Tag Archives: Browning Machine Gun Caliber .50 AN-M2

21 August 1944

August 21, 2024Aviation20 mm Aircraft Automatic Gun M3, Aeroproducts Propeller Company, Browning Machine Gun Caliber .50 AN-M2, Bu. No. 90460, Fighter, First Flight, Grumman Aircraft Engineering Corporation, Grumman G-58, Grumman XF8F-1 Bearcat, Pratt & Whitney Double Wasp 2SC13-G, Pratt & Whitney R-2800-22, Prototype, Robert Leicester HallBryan Swopes

Robert L. Hall in the cockpit of the prototype Grumman XF8F-1 Bearcat. (Northrop Grumman)

21 August 1944:¹ The first of two Grumman XF8F-1 Bearcat prototypes, Bu. No. 90460, made its first flight at Bethpage, New York, with Grumman’s Chief Engineer and test pilot Robert Leicester Hall at the controls. The Bearcat was a light-weight high performance interceptor, designed to operate from the U.S. Navy’s smaller aircraft carriers. It used an air-cooled, supercharged, 2,804.4-cubic-inch-displacement (45.956 liter) Pratt & Whitney Double Wasp 2SC13-G (R-2800-22) two-row, 18-cylinder radial engine, an uprated version of the engine used in its predecessor, the Grumman F6F Hellcat.

The R-2800-22 engine was rated at 1,700 horsepower at 2,600 r.p.m. at Sea Level, and 2,100 horsepower at 2,800 r.p.m., for takeoff and Military Power. In order to use the engine’s power more effectively, the prototype Bearcat used a 12-foot, 4-inch (3.759 meter) diameter, four-bladed Aero Products, Inc., propeller, driven through a 0.45:1 gear reduction.

Prototype Grumman XF8F-1 Bearcat. (Northrop Grumman)

The Bearcat was 20% lighter than the Hellcat. It was 50 miles per hour faster and had a much higher rate of climb.

For aircraft carrier operations, the new fighter could not sacrifice structural strength. In order to limit the weight, armament was reduced to four .50-caliber machine guns, and fuel capacity was also less than that of the Hellcat, giving it reduced range.

Grumman F8F-1 Bearcat with wings folded. (U.S. Navy) — Grumman F8F-1 Bearcat with wings folded, 20 March 1945. (Northrop Grumman)

The production F8F-1 Bearcat was 27 feet, 6 inches (8.382 meters) long with a wingspan of 35 feet, 6 inches (10.820 meters) and overall height of 13 feet, 10 inches (4.216 meters) (to tip of propeller, in three-point position). With its wings folded, the width of the Bearcat was reduced to 23 feet, 9½ inches (7.252 meters).

The Bearcat’s wings are sharply tapered. Their angle of incidence is −1½°, and there is 5° 30′ dihedral. The leading edges are swept aft 5° 5′. The chord decreases from 9 feet, 7.87 inches (2.943 meters) at the root to 4 feet, 3.5 inches (1.308 meters) at a point 6 inches (15.24 centimeters) inboard from the tip. The total wing area is 244 square feet (22.7 square meters).

The fighter’s horizontal stabilizer has a span of 15 feet, 9 inches (4.801 meters) and a total area of 52.2 square feet (4.85 square meters). Its angle of incidence is +½°. The rudder has a height of 6 feet, 1–13/16 inches (1.875 meters). The vertical tail has a total area of 20.8 square feet (1.93 square meters), and is offset 2° left.

The F8F-1’s empty weight was 7,070 pounds (3,207 kilograms) and maximum takeoff weight was 12,947 pounds (5,873 kilograms). The F8F-2’s empty weight increased to 7,650 pounds (3,470 kilograms), and its maximum takeoff weight was 13,460 pounds (6,105 kilograms).

