Martin XB-16 (Model 145)

History

The 1930s saw significant technological development in military aircraft. The classic "woodcloth" biplanes that debuted during and after the First World War (1914-1918) lost inventory space and these were actively replaced by metal skin types that relied on stronger metal substructures.

While biplanes still exist in various forms of front-line combat, monoplanes have gained momentum as the preferred aircraft wing design from newer entries.

In 1933, U.S. military personnel at Wrightfield set out to design a new, state-of-the-art bomberone that could carry a wartime load of at least 2,500 pounds over a distance of 5,000 miles while maintaining a 5,000-mile range Maintain a speed of 200 miles per hour. The U.S. Army Air Corps (USAAC) developed "Project-A" around these specifications and submitted it to major aircraft manufacturers Boeing and Martin in 1934.

The aim was to develop a bombing platform capable of reaching (and subsequently protecting) U.S. interests in remote areas such as Alaska, Hawaii, and Panama.

The Glen L. Martin Company, founded in 1912, contributed to America's aircraft efforts in World War I - its greatest success was the MB-1 biplane bomber in 1918. From there came the MB-2 of the 1920s, culminating with the B-10 in 1932. The entry of the B-10 was particularly significant, as it was the first mass-produced bomber capable of surpassing the "pursuit aircraft" of the period.

Nearly 350 examples of this Martin product were produced.

Martin's project template is known internally as "Model 145". To meet the required range and performance, a four-engine layout was chosen - powered by four Allison V-1710 liquid-cooled inline piston engines, each producing 1,000 horsepower.

This proved to be a departure for USAAC, as their current fleet of large aircraft relies heavily on reliable air-cooled radial piston engines. A liquid-cooled inline engine contributes to high-altitude performance and can be fitted into a more streamlined cabin, inherently improving aerodynamic efficiency.

However, due to the internal vulnerability of this engine, the trade-off of choosing an inline engine increases vulnerability to enemy fire.

For the USAAC program, the Type 145 was designated "XB-16" and the prototype was in service (Boeing's entry became "XB-15", as detailed elsewhere on this site). A dual-arm form was achieved, with the crew section, bomb loading and other major mission components installed in the central nacelle. Large-span wing members (140 feet total span) are attached to the structure and mounted high. Each wing is designed to accommodate a pair of engine nacelles, whose contours fit nicely into the general shape of the wing elements themselves.

The cockpit was stepped (the pilot examined the nose section of the plane), and the window panes accompanied the position of the nose bombardier. The tail boom extends from the trailing edge of the wing and is covered by a vertical tail at its absolute end. The legs are connected by a common horizontal plane that also protrudes outward from the vertical fin side.

The final design envisaged a three-wheeled landing gear (fully retractable) with a standard operator of 10 people.

Initially, the XB-16 was designed to roughly match Boeing's proposed dimensions, but Martin decided to increase the size of his bomber to meet the expected bomb load and range requirements (increasing interior space allowed for a larger fuel load). And the lift and power characteristics can be assigned to larger aircraft. The wings now measure 173 feet -- even bigger than the upcoming World War II-era Boeing B-29 "Superfortress" -- and the changes required the use of a new company model name, "Model 145B."

Larger planes require more power, so an extra pair of engines is added. Since the original unit faced forward on the leading edge of each wing, the location of the two additional engines faced aft on the trailing edge of each wing.

All told, each wing can accept three motors, with the new motors mounted behind the existing outboard fittings.

In the end, USAAC authorities determined that the Martin bomber could not meet expectations, especially in the speed category. The XB-16 is estimated to have a top speed of 237 mph, a range of 5,000 miles (3,200 mi), and an altitude of 22,500 feet.

It has a nominal bomb load of 12,180 pounds of internal ammunition. As such, the XB-16 was canceled before any concrete work on the prototype was completed.

Boeing's XB-15 showed greater promise, and a single, airworthy prototype was completed, becoming the development model "Y1B-20". Boeing's work on large bombers culminated in two of the classics of the day -- the B-17 Flying Fortress and the aforementioned B-29 -- both of which proved themselves in the European and Pacific theaters during World War II.

Ability.

Specification

Base

Years of Service

1935

Origins

United States

Status

Cancel

Development ended.

Crew

10

Production

0

Manufacturer

Glen L. Martin Company - USA

Carrier

United States (removed)

Roles

Ground attack (bombing, strafing)

The ability to conduct air strikes against ground targets using (but not limited to) artillery, bombs, rockets, rockets, etc.

X-Plane (development, prototype, tech demo)

Aircraft designed for prototyping, technology demonstration, or research/data collection.

Dimensions and Weight

Length

114. 8 feet

(35.00m)

Width/span

141. 1 ft

(43.00m)

Height

18. 0 feet

(5.50m)

Cured weight

31,967 lbs

(14,500 kg)

MTOW

104,940 lbs

(47,600 kg)

Wgt Difference

+?72,973

(+33,100 kg)

Performance

Installed:

Model 145A: 4 x Allison V-1710-3 V12 liquid-cooled inline piston engines, each producing 1,000 hp, driving three-blade propeller units (inboard "draw rod"; outboard "propeller").

Maximum speed

236 km/h

(380 km/h | 205 knots)

Maximum

22,507 feet

(6,860 m | 4 km)

Area

5,002 km

(8,050 km | 14,909 nautical miles)

rate of climb

740 ft/min

(226 m/min)

Range (MPH) Subsonic: <614mph | Transonic: 614-921 | Supersonic: 921-3836 | Hypersonic: 3836-7673 | Hypersonic: 7673-19180 | Reentry: > 19030

Weapons

Proposed standard, assuming: 2 x .30 caliber machine guns in rear turret. 2 x .30 caliber machine guns in port engine nacelle (inboard). 2 x .30 caliber machine guns in the starboard engine nacelle (inboard). 2 x .30 caliber machine guns at the rear of the fuselage.

2 x .30 caliber machine guns on the port tail boom. 2 x .30 caliber machine guns on the starboard tail boom. Recommended, optional: Internal bomb load up to 12,180 lbs (regular gun/throwing bomb).