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98-102 / C-103A "Attack Bomber" spec (alternatives to the Douglas DB-7/A-20)

Stargazer2006

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When Northrop's first company was purchased by Douglas, it became their El Segundo division. Along with the facilities, Douglas also inherited a few projects and ongoing programs from Northrop. The most famous one was the Model 8A (Army A-17 and A-33) but there was also a small bomber design, the Model 7, now the Douglas Model 7, the prototype of which was completed and submitted in a USAAC attack competition (Circular Proposal CP38-385, March 1938) against the North American NA-40 (forerunner of the Mitchell), Stearman X100, Bell Model 9 (an Airacuda derivative with V-1710 engines) and the Martin 167 (which would become the Maryland).

CP38-385 did not require prototypes, only proposals, yet Douglas, North American and Stearman produced one each. However, none of them proved satisfactory to the Air Corps, and soon a modified version of the Circular Proposal (CP39-460) was issued, and this time prototypes were mandatory. A prototype of the Martin 167 (Model 167W) was completed. It was a much more streamlined and advanced design, produced by James S. McDonnell, Jr. during his stint at Martin and incorporating most of the Air Corps specifications from the start, so that the prototype didn't have to undergo any major redesign after evaluation by the Air Corps. Only Bell declined to join the second phase of the competition. They did produce a more advanced attack design, the Model 17, but it remained unbuilt.

The three prototypes initially submitted had to be reworked to CP39-460, the most obvious change being a complete redesign of the nose section. The NA-40 and Douglas Model 7, which both had full noses, were redesigned to feature a glazed gunner position, becoming the NA-40B (or NA-40-2) and Model 7B respectively. The Stearman X100 (now known internally as the Boeing Model 329), which alone featured an all-round glazed cockpit for both gunner and pilot was also reworked: cockpit and nose were stepped to reduce the glazing and make the nose more sturdy, but also to improve pilot visibility.

The Boeing/Stearman prototype became the XA-21 and the Martin prototype became the XA-22. The North American NA-40B was not found satisfactory for the attack role and didn't even get a designation. The Douglas 7B didn't have time to get the "XA-20" designation that was presumably reserved for it because it crashed during tests. In all logic, considering Martin's lead in bombers and the quality of their design, and now the loss of the Douglas prototype, the odds seemed to be in favor of the Model 167. And yet it was the Douglas 7B that obtained the best evaluation of all four aircraft (905 points out of 1000) and was declared the winner, being produced as the A-20 Havoc (Model DB-7 series).

The losing Martin 167W got only 718 points in the evaluation — it didn't have the tricycle gear favored by the USAAC Committee for increased visibility. However, it didn't fare too badly, being produced in quantity for France and then Britain as the Model 167F/167B Maryland. As for the unfortunate NA-40B, it enjoyed an even greater career, becoming the prototype of the B-25 Mitchell medium bomber...
 

Stargazer2006

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Douglas Model 7A

"In anticipation of the Army Air Corps' needs for the previous year, Douglas Aircraft had gone ahead in developing a multi-engine attack plane.
Although detailed requirements didn't exist, we began work in March 1936 and by year's end the design was half completed. It was called the Model 7A attack bomber.
It would gross out at 9,500lbs, carry a crew of three, pilot, bombardier, and aft gunner, and be capable of 250 knots airspeed. A pair of 450hp Pratt & Whitney Wasp
Juniors would power it.
The Air Corps changed requirements, and in late 1937 announced a design competition based on requirements arising from studies of the Chinese ans Spanish wars.
The Army wanted at least a 1,200 mile range, a bomb-load of 1,200lbs, and a speed in excess of 200mph.
Jack Northrop was the general manager as well as the chief engineer of the bomber program... I was assigned as project engineer for the model 7A.
The 7A featured an interchangeable bomber and gun nose. The attack version had six .30 calibre and two .50 calibre nose-mounted guns.

From: Combat Aircraft Designer, pp.55-57


"The Model 7A project was set up by John Northrop with Edward Heinemann as the designer. However, by the time that the design was about half complete and a mockup had been built, combat information coming in from the Spanish Civil War indicated that the Model 7A would probably be obsolete even before it flew. The project was shelved in December of 1936. In the autumn of 1937, the Army issued its own set of requirements for a twin-engined light attack aircraft. The Army was interested in an aircraft that had a range of 1200 miles, a speed of 200 mph and a 1200-pound bombload. In late 1937, the Army invited companies to submit designs for such an aircraft, with the stipulation that proposals being ready for submission by July of 1938.

