The Martin Model 139 was a twin-engined mid-wing monoplane bomber developed from the experimental Model 123 of 1932. Introduced in 1934, Glenn Martin‘s B 10, the first American bomber with 200 plus mph speeds, revolutionized bomber development with retractable landing gear, cowled engines, all metal cantilever monoplane configuration, enclosed cockpit, internal bomb-bay and movable gun turrets.
During 1934 48 Model 139 were delivered to the USAAC. Fifteen were fitted with 503kW Wright R-1820 Cyclone engines as YB-10 and 33 with 577.5kW Pratt & Whitney R-1690 Hornet engines as YB-12 and B-12A, a number of which were later converted into twin-float seaplanes for coastal patrol duties.
Development of the Model 139 led to numerous improvements being made, including the installation of 551.4kW SGR- 1820-G3 Cyclone engines, a Sperry automatic pilot and the addition of wing flaps, constant-speed propellers, de-icers and numerous structural and maintenance refinements. During 1935 and 1936 103 of the improved aircraft (B-10B) were delivered to the USAAC.
The 1935 Martin 146 was an enlarged B-10 with two Wright R-1820 engines. With a widened fuselage, it was the first large airplane to use Fowler flaps. One was built for Wright Field testing, NX15550, plus exports as the B-10B. Licensed production in 1936 to Fokker Netherlands was never implemented and was replaced by an order for Model 139WH to use in the East Indies.
On 1 July 1936 the bomber was released for export and was subsequently ordered by six foreign governments, the Netherlands East Indies alone receiving 120 Model 139W and Model 166 with 670.7kW Cyclone engines. The Model 166 aircraft introduced improved aerodynamics and performance characteristics and featured a continuous cockpit enclosure instead of the previous separate enclosures.
In 1973 a B-10 was located in Argentina and obtained by the USAF. At Kelly Air Force Base, Texas, members of the 96th Maintenance Squadron were rebuilding it for display in the Air Force Museum.
Model 139 / YB-10 Engines: 2 x 503kW Wright R-1820 Cyclone
Model 139 / YB-12 / B-12A Engines: 2 x 577.5kW Pratt & Whitney R-1690 Hornet
Model 139 / B-10B Engines: 2 x 551.4kW Wright SGR-1820-33 Cyclone Propellers: constant-speed Top speed: 343 km/h / 212 mph Take-off weight: 7439 kg / 16400 lb Empty weight: 4391 kg / 9681 lb Wingspan: 21.49 m / 70 ft 6 in Length: 13.64 m / 44 ft 9 in Height: 4.70 m / 15 ft 5 in Wing area: 62.99 sq.m / 678.02 sq ft Ceiling: 7375 m / 24200 ft Range w/max.fuel: 2000 km / 1243 miles Armament: 3 x 7.62mm machine-guns, 1000kg of bombs Crew: 3
Model 139W Engines: 2 x 670.7kW Cyclone
Model 146 Engines: 2 x Wright R-1820 Wingspan: 75’0″ Length: 50’0″ Useful load: 5057 lb Max speed: 234 mph Cruise speed: 170 mph Range: 1237 mi
The Martin 130 was a large four-engined monoplane flying-boat designed for transoceanic services. Three were built for Pan American Airways in 1934-1935 and on 21 October 1936 began operating over the Pacific from San Francisco to Manilla, Philippine Islands.
The first designated flight engineer was required on the Martin M-130 ‘China Clipper’, flying boat. On the M-130, a separate cabin was constructed for the flight engineer, communication with the pilots being carried out via interphone. His principal responsibilities were supervision of aircraft maintenance on the ground, advising the flight crew of the aircraft maintenance status, and in-flight operation of the engines and aircraft systems. In the absence of flight time limitations, these engineers performed some prodigious feats of repair in addition to their normal functions.
Lateral buoyancy of the hull was provided by stub wings or ‘seawings’ instead of the conventional sponsons or outboard stabilising floats. Accommodation was provided for a crew of four and 36-48 daytime passengers or 18 sleeping bunks for night flying.
First flying in 1934, the four engine Martin Model 130 flying boat entered service on 21 October 1936 with Pan American Airways on the San Francisco Manila air route in 1935. The Martin Clipper carried 10 passengers on overseas flights with a range of 3,200 miles. The M-130 had a cruising speed of 163 mph, weighed 53,000 pounds when fully loaded, and a wingspan of 130 feet.
