Northrop Gamma 7A twin-engined attack bomber

hesham

hesham

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Also from that great site;
http://www.aerofiles.com/_north.html

The Northrop Gamma 7A was a twin engined attack bomber version
of Gamma,it was never built.
 
So if it wasn't built and there is no dat or picture of it, why create a topic for it? :-\

(just to add a bit to it, the 7A probably evolved into the the 7B, which was by then a Douglas El Segundo model).
 
The Northrop line became the Douglas El Segundo line when Northrop sold the company to Douglas (and moved on to create a new Northrop company).
The Gamma 8 became the Douglas Model 8 (USAF A-33)... Quite logically the Gamma 7 became the Douglas Model 7! Of course, these Model numbers were not standard Douglas designations.
 
Apparently a 3-view drawing of the Northrop 7A concept exists. Anyone have access to the San Diego Air & Space Museum?

http://www.sandiegoairandspace.org/library/pdf/RolledDrawingIndex.pdf
Northrop Model 7A RD0157 Layout, General Information, 3-view drawing Blueprint 38" X 57" 1937.

Airpower (Jan 2002), "Ed Heinemann & The Legend Of The Skyraider", hints at the 7A's layout:

"Early in 1937 Ed Heinemann became project engineer on what had been John Northrop's last effort for Douglas, the Model 7A twin engined attack bomber. As conceived by Northrop, the design was too small and greatly underpowered for its chosen mission. Ostensibly working under a senior manager, but actually in charge of the redesign, Heinemann completely changed the layout with a major overhaul of the 7A on which work had been suspended. Although he retained Northrop's high-wing configuration, almost everything else was new in the resultant 7B. But it, too, was again reconfigured to meet more demanding requirements, before becoming the DB-7 for foreign air arms and the A-20 Havoc in U.S. service."
 
Hi Apophenia,

There was an error finding /library/pdf/RolledDrawingIndex.pdf. ??? ??? ???
 
Yep. I agree. However I can testify that this link used to work until quite recently. It seems like all the linked documents from this museum's site have gone missing recently, I happened on the same error page this very week a few times myself.
 
From 'Combat Aircraft Designer', pp.55-7,

"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.
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."
(my bold)

cheers,
Robin.
 
...There was also an observation variant planned
with a largely glazed lower fuselage...

from :Douglas Havoc and Boston-the DB-7/A-20 series.
Scott Thompson-Crowood Aviation Series.
 
Sorry, I got to that pdf through Google 'Quick View' (I'd assumed that my problem with the pdf was due to my antiquated OS).

Baugher says that the Model 7A "was a two-seater" -- other sources say 3-seater. He goes on to say that 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.

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."

http://www.joebaugher.com/usattack/a20_1.html
 

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