Grumman XF8F-1 Bearcat prototype at NACA Langley Memorial Aeronautical Laboratory, Hampton, Virginia, 5 February 1945. (NASA)

The production F8F-1 was powered by a Pratt & Whitney Double Wasp 2SC14-G (R-2800-34W) engine which had the same Sea Level power ratings as the R-2800-22. It produced 1,500 horsepower at 2,600 r.p.m. at 18,500 feet (5,639 meters) and had a Military Power rating of 1,700 horsepower at 2,800 r.p.m. at 16,000 feet (4,877 meters). The gear reduction drive ratio was also 0.45:1. A slightly larger Aero Products propeller with a diameter of 12 feet, 7 inches (5.835 meters) was installed. The R-2800-34W was 6 feet, 2.134 inches (1.883 meters) long, 4 feet, 4.80 inches (1.341 meters) in diameter and weighed 2,358.5 pounds (1,069.8 kilograms).

The F8F-2 was powered by a Pratt & Whitney R-2800-30W. The Normal Power rating increased to 1,720 horsepower at 2,600 r.p.m. at Sea Level, and 1,450 horsepower at 22,000 feet (6,706 meters). Takeoff and Military Power also increased: 2,250 horsepower at 2,800 r.p.m. at Sea Level, and 1,600 horsepower at 22,000 feet (6,706 meters). The R-2800-30W also drove an Aero Products propeller. The gear reduction ratio was the same. Its dimensions were slightly different than the -34W: 7 feet, 8.75 inches (2.356 meters) long, and 4 feet, 5.00 inches (1.346 meters) in diameter. The engine’s weight increased to 2,560 pounds (1,161 kilograms).

Grumman F8F-1 Bearcat Bu. No. 90448 in the Full Scale Tunnel at NACA Langley Memorial Aeronautical Laboratory. (NASA EL-2003-00320)

The Bearcat had a top speed of 336 knots (387 miles per hour/622 kilometers per hour) at Sea Level, and 388 knots (447 miles per hour/719 kilometers per hour) at 28,000 feet (8,534 meters). The airplane had initial rate of climb at Sea Level of 4,465 feet per minute (22.68 meters per second) and it could climb to 20,000 feet (6,096 meters) in 8.4 minutes. Its ceiling was 38,200 feet (11,643 meters).

Fuel capacity is 185 U.S. gallons (700 liters). The fighter’s range could be extended with a jettisonable centerline and two underwing tanks. The Bearcat’s combat radius was 235 nautical miles (270 statute miles/435 kilometers). Its maximum range, with three external tanks (350 gallons/1,325 liters), was 1,595 nautical miles (1,835 statute miles/2,954 kilometers).

The F8F-1 Bearcat was armed with four Browning AN-M2 .50-caliber machine guns. Inboard guns were provided with 325 rounds of ammunition, each, while the outboard guns had 200 rounds per gun. The F8F-2 replaced these with four M3 20 mm autocannon. Each inboard cannon had 325 rounds per gun, and the outboard guns had 188 rounds each. The F8F could also be armed with up to three 11.75-inch (29.845 centimeters) Tiny Tim air-to-ground rockets, or four 5-inch (12.7 centimeter) High Velocity Aerial Rockets (HVAR). For bombing missions, the Bearcat could carry one 1,600 pound (726 kilograms) bomb on the centerline and two 1,000 pounders (454 kilograms, each) under the wings.

The first prototype Grumman XF8F-1 Bearcat, Bu. No. 90460, crashed into Chesapeake Bay during gunnery tests at NAS Patuxent River, Maryland, 18 March 1945. Its pilot was missing, presumably killed. The airplane has recently–probably—been located.²

“Multi-beam echo image of the aircraft at the bottom of the Chesapeake Bay believed to be the XF8F-1 Bearcat lost out of NAS Patuxent River March 18, 1945.” (NOAA/Naval Aviation News)

Between 1945 and 1949, Grumman produced 1,265 F8F Bearcats, including a civilian G-58A and a G-58B. A number of American test pilots and astronauts flew the Bearcat in naval service, and several, including Neil Armstong, described it as their all-time favorite airplane.