Engines: 4 x Pratt & Whitney R-1830-S1A4G Twin Wasp, 830 hp / 610kW Prop: three blade. Wing span: 130 ft 0 in (39.62 m). Length: 90 ft 71 in (27.62 m). Height: 7.3 m / 23 ft 11 in Wing area (incl. sponsons): 2,315 sq.ft (215.07 sq.m). Empty weight: 13160 kg / 29013 lb Gross weight: 52.000 lb (23,587 kg). Max. speed: 290 km/h / 180 mph Max cruising speed: 163 mph (262 kph) at 7000 ft (2,135m). Range: 3,200 miles (5,150 km). Crew: 4. Pax cap: 36 43 (18 in sleeper configuration). Ceiling: 5200 m / 17,000 ft.
The Glenn L. Martin Company produced the first successful twin-engined aeroplane of American design, as the W. F. Night Bomber or “Seven Ton” bomber (first flown on 15 April 1918). As it is generally accepted that the first bomber built for the USAAS was the MB-1, the view can be taken that the W.F. and MB-1 are one and the same.
The MB-1 bomber first flown 17 August 1918. Contemporary reports state that the W.F. was converted into the passenger and cargo-carrying Commercial type. Again it is known that one of the ten MB-1 was so converted, although a drawing of the Commercial made in 1921 shows a rounded-nose aircraft with folding outer-wing sections, single-wheel landing-gear units and open cockpit for the pilots, while the MB-1-type Commercial was actually produced with an enclosed cockpit. Nevertheless as features of the Commercial were subsequently to be found on the improved MB-2 bombers, including the revised single- instead of double-wheel landing gear units, it can be taken that the W.F. Commercial and MB-1-type Commercial or T-1 were the same aircraft. All but one of the remaining MB-1 were produced as bombers or observation aircraft, followed by four more military MB-1 for US Government air mail services. A further two were produced as torpedo bombers for the US Navy, which designated them MTB-1.
In 1921, Martin produced its KG.1 variant of the MB-1, designed as an antiship torpedo bomber under the designation MBT. As an interim stage between the MB-1 and the later MB-2, Martin produced the MT-1 extended-wing torpedo bomber, eight of which were operated by the US Marine Corps. The MB-2 itself was powered by 313kW instead of 298kW Liberty engines and had the wing span of the MT-1 and the landing gear of the Commercial. The NBS-1 was a wood-and-canvas biplane without staggered wings, employing twin rudders on a twin vertical tail.
The first 20 (five MB-2 and 15 NBS-1) were ordered from the Martin Company by the USAAS in June of 1920. 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 0.50-in machine guns, two in the front cockpit, two in the rear, and one aimed downwards and to the rear. Bombs were carried in racks in a compartment in the fuselage, or, in the case of large bombs, on special racks or chocks directly under the fuselage. A crew of four could be carried. The NBS-1 also had a unique folding-wings system, hinged outside the engine nacelles to fold backwards for storage in small hangars.
The first flight of the MB-2 (serial number AS 64195) took place on September 3, 1920. 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 aerial bombardment.
The NBS-1 was the primary bomber used by Brigadier General Billy Mitchell during Project B, the demonstration bombing of naval ships in July 1921. Six NBS-1 bombers, led by Captain Walter Lawson of the 96th Squadron operating out of Langley Field, bombed and sank the captured German battleship SMS Ostfriesland on 21 July 1921, using specially-developed 2,000 lb (907 kg) demolition bombs externally mounted beneath the fuselage. Other MB bombers and flying-boats destroyed a submarine, cruiser and destroyer.
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. One XNBS-1 was built in 1921 with two 400hp Liberty 12 engines.
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, in 1921.
Aeromarine contract-built twenty-five Martin MB-2 in 1921 as NBS-1; 22-201 to 22-225.
The 50 NBS-1 built by Curtiss (AS68478 to 68527) were powered by two 400hp Liberty 12 engines. 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.
Curtiss built two XNBS-4 (Model 36: AS68571/68572) in 1924, powered by two 435hp Liberty 12A. These evolved into the B-2.
Curtiss XNBS-4
One MB-2, fitted with super-chargers, attained an altitude of about 8,077m while carrying a pilot and three observers. A contemporary report states that, had it not been for the extreme cold and lack of fuel, a still greater altitude could have been reached.
The NBS-1 were built with a unit cost of US$23,485 (1920).
The first two Martin MB-2s, Air Service s/n AS64195 and AS64196, were retained at McCook Field in Dayton, Ohio, for R&D flight testing, marked with project numbers P162 and P227 respectively, as was the second NBS-1 (AS64201), marked as P222. Four Curtiss NBS-1s were also assigned to McCook.
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.
The Martin MP was a 1919-20 version of the bomber built for the Post Office Dept. Only six were built.
