Tag Archives: Browning Aircraft Machine Gun Caliber .50 AN-M3

29 June 1955

Aviation, , , , , , , , , , , ,
The first operational Boeing B-52 Stratofortress, RB-52B-15-BO 52-8711. (U.S. Air Force)
The first operational Boeing B-52 Stratofortress, RB-52B-15-BO 52-8711. (U.S. Air Force)

29 June 1955: The first operational Boeing B-52 Stratofortress, RB-52B-15-BO 52-8711, was delivered to the 93rd Bombardment Wing, Heavy, at Castle Air Force Base, Merced, California. The bomber was accepted from Boeing at Larson Air Force Base, Moses Lake, Washington, by the 93rd’s commanding officer, Brigadier General William Emanuel Eubank, Jr., U.S. Air Force, before flying to Castle. The new long-range heavy bombers would replace the 93rd’s Boeing B-47 Stratojets.

Fifty B-52Bs were built by Boeing at its Plant 2, Seattle, Washington. Twenty-seven of these were RB-52B reconnaissance bombers. They were designed to accept a pressurized electronic intelligence and photographic reconnaissance capsule with a two-man crew that completely filled the bomb bay. Without the capsule aboard, the RB-52s were capable of the same bombing missions as their sister B-52Bs. The change could be made within a few hours.

Pressurized two-man RB-52 reconnaissance pod.
Pressurized two-man RB-52 reconnaissance pod. (U.S. Air Force)

The B-52B/RB-52B was operated by a six-man flight crew for the bombing mission, and eight for reconnaissance. These were the aircraft commander/pilot, co-pilot, navigator, radar navigator/bombardier, electronic warfare officer, and gunner, plus two reconnaissance technicians when required.

The airplane was 156.6 feet, (47.7 meters) long with a wingspan of 185.0 feet (56.4 meters) and overall height of 48.3 feet (14.7 meters). The wings were mounted high on the fuselage (“shoulder-mounted”) to provide clearance for the engines which were suspended on pylons. The wings’ leading edges were swept aft to 36° 54′. Their angle of incidence was 6° and there was 2° 30′ dihedral. The wing area was 4,000 square feet (372 square meters). The B-52B’s calculated empty weight was 164,081 pounds (74,426 kilograms), with a combat weight of 272,000 pounds (123,377 kilograms) and a maximum takeoff weight of 420,000 pounds (190,509 kilograms).

The bomb bay of this RB-52B-10-BO Stratofortress, 52-012, is open, revealing the reconnaissance pod. (U.S. Air Force)

Early production B-52Bs were powered by eight Pratt & Whitney J57-P-1W turbojet engines, while later aircraft were equipped with J57-P-19W and J57-P-29W or WA turbojets. The engines were grouped in two-engine pods on four under-wing pylons. The J57 was a two-spool, axial-flow engine with a 16-stage compressor section (9 low- and 7-high-pressure stages) and a 3-stage turbine section (1 high- and 2 low-pressure stages). The J57-PW-1 engines had a Normal Power rating of 8,250 pounds of thrust (32.698 kilonewtons) at 9,720 r.p.m., N1, continuous; Military Power, 9,500 pounds thrust (42.258 kilonewtons) at 9,950 r.p.m., N1, for 30 minutes; and Maximum Power, 11,100 pounds of thrust (49.375 kilonewtons) with water injection, at 9,950 r.p.m., N1, 5 minute limit. The J57-PW-1 was 3 feet. 4.5 inches (1.029 meters) in diameter, 13 feet, 1.2 inches (3.993 meters) long, and weighed 4,210 pounds (1,910 kilograms).

Boeing RB-52B-10-BO Stratofortress 52-013. (U.S. Air Force)

The B-52B/RB-52B had a cruise speed of 453 knots (521 statute miles per hour/839 kilometers per hour) at 34,950 feet (10,653 meters). The maximum speed was 551 knots (634 miles per hour/1,020 kilometers per hour) at 20,300 feet (6,187 meters). The service ceiling at combat weight was 47,700 feet (14,539 meters). The maximum service ceiling was 55,700 feet (16,977 meters).

The B/RB-52B had a maximum fuel capacity of 37,550 gallons (142,142 liters) of JP-4. It also carried 360 gallons (1,363 liters) of water for injection during takeoff. The bomber’s maximum ferry range was 6,380 nautical miles (7,342 statute miles/11,816 kilometers). With a 10,000 pound (4,536 kilogram) bomb load, the B/RB-52B had a combat radius of 3,070 nautical miles (3,533 miles/5,686 kilometers). With inflight refueling, the bomber’s range was world-wide.