Grumman F8F bearcat fighters aboard the Essex-class aircraft carrier, USS Tarawa (CV-40) circa 1948. (U.S. Navy) — Grumman F8F Bearcat fighters ready for takeoff aboard the *Essex*-class aircraft carrier, *USS Tarawa* (CV-40) circa 1948. (U.S. Navy)

Robert Leicester Hall was born at Taunton, Massachussetts, 22 August 1905. He was the son of Bicknell Hall, a mechanical engineer, and Estella Beatrice Lane Hall.

Hall attended the University of Michigan, graduating in 1927 with Bachelor of Science degree in Mechanical Engineering (B.S.M.E.). He was a member of the Phi Gamma Delta (ΦΓΔ) fraternity and the glee club. While at the University, Hall became a member of the American Society of Mechanical Engineers.

In 1929 he went to work for the Fairchild Airplane Manufacturing Company at Farmingdale, New York. While there, Hall met his first wife, Eugenie Therese Zeller, a 1928 graduate of Cornell University, and a secretary at the plant. They were married in 1930, and lived in a rented home on St. James Avenue, Chicopee City, Massachusetts. Their son, Robert Jr., was born 5 November 1931. They later divorced.

Also in 1931, Hall began working for Granville Brothers Aircraft at Springfield, Massachusetts. He designed the Gee Bee Model Z Super Sportster air racer. He left Granville Brothers in 1933 to go to work for the Stinson Aircraft Company in Dayton, Ohio. There he designed the Stinson Reliant.

In 1936, Bob Hall became the Chief Engineer for the Grumman Aircraft Engineering Corporation, Bethpage, Long Island, New York. He designed the F4F Wildcat, F6F Hellcat, F7F Tigercat, and F8F Bearcat fighters, and the TBF Avenger torpedo bomber. As corporate vice president, he supervised the design of the F9F Panther and Cougar jet fighters.

A U.S. Navy Grumman F4F-3 Wildcat in non-specular blue-gray over light-gray scheme in early 1942. (U.S. Navy)

Two Grumman F6F-3 Hellcat fighters, Summer 1943. (U.S. Navy)

Grumman TBF Avenger torpedo bomber. (U.S. Navy)

Ensign Neil A. Armstrong, as wingman to Lieutenant (j.g.) Ernie Moore, is flying the second Grumman F9F-2 Panther, Bu. No. 125122 (marked S 116), assigned to VF-51, USS Essex (CV-9), 1951. (Naval Aviation Museum)

Hall married his second wife, Rhoda C. Halvorsen, 18 January 1939, at New York City, New York.

Robert Hall retired from Grumman in 1970. Two of his sons, Eric and Ben Hall, founded Hall Spars and Rigging of Bristol, Rhode Island.

Robert Leicester Hall died at Newport, Rhode Island, 25 February 1991 at the age of 85 years.

¹ Some sources give 31 August 1944 as the date of the first flight.

² Naval Aviation News, 31 August 2017:

http://navalaviationnews.navylive.dodlive.mil/2017/08/31/lost-bearcat-found-or-still-missing/

19 August 1940

August 19, 2024Aviation40-2165, Browning Aircraft Machine Gun Caliber .30 M2, Browning Machine Gun Caliber .50 AN-M2, c/n 62-2834, First Flight, Medium Bomber, Mines Field, North American Aviation B-25 Mitchell, North American Aviation Inc., North American Aviation Model NA-62, Roy Ferren, Test Pilot, Vance Breese, Wright Aeronautical Division, Wright Cyclone 14 GR2600B665, Wright R-2600-9Bryan Swopes

North American Aviation NA-62, serial number 62-2834, the first B-25 Mitchell, (U.S. Army Air Corps serial number 40-2165), at Mines Field, Los Angeles California, August 1940. (U.S. Air Force)

19 August 1940: At Mines Field (now known as Los Angeles International Airport), the first North American Aviation B-25 twin-engine medium bomber, serial number 40-2165, took off on its first flight with test pilot Vance Breese at the controls and engineer Roy Ferren in the co-pilot’s position.

The airplane, North American model NA-62, serial number 62-2834, was developed from two earlier designs which had been evaluated by the U.S. Air Corps but rejected, and it was ordered into production without a prototype being built.