United States Army Air Corps 1st Day Bombardment Group, Kelly Field, Texas (2nd Bombardment Group, Langley Field, Virginia) 11th Bomb Squadron – operated MB-2 1920-1927 20th Bomb Squadron – operated NBS-1 1920-1929 49th Bomb Squadron – operated NBS-1 1920-1929 96th Bomb Squadron – operated NBS-1 1920-1928 4th Composite Group, Nichols Field, Luzon, Philippines 28th Bomb Squadron – operated NBS-1 1924-1929 5th Composite Group, Luke Field, Territory of Hawaii 23d Bomb Squadron – operated NBS-1 1922-1929 72d Bomb Squadron – operated NBS-1 1923-1929 6th Composite Group, Albrook Field, Panama Canal Zone 25th Bomb Squadron – operated NBS-1 1922-1929
Martin MB Engines: 2 x Liberty, 295kW Max take-off weight: 5477 kg / 12075 lb Empty weight: 3322 kg / 7324 lb Wingspan: 21.8 m / 71 ft 6 in Length: 14.1 m / 46 ft 3 in Height: 4.3 m / 14 ft 1 in Wing area: 99.4 sq.m / 1069.93 sq ft Max. speed: 172 km/h / 107 mph Range w/max.fuel: 2400 km / 1491 miles Range w/max.payload: 772 km / 480 miles Armament: 4-5 machine-guns, 750kg of bombs or torpedos Crew: 2 Passengers: 12
NBS-1 Engines: 2 x Liberty 12-A, 420 hp (325 kW) each Length: 42 ft 8 in (13.0 m) Wingspan: 74 ft 2 in (22.7 m) Height: 14 ft 8 in (4.8 m) Wing area: 1,121 sq.ft (104.2 sq.m) Empty weight: 7,232 lb (3,280 kg) Loaded weight: 12,027 lb (5,460 kg) Maximum speed: 99 mph (85 kn, 160 km/h) at sea level Cruise speed: 92 mph (80 kn, 150 km/h) Landing speed 59 mph Range: 400 mi (345 nmi, 650 km) with 2000 lb bomb Maximum range: 558 miles Service ceiling: 7,700 ft (2,350 m) Maximum ceiling: 9900 ft Rate of climb: 391 ft/min (2.0 m/s) Armament: 5 x .30 in (7.62 mm) Lewis machine guns Bombload: 1,800 lb (820 kg) internal; 2,000 lb (907 kg) external Crew: 4
Curtiss XNBS-1 Engine: 2 x 400hp Liberty 12
Curtiss NBS-1 Engines: 420hp Liberty 12 Wingspan: 74’2″ Length: 42’8″ Useful load: 4795 lb Max speed: 99 mph Cruise speed: 91 mph Stall: 62 mph Range: 430 mi Ceiling: 8,500′
Curtiss XNBS-4 / Model 36 Engines: 2 x 435hp Liberty 12A Wingspan: 90’2″ Length: 46’6″ Useful load: 5951 lb Max speed: 100 mph Cruise speed: 95 mph Stall: 53 mph Range: 620 mi Ceiling: 13,000′
After withdrawal from Wright Martin Aircraft Corporation, Glenn L. Martin formed his own company at Cleveland, Ohio, in 1917, occupying a new factory at Baltimore, Maryland, in 1929.
MB-1 twin-engined biplane bomber first flown 17 August 1918, followed by improved MB-2. Other inter-war military aircraft included MO-1 three-seat observation aircraft, PM-1 and PM-2 flying-boats for the U.S. Navy and the B-10 and B-12 bombers. Latter developed into Model 167, supplied to RAF from 1940 as Maryland, and Model 187 which RAF used as Baltimore. B-26 Marauder bomber, first flown November 25,1940, ordered from drawing board, of which total production exceeded 4,700.
During Second World War operated U.S. government plant at Omaha, Nebraska.
U.S. Navy flying-boats included five Mars transports, Mariner and Marlin patrol flying-boats, and XP6M-1 Seamaster four-jet flying-boat flown 14 July 1955. U.S. Navy acquired AM-1 Mauler carrier-attack and P4M Mercator patrol aircraft, USAF ordered English Electric Canberras license-built as Martin B-57 from 1953. Civil production comprised Martin 130 26- seat flying-boats for Pan American 1934-1935, and Model 2-0-2 and 103 Model 4-0-4 airliners from 1947.
Aircraft production ceased December 20,1960 when the last P5M- 2 Marlin was handed over to U.S. Navy. The Martin Company became Martin Marietta Aerospace in 1961.
James V. Martin was a consultant to the U.S. Air service, and an associate to General Billy Mitchell. He held patents on aerospace technologies including the retractable landing gear and once held the World’s speed record of 70 mph in an airplane.