The Model 7A was powered by a pair of 450 hp Pratt & Whitney R-985 Wasp Junior nine-cylinder air-cooled engines housed in nacelles on a shoulder-mounted wing. The aircraft was very slim and had tricycle landing gear. Provisions were made for a number of flexible and fixed 0.30-inch machine guns to be carried and a light bomb load of up to 40 17-lb fragemtation bombs. As an alternative, a glazed lower mid-section reconnaissance or observation platform could be fitted in place of the bomb bay. A single fixed 0.30-inch machine gun was to be fitted in the nose firing forward, a single 0.30-inch gun was fitted in a manually-operated dorsal turret, and another 0.30-inch gun was installed in a dowarward-firing dorsal station. A bomb load of 1000 pounds could be carried. It was estimated that the Model 7A would have a maximum weight of 9500 pounds and would be capable of achieving a maximum speed of 250 mph.""

From: Joe Baugher's website

NOTE: Baugher says that the Model 7A "was a two-seater" -- other sources say 3-seater.
 

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Stargazer2006

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Douglas Model 7B

An alternate bomber nose was designed, which featured a bombardier station and bombsight. In addition, Pratt & Whitney R-1830 powerplants, of 1,100hp each, were specified, which increased the planes performance. Thus the 7B evolved, flying for the first time in October 1938.

From: Combat Aircraft Designer, pp.55-57

There was also an observation variant planned with a largely glazed lower fuselage."

from: Douglas Havoc and Boston - the DB-7/A-20 series, by Scott Thompson (Crowood Aviation Series)
 

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Stargazer2006

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North American NA-40
 

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Stargazer2006

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North American NA-40B (NA-40-2)

NOTE: last file is a PDF depicted a "NA-40A" though it's not sure if this was simply a mistake by the artist or an alternate design.
 

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Stargazer2006

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Martin Model 167W (U.S. Army XA-22)
 

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Stargazer2006

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Stearman X100
 

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Stargazer2006

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Stearman X100 / Stearman Model 19 / Boeing Model 329 (U.S. Army XA-21)

Stearman started the design of a new twin-engine light bomber for a US Army attack plane competition and completed it after becoming Boeing's Stearman Division.

The new model, c/n 100000, was delivered to the Army as the XA-21, 40-191 in September, 1939. Normal crew seating was for three, a bombardier, the pilot and a radioman/gunner, but an additional crew member could also be carried. In addition to being Stearman's first monoplane, Model X-100 incorporated other features that were new to the industry. Electrical actuated retractable landing gear, integral fuel tanks, fully feathering constant speed props and sealed compartments in the outer wing panels, central fuselage and tail for flotation in case of forced landings in water.

The engines were the new Pratt & Whitney R2180-S1AG Twin Hornets that produced 1150hp but could be boosted to 1400hp for takeoff. The XA-21 and North American XB-21 were the only aircraft to use it.

The Army did purchase the Stearman/Boeing prototype assigning designation XA-21. However, it was never put into production.

From: http://www.opencockpit.net/other_stearmans.html
 

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Stargazer2006

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Bell Model 9

"Not much is known about this proposal design. There is some reason to believe it was a derivative of the YFM-1 Airacuda, but reconfigured to use Allison V-1710 tractor engines. This Bell proposal was submitted in response to a 1938 Army design competition for a twin-engine attack bomber. The Army invited Bell, Stearman, Martin and Douglas to build prototypes (at their own expense) and Bell declined, no doubt for financial reasons. The latter three companies plus North American eventually did build aircraft for Army test and evaluation. In hindsight, Bell Aircraft saved a considerable amount of money because no production contracts were ever awarded in this competition. Bell's Jack Strickler was the project engineer."

From: Cobra! Bell Aircraft Corporation 1934-1946 by Birch Matthews (Schiffer Military/Aviation History)

Of course when the author says "no production contracts were awarded" in the competition, he fails to mention that the competition was modified and that a winner emerged from the revised Circular Proposal tender...

NOTE: I haven't been able to locate any image of the Model 9.
 