The first few B-25s built—sources vary, but 8–10 airplanes—were built with a constant dihedral wing. Testing at Wright Field showed that the airplane had a slight tendency to “Dutch roll” so all B-25s after those were built with a “cranked” wing, with the outer wing panels having very slight dihedral ¹ and giving it the bomber’s characteristic “gull wing” appearance. The two vertical stabilizers were also increased in size.

40-2165 was retained by North American for testing while the next several aircraft were sent to Wright Field.

The B-25 was named Mitchell in honor of early air power advocate Brigadier General Billy Mitchell. A total of 9,984 B-25s, F-10 reconnaissance variants and U.S. Navy and Marine Corps PBJ-1 patrol bombers were built by North American Aviation at Inglewood, California and Kansas City, Kansas. The last one, a TB-25J, remained in service with the U.S. Air Force until 1960.

Twenty-three B-25s were built before the B-25A Mitchell went into production. The B-25 was operated by a crew of five. It was 54 feet, 1 inch (16.485 meters) long with a wingspan of 67 feet, 6.7 inches (20.592 meters) and overall height of 16 feet, 4 inches (4.978 meters). The empty weight was 17,258 pounds (7,828 kilograms) and the maximum gross weight was 28,557 pounds (12,953 kilograms).

Scale model of a North American Aviation B-25 medium bomber being tested in a wind tunnel. (4″ × 5″ Kodachrome transparency by Alfred Palmer)

The B-25 was powered by two air-cooled, supercharged, 2,603.737-cubic-inch-displacement (42.688 liter) Wright Aeronautical Division Cyclone 14 GR260

0B665 (R-2600-9) two-row 14-cylinder radial engines which were rated at 1,500 horsepower at 2,400 r.p.m., and 1,700 horsepower at 2,600 r.p.m. for takeoff. These engines (also commonly called “Twin Cyclone”) drove three-bladed Hamilton Standard Hydromatic variable-pitch propellers through 16:9 gear reduction. The R-2600-9 was 5 feet, 3.1 inches (1.603 meters) long and 4 feet, 6.26 inches (1.378 meters) in diameter. It weighed 1,980 pounds (898 kilograms).

Workers installing a Wright Cyclone 14 R-2600 engine on a B-25 at the North American Aviation, Inc., plant, Inglewood, California, circa 1942. (Alfred T. Palmer/Library of Congress LC-DIG-fsac-1a35281)

The medium bomber had a maximum speed of 322 miles per hour (518 kilometers per hour) at 15,000 feet (4,572 meters) and a service ceiling of 30,000 feet (9,144 meters). It could carry a 3,000 pound bomb load 2,000 miles (3,219 kilometers).

Defensive armament consisted of three air-cooled Browning M2 .30-caliber aircraft machine guns and one Browning AN-M2 .50-caliber machine gun.

After testing was completed, B-25 40-2165 was retained by North American and modified as a company transport. On 8 January 1945, flown by Edgar A. Stewart, the airplane suffered an engine failure and made a forced landing at Mines Field—the location of its first flight. The prototype B-25 was damaged beyond repair.

Front view of the first North American B-25 Mitchell, 40-2165. The constant dihedral wing was used on the first nine airplanes built. (U.S. Air Force) — Front view of the first North American Aviation B-25 Mitchell medium bomber, 40-2165, at Mines Field, August 1940. The constant dihedral wing was used on the first nine airplanes built. (U.S. Air Force)

North American Aviation NA-62, B-25 Mitchell 40-2165, left front. (U.S. Air Force)

North American B-25 Mitchell 40-2165, left rear. (U.S. Air Force) — North American Aviation B-25 Mitchell 40-2165, left rear. (U.S. Air Force)

North American Aviation B-25A Mitchell twin-engine medium bomber in flight near Wright Field, Ohio, 1 May 1941. (Rudy Arnold Photo Collection, Smithsonian Institution National Air and Space Museum XRA-4945)

Compare the “cranked” wing of this North American Aviation B-25J Mitchell medium bomber to the prototype in the images above. (U.S. Air Force)

¹ The wing center section of the B-25H and B-25J has 4° 38′ 23″ dihedral. The outer sections have 0° 21′ 39″. The wing has 2° 29′ 37″ negative twist.

