Subject: Bomber Series--Martin MB-2

From: [email-masked] (joseph.f.baugher)
Date: 22 May 94 03:42:59 GMT

An improved version of the Martin MB-1, the MB-2, was ordered by the 
USAAS in June of 1920.  This model had new and larger wings that were 
intended to enable it to carry a heavier bomb load.  In the MB-1, the 
Liberty engines were suspended between the wings by a system of 
struts, but on the MB-2, the twin Liberty engines were lowered to sit 
inside nacelles attached to the lower wing.  As compared to the MB-1, 
the landing gear was simplified to only two wheels.  The non-staggered 
wings were hinged at the rear spars just outboard of the engines, and 
could be folded aft for storage.  The armament consisted of five Lewis 
machine guns, two in the front cockpit, two in the rear, and one aimed 
downwards and to the rear.  A crew of four could be carried.

The MB-2 was designed specifically as a night bomber, and sacrificed 
the high speed and maneuverability of the MB-1 for a greater bombload.  
Ten MB-2s were built by the Glenn L. Martin company in Cleveland, and 
were redesignated NBS-1 when the new Army designation scheme was 
introduced.  Their serials were 64195/64214.  These planes are best 
remembered today as being the aircraft which participated in the 
famous Billy Mitchell demonstration of July 21, 1921 in which the 
ex-German battle cruiser *Ostfreisland* was sunk by aerial 
bombardment.  Special 2000-pound bombs had to be designed for the 
test.  

Martin proposed to the Army that 50 more NBS-1 bombers be built.  
However, under the prevailing policy of the time, the rights to the 
NBS-1 design were owned by the Army rather than by Martin.  
Consequently, the Army had the right to ask for competitive bids on 
the project from other manufacturers.  In 1921, Curtiss underbid the 
Glenn L. Martin Co. for the production of 50 examples of the NBS-1.  
In order to spread scarce military procurements among as many 
manufacturers as possible, contracts for 35 other NBS-1s were granted 
to the L.W.F. (Lowe, Willard, and Fowler) Engineering Company of 
College Point, New York and a contract for 25 more was granted to the 
Aeromarine Plane and Motor Co. of Keyport, New Jersey.  

The last 20 Curtiss-built NBS-1 bombers were equipped with General 
Electric turbosuperchargers.  These were the first airplanes to use 
turbosuperchargers in production quantities.  With these 
turbosuperchargers, the NBS-1 could reach a service ceiling of 25,341 
feet.  However, the use of turbosuperchargers in bombers proved to be 
premature, the early superchargers being notoriously unreliable.  
Practical application of turbosuperchargers to bombers did not take 
place until the B-17B of 1939.  

Eight Army bombing squadrons used the NBS-1--the 11th, 20th, 49th and 
96th Squadrons with the 2nd Bomb Group based at Langley Field in 
Virginia, the 23rd and 72nd Squadrons with the 5th Composite Group in 
Hawaii, and the 28th Squadron with the 4th Composite Group in the 
Philippines.  They remained in service until replaced by Keystone 
bombers in 1928-29.  

Serials of MBS-1: 

Martin MB-2 		64195/64214 
L.W.F. NBS-1 		68437/68471 
Curtiss NBS-1 		68478/68527 
Aeromarine NBS-1 	22-201/225 

Specification of NBS-1: 

Two 420hp Liberty 12 liquid-cooled Vee engines.  Maximum speed 99 mph 
at sea level.  Cruising speed 92 mph.  Landing speed 59 mph.  Initial 
climb rate 391 feet per minute.  Service ceiling 8500 feet.  Maximum 
ceiling 9900 feet.  Range 400 miles with 2000 pounds of bombs.  
Maximum range 558 miles.  Wingspan 74 feet 2 inches, length 42 feet 8 
inches, height 14 feet 8 inches, wing area 1121 square feet Armament 
consisted of five 0.30-inch machine guns.  An internal bombload of up 
to 1800 pounds could be carried.  Instead of the internal bombload, an 
external bombload of up to 2000 pounds could be carried.  

Sources: 

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

  American Combat Planes, Ray Wagner, Doubleday, 1982.  

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

Joe Baugher			**************************************
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