet 10 inches behind the nose. An empty weight of 50,660 pounds was determined with the gross being 104,880 pounds.
Although the engineering design was purchased by the A.A.F., no models of the Martin XB-16 were built and the project was cancelled.
© Aero Publishers 1974

Please note that Jones does not give a Martin designation for the second design, and that he calls both "XB-16" (which may be due to the fact that at the time of his book the subject had not been as researched as it has now).

Also, a comparison between the oft-circulated artist's view of the Model 145B and the actual model photographed at the time shows tremendous difference. It has been suggested that the painting may have emanated from the Air Force and not from Martin itself.
 

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Nik

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Wow !! The 145_B sure has a 'Northrop' look to it !!
 

lark

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Star ...
The painting comes indeed from military sources and not from Martin.
This and some other illustrations were released under the auspices of the Army Air Force in 1942
and are typical of the period.

There was an article about in Wings/Airpower by Walt Boyne
"Diagramming the Dream Planes-the Future of the Forties"
 

Antonio

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"US Bombers" by Lloyd S. Jones. 1966 Edition. Martin XB-16 entry
 

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Grey Havoc

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The Model 145A looks almost British, dare I say.
 

ACResearcher

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I have reason to question whether the XB-16 (Final Design) was a Martin design at all.

During recent research at NARA II I came across a series of designs done by the Material Division in 1935, one of which is unquestionably the same aircraft. There is a wind tunnel report and five photos of the wind tunnel model, all of which I have.

I suspect what may have happened is that the Material Division may have given this design to Martin to submit for a Circular Proposal on Heavy Bombers. This appears to have happened earlier with Martin's XB-15 as well. The AAC needed additional sources for heavy bombers and this could have been one way to get them while comparing their design to those of other manufacturers. This last is purely speculation on my part as I've not come across any command-level documents that discuss it.

I would post one of the previously-metioned photos if I could figure out how!

Alan Griffith
 

lark

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You hit something interesting ACR... !

I think it's also possible that the Army A.F. obtained the design rights of the Martin-XB-16
as was usual in those days and that the Material Division did it's own research...

On the other hand , in the edge of a Martin drawing depicting
the 'long range bomber model B-15' - Martin drawing S-145-1 -
is noted " --note- this is not a Martin design but was traced directly from an Air Corps
drawing submitted--"

drawing information via Skybolt.
 

Antonio

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Then, the North American NA-116 intercontinental bomber could had been originated at Martin?
 

lark

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Dear Pome...

Given the design number,the NAA-116 fits somewhere in the 1943 timeframe
thus much later than the XB-16 (Martin design 145B)

At that time the AAF practice of purchasing engineering designs was no longer in use.
Since the NAA-116 drawing stemms from the Boeing archives,it is unlikely that
it had Martin origings I think...
 

Arjen

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I posted this earlier in the XB-19 thread.
Arjen said:
Breihan/Piet/Mason(p.120) write:
The Martin Model 145, a very long-range bomber projected in 1936 as the XB-16, was initially similar to Boeing's XB-15; both were designed for four Allison V-1710 liquid-cooled engines. The XB-16's wingspan was to be 140 feet and the loaded weight 65,000 pounds. The following year Martin proposed the Model 145A, a most unconventional six-engine bomber with twin booms, a span of 173 feet and a weight of more than 100,000 pounds. It was expected to attain 256 mph. Neither design went past the drawing stage, although the Air Corps purchased the engineering data and later publicized a four-engine version of the 145A as one of its "Airplanes of the Future".
This is the book's caption of the picture I posted:
This "4-engine bomber of the future" was based on the second XB-16 design, which had six engines rather than the nacelle guns shown.
... so I understand the picture was produced by the Air Corps, not by Martin.
Just to confuse me, page 121 shows a 3-view drawing of a design very much like the model in Stargazer2006's pictures - also labeled Model 145A.
http://www.marylandaviationmuseum.org/history/martin_aircraft/10_bombers.html ...is where you can find even more information, including a pdf with model 145/146 specs: http://www.marylandaviationmuseum.org/pdf/146_spec.pdf
'Breihan/Piet/Mason' refers to 'Martin Aircraft 1909-1960' by John R. Breihan & Stan Piet & Roger S. Mason, Narkiewicz/Thompson 1995.
'This is the book's caption of the picture I posted' refers to an identical picture to 'martin145b.jpg' in Stargazer2006's start of this thread.