6 August 1945

August 6, 2024Aviation44-85048, Ace, Ace of Aces, Aircraft Accident, Browning Machine Gun Caliber .50 AN-M2, Dick Bong, Fighter Pilot, Lockheed Air Terminal, Lockheed Aircraft Company, Lockheed P-80A-1-LO Shooting Star, Medal of Honor, North Hollywood, Richard Ira Bong, Test PilotBryan Swopes

Major Richard Ira Bong, United States Army Air Forces. (U.S. Air Force)

6 August 1945: After serving three combat tours flying the Lockheed P-38 Lightning in the Southwest Pacific, Major Richard Ira Bong, Air Corps, United States Army, was assigned as an Air Force acceptance test pilot for new Lockheed P-80 Shooting Star jet fighters at the Lockheed Air Terminal, Burbank, California.

The P-80A was a brand new jet fighter, and Major Bong had flown just 4 hours, 15 minutes in the type during 12 flights.

Shortly after takeoff in P-80A-1-LO 44-85048, the primary fuel pump for the turbojet engine failed. A back-up fuel pump was not turned on. The Shooting Star rolled upside down and Bong bailed out, but he was too low for his parachute to open and he was killed. The jet crashed at the intersection of Oxnard Street and Satsuma Avenue, North Hollywood, California, and exploded.

Site of the crash of Major Richard I. Bong’s Lockheed P-80A-1-LO fighter, 44-85048, at Oxnard Street and Satsuma Avenue, North Hollywood, California. (Contemporary news photograph)

This graphic appeared in the Los Angles Times, 7 August 1945, at Page 3. (Los Angeles Times)

General Douglas MacArthur with Major Richard I. Bong.

Richard I. Bong was known as the “Ace of Aces” for scoring 40 aerial victories over Japanese airplanes between 27 December 1942 and 17 December 1944 while flying the Lockheed P-38 Lightning. He was awarded the Medal of Honor, which was presented by General Douglas MacArthur, 12 December 1944. [The following day, General MacArthur was promoted to General of the Army.]

The citation for Major Bong’s Medal of Honor reads: “For conspicuous gallantry and intrepidity in action above and beyond the call of duty in the Southwest Pacific area from 10 October to 15 November 1944. Though assigned to duty as gunnery instructor and neither required nor expected to perform combat duty, Major Bong voluntarily and at his own urgent request engaged in repeated combat missions, including unusually hazardous sorties over Balikpapan, Borneo, and in the Leyte area of the Philippines. His aggressiveness and daring resulted in his shooting down eight enemy airplanes during this period.”

General of the Army Henry H. (“Hap”) Arnold and Major Richard I. Bong, circa 1945.

The Lockheed P-80-1-LO was the United States’ first operational jet fighter. It was a single-seat, single-engine low-wing monoplane powered by a turbojet engine. The fighter was designed by a team of engineers led by Clarence L. (“Kelly”) Johnson. The prototype XP-80A, 44-83020, nicknamed Lulu-Belle, was first flown by test pilot Tony LeVier at Muroc Army Air Field (now known as Edwards Air Force Base), 8 January 1944.

Lockheed P-80A-1-LO shooting Star 44-85004, similar to the fighter being test flown by Richard I. Bong, 6 August 1945. (U.S. Air Force)

The P-80A was a day fighter, and was not equipped for night or all-weather combat operations. The P-80A was 34 feet, 6 inches (10.516 meters) long with a wingspan of 38 feet, 10.5037 inches (11.84919 meters) ¹ and overall height of 11 feet, 4 inches (3.454 meters).

The leading edges of the P-80A’s wings were swept aft 9° 18′ 33″. They had an angle of incidence of +1° at the root and -0° 30′ at the tip. There was 3° 50′ dihedral. The total wing area was 237.70 square feet (22.083 square meters).

