In 1934, the Curtiss company began work on a two-seat, twin-engined attack aircraft. The aircraft was known as Model 76 by the company. It was a twin-engined aircraft with a cantilever mid-mounted wing. The aircraft was of all-metal construction but with fabric covering for the moveable control surfaces and on the wing aft of the front spar. The pilot sat well forward underneath a sliding canopy, whereas the observer/gunner sat well to the rear underneath his own sliding canopy.
All three undercarriage members retracted rearward, leaving half of each wheel exposed. The Model 76 was powered by a pair of Wright R-1670-5 twin-row radial air-cooled engines housed underneath circular cowlings and driving twin-bladed two-position propellers.
The short nose had four 0.30-inch machine guns, and a single flexible 0.30-inch machine gun in the rear cockpit. Bombs were carried internally in a fuselage bomb bay.
The aircraft took off on its first flight on July 17, 1935. Since it was a company-owned demonstrator, the Model 76 carried a civil registration of X15314. It was tested by the Army at Wright Field in Ohio, and then returned to Curtiss for modifications. These modifications included a change in engine cowling shape and the installation of new constant-speed propellers. In December of 1935, the Army purchased the Model 76 under the designation XA-14. The serial number was 36-146.
Although the maximum speed of 254 mph made the XA-14 ten mph faster than the contemporary Consolidated P-30 two-seat fighter and 20 mph faster than the Boeing P-26A single-seat fighter, the Army was reluctant to enter into any large-scale contract for the A-14 because of its high cost. In depression-ridden America, the $90,000 (without engines) pricetag on each A-14 made it much too expensive for a large scale order. Nevertheless, thirteen service test examples were ordered on July 23, 1936. They were powered by single-row Wright R-1820-47 Cyclones driving three-bladed propellers. As was typical in those days, the change of engine resulted in a change of designation, to Y1A-18. Despited the added power, increased weight cut the top speed of the Y1A-18 to 238 mph, although the range was improved.
Deliveries of the Y1A-18 began in July 1937 and were completed by October. The Y1A-18s served initially with the 8th Attack Squadron of the Third Attack Group at Barksdale Field, Louisiana. The chief drawback of the Y1A-18 was its small bomb load (only 670 pounds), plus the fact that the aircraft could not easily be reconfigured for less range with a higher load. The armament was fairly light, the Y1A-18 relying on speed rather than armament to evade interceptors. However, the advances in aircraft design were so rapid that the Y1A-18 rapidly became obsolescent and its performance no longer adequate to escape interception. In 1940, the Y1A-18s were transferred to the Third Bombardment Group at Lawson Field for operational training as plain A-18s. They saw no combat, and the last A-18 was withdrawn from service in 1943.
An improved Model 76B with Pratt & Whitney R-1830 engines was proposed to the Army, but was not accepted. Curtiss also proposed a Model 76B for export, but no customers materialized, probably because of its high cost.
37-052/064 Curtiss Y1A-18 c/n 12187/12199
Engines: Two Wright R-1820-47 Cyclone air-cooled radials, each rated at 930 hp
for takeoff and 850 hp at 2500 feet.
Performance: Maximum speed 239 mph at 2500 feet. Cruising speed 211
mph. Landing speed 73 mph. Service ceiling 28,560 feet, absolute
ceiling 30,000 feet. An altitude of 5000 feet could be attained in
2.2. minutes. Range 1443 miles with 654 pounds of bombs. 1700 miles
Dimensions: Wingspan 54 feet 5 inches, length 41 feet 0 inches,
height 11 feet 6 inches, wing area 526 square feet.
Weights: 9580 pounds empty, 12,849 pounds gross, 13,170 pounds
Armament: Four fixed 0.30-inch forward-firing machine guns in the
nose, plus one flexible 0.30-inch machine gun in the rear cockpit. A
maximum internal bomb load of 654 pounds could be carried.