Breihan/Piet/Mason say 'the Air Corps purchased the engineering data' of the six engine twin-boom bomber design from Martin. Then the Air Corps commissioned an artist to make a pretty picture of it, in which the artist replaced two engines with gun turrets.

If you take a look at the 146spec.pdf in the second link, you'll find that the 145B had six engines in a special configuration: four Allison inlines in tractor/pusher installations, and two unspecified tractor radials.
Engine: Four 1,000 hp Allison V-1710 liquid cooled V-12's / XB-
16A: four Allison V-1710-3's (2 tractors, 2 pushers) and
two tractor radials
This pdf also identifies the four engine conventional design as the 145A, the six engine twin-boom design as the 145B.
 

lark

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I have all the books and other sources you mentions...
The point is that there's still much confusion about the Martin 145 design.
For exemple , both 'Aerofiles' and the 'Maryland museum' produced an illustration
of the ,Flying Whale 'Bomber of the future -AirForce illustration with the gun turrets
in the leading edge, and they labelled it as model 145A...
 

Arjen

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I don't know what the exact designations are for the conventional and twin-boom B-16 designs. I am satisfied that they both came from Martin. I suspect some of the knowledge about these designs resides in the Maryland museum, or possibly in Lockheed-Martin's archives, if they have anything left from that long ago.
The Glenn L Martin Maryland Museum has a new website, they're still doing their thing.
 

Stargazer2006

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So if I get what's been written above, what we have here is three separate configurations, but only two by Martin: the first one being from Martin (the conventional XB-16), the second one being also from Martin (being the twin-boom XB-16A with 6 engines), and a third one (twin-boom with 4 engines and two turrets) being pure Air Force fantasy, right? What I do not get is whether the latter preceded the XB-16A or came after it.

ACResearcher said:
I suspect what may have happened is that the Material Division may have given this design to Martin to submit for a Circular Proposal on Heavy Bombers. This appears to have happened earlier with Martin's XB-15 as well.

Do you mean Boeing's XB-15 or Martin's XB-14 here? :eek:
If we don't use the correct designations here we will be lost even more! :(


Arjen said:
I don't know what the exact designations are for the conventional and twin-boom B-16 designs.

Lloyd S. Jones's U.S. Bombers B-1 to B-70, published by Aero in 1962, described the XB-16 and XB-16A designs as the Model 145A and Model 145B, respectively.

Since the author couldn't possibly have made them up, why is it so difficult to just accept these designations as fact passed onto him at the time?
 

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Time to share a bit more of the information I have. I'm using it in my next book so that is why I've been a bit hesitant to "spill the beans" as it were.

The twin-boom "Martin" design is from Air Corps Technical Report No. 4166 "TEST OF 1/60 SCALE MODEL MATERIAL DIVISION DESIGN NO. 319. - PROPOSED LONG-RANGE BOMBARDMENT AIRPLANE. FIVE FOOT WIND TUNNEL TEST NO. 158." It is dated December 20, 1935. It was one of a series of at least three 4-engine bomber projects by the Material Division, the others being No. 318 and 320.

I have absolutely no doubt that it is the same aircraft as that shown as the later Martin XB-16A. Unfortunately, there was no copy I could find of the original GA 3-view of any of these designs in the National Archives II. However, the photos of the wind tunnel models are such that they will make it relatively easy to do reasonable line drawings. Fortunately, the "Martin B-15" original GA 3-view and Interior Profile were at NARA and I copied them as well.

As for the North American NAA-116, I have copied the original Model Specifications document on this aircraft (57 pages) and there is no question of it being a North American project. The aircraft had a span of roughly 155 feet and a length of over 84 feet and was armed with at least seven turrets. The artist concepts are quite nice.

The NA-116 was to be powered by four P&W XR-4360 turning four Ham Standard Dual Rotation six-blade props. Its tactical mission was "...the destruction by bombs of land or naval material without recourse to fighter escort." The report is dated August 20, 1943, the point at which reality finally forced the AAF to stop paying lip service to the notion that unescorted bombers could do the job alone.

