Captain Jack (Updated: 5/12/2015):
Army officials preferred to stay away from more complex twin-engined designs and favored development of a single-engine, monoplane wing form utilizing a crew of two or three. Defensive armament was a must to help defend what would most likely be a slow-moving airplane. Several initiatives were pushed including the Douglas A-17, the Curtiss A-18, and the Vultee A-19 though none were winners in the Army search until the service took on a small stock of U.S. Navy Douglas SBD "Dauntless" dive bombers in July of 1940. With a few revisions - namely the deletion of the carrier deck arrestor equipment and replacement of Navy radio kits - the SBD was reconstituted for the Army in the new A-24 "Banshee" form. While not the complete solution for the Army, the Banshee would suffice until a proper aircraft was adopted. The initial Army mark was the SBD-3 (SBD-3A) model of the Navy as the "A-24" and the Army order was absorbed into the existing Navy order of July 1940. Army versions also replaced the solid tailwheels with pneumatic types for land-based take-offs and landings.
As with other American dive bombers of the period, the aircraft featured perforated dive brakes along its wing trailing edges to slow its drop when attacking. Self-sealing fuel tanks were a must as was armoring for self-preservation of crew and aircraft. As with the SBD before it, the Banshee used a modest machine gun armament as standard: 2 x 0.50 caliber heavy machine guns were fixed into the cowling for operation by the pilot and 1 x 0.30 caliber medium machine gun was added to a flexible mounting at the rear cockpit for protecting the vulnerable "six" of the aircraft. Like the SBD, the Banshee carried a crew of two - pilot and gunner. The aircraft's bombload was set across three available hardpoints - one under fuselage centerline and one under each wing. A typical load was 1 x 500lb / 1,000lb bomb under centerline or 1 x 100lb bomb at each wing station.
The first Banshees arrived in U.S. Army hands for June of 1941 and these were outfitted with Wright R-1820-52 radial engines of 1,000 horsepower. The Banshee's initial assignment was with the 27th Bombardment Group (Light) of Hunter Field, Georgia and training began in earnest. Three squadrons were ultimately formed during the early part of the war.