Northrop BT Series bomber
The BT-1 was a pre-war dive bomber used by the US Navy. It was a product of the first Northrop air craft company, formed by John Northrop in 1932 with support from Douglas Aircraft.
The XBT-1 was designed in 1934 in response to a navy request for a dive bomber. It was a low wing monoplane, of all metal construction apart from fabric covered control surfaces. The prototype was powered by a 700hp Pratt & Whitney R-1535-66 Twin Wasp Jr. engine, later replaced by a 825 hp R-1535-94. Powered by the latter engine the BT-1 was capable of carrying a 1000lb bomb, had a service ceiling of 22,500ft and a top speed of 212 mph.
The US Navy placed an order for 54 BT-1s in 1936. The aircraft entered service during 1938, and served on the USS Yorktown and USS Enterprise. The aircraft was not a success in service. It had poor handling characteristics, especially at low speeds, a fatal flaw in a carrier based aircraft. It was also prone to dangerously unexpected roles. A number of aircraft were lost in crashes.
Aware of the failings of the BT-1, Northrop soon began work on an improved XBT-2. The new aircraft was given a more powerful Wright XR-1820-32 Cyclone engine, providing 1,000 hp, combined with a redesigned control system. It first flew on 25 April 1938, but was not a significant improvement on the BT-1. Northrop flew his aircraft to NACA to use their full sized wind tunnel.
Six months of tests followed, resulting in a significantly better aircraft. However, during this process Northrop resigned from his company, which by now was a fully owned subsidiary of Douglas. The new aircraft was thus given the designation XSBD-1 (eXperiment, Scout Bomber, Douglas). It would go on to be the most successful American dive bomber of the war, named the Dauntless. Northrop would also go on to greater success, founding Northrop Aircraft Inc. in August 1939.