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Bell Model 17

"In an effort to breathe some life into the multiplace fighter concept, Bell proposed their Model 17 whose only distinctive change involved the substitution of liquid-cooled Lycoming XH-2470 engines. In theory, this would have increased Airacuda performance dramatically because the H-2470 was supposedly capable of 2,300 horsepower at 3,300 revolutions up to 15,000 feet. This horizontally opposed engine first ran in July, 1940, and though development carried on for at least two years, the engine only flew in one airplane, the Convair XP-54. Needless to say, about the time Bell proposed Lycoming engines for its FM-1 design, the era of a multi-place fighter was receding rapidly into the background of aviation history."

From: Cobra! Bell Aircraft Corporation 1934-1946 by Birch Matthews (Schiffer Military/Aviation History)

The author seems to consider the Model 17 as a multiplace fighter and simply a variant of the Airacuda. Several sources indeed quote the Model 17 as the YFM-1C proposal. And yet, here is an image from American Bomber Development by Bill Norton (courtesy of lark), presented as the Model 17, the caption of which states clearly that this 1938 design resulted from an "Air Corps effort to develop a twin-engine attack bomber." One can reasonably assume that if Bell had submitted a prototype to CP38-460, it would have been that Model 17.

Also, please note that the artwork shows two different engines, reflecting two proposals, one with a radial engine on the port side, and an inline Allison V-1710 on the starboard side.
 

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toura

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Bonjour Stephane.
Here, from "Aviation magazine"
The DB 7 with 2 fins. Query of French Air Force.
Cancel.
 

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Antonio

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Just impressive!, thanks a lot Stéphane
 

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Excellent thread, Star. You might want to change the designation in the title to CP 38-385 vs 39-385.

Here is some more information on this topic which I’ve found quite interesting over the years.

Stearman X100
Stearman submitted no less than eight different designs for CP 38-385. They were the Model X100, X100-H2, X100-H3, X100-H4, X100-H6, X100-H7(referred to as the “physical article”), X100-G1 and the X100-T1.

The AAC’s Conclusions and Recommendation, dated March 27, 1939, stated.
a. It is concluded that the design falls considerably short of meeting Air Corps desired
requirements for the type.

b. It is recommended that the changes recommended below and the features covered in the Table of Percentage Deductions in this report be considered in the event of procurement of any
articles of this design.

c. It is also recommended that this design be considered by the Evaluation Committee.

There has been a certain amount of speculation about the reason for the change from the rounded nose to the stepped nose configuration. At least one reason can be found in the comment of one test pilot that while flying the rounded nose at night you had “26 different instrument panels staring you in the face” from reflection in the windows.

NA-40
North American also submitted eight different versions of the NA-40. These were labeled by the AAC as the NA-1 thru NA-8. NA-1 was the Basic Bid and appears to be the one originally built. Of interest in the papers I have is an entry under Blue Print Copy of a 3-view for a 5-place twin engine attack bomber and another for an Inboard Profile for a 3-place twin engine attack bomber, both powered by the R-2800 engine. I’ve not yet found these but am still looking.

Martin 167
One of the more interesting comments in the design analysis by the AAC was that “…in most instances drawings were submitted which called out details not furnished…”

I’ve not yet had time to go through all the Martin documents, either, so I can’t really comment on how many different design proposals Martin submitted under the Model 167 heading. I assume the drawings Stephane put up are from those proposals?

There were a number of change orders and requests for change orders during 1938 as the prototypes were being built. One of the more important in the long run was the request to allow placement of exhaust outlets on the bottom of the wing vs across the top. Placing them on top of the wing caused disturbances n the air flow as well as weakening the structure of the wing from heat. Building up the metal was not an adequate solution as it could add significantly to the weight of the wing. Moving the exhausts also enabled designers to lower the nacelle so the top was roughly even with the top of the wing. This change is especially noticeable in a comparison of nacelle settings between the original Douglas DB-7A and the ultimate production A-20.


I can find no reference in any of the documents to a Bell 9 or even a mention of Bell. That could, of course, just mean I haven’t come across the right documents yet. However, I do have the various Section analyses (Armament, Engineering, Propeller Lab, etc.) for most of these proposals and nothing about Bell. Does anyone know where the Bell archives might be found??