If someone who knows how to post photos here will drop me an email I'll share photos to be put here reflecting the above. My email is ag122651@hotmail.com

Alan G
 

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Addendum: Re: Martin XB-16 and XB-16A bomber projects (Model 145)

I state that I have no doubt that the the Material Division Model 319 is the one shown as the Martin XB-16A.

I MEANT to say it is the one shown as the camouflaged XB-16A. The intimation in Jones' book is that it is a Martin Project, but he does not actually come out and say it as I recall.

AlanG
 

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ACResearcher said:
If someone who knows how to post photos here...

I believe you need to psot here ten times before the ability to post photos becomes available to you... an anti-spam system. You've posted 8 times... twice more and you'll be a full-up member, I think.
 

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Martin XB-15

Stargazer,

I did indeed get my designations correct. The Martin Detail Specification for the Model B-15 Airplane Four Engine Long Range Bombardment (aircraft) is dated June 6, 1934. I also copied the General Arrangement 3-view (Martin Drawing No. S-145-1) and the Inboard Profile (Drawing No. S-145-2) directly from the copies at NARA II. There is no reference on any of these documents regarding being copied from Air Corps drawings or specifications, making this an even more interesting paper chase. I believe it is the XB-15 3-view from the Martin museum that has the attribution, but that from the USAAC certainly does not.

There is clearly quite a bit of additional original documentation to be shared/read/discovered to clarify this and other pre-war projects. Time for another phone call to Stan (Piet)!

AlanG
 

Stargazer2006

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Re: Martin XB-15

ACResearcher said:
Stargazer,

I did indeed get my designations correct. The Martin Detail Specification for the Model B-15 Airplane Four Engine Long Range Bombardment (aircraft) is dated June 6, 1934. I also copied the General Arrangement 3-view (Martin Drawing No. S-145-1) and the Inboard Profile (Drawing No. S-145-2) directly from the copies at NARA II. There is no reference on any of these documents regarding being copied from Air Corps drawings or specifications, making this an even more interesting paper chase. I believe it is the XB-15 3-view from the Martin museum that has the attribution, but that from the USAAC certainly does not.

The plot thickens... What is interesting here is that at the time of this "Martin XB-15", the aircraft previously designated XB-15 (the Boeing 294) had been redesignated the XBLR-1 (it was to become the XB-15 again a couple of years later). Was the "XB-15" designation a typo in the documents, or a reallocation of the B-15 slot, however unlikely?
 

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Reallocation of designation?

I have absolutely no idea about any misprint or misindentification. The documents and drawings are quite unequivocal about being labeled Martin B-15 with the Martin logo, internal identifiers, etc.

Perhaps the most frustrating aspect of researching these documents is that you get a lot of discussion about what size rivets to be used, what previous general specifications are being followed, etc., etc., etc. Or you get the notes saying "We need a decision about X because of Y." Then you find another document dated several days to several months later stating that "General Arnold has directed that we will do Z with X, to be instituted immediately."with absolutely nothing on the discussions that resulted in that decision.

If anyone has documentation of discussions by decision-makers I'd sure like to chat with you.

AlanG
 

Arjen

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Stargazer2006 said:
Arjen said:
I don't know what the exact designations are for the conventional and twin-boom B-16 designs.

Lloyd S. Jones's U.S. Bombers B-1 to B-70, published by Aero in 1962, described the XB-16 and XB-16A designs as the Model 145A and Model 145B, respectively.

Since the author couldn't possibly have made them up, why is it so difficult to just accept these designations as fact passed onto him at the time?
Lloyd S Jones's book is still on my wish list. I have a copy of Breihan/Piet/Mason's book, but that - otherwise excellent - book contradicts itself on the designations. After reading this topic: designations 145A for the four engine conventional design, 145B for the six engine twin-boom design look perfectly acceptable to me.

Having read ACResearchers contributions, I'm reconsidering my opinion about the four engine twin-boom just being something of an artist's dream. I'm very curious as to what else is to be revealed on this subject.
 