Tail gun turret of an early B-52 Stratofortress
B-52 tail gun turret

Defensive armament consisted of four Browning Aircraft Machine Guns, Caliber .50, AN-M3, mounted in a tail turret with 600 rounds of ammunition per gun. These guns had a combined rate of fire of 4,800 rounds per minute.

The B-52B could carry twenty-seven 1,000 pound (454 kilogram) bombs, or two Mk.21 17,000 pound (7,711 kilogram) Special Weapons (thermonuclear bombs). The maximum bomb load was 43,000 pounds (19,505 kilograms). (At the time 52-8711 entered service, only fission weapons were available. The most powerful of these was the variable yield Mk.6, which could produce a maximum 160 kilotons of energy.)

Boeing manufactured 744 B-52 Stratofortress bombers, with the final one rolled out at Wichita, Kansas, 22 June 1962. As of June 2016, 75 B-52H bombers remained in service with the United States Air Force.

RB-52B 52-8711 remained in active service until 29 September 1965. Today it is on display at the Strategic Air and Space Museum, Ashland, Nebraska.

A Strategic Air Command alert crew runs to man their bomber, Boeing RB-52B-15-BO Stratofortress 52-8711, 22 Bombardment Wing (Heavy), the first operational B-52, at March Air Force Base, California, 1965. (U.S. Air Force)
A Strategic Air Command alert crew runs to man their bomber, Boeing RB-52B-15-BO Stratofortress 52-8711, 22 Bombardment Wing (Heavy), the first operational B-52, at March Air Force Base, California, 1965. (U.S. Air Force)

© 2023, Bryan R. Swopes

3 June 1946

Aviation, , , , , , , , , , ,
Lieutenant Howard A. Johnson, USAAF, with Lockheed P-80A-1-LO Shooting Star 44-85123. (FAI)
Lieutenant Henry A. Johnson, USAAF, with Lockheed P-80A-1-LO Shooting Star 44-85123. (FAI)

3 June 1946: Lieutenant Henry A. Johnson, U.S. Army Air Force, set a Fédération Aéronautique Internationale (FAI) World Record for Speed Over a Closed Circuit of 1,000 Kilometers Without Payload flying a Lockheed P-80A-1-LO Shooting Star, serial number 44-85123, at Dayton, Ohio. The average speed was 745.08 kilometers per hour (462.97 miles per hour). The elapsed time was 1 hour, 20 minutes, 31 seconds.¹

This airplane had earlier set a transcontinental speed record when Colonel William H. Councill flew it from Daugherty Field, Long Beach, California to La Guardia Field, New York, in 4 hours, 13 minutes, 26 seconds on 26 January 1946. It would go on to win the Thompson Trophy Race J Division, 2 September 1946, when Major Gustav E. Lundquist flew it to an average speed of 515.853 miles per hour (830.185 kilometers per hour) over the 180-kilometer course.

Lockheed P-80A-1-LO 44-85123, photographed 22 June 1946 at the General Electric Air Research Laboratory, Schenectady, New York, by Richard Lockett. (Brian Lockett/Air-and-Space.com)

The Lockheed P-80-1-LO was the United States’ first operational jet fighter. It was a single-seat, single engine airplane, 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 AFB) 8 January 1944.

The P-80A was 34 feet, 6 inches (10.516 meters) long with a wingspan of 38 feet, 10.5 inches (37 feet, 7.5 inches with “clipped” wing tips) (11.849 or 11.468 meters) and an overall height of 11 feet, 4 inches (3.454 meters). The wings had 1° incidence with -1° 30° twist, and 3° 50′ dihedral. The leading edges were swept aft 9° 18′ 33″. The total wing area was 237.70 square feet (22.08 square meters). The P-80A weighed 7,920 pounds empty (3,593 kilograms) and had a maximum takeoff weight of 14,000 pounds (6,350 kilograms).

Lockheed P-80A-1-LO Shooting Star 44-85123, World Speed Record Holder. (FAI)

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) at 11,500 r.p.m. They 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-1 had a maximum speed of 510 miles per hour (821 kilometers per hour) at Sea Level, 520 miles per hour (837 kilometers per hour) at 20,000 feet (6,096 meters), and 495 miles per hour (797 kilometers per hour) at 40,000 feet (12,192 meters). The service ceiling was 45,000 feet (13,716 meters).

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 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.

The P-80A Shooting Star was armed with six Browning AN-M3 .50-caliber  aircraft machine guns mounted in the nose, with 300 rounds of ammunition per gun.

44-85123 is undergoing restoration at Edwards Air Force Base, California.