As a final tidbit, the Dayton Herald, Saturday March 18, 1938 headline was “All Three Attack-Bomber Bidders May Get Order”. Speculating on the assumption that Congress would pass the Air Corps expansion legislation, and being a “Company Town”, the Herald went into a bit of detail on the proposal.

According to the article, promised delivery schedules were as follows:

“Martin offered delivery of the first three planes within eight months with mass production gradually stepping up to a maximum of 100 a month on the 22nds month, on an order of 2000 planes. North American specified delivery of the first three ships in nine months, with a mathematical equation on the gradual stepping up of mass production which would result in a maximum of 195 planes a month on the maximum 2000 order. Stearman promised a delivery of three planes within 18 months with a maximum production rate on larger orders of 12 a month thereafter.”

Clearly the Stearman production plans were a pale shadow of those planned by Martin and North American. While I haven’t had time to wade through the hundreds of documents I’ve copied on CP 38-385 and the entries, this tepid production plan certainly had to have a significant negative impact on this aircraft as a choice.

Sorry that this is a bit disjointed. As I said, I have hundreds of pages just on this CP to arrange and analyze for a project of my own. Too many irons in the fire!

AlanG
 

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ACResearcher said:
You might want to change the designation in the title to CP 38-385 vs 39-385.

Oops. A horrible typo, now fixed throughout the thread.

Thanks for pointing it out and for your extremely valuable input on the subject!
 

Triton

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Lockheed Bid for Specification C-103A booklet titled General Arrangement Lockheed 29-A Twin-Engine Attack Bomber Airplane circa 1939 found on eBay.

Seller's description:
Spiral bound booklet has a plastic overlay, measures 10" X 14" and has 28-pages (not including covers), and two silver-color pages. Most pages depict the proposed plane "(showing the position of the crew - pilot, bomber, and gunner-the triple vertical tail surfaces and ducted nacelles", "Tricycle Landing Gear", "The Bomber's Station", "Rear Gunner's Turret" and more., Other pages have diagrams ("design factors" and "flight characteristics"), as well as text pages on "Design Features" and "Estimated Performance").
URL:
http://www.ebay.com/itm/RARE-Concept-Design-LOCKHEED-29-A-Drawings-ATTACK-BOMBER-AIRPLANE-Prototype-P-38-/290884143327?pt=LH_DefaultDomain_0&hash=item43ba0bc8df
 

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Stargazer2006

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Triton said:
Concept for the Lockheed A-29 Hudson?

What makes you say that? The number "29"?!? No relation here! It is simply the Lockheed Model 29-A.

A most fabulous find!!!
 

Stargazer2006

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And this extra picture which was not in your initial post:
 

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Triton

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Stargazer2006 said:
Triton said:
Concept for the Lockheed A-29 Hudson?

What makes you say that? The number "29"?!? No relation here! It is simply the Lockheed Model 29-A.

A most fabulous find!!!

A wild and regrettable guess on my part. If this concept is indeed from 1939, it would have been submitted after the first flight of the Lockheed A-29 Hudson in 1938. The seller claims that this concept was a prototype P-38 Lightning, but the first flight was January 27, 1939, so this concept is not for the P-38 Lightning.
 

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26P-2 NeptuneMay 17, 1945patrol bomber and anti-submarine warfare aircraft
27 proposed twin-engine canard transport
28model number not used
29 proposed twin-engine bomber
30 proposed twin-engine canard bomber
31 proposed export version of Model 29
32 proposed reconnaissance version of Model 18
33Little DipperAugust, 1944
34Big DipperDecember 10, 1945

From Wikipedia. Not found anything more about the Model 29 in a quick search of my sources.
 

Stargazer2006

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All I was able to find in my notes was that there were two variants of that design: 29-A and 29-B, both attack bombers (no details as to what differed in the latter).

Since no book on Lockheed has ever shown the slightest picture of the Model 29 before, the document for sale on eBay may very well be the only remaining trace of that elusive project...
 