The fighter had an empty weight of 7,920 pounds (3,592 kilograms) and a gross weight of 11,700 pounds (5,307 kilograms). The maximum takeoff weight was 14,000 pounds (6,350 kilograms).

Lockheed P-80 Shooting Star production, alongside P-38 Lightnings. (SDASM)

Early production P-80As were powered by either an Allison J33-A-9 or a General Electric J33-GE-11 turbojet engine. The J33 was a licensed version of the Rolls-Royce Derwent. It was a single-shaft turbojet with a 1-stage centrifugal compressor section and a 1-stage axial-flow turbine. The -9 and -11 engines were rated at 3,825 pounds of thrust (17.014 kilonewtons). The J33s were 8 feet, 6.9 inches (2.614 meters) long, 4 feet, 2.5 inches (1.283 meters) in diameter and weighed 1,775 pounds (805 kilograms).

The P-80A had a cruising speed of 445 miles per hour (716 kilometers per hour) at 20,000 feet (6,096 meters). Its maximum speed was 548 miles per hour (882 kilometers per hour) at 2,700 feet (823 meters) and and 501 miles per hour (806 kilometers per hour) at 34,700 feet (10,577 meters).² The service ceiling was 45,000 feet (13,716 meters).

Lockheed P-80A-1-LO Shooting Star 44-85155, similar to the jet fighter which Major Bong was flying, 6 August 1945. (U.S. Air Force)

The P-80A Shooting Star was armed with six air-cooled Browning AN-M2 .50-caliber aircraft machine guns mounted in the nose.

Dick Bong poses with “Marge,” his Lockheed P-38J Lightning. A large photograph of his fiancee, Miss Marjorie Vattendahl, is glued to the fighter’s nose.

¹ Wing span with rounded wing tips. P-80As with squared (“clipped”) tips had a wing span of 37 feet, 7.5037 inches (11.46819 meters).

² Several hundred of the early production P-80 Shooting stars had all of their surface seams filled, and the airplanes were primed and painted. Although this process added 60 pounds (27.2 kilograms) to the empty weight, the decrease in drag allowed a 10 mile per hour (16 kilometers per hour) increase in top speed. The painted surface was difficult to maintain in the field and the process was discontinued.

31 July 1923: Browning Machine Gun, Caliber .50, AN-M2

July 31, 2024Aviation.50 BMG, Aircraft Machine Gun, Browning Machine Gun Caliber .50 AN-M2, Heavy Machine Gun, John Moses Browing, Patent No. 1628226Bryan Swopes

This photograph shows SSGT Maynard H. Smith with a Browning .50-caliber machine gun at the left waist position of a B-17 Flying Fortress. (U.S. Air Force)

31 July 1923: The original patent application, Serial No. 654,955, for the legendary Browning .50-caliber machine gun was filed with the United States Patent Office on 31 July 1923. Patent Number 1,628,226 was issued to the estate of John Moses Browning by the Patent Office on 10 May 1927.

The majority of United States combat aircraft during World War II were armed with the Browning Machine Gun, Caliber .50, AN-M2. The machine gun could be mounted as a fixed weapon in the aircraft’s wings or nose, in flexible mounts, or power-operated turrets.

Three Browning .50-caliber machine guns and belted ammunition installed in the left wing of a Vought-Sikorsky F4U-1 Corsair, 11 August 1942. (Vought-Sikorsky)

The basic aircraft Browning machine gun, cal. .50, AN-M2. . . is an automatic, recoil-operated, belt-fed, air-cooled machine gun. The metallic link disintegrating belt is used in all firing of the gun. The gun is designed for all cal. .50 aircraft machine gun installations. By properly repositioning some of the component parts, ammunition may be fed into the gun from either the right or the left side.

