Subject: Bomber Series--Keystone B-3A

From: [email-masked]
Date: 16 Jun 94 02:21:32 GMT

>From [email-masked]

The 17th production Keystone LB-6 on the 1929 contract (29-027) was 
completed as the LB-10.  The LB-10 differed from the LB-6 in being 
powered by by a pair of experimental 525 hp Wright R-1750-1 Cyclone 
radial engines, plus it had a single rudder in place of the twin 
rudders which Keystone had standardized on the LB-5A.  

The single-rudder adaptation introduced by the LB-10 impressed the 
USAAC, and 63 examples were ordered under the designation LB-10A.  
Serials were 30-281/343.  The LB-10A differed from the LB-10 in being 
powered by a pair of Pratt & Whitney R-1690-3 radials.  The LB-10A had 
a slightly smaller wingspan and had a slightly shorter fuselage, but 
was otherwise similar to the LB-10.  

However, before the first LB-10A could be delivered, the USAAC had 
dropped the LB designation and was listing all of its bombers under 
the B series.  The LB-10A was redesignated B-3A.  

The first B-3A was delivered in October of 1930.  The B-3A carried a 
crew of five--pilot, copilot, bombardier, front and rear gunners.  The 
sixty-three B-3A bombers ended up serving with the 6th Composite Group 
based in the Canal Zone and the 4th Composite Group based in the 
Philippines.  In addition, the 19th Bomb Group was activated in June 
1932 with nine B-3As.  

The Keystone B-3A of the early 1930s was not very much faster than the 
biplane bombers that flew during the First World War.  It would seem 
at first sight, then, that the state of the art had not advanced very 
far in the past fifteen years.  However, performance was not the 
entire story--the Keystone bombers were far more safe and much more 
reliable than the Handley Page, Gotha, or Friedrichshafen bombers of 
World War 1.  

In May of 1932, a group of B-3A biplane bombers flew down the 
Hudson River to parade above New York City in a display of America's 
aerial strength.  At that time, this parade of lumbering Keystone 
bombers represented virtually the entire bomber strength of the Army 
Air Corps.  

30-281/343 	Keystone B-3A 

Specification of the Keystone B-3A: 

Two 525 hp Pratt & Whitney R-1690-3 Hornet air-cooled radial engines.  
Maximum speed 114 mph at sea level, 109.5 mph at 5000 feet.  Cruising 
speed 98 mph.  Landing speed 56 mph.  Service ceiling 12,700 feet.  
Initial climb rate 650 feet per minute.  An altitude of 5000 feet 
could be attained in 9.4 minutes.  Range was 860 miles.  Weight: 7705 
pounds empty, 12,952 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

Joe Baugher		AT&T Bell Laboratories   	
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