Subject: Keystone LB-7

From: [email-masked] (joseph.f.baugher)
Date: 4 Jun 94 19:55:05 GMT

The Keystone LB-7 was identical to the LB-6 except for the replacement 
of the Wright Cyclones by Pratt & Whitney R-1690-3 Hornet radials.  16 
production LB-7 aircraft were delivered to the USAAC between February 
and June of 1929.  Serials were 28-388/395 and 29-001/010.  

The Cyclone-powered LB-6s could be externally distinguished from the 
Hornet-powered LB-7s by looking at the exhaust collector rings on 
their engines.  The Hornet had exhaust collector rings AHEAD of the 
cylinders, whereas the Cyclone had exhaust collector rings BEHIND the 
cylinders.  The aircraft were otherwise externally identical.  

The LB-7 actually preceded the LB-6 into service.  The LB-7 served 
alongside the LB-6 with the 2nd Bomb Group based in the US, plus the 
5th Composite Bomb Group based in Hawaii.  Like the LB-6, the LB-7 was 
known as *Panther* by Keystone, but this was not an official USAAC 
name.  

Specification of the Keystone LB-7: 

Two 525 hp Pratt & Whitney R-1690-3 Hornet alr-cooled radial engines.  
Maximum speed 114 mph at sea level, 110 mph at 5000 feet.  Cruising 
speed 95 mph.  Landing speed 55 mph.  Service ceiling 13,325 feet, 
Absolute ceiling 15,700 feet.  Initial climb rate 660 feet per minute 
An altitude of 5000 feet could be attained in 9.1 minutes.  Range 432 
miles with 2000 pounds of bombs.  Weights: 6556 pounds empty, 12,903 
pounds gross.  Wingspan 75 feet, length 43 feet 5 inches, height 18 
feet 1 inches, wing area 1148 square feet.  Two Lewis machine guns in 
an open gunner's position in the nose, two Lewis machine guns in an 
open dorsal gunner's position, one Lewis gun firing downward through 
an opening in the lower fuselage.  

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

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