Subject: Bomber Series--Curtiss B-2 Condor

From: [email-masked] (joseph.f.baugher)
Date: 13 Jun 94 21:32:35 GMT

The Curtiss XB-2 (26-211) was a direct development of the Curtiss-built 
Martin MB-2 (NBS-1) through the two Curtiss XNBS-4s.  Steel tubing was 
used instead of wood for fuselage construction.  Curtiss Conqueror 
liquid cooled engines were used in place of the war-surplus Liberty 
engines, and the thicker Curtiss C-72 airfoil was used.  

A single XB-2 prototype was ordered by the Army in 1926.  The serial 
number was 26-211.  First flight of the XB-2 took place in September 
1927.  The Conqueror engines were housed inside nacelles mounted on 
top of the lower wing.  The engines were cooled by rather angular 
radiators which jutted up vertically from each nacelle.  Like the NBS 
from which it had evolved, the XB-2 had twin rudders with twin 
horizontal stabilizers, which was a rather old-fashioned arrangement 
even by the standards of 1927.  One of the more unusual innovations 
introduced by the XB-2 was the addition of a defensive gunner position 
in the rear of each nacelle.  It was hoped that this arrangement would 
offer a clearer field of fire for the gunners than the more 
conventional fuselage-situated positions.  A similar arrangement was 
fitted to the competing Keystone XB-1B.  

The XB-2 found itself in competition against the Keystone XB-1B, the 
Keystone XLB-6, the Sikorsky S-37B, and the Atlantic-Fokker XLB-2.  
When an Army board of review met in February of 1928 to decide which 
design was to be awarded a contract, they immediately ruled out the 
XB-1B, the XLB-2, and the S-37.  However, the Board were unable to 
decide between the XB-2 and the XLB-6.  The XB-2 had the better 
performance, but the XLB-6 was cheaper.  In a split decision, the 
Board opted for the Keystone design, but on June 23, 1928 Curtiss was 
given a contract for two B-2s (28-398/399).  A further ten examples 
were ordered in 1929 (serials were 29-28/37).  

The twelve production B-2s were delivered from May 1929 to January 
1930.  Notable differences from the XB-2 included the use of 
three-bladed propellers and somewhat shorter and wider radiators 
mounted on top of the engine nacelles.  A machine gunner was housed in 
the rear of each engine nacelle.  A pair of Lewis machine guns was 
provided for each gunner, with an additional pair being mounted in the 
nose.  

One B-2 (serial number 29-30) became B-2A when fitted with full dual 
controls.  

The advances in bomber design were so rapid that canvas-covered 
biplanes such as the B-2 rapidly became obsolete.  Consequently, the 
B-2 served only briefly with the Army, being taken out of service in 
1934.  The last B-2 was surveyed in July of 1936.  So far as I am 
aware, none survive today.  

Specification of the Curtiss B-2 Condor: 

Two 633 hp Curtiss V-1570-7 Conqueror liquid-cooled engines.  Maximum 
speed 132 mph at sea level, 128 mph at 5000 feet.  Cruising speed 114 
mph, landing speed 53 mph.  Service ceiling 17,100 feet, absolute 
ceiling 16,400 feet.  Initial climb rate 850 feet per minute.  An 
altitude of 5000 feet could be attained in 6.8 minutes.  Range was 780 
miles with 2508 pounds of bombs.  Empty weight 9039 pounds, gross 
weight 16,516 pounds.  Wingspan 90 feet, length 47 feet 6 inches, 
height 16 feet 3 inches, wing area 1499 square feet.  Armed with two 
Lewis machine guns in each of the gunner positions at the rear of the 
engine nacelles, plus an additional pair of Lewis guns in the nose 
position.  Bombload was normally 2508 pounds, but could be increased 
to 4000 pounds on short flights.  

Sources:

  Curtiss Aircraft, 1907-1947, Peter M. Bowers, Naval Institute
  Press, 1979.

  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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