|Keystone Y1B-4 (S/N 30-281)|
|Primary user||United States Army Air Corps|
|Number built||5 Y1B-4|
|Developed from||Keystone B-3|
Originally ordered by the United States Army Air Corps as the LB-13 light bomber. When the LB- designation was dropped in 1930, the first five planes were redesignated Y1B-4. (The Y1B- designation indicates that funds for the design did not come from the normal annual funds.)
The first B-3A (S/N 30-281) was converted to Y1B-4 configuration with the addition of R-1860-7 radial engines and low pressure tires. Because of more powerful engines, the performance of the Y1B-4 was a slight improvement on the B-3, but the only difference between the two planes was their engines. On April 28, 1931, the army ordered 25 improved Y1B-4s as the Keystone B-4A. This production version was part of the last biplane bomber order made by the Army Air Corps (along with 39 B-6As, identical in all respects except their make of engine), and the B-4As, delivered between January and April 1932, were the last biplane bombers delivered to the Air Corps.
B-4 was the last of the Keystone biplane bombers ordered by the U.S. Army in late 1931. These aircraft were used primarily as observation and reconnaissance aircraft as early as 1934 when the Martin B-10B went into operational service. Some remained in service into the early 1940s.
Keystone Aircraft Corporation was an early pioneer in airplane manufacturing. Headquartered in Bristol, Pennsylvania, it was formed as Ogdensburg Aeroway Corp in 1920 by Thomas Huff and Elliot Daland, but its name was quickly changed to Huff-Daland Aero Corp, then to the Huff-Daland Aero Company. The company made a name for itself in agricultural aircraft, and then in the United States Army Air Corps' early bomber aircraft. From 1924, James McDonnell was the chief designer.
In 1926, Huff left the company, and it was soon purchased by Hayden, Stone & Co., who increased capital to $1 million (United States) and renamed it Keystone. In 1928, it merged with Loening and was known as Keystone-Loening. In 1929, it was taken over by Curtiss-Wright. Also in 1929, the Keystone- Loening plant on the East River in New York City was closed by Curtis- Wright and the operation was moved to the Bristol, Pa. Keystone plant. A small band of the top Loening management, design and shop workers (all New Yorkers) did not want to go to Bristol. They instead started their own aircraft company in a small rented shop in Baldwin, NY in Jan. 1930. The principal players were Leroy R. Grumman, Leon "Jake" Swirbul and William Schwendler. Grumman Aircraft went on to stellar heights with some of the top Naval aircraft in Navy history. Grumman also designed and built the Lunar Excursion Module (LEM) that landed US astronauts on the moon. Keystone itself became a manufacturing division of Curtiss-Wright and ceased production in 1932.Lieut. Comdr. Noel Davis and Lieut. Stanton H. Wooster were killed in their Keystone Pathfinder American Legion while conducting a test flight, just days before they were to attempt a trans-Atlantic flight for the Orteig Prize.Keystone B-3
The Keystone B-3A was a bomber aircraft developed for the United States Army Air Corps by Keystone Aircraft in the late 1920s.Keystone B-5
The Keystone B-5 is a light bomber made by the Keystone Aircraft company for the United States Army Air Corps in the early 1930s. The B-5A was a Keystone B-3A with Wright Cyclone rather than Pratt & Whitney engines.Keystone B-6
The Keystone B-6 was a biplane bomber developed by the Keystone Aircraft company for the United States Army Air Corps.