The Martin K-3 was brought out in 1911 as a scout. It was a biplane with a span of 18 ft and overall length of 13 ft 4 in. The Martin landing gear was manually retractable, the wheels folding backward and up between the wing spars into streamlined housings built against the sides of the fuselage.
The wheels used Ackermann flexible spokes for shock absorption. It was powered by an ABC Gnat 40 hp engine and weighed 350 lb. Its high speed was 185 mph. The 9-gallon fuel tank was supposed to provide a flight time of two hours.
When viewed from the side, the wing supports formed a letter “K” shape. The fuselage was all wood with plywood and fabric covering. The aircraft featured air tanks, and electrical power for flightsuit heating. The design included floating ailerons, wing trusses, K-struts and controlled vertical empennage.
Since J.V. Martin did not have a manufacturing facility of his own, building of the K-III and K-IV were contracted out to the Gallaudet Aircraft Corporation, though the J.V. Martin name is the one that applies.
The K.III Kitten was marketed as an “altitude fighter” for the U.S. Army. It is considered the first aircraft in the United States with retractable landing gear.
In December 1918, the aircraft was delivered to McCook Field where it was considered structurally unsound. Martin appealed to Congress in 1920 to no avail. The military refused to fly on it and returned Kitten to the inventor. Only in the spring of next year the plane was tested by a civilian pilot. In 60 test flights at Dayton, Ohio, the high altitude aircraft could only reach 295 ft of altitude.
The prototype K.III Kitten was donated to the National Air and Space Museum in 1924 and survives in the collection.
The 1921 J.V. Martin K.IV was a model III with a more powerful 60 hp Lawrance engine and floats. In 1921 3 with float landing gear were built and sold to the U.S. Navy as Navy KF-1.
Martin K-3 Kitten Engine: ABC Gnat, 45 hp (34 kW) Wingspan: 20 ft 2 in (6.15 m) Wing area: 105 sq ft (9.8 m2) Length: 13 ft 3 in (4.04 m) Height: 7 ft 4 in (2.24 m) Empty weight: 350 lb (159 kg) Normal takeoff weight: 300 kg Fuel capacity: 9 US gallons (34 litres) Maximum speed: 117 kn (135 mph, 217 km/h) Cruising speed: 175km / h Practical range: 335km Practical ceiling: 7620 m Capacity: 1 Undercarriage: retract tail
The Martin Monoplane was designed and built in 1937 by C.H.Latimer-Needham and H.Best-Deveraux at Denham, UK, as a low wing, single braced 30.00 ft span monoplane.
It was built using the wings of the Clarke Cheetah G-AAJK and some DH.53 components. It was registered G-AEYY c/n 1 and powered by a Bristol Cherub III engine.
It first flew in October 1937 but crashed on its second flight. It was rebuilt but again was damaged at Meir in 1938. This time it was not rebuilt and it was put into store in Stoke-on-Trent.
Engine: 1 x 225hp Jacobs L-4B Wingspan: 13.60 m / 45 ft 7 in Length: 9.73 m / 32 ft 11 in Height: 2.60 m / 9 ft 6 in Max take-off weight: 2852 kg / 6288 lb Empty weight: 1847 kg / 4072 lb Max. speed: 230 km/h / 143 mph Cruise speed: 195 km/h / 121 mph Crew: 2
Engine: 1 x 525hp Armstrong Siddeley Panther IIA Wingspan: 10.55/15.41 m / 35 ft 7 in / 51 ft 7 in Length: 11.63 m / 38 ft 2 in Height: 4.45 m / 15 ft 7 in Wing area: 53.50 sq.m / 575.87 sq ft Max take-off weight: 2852 kg / 6288 lb Empty weight: 1847 kg / 4072 lb Max. speed: 235 km/h / 146 mph Cruise speed: 170 km/h / 106 mph Ceiling: 5000 m / 16400 ft Range: 800 km / 497 miles Range w/max.fuel: 1200 km / 746 miles Armament: 3 x 7.92mm, 300kg of bombs Crew: 3
Engine: 1 x 300hp Armstrong Siddeley Cheetah IV Wingspan: 12.40 m / 41 ft 8 in Length: 8.00 m / 26 ft 3 in Height: 3.40 m / 11 ft 2 in Wing area: 34.00 sq.m / 365.97 sq ft Max take-off weight: 1380 kg / 3042 lb Empty weight: 960 kg / 2116 lb Max. speed: 205 km/h / 127 mph Cruise speed: 185 km/h / 115 mph Crew: 2
All Aero 