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I have found absolutely nothing in the files at NARA that suggest a Martin Model 145B. I'd love to have Lloyd Jones' email address so I could ask him if he recalls or still has the documents that indicated these things. At best I would have to say that in lieu of documentation to the contrary the XB-16A is conjectural. This is especially true in light of the documentation I have (some examples are hopefully attached here) on the Material Division design No. 319.

Assuming my luck holds out, I'm attaching a variety of drawings and photos from my collection on the aircraft under discussion, including the NAA-116.

AlanG
 

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Arjen

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Alan, wonderful stuff. When will you publish?
 

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Arjen, thanks for the kind words.

I'm not sure when publication will be. When I started the project I hoped to get it done this year, but the amount of data I have, the number of drawings I need to redo (the B-15 drawings are a 10 in quality. Most are about a 2) and the topics I want to cover make this look like it might be a two volume effort. I am, in fact, still gathering data from those researchers kind enough to share their collections.

In some cases I've collected so many photos that I'm sending them all to my publisher to choose which ones he wants to use and will write about that subject around those photos and the drawings I have (which are substantial). On others I'm still trying to get factory GA 3-views to redraw and am not quite sure how I shall handle that if not forthcoming. I know there are some folks who will be enshrined in Glory and the book(s) for their assistance.

I wish I could give you a better answer, but I have nearly 50,000 pages of photos and data to sort through to do this right.

AlanG
 

Stargazer2006

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Alan, this sample is pretty impressive in itself. Wow! The NAA NA-116 artwork is especially nice.

Please note that the beautiful Model 145 general arrangement does describe the type as the "Model B-15" but this may well have been wishful thinking on the part of Martin and not an official designation at all. Don't forget that apart from the B-11 slot (used by Douglas) Martin had had B-10, B-12, B-13 and B-14. In all logic they would have been tempted to call their next bomber proposal "B-15" even before any formal contract was considered.

What you're saying about not finding any mention of a "Model 145B" anywhere is certainly worthy of consideration, but let's not forget that Martin seldom communicated on their inhouse designations anyway.


Back to the subject of Model 145, I just realized that the Jones book does NOT mention the designation "XB-16A" anywhere. It talks about two different XB-16 proposal, one for 1934 and a revised one a year later. Allow me to quote from the book (I need to retype so I'll only use excerpts):

Late in 1934, the Martin Company laid down a proposal for a fast, long range, heavy bomber, the Martin Model 145-A, and received the Air Corps designation XB-16.

Since the so-called "B-15" design is dated June 1934, it can't have been approved or accepted by the Army, let alone been given a designation prior to that December contract.

Continued development of the original XB-16 design in 1935 led to a grotesque giant featuring a huge 4,256 square foot wing to which two thin tail booms were attached. (...) It is interesting to note the first appearance of the tricycle type landing gear on this projected design. (...) Although the engineering design was purchased by the A.A.F., no models of the Martin XB-16 were built and the project was cancelled.

This confirms previous posts about the purchase of the design by the Army, which likely resulted in the four-engine/two-turret artist's view that had nothing to do with Martin.


I'd like to venture the notion that there may have been three sub-designations for three completely different variants:
  • Model 145 - June 1934 (four-engine tractor, single tail fin, depicted above as the "Model B-15")
  • Model 145A - 1934 (four-engine tractor, twin tail, the second XB-16 project)
  • Model 145B - 1935 (six-engine tractor/pusher, twin-boom, the second XB-16 project)
What I do not understand, however, is why the Boeing, Douglas and even Sikorsky projects were allocated BLR- designations and not the Martin one.
 

lark

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It seems that the '145' riddle is solved...

When may we expect your book Alan .

Any clue about the title...?
 

Antonio

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Good work!

Alan, I'm in the buyers list for your book too ;)
 

Stargazer2006

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Meanwhile I've attempted a series of comparative views (roughly to scale):
 

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ACResearcher

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Stargazer,

Very nicely done comparison and solid logic - PART of which is supported by documentary evidence, but still leaving the elusive (and ugly) 145B out in the cold.