Lockheed test pilots Anthony W. ("Tony") LeVier and David L. Ferguson stand in front of P-80A 44-85123 and an F-117A Nighthawk at the Lockheed Skunk Works, Palmdale, California, 17 June 1993. (Denny Lombard, Lockheed Martin)
Lockheed test pilots Anthony W. (“Tony”) LeVier and David L. Ferguson stand in front of P-80A 44-85123 and an F-117A Nighthawk at the Lockheed Skunk Works, Palmdale, California, 17 June 1993. (Denny Lombard, Lockheed Martin)

¹ FAI Record File Number 10973

© 2019, Bryan R. Swopes

20 May 1948

Aviation, , , , ,
North American Aviation P-86A-1-NA Sabre 47-605, the first production aircraft. (U.S. Air Force)

20 May 1948: The first production North American Aviation, Inc., P-86A-1-NA, 47-605, made its first flight.

The P-86A-1-NA was very similar to the three XP-86 prototypes. As an operational fighter, its empty weight increased 347 pounds to 10,077 pounds. The Chevrolet J35-C-3 and Allison J35-A-5 engines were replaced with a more powerful General Electric J47-GE-1. The fighter’s maximum speed increased 74 miles per hour to 673 miles per hour at Sea Level.

The P-86 was unlike any airplane before it. (The designation was changed to F-86 the following month.) It was the first airplane produced with a swept wing. After analyzing World War II test data for the Messerschmitt Me 262, North American’s engineers designed a wing with a 35° degree sweepback to its leading edge. The wing sweep allowed high speed shock waves to form without stalling the entire wing. The wing tapered toward the tips, and its thickness also decreased from the root to the tip. In order to create a very strong but very thin wing, it was built with a two-layered aluminum skin, instead of ribs and spars, with each layer separated by “hat” sections. The thickness of the skin panels also tapered to decrease weight.

Cutaway illustration XP-86 concept. The side speed brakes were altered in production and the ventral brake eliminated. (North American Aviation, Inc.)

The wing  incorporated leading edge “slats” which were airfoil sections that automatically extended below 290 knots, smoothing the air flow over the wing’s upper surface and creating more lift at slow speeds. Above that speed, aerodynamic forces closed the slats, decreasing drag and allowing for higher speeds. Effectively, the wing could change its shape in flight.

Like the XP-86, the P-86A was 37 feet, 6.5 inches (11.443 meters) long with a wingspan of 37 feet, 1.4 inches (11.313 meters) and overall height of 14 feet, 8.9 inches (4.493 meters). The empty weight was 10,077 pounds (4,571 kilograms), gross weight, 14,050 pounds (6,373 kilograms) and maximum takeoff weight was 15,876 pounds (7,201 kilograms).

The J47-GE-1 was an axial-flow turbojet with a 12-stage compressor, 8 combustion chambers, and single stage turbine. It had a normal power rating of 4,320 pounds of thrust (19.216 kilonewtons) at 7,370 r.p.m.; and military power, 5,200 pounds (23.131 kilonewtons) at 7,950 r.p.m. (30-minute limit).

The P-86A had an initial rate of climb 7,470 feet per minute (37.95 meters per second) and could reach 40,000 feet (12,192 meters) in 10 minutes, 24 seconds. Its service ceiling was 48,000 feet (14,630 meters).

North American Aviation F-86A-5-NA 48-273. Note the gun port doors on this early production aircraft. They opened in 1/20 second as the trigger was pressed. Proper adjustment was complex and they were soon eliminated. (U. S. Air Force)

The Sabre was armed with six Browning AN-M3 .50-caliber aircraft machine guns placed in the nose, with three on either side of the engine intake. These were lighter and had a higher rate of fire than the World War II AN-M2 machine guns. Ammunition containers had a capacity of 300 rounds, but normally they carried 267 rounds per gun. Early aircraft had small doors covering each gun port. They opened in 0.05 seconds but were difficult to keep properly adjusted, so they were soon deleted.

The airplane could also be armed with two bombs and up to sixteen 5-inch (12.7 centimeter) High Velocity Aerial Rockets (HVAR) on underwing hardpoints.

North American Aviation built thirty-three P-86A-1-NAs. The U.S. Air Force ordered 190 F-86Bs, but these were cancelled in favor of the F-86A-5-NA.

The F-86A became operational with the 1st Fighter Group at March Air Force Base, near Riverside, California. In February 1949, a contest was held within the group to select a name for the new fighter. “Sabre” was chosen.

47-605 was the first production P-86A-1-NA Sabre. (U.S. Air Force)

© 2019, Bryan R. Swopes