The MB-2 bomber was ordered by the USAAS in June 1920 with view to carry a larger load than its predecessor the MB-1. On the MB-1, two Liberty engines that were suspended between the wings by a system of struts, while on the improved MB-2, the twin Liberty were lowered to sit inside the nacelle attached to lower wing.

 The MB-2 was designed specifically as a night bomber but sacrificed the high speed and manoeuvrability of the MB-1 for a greater bomb load. Ten MB-2s were built by Glenn L.Martin in Cleveland. These were redisignated NBS-1 when the new designation system scheme was reintroduced. Their serials were 64195-64214. The MB-2 is best remembered today as being the aircraft, which participated, in the famous Billy Mitchell demonstration of July 21^st 1921 when the ex-German battle cruiser Ostfreisland was sunk by aerial bombardment using special 2,000 lb bombs used for the test.

 A competitive bid in 1921 resulted that the Curtiss Company underbid the Glenn L.Martin Co. for the production of 50 examples of NBS-1. Other contracts for 35 other NBS-1 granted to LWF (Lowe, Willard & Fowler) Engineering Company of College Point, New York, and a contract for 25 more granted to Aeromarine Plane and Motor Co. of Keyport, New Jersey.

 The last 20 Curtiss built NBS-1 bombers were equipped with General Electric turbo superchargers and these were the first aeroplanes to use turbo superchargers in production quantities. Being so equipped the NSB-1 could reach an altitude of 25,300 ft. Eventually the use of superchargers in bombers proved to be premature and notoriously unreliable and practical application of turbo superchargers to bombers came many years later in 1939 on B-17B.

 Eight Army bombing squadrons that used the NBS-1 were the 11^th, 20^th, 49^th,and the 96^th Sq. No 2 Bombing Group based at Langley Field in Virginia; the 23^rd and 72nd Sqd with the 5^th Composite Group in Hawaii; and the 28^th Sq with 4^th Composite Group in the Philippines. They remained in service until replaced by Keystone bombers in 1928-29.

 The NBS-1 (MB-2) had a maximum sped of 99 mph at sea level, a cruising speed of 92 mph, landing speed of 59 mph. It had a service ceiling of 8,500 ft, maximum ceiling 9,200 ft. A range of 400 miles with a bomb load of 2,000 lbs. Wing span was 74’2”, length of 42’8” and a height of 14’8”.

 

The MB-2 bomber by Glencoe is a reissued kit and although I bought it from the model shop at Flinders Street, Melbourne in 1997 the instructions date back to 1988, which is apparently the time when Glencoe Company acquired the moulds. Box states that the kit is to 1/72 scale but in reality it worked to a scale of 1/74 upon checking. The kit is moulded in dark green plastic, rather heavy thick sections by today’s kit standard but the parts are almost free of flash. External detail on kit parts consist of rather heavy rib detail and rivet detail on the fuselage. As for interior detail this is very sparse with plain bulkheads and floors. Crews are provided and I elected to place them on the aircraft for two reasons: they give indication of size of aircraft and secondly there is lack of interior detail which apart from being hard to find reference material then the pilot and seat as well as other crew members take much of the available space and interior detail even if ever added would be obscure.

 

 

 The first step in building the model is to connect the fuselage halves together, which is followed by assembling the wing both of which are two-part assembly. When the lower half is fitted within the leading edge and the trailing edges it leaves a joint line that is filled in with putty and carefully rubbed and smoothened sown. This is no difficult task as the ribbing detail is only on the upper side and I have my doubts if the under side contained no ribbing on the real aircraft. The tail plane is a single moulding and two fins and rudders are fixed on it. The sub assembly is then fitted to the fuselage.

Now is the step to place the struts on lower wings. These were somewhat cumbersome and needed to reduce in size before struts are in place. Rigging holes are now drilled on the wings. Unfortunately there are no rigging details on the instructions and the box art cover only provided partial detail in this respect since the close up picture only shows the front of the aircraft and part of main wings. So I made reference to “US ARMY and Air Corps Guide” Vol 1. Leaving the rigging detail for a while I turned my attention to assembling the engines which are mounted on the lower wing. The exposed engine detail was to create a contrast in colour finishes with the rest of the aircraft. This was painted at this stage followed by a somewhat tedious masking job that would need to be removed little by little in the end once the kit and rigging were complete. Exhausts of engine were added as per artwork as these were not supplied.

 The huge biplane contains 12 whole struts positioned vertically over the wings and around 24 half struts fitted around the engine nacelles and over the fuselage bay area. This is a complex assembly by itself but one should consider that the main structure is moulded in two sections with just the connecting struts being the separate items. With all the struts set in place the upper wing was then lowered and secured on the struts. The outer wing struts consisting of two pairs in all were then slotted into the locating holes. It was then the turn to assemble the undercarriage. The wheels are enclosed in a fairings which are supported by Vee struts with the wheel and axle suspended in holes in the inner side of the fairing. In view of this situation I had to paint the wheels before these were inserted in the undercarriage housing.

 

Looking hindsight I should recall that masking, painting and rigging needed some good planning in using the most promising sequence. I always prefer to use the invisible thread method of rigging and only the lack of detail of rigging layout caused some delay and the job was carried out little by little. Wires were fitted to side control brackets; again these were on the heavy side and were reduced in size and reshaped by filing. Another extra work was adding a wind screen frame with Krystal Kleer added to, modified the guns, added struts to wheel mud guards and adding some minor cockpit detail. Model was finished in a lighter shade of olive drab overall having as semi gloss sheen. Decals adhered well and other refinements added to paintwork of prop hubs, crew figures, elevator control wires and so on.

 

 My Martin MB-2 represents a bomber belonging to the 11^th Bombardment squadron, which continued in service until 1928 and carries an ID No 42. This was a pleasant kit to build and at the same a challenge in some respects, but definitely not the type to complete a whole squadron of them.

 

 

 

US Military Aircraft since 1909 (Swanborough & Peter M.Bowers)

 Curtiss Aircraft 1907-1947 by Peter M.Bowes. Naval Institute Press 1979

 

August 2006