Attached are some photos of the XB-16 (145 - A?) wind tunnel model, page 1 of an extensive evaluation of both the XB-15 and the XB-16, info on the Contract for the XB-16, drawing list for the XB-16, identifier plaque off the XB-16 GA 3-view. If you compare the last to that on the XB-15 I posted earlier, you will find the XB-15 identified as S-145-1, and that of the XB-16 labeled S-145-1A. Following Star's excellent logic that would make the twin boom aircraft the S-145-1B. Again...I found no documents whatsoever on this aircraft under the Martin name, but do have documents clearly calling it "Material Division Design No. 319". This document section and a copy of the Patent are also attached.

While I'd love to simply call the Twin Boom Beast the XB-16B/145B, at this point it has to be labeled as informed speculation but not proof. But dang....I'd sure like some proof!

As for the name and full subject(s) of my next book, I'm keeping that a bit quiet. There is at least one "researcher" who will claim it is his idea and he thought of it fifteen years ago. You know the type.

AlanG
 

Attachments

  • Mat Div Design 319 ID.jpg
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  • XB-16 Wind tunnel 006.jpg
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  • XB-16 GA 3-view identifier.jpg
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  • XB-16 designation reference.jpg
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  • XB-16 contract info excerpt.jpg
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  • XB-15 & XB-16 Evfaluation Write-ups 001.jpg
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  • Twin-boom patent.jpg
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Stargazer2006

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The more I browse through Martin's model list, the more I'm convinced that the -1, -2... system was used for studies while the -A, -B... suffixes were for definite contracted models.

A case in point is the Martin 202 ("2-O-2" or "Martinliner"). Studies carried suffixes such as -7 or -12 while contracted variants had letter suffixes such as A, E, FL, NW etc. corresponding to specific airlines.

In this respect, Martin would have used a series of designations such as 145-1, 145-1A or 145-3 for studies, while definite contracts resulted in designations such as 145A. I have found a few more examples of the same.


Another thing I found pretty interesting while working on the general arrangements is how the wing planform of the early 145-1 design matches exactly that of the later 145B, despite the totally different tail and engine arrangement, and the fact that the 145A design presented a whole different design approach.
 

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BLR designations

While I still have to plow through my data on this particular designation, I have noticed a couple of things:

1. The XBLR aircraft were substantially larger than anything before the B-36.

2. Both the range and the endurance of the XBLRs were much greater. For instance, the XB-16 had a listed endurance of 42 hours, but those of the BLRs were up in the mid-50s IIRC.

I dont believe the AAF ever had any intention of building fleets of B-19s, but it and the B-15 served to help set the requirements for a true intercontinental bomber that would express themselves in the Circular Proposal that resulted in the B-36 only a few years later.

AlanG
 

Stargazer2006

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In his book The B-29 Superfortress Chronology, 1934-1960, Robert A. Mann gives the following chronology:
  • 14 April 1934 Army General Staff approves "Project A" — a feasibility study for a bomber that could fly 5,000 miles with a one ton bomb load.
  • 12 May 1934 General Conger Pratt, Head of the Material Command, authorized to begin negociations with Boeing and Martin.
  • 14 May 1934 Clairmont L. Egtvedt, Boeing President, and C.A. Van Dusen, President of Martin, were given presentation in Pratt's office at Wright Field by Colonel Leonard "Jake" Harmon on Project "A." They were given one month to come up with designs.
  • 14 June 1934 Designs for the Boeing Model 294 and Martin Model 145 delivered to Wright Field.
  • August 1934 Egtvedt is back at Wright Field and learns of a new project for a second bomber, smaller that the XB-15 and standing a better chance of going into production before the XB-15.
  • 16 August 1934 Egtvedt tasked Boeing designers to start work on low wing monoplane bomber designated Model 299.
It is now easy to see that the 145-1 design presented by Alan a few posts ago was the one submitted on June 14.

So perhaps we could infer from this that the "B-15" slot was clearly announced to both companies as being reserved to whoever was the winner on the "Project A" competition, which therefore explains why Martin gave it that name on the original plan.

We can imagine that while Boeing was given the go-ahead on their Model 294 (now assigned the XB-15 designation), Martin was asked to rework their proposal.
This would have resulted in the 145-1A proposal (Model 145A) accepted in December 1934 and assigned the XB-16 designation.

As for the Model 145B twin-boom proposal, what if the A.A.C. suggested that Martin work on an alternate design so that both contenders of "Project A" could display two very different configurations? One "classic" layout (the Boeing) and a more daring approach (the twin-boom Martin)? Just a thought.
 