—TM9-225 War Department Technical Manual, BROWNING MACHINE GUN, CALIBER .50, AN-M2, AIRCRAFT, BASIC, 28 January 1947, Section II., Paragraph 3. General, at Page 2

Illustration of the basic .50-caliber Browning machine gun, AN-M2. (War Department)

The Browning Machine Gun (“BMG”) was designed by John Moses Browning, who had also designed the Automatic Pistol, Caliber .45, M1911, the standard sidearm of the U.S. military for 74 years; the Rifle, Caliber .30, Automatic, Browning, M1918 (best known as the “Browning Automatic Rifle” or “BAR”); the Browning Machine Gun, Caliber .30, M1919; and the Browning Hi-Power, a 9 × 19 mm double-action semiautomatic pistol designed for Fabrique National (FN) of Herstal, Belgium.

The AN-M2 aircraft machine gun has an overall length of 56.25 inches (1.429 meters) and weighs 61.00 pounds (27.67 kilograms). The barrel is cylindrical, and 36.00 inches (0.91 meters) long. It is surrounded by a barrel jacket with ventilation holes to dissipate heat. The bore has 8 rifled-grooves with a right-hand twist, making one complete turn in every 15.00 inches (0.381 meters).

John Browning with a water-cooled version of his .50-caliber machine gun. (Museums at Union Station/The Wall Street Journal)

The basic AN-M2 gun could be modified to be manually fired with the substitution of a “spade grip” back plate. It could also be changed from left-hand ammunition feed to right hand by reversing some internal parts.

The M2 machine gun had a rate of fire of 750 to 850 rounds per minute.

Armorers load disintegrating-link belts of .50-caliber ammunition for the eight machine guns of a Republic P-47 Thunderbolt. (U.S. Air Force)

Ammunition is ball, armor-piercing, armor-piercing-incendiary, tracer, blank (no bullet), and dummy. The armor-piercing cartridge, M2, has a muzzle velocity of 2,840 feet per second (866 meters per second) and maximum range of 7,275 yards (6,652 meters). Some .50-caliber rounds have muzzle velocities as high as 3,450 feet per second (1,052 meters per second), though most range from 2,730 fps to 2,900 fps (832–884 m/s). The ammunition produces chamber pressures of approximately 55,000 pounds per square inch (3,792 bar).

A gunner fires the two Browning .50-caliber machine guns of a B-17’s ball turret. (U.S. Air Force)

The .50 BMG cartridge is 5.45 inches (13.843 centimeters) long (NATO 12.7 × 99). The rimless, tapered bottleneck case is 3.91 inches (9.931 centimeters) long, with diameters of 0.560 inches (14.224 millimeters) at the neck, 0.735 inches (18.669 millimeters) at the shoulder, and 0.804 inches (20.422 millimeters) at the base. The bullet is 2.31 inches (58.67 millimeters) long, with a maximum diameter of 0.510 inches (12.954 millimeters) and weighs 706.7 grains (1.6 ounces, 45.8 grams).

Lieutenant Clark Gable with a belt of linked .50-caliber machine gun cartridges. The colored tips of the bullets identify armor piercing, incendiary or tracer ammunition.

Armorers carry Browning AN-M2 .50-caliber machine guns and belts of linked ammunition to a P-51 Mustang. (U.S. Air Force)

16 July 1935

July 16, 2024AviationBoeing Airplane Company, Boeing B-17 Flying Fortress, Boeing Field, Boeing Model 299, Boeing XB-17, Bomber, Browning Machine Gun Caliber .30 M2, Browning Machine Gun Caliber .50 AN-M2, c/n 1963, Model 299, Pratt & Whitney Hornet S1E-G, Prototype, Rollout, World War II, X13372Bryan Swopes

16 July 1935: Just over a year after design began, the Boeing Model 299, X13372,¹ a prototype four engine long range heavy bomber, was rolled out of its hangar at Boeing Field, Seattle, Washington for the first time. The largest land airplane built up to that time, it seemed to have defensive machine guns aimed in every direction. A Seattle Times reporter, Roland Smith, wrote that it was a “flying fortress.” Boeing quickly copyrighted the name.

After several years of testing, the Model 299 went into production as the B-17 Flying Fortress. By the end of World War II, 12,731 B-17 Flying Fortresses had been built by Boeing, Douglas and Lockheed Vega.