Stargazer2006

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Just took a look at the list of aircraft that were relatted to the C-103A data specification, and somehow the confusion between Model 29 and A-29 was not that far-fetched, since the latter was ALSO contracted in answer to that general specification:

C-103

BomberDouglas DB-10 = DS-259
C-103A

Photo reconnaissanceDouglas YF-3 a version of A-20
C-103A-1

AttackDouglas A-20D, A-20E, XA-20F
C-103A-2

AttackDouglas A-20, A-20A
C-103A-3A

AttackDouglas A-20B
C-103A-3B

AttackDouglas A-20B, XA-20B
C-103A-4

AttackDouglas O-53
C-103A-5A

AttackDouglas A-20C
DA-C-103-A-5C

AttackDouglas A-20C / Boston
DA-C-103-A-6A


Lockheed A-28
DA-C-103-A-7A

AttackLockheed A-29
DA-C-103-A-8

AttackLockheed A-29A
DA-C-103-A-8A

AttackLockheed A-29B
DA-C-103-A-9

AttackLockheed A-28A
DA-C-103-A-9A

AttackLockheed A-28A
C-103-A-10A

AttackDouglas A-20G
C-103-A-11


Douglas A-20G, A-20J
C-103-A-12A


Douglas A-20H, A-20K
However, the way I see it, judging from the size, style and configuration of the project, the Model 29 must have been an unsuccessful competitor of the Douglas A-20. Any thoughts?
 

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So, reading though some books on the A-20 Havoc. Mostly this is from the Crowood book on A-20 Havoc.


1936 - Northrop (with Ed Heinemann as chief designer) start work on private venture Model 7A light bomber. Two-man crew, all-metal, slim, high-wing design powered by a pair of
450hp Pratt & Whitney R-985 Wasp Jr engines. Had tricycle landing gear and a bomb bay that could be fitted as an observation or reconnaissance position. 1,000lb bomb load and a maximum speed of 250mph (400km/h).

December 1937 : USAAF 98-102 (CP 38-385) requirement released for an experimental twin-engine bomber -

Speed: 250mph minimum, 280mph preferred.
Ceiling: 20,000ft minimum, 25,000ft preferred.
1200 mile range
1200kg payload

Bids (including prototype ready for flyoff) to be completed for March 1939.

Proposals received from 4 manufacturers, who proceed to build prototypes:

Martin Model 167
Stearman X-100
North American NA-40
Douglas (ex Northrop) Model 7B

Douglas design is based on Model 7A basic shape but scaled up and with bigger engines.

Meanwhile, even as this work is progressing, worrying world developments lead to release of the new C-103 attack bomber requirement in September 1938. Specs are similar to 98-102 but max speed is now 350mph minimum and 375mph preferred. The requirement is for a single prototype. Douglas revise Model 7B into DB-7.

In December 1938, C-103A (CP. 39-460) is issued, now an urgent requirement with immediate production, with bids required by 17th April 1939.

C-102 bids were examined March 1939 but this requirement was effectively superceded by C-103A bids in April 1939. Martin and Stearman resubmitted their C-102 designs to C-103A. Douglas made 3 submissions (DB-7, B-23, Model 288). North American made a cursory effort as they were reworking NA-40 into NA-62 medium bomber (Later, B-25 Mitchell). Bell, Consolidated, Curtiss and Lockheed all made bids as well.

Douglas DB-7 was the clear winner, entered service as A-20 Havoc (already being produced for France as DB-7)

Stearman X-100 prototype was purchased, became XA-21. No production.
Martin 167 prototype purchased as XA-22. Entered limited production as Maryland.

So Model 29A is the Lockheed bid for what became the A-20 Havoc.
 

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Stargazer2006

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Excellent stuff, Paul!

One tiny detail: the manufacturer of the X-100 should read SteaRman and not Steadman. Since you repeated the typo, I believe you must know someone by the latter name and got mixed up!!
 

overscan (PaulMM)

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Lockheed were working on P-38 at the time so were unlikely to get C-103A, plus Douglas's design was already flying, so Model 29A never stood a chance.
 

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This is to let you know that I am bidding on the Lockheed 29A package and will make information available here when I have it.

AlanG
 

Stargazer2006

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ACResearcher said:
This is to let you know that I am bidding on the Lockheed 29A package and will make information available here when I have it.

AlanG

It would be so great if you could win that bid! All the best to you on this attempt...
 

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The model number '29' - cited by Paul 'Overscan' - is confirmed in
'Lockheed Aircraft since 1913' by R.J.Francillon-Putnam.

chapter :Airplane model designation page 480-481.