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Excellent information, Star. I appreciate your sharing it. I'm looking for a source or sources that list and describe or analyze the various Circular Proposals and Projects such as you pulled out of Mann's book. Do you know of any such sources or books? Do you happen to know if Mann is still alive?

Going back to some nearly prehistoric notes from a conversation with Lloyd Jones at some IPMS convention in the 1980s, one of the books he used for information on pre-war aircraft was named "Characteristics of Army Aircraft". It was marked Secret and it was there that he got the information on the twin-boom XB-16 aircraft. While I don't have this book (but would love to find a copy), I do have experience with other government publications and, like any such thing, they do have their errors. I don't know if this is one of them or not.

Again, I have no quibble with your logic. I'm just a guy who needs to see original documents before I can tell myself "Asked and answered." Unfortunately, the shelves are full of books written by people masquerading as researchers but who are really just gatherers and repackagers of what others have said (often incorrectly). I'm not saying that is the case here at all, but there are clearly some major questions to be resolved by documentary evidence before this is finally put to bed.

AlanG
 

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Alan and Star,

many thanks for the info on that interesting subject. I'm also working in additional info from "Consolidated B-32 Dominator by William Wolf. Ed Schiffer" plus some bits from other books to compile a summary. I'll post it as soon as possible.

Antonio
 

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Today I've decided to go with an extensive amateur compilation about US Bomber designs. That will take several weeks to finish it. In the process I'll post any Project A information I could discover.

Source: Superfortress. The Boeing B-29 and American Air Power in World War II. General Curtis LeMay and Bill Yenne. Westholme Publishing. 2007

General Conger Pratt lost little time in getting requests for proposals into the mail. He addressed to the responsible of the manufacturers of the revolutionary B-9 and B-10 bombers. From the two, the Materiel Division boss picked the Boeing design. Originally designated as XBLR-1, this designation was cancelled and the nomenclature would follow the traditional "B for bomber" convention. The Boeing entry was re-designated as XB-15 and the Martin entry as XB-16.

So I agree with Stargazer's theory that Martin's original design is labelled B-15 because the next designation available for the Project A was the number 15. I think that's logical.

Martin never received an XBLR designation because XBLR-1 went to Project A winning design only.


XBLR-2 and XBLR-3 went to Project D competing designs. See Boeing XB-15 and Douglas XB-19 by Bill Yenne at International Air Power Review Volume 5 and Sikorsky XBLR-3 entry at Lloyd S. Jones "US Bombers 1928 to 1980". Aero Pub.
 

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All that you have written is correct, Antonio, except for one thing: the Boeing 294 was FIRST designated as XB-15, THEN redesignated XBLR-1 when the BLR mission was defined, and THEN reverted back to XB-15 when BLR was canceled... This explains why the BLR-2 didn't become the B-17 or B-18, but the B-19 because the B-15 simply took over its initial designation while the B-19 took the first one that was available.
 

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ok, thanks Stéphane!

after reading several contradictory sources, it seems that the puzzle is taking shape here. The power of networking, and the pleasure of collaborative research.
 

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What a lot of fun to be sharing information and tossing out ideas!

Stephane, I need to make a slight correction in a statement you made. The B-17 and B-18 were submitted to an entirely different Specification/Circular Proposal than those for the Project A and D/BLR aircraft. Requirements for range, etc. were substantially smaller. The requirements that were to be met by what became the B-17 and B-18 were "loose" enough that both dramatically-different aircraft met them. In fact, if I remember correctly, there was no Specification as to the number of engines so Boeing asked if it had to be a two-engine aircraft. As the answer was "no" they went with the now-classic Model 299.

Then again, I could just be having another late-night hallucination...

Alan
 

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While Project A and D were experimental machines intended to push the limits, the B-17 and B-18 competition asked for an aircraft to be produced in series. The Army asked for 2,000 mile range/1 ton bombload/ 200 mph speed. It was the B9/B10 replacement. The B-18 was selected because it was cheaper than the B-17, but the Boeing aircraft was so good that about 15 YB-17 were purchased for development. The B-18 order was about 130 airplanes.
 

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