Subject: Bomber Series--Keystone B-6

From: [email-masked] (joseph.f.baugher)
Date: 16 Jun 94 22:48:03 GMT

In 1930, seven Keystone bombers were ordered under the designation 
LB-13.  They were to be equipped with single vertical tails and were 
to be powered by a pair of 525 hp Pratt & Whitney GR-1690 radials.  
Serials were 30-344/353.  In 1930, the USAAC abandoned its separate 
designation categories for light (LB) and heavy (HB) bombers, and 
classified them both under the B category.  Of seven LB-13s ordered, 
five were completed as Y1B-4s with 575 hp Pratt & Whitney R-1860-7 
Hornet engines (30-344/348) and the other two were completed as Y1B-6 
with 575 hp Wright R-1820-1 Cyclone engines (30-349/350).  Three more 
Wright-powered Y1B-6s were produced by conversion from production 
Pratt & Whitney-powered B-3As The serials of these planes were 
30-351/353.  

On April 28, 1931, the Army ordered 39 B-6A bombers.  The B-6A was an 
improved production version of the Y1B-6.  At the same time, the Army 
ordered 25 B-4As, which were similar but were powered by Pratt & 
Whitney Hornets.  Despite their later sequence number, the 
Cyclone-powered B-6As were delivered first, being manufactured from 
August 1931 to January 1932, with the Hornet-powered B-4As being 
delivered from January to April of 1932.  Both the B-4 and the B-6 had 
three-bladed propellers.  They could be distinguished from each other 
by the engine exhaust rings, which were in the front on the 
Cyclone-powered B-6 and in the rear on the Hornet-powered B-4.  The 
two planes were otherwise almost completely identical.  

The B-6A served with the 20th, 49th and 96th Squadrons of the 2nd Bomb 
Group based at Langley Field, Virginia.  

Well over 200 Keystone biplane bombers were built.  Only 120 of them 
served in the continental USA, the remainder being deployed in Hawaii, 
the Philippines, and in the Canal Zone.  

Several Keystone bombers took part in the National Air Races.  They 
also performed as mail carriers during the few months in 1934 when the 
Army took over the flying of the air mail.  

A few B-6As were still in service when World War 2 began, but none saw 
any action.  

30-349/353 	Keystone Y1B-6 
32-142/180 	Keystone B-6A 

Specification of the Keystone B-6A: 

Two 575 hp Wright R-1820-7 Cyclone air-cooled radial engines.  Maximum 
speed 121 mph at sea level, 116mph at 5000 feet.  103 mph cruising 
speed.  Landing speed 57 mph.  Initial climb rate 690 feet per minute.  
An altitude of 5000 feet could be reached in 8.6 minutes.  Service 
ceiling 14,100 feet, absolute ceiling 16,500 feet.  Range 363 miles 
with 2500 pounds of bombs, maximum range 855 miles.  Weight: 8057 
pounds empty, 13,334 pounds gross.  Wingspan 74 feet 8 inches, length 
48 feet 10 inches, height 15 feet 9 inches, wing area 1145 square 
feet.  Armed with three Browning machine guns, one in each of nose, 
dorsal, and ventral positions.  A bomb load of 2500 pounds could be 
carried.  

Sources:

  United States Military Aircraft Since 1909, Gordon Swanborough and
  Peter M. Bowers, Smithsonian, 1989.

  American Combat Planes, Ray Wagner, Third Edition, Doubleday, 1982.

  American Warplanes, Bill Gunston

  Jane's Encyclopedia of Aviation

  U.S. Army Aircraft, 1908-1946, James C. Fahey

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