Model 29 : proposed twin engined attack bomber.
 

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I too confirm this from my copy of Lockheed Aircraft since 1913. -SP
 

hesham

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PaulMM (Overscan) said:
So, reading though some books on the A-20 Havoc. Mostly this is from the Crowood book on A-20 Havoc.


1936 - Northrop (with Ed Heinemann as chief designer) start work on private venture Model 7A light bomber. Two-man crew, all-metal, slim, high-wing design powered by a pair of
450hp Pratt & Whitney R-985 Wasp Jr engines. Had tricycle landing gear and a bomb bay that could be fitted as an observation or reconnaissance position. 1,000lb bomb load and a maximum speed of 250mph (400km/h).

December 1937 : USAAF 98-102 (CP 38-385) requirement released for an experimental twin-engine bomber -

Speed: 250mph minimum, 280mph preferred.
Ceiling: 20,000ft minimum, 25,000ft preferred.
1200 mile range
1200kg payload

Bids (including prototype ready for flyoff) to be completed for March 1939.

Proposals received from 4 manufacturers, who proceed to build prototypes:

Martin Model 167
Stearman X-100
North American NA-40
Douglas (ex Northrop) Model 7B

Douglas design is based on Model 7A basic shape but scaled up and with bigger engines.

Meanwhile, even as this work is progressing, worrying world developments lead to release of the new C-103 attack bomber requirement in September 1938. Specs are similar to 98-102 but max speed is now 350mph minimum and 375mph preferred. The requirement is for a single prototype. Douglas revise Model 7B into DB-7.

In December 1938, C-103A (CP. 39-460) is issued, now an urgent requirement with immediate production, with bids required by 17th April 1939.

C-102 bids were examined March 1939 but this requirement was effectively superceded by C-103A bids in April 1939. Martin and Stearman resubmitted their C-102 designs to C-103A. Douglas made 3 submissions (DB-7, B-23, Model 288). North American made a cursory effort as they were reworking NA-40 into NA-62 medium bomber (Later, B-25 Mitchell). Bell, Consolidated, Curtiss and Lockheed all made bids as well.

Douglas DB-7 was the clear winner, entered service as A-20 Havoc (already being produced for France as DB-7)

Stearman X-100 prototype was purchased, became XA-21. No production.
Martin 167 prototype purchased as XA-22. Entered limited production as Maryland.

So Model 29A is the Lockheed bid for what became the A-20 Havoc.


My dear Paul,


also from the book; Douglas Havoc and Boston the DB-7/A-20 series,here is the same
picture with more for DB-7A and A-20 variants.
 

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hesham

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Stargazer2006 said:
Very nice. Thanks for sharing.


Thank you Stargazer,


and from the same source,here is a little info about DS-527.
 

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lark

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I think that the designation in Mr.Nortons book for the Bell attack bomber is a mistake...(post#9)

Instead of model '17' it should be '10'.
According to Birch Mathews in "Cobra" the model 17 was just an Airacuda with engines in the pull mode
wile the model 10 was an all new design with an all glazed nose and offered with a choise
of engines as can be seen in the illustration.

Skyblazer also had already his doubs ...
 

hesham

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From Le Fana No.14,

a strange variant ?.
 

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Arjen

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As the French caption explains, the lower profile shows the Turbinlite-Havoc.
Text and first image from wiki:
The Helmore/GEC Turbinlite was a 2,700 million candela (2.7 Gcd) searchlight fitted in the nose of a number of British Douglas Havoc night fighters during the early part of the Second World War and around the time of The Blitz. The Havoc was guided to enemy aircraft by ground radar and its own radar. The searchlight would then be used to illuminate attacking enemy bombers for defending fighters accompanying the Havoc to shoot down. In practice the Turbinlite was not a success and the introduction of higher performance night fighters with their own radar meant they were withdrawn from service in early 1943.
The caption further mentions a 'Pandora' variant which would suspend a bomb on a line in front of approaching bombers. Blam - or so it was hoped.
Second image found here: https://no23squadron.wordpress.com/2013/06/22/r-c-harris-radar-operator/havoc-turbinlite/
 

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hesham

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Hi,

also Consolidated LB-8,LB-9,LB-12,LB-19 & LB-20 were involved.
 

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