Subject: Bomber Series--Huff-Daland/Keystone XLB-3

From: [email-masked]
Date: 1 Jun 94 16:39:02 GMT

>From [email-masked]

The Huff-Daland XLB-3 was the first example of the twin-engined 
Huff-Daland/Keystone bombers.  The Huff-Daland LB-1 three-seat biplane 
bomber of 1923 had been powered by a single enormous 800 hp Packard 
2A-2540 V-12 water-cooled engine instead of the more traditional pair 
of lower-powered engines.  Ten examples were delivered to the Army.  
However, the Army found the single-engined format to be 
unsatisfactory, and decided to revert to a more conventional 
twin-engined format.  

In response to this need, the Huff-Daland company submitted the XLB-3.  
A single example was ordered by the Army.  The serial number was 
27-333.  The Huff-Daland XLB-3 was powered by a pair of experimental 
air-cooled and inverted Liberty V-1410-1 engines mounted on top of the 
leading edges of the lower wing, one on each side.  The single 
vertical rudder of the LB-1 was supplemented by a pair of smaller 
vertical rudders mounted outboard on the horizontal tailplane.  A crew 
of five was carried, with the two additional members being housed in 
the nose gunner and bombardier positions.  The XLB-3 was designed in 
parallel with the Huff-Daland LB-5, which had the same overall format 
but was powered by a pair of ordinary water-cooled upright Liberty 
engines.  

By that the time that the XLB-3 appeared in December of 1927, the 
Huff-Daland company had been reorganized as the Keystone Aircraft 
Corporation and had moved its headquarters to Bristol, Pennsylvania.  
The experimental Liberty engine installation in the XLB-3 proved to be 
unsatisfactory, and before the first flight could take place the 
Liberty engines were replaced by a pair of 410 hp air-cooled Pratt & 
Whitney R-1340-1 radial engines.  The engine change caused a 
designation change to XLB-3A.  

The performance of the XLB-3A was actually poorer than that of the 
single-engined LB-1 that it was designed to replace, and no production 
examples were ordered.  However, the parallel LB-5 project was to 
prove more successful, and was the first of Keystone's successful 
biplane bombers.  

Specification of the Huff-Daland XLB-3A: 

Two 410 hp Pratt & Whitney R-1340-1 air-cooled radials.  Maximum speed 
116 mph at sea level, 113 mph at 5000 feet.  Cruising speed 93 mph.  
Landing speed 59 mph.  Service ceiling 11,210 feet, Absolute ceiling 
13,700 feet.  Initial climb rate 550 feet per minute.  An altitude of 
5000 feet could be attained in 11.3 minutes.  Range 544 miles.  
Weights: 6065 pounds empty, 11,682 pounds gross.  Wingspan 67 feet, 
length 45 feet, height 16 feet 10 inches, wing area 1138.7 square 
feet.  

Sources:

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

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

Joe Baugher		AT&T Bell Laboratories   	
263 Shuman Boulevard 		Naperville, Illinois 60566-7050