Rollout of teh Boeing Model 299, NX13372, prototype XB-17. (Museum of Science and Industry) — Rollout of the Boeing Model 299, X13372, prototype XB-17. (Museum of Science and Industry via *Seattle Post-Intelligencer*)

The Boeing Model 299 was a four-engine bomber operated by a crew of eight. It was designed to meet a U.S. Army Air Corps proposal for a multi-engine bomber that could carry a 2,000 pound (907 kilogram) bomb load a distance of 2,000 miles (3,219 kilometers) at a speed greater than 200 miles per hour (322 kilometers per hour). Design of the prototype began in June 1934 and construction was started 16 August 1934. The Air Corps designated it B-299, and later, XB-17. It did not carry a military serial number, being marked with civil registration NX13372.

The Model 299 was 68 feet, 9 inches (20.955 meters) long with a wingspan of 103 feet, 9–3/8 inches (31.633 meters) and height of 14 feet, 11–5/16 inches (4.554 meters). Its empty weight was 21,657 pounds (9,823 kilograms). The maximum gross weight was 38,053 pounds (17,261 kilograms).

The prototype was powered by four air-cooled, supercharged, 1,690.537-cubic-inch-displacement (27.703 liter) Pratt & Whitney Hornet S1E-G nine-cylinder radial engines with a compression ratio of 6.5:1. The S1E-G was rated at 750 horsepower at 2,250 r.p.m., and 875 horsepower at 2,300 r.p.m. for takeoff, using 87-octane gasoline. They turned 11 foot, 6 inch (3.505 meters) diameter, three-bladed Hamilton Standard Hydromatic constant-speed propellers through a 3:2 gear reduction. The S1E-G was 4 feet, 1.38 inches (1.254 meters) long, 4 feet, 6.44 inches (1.383 meters) in diameter and weighed 1,064 pounds (483 kilograms)

Cockpit of the Boeing Model 299. (U.S. Air Force) — Cockpit of the Boeing Model 299. (Boeing)

In flight testing, the Model 299 had a cruise speed of 204 miles per hour (328 kilometers per hour) and a maximum speed of 236 miles per hour (380 kilometers per hour) at 10,000 feet (3,048 meters). The service ceiling was 24,620 feet (7,504.2 meters). The maximum range was 3,101 miles (4,991 kilometers). Carrying a 2,573 pounds (1,167 kilograms) load of bombs, the range was 2,040 miles (3,283 kilometers).

Boeing XB-17 (Model 299) bombers and front gunners compartment. (U.S. Air Force photo) 060706-F-1234S-007

Nose turret of the Boeing Model 299, with .50-caliber machine gun, photographed 24 July 1935. (Boeing 8195)

Bomb sight position., 9 August 1935. (Boeing 8227-B)

The XB-17 could carry eight 500 pound (227 kilogram) bombs in an internal bomb bay. Defensive armament consisted of five air-cooled .30-caliber or .50-caliber Browning machine guns.

Starboard waist gunnner’s position of the Boeing 299. (Boeing)

Starboard waist gunners position, with Browning M2 .50-caliber machine gun and ammunition canisters. (Boeing)

NX13372 was destroyed when it crashed on takeoff at Wright Field, Dayton, Ohio, 30 October 1935. An Army Air Corps pilot making his first familiarization flight neglected to remove the control locks. This incident led directly to the creation of the “check list” which today is used by all aircraft crew members.

Boeing Model 299, left quarter, at Boeing Field, south of Seattle, Washington,August 1935. (Boeing)

Boeing Model 299, NXxxx72, the prototype XB-17. (U.S. Air Force) — Boeing Model 299, X13372, the prototype XB-17, at Wright Field, Ohio. (U.S. Air Force)

Boeing Model 299, left profile, at Boeing Field, 13 August 1935. (Boeing 8234-B)

Boeing Model 299 X13372, designated XB-17, at Wright Field, Ohio, 1935. (U.S. Air Force)

¹ At that time, experimental and restricted category aircraft were prohibited from displaying the letter “N” at the beginning of their registration mark.

This Day in Aviation

Important Dates in Aviation History