Tag Archives: Curtiss Electric Propellers

6 May 1941

Republic XP-47B 40-3051 prototype in flight. (Republic Aircraft Corporation)

6 May 1941: Just eight months after a prototype for a new single-engine fighter was ordered by the U.S. Army Air Forces, test pilot Lowery Lawson Brabham took off from the Republic Aviation Corporation factory airfield at Farmingdale, New York, and flew the prototype XP-47B Thunderbolt, serial number 40-3051, to Mitchel Field, New York.

During the flight, oil which had collected in the exhaust duct began burning. There was so much smoke that Brabham considered bailing out. He stayed with the prototype, though, and when he arrived at Mitchel Field, he exclaimed, “I think we’ve hit the jackpot!”

Alexander Kartveli

The prototype was designed by Alexander Kartveli, a Georgian immigrant and former chief engineer for the Seversky Aircraft Corporation, which became the Republic Aviation Corporation in 1939.

Alexander Kartveli (née Kartvelishvili, ალექსანდრე ქართველი) was born in Tbilisi, in the Kutais Governorate of the Russian Empire, (what is now, Georgia). After World War I, during which he was wounded, Kartvelishvili was sent to study at the Paris Aviation Higher College of Engineering in France by the government of the Democratic Republic of Georgia. He graduated in 1922. Kartvelishvili did not return to his country, which had fallen to the Red Army in the Soviet-Georgian War. He worked for Blériot Aéronautique S.A. until 1928, when he was employed by the Fokker American Company (also known as Atlantic Aircraft, or Atlantic-Fokker) which was headquartered at Passaic, New Jersey, in the United States. In 1931, he became chief engineer for the Seversky Aircraft Company in Farmingdale.

Republic XP-47B Thunderbolt prototype 40-3051 at Farmingdale, New York, 1941. The pilot standing in front of the airplane gives a scale reference. (Republic Aviation Corporation)

The XP-47B was the largest single-engine fighter that had yet been built. The production P-47B was 34 feet, 10 inches (10.617 meters) long with a wingspan of 40 feet, 9-5/16 inches (12.429 meters), and height of 12 feet, 8 inches (3.861 meters).¹ The wing area was 300 square feet (27.9 square meters). At a gross weight of 12,086 pounds (5,482 kilograms), it was nearly twice as heavy as any of its contemporaries.

Republic XP-47B Thunderbolt 40-3051 at Wright Field, Dayton, Ohio.(Ray Wagner Collection, San Diego Air & Space Museum Archives )

The XP-47B was powered by an air-cooled, supercharged and turbocharged, 2,804.4-cubic-inch-displacement (45.956 liter) Pratt & Whitney R-2800-21 (Double Wasp TSB1-G) two-row, 18-cylinder radial with a compression ratio of 6.65:1 had a normal power rating of 1,625 horsepower at 2,550 r.p.m., to an altitude of 25,000 feet (7,620 meters), and a takeoff/military power rating of 2,000 horsepower at 2,700 r.p.m. at 25,000 feet (7,620 meters). The engine drove a 12-foot, 2 inch (3.708 meter) diameter, four-bladed Curtiss Electric constant-speed propeller through a 2:1 gear reduction. The R-2800-21 was 4 feet, 4.50 inches (1.340 meters) in diameter and 6 feet, 3.72 inches (1.923 meters) long. The engine weighed 2,265 pounds (1,027 kilograms). Approximately 80% of these engines were produced by the Ford Motor Company. It was also used as a commercial aircraft engine, with optional propeller gear reduction ratios.

A large General Electric turbosupercharger was mounted in the rear of the fuselage. Internal ducts carried exhaust gases from the engine to drive the turbocharger. This supercharged air was then carried forward through an intercooler and then on to the carburetor to supply the engine. The engine’s mechanical supercharger further pressurized the air-fuel charge.

Republic XP-47B 40-3051. The pilot enters the cockpit through a hinged canopy segment. (Ray Wagner Collection Catalog, San Diego Air and Space Museum)

During flight testing, the XP-47B Thunderbolt demonstrated speeds of 344.5 miles per hour (554.4 kilometers per hour) at 5,425 feet (1,654 meters), and 382 miles per hour (615 kilometers per hour) at 15,600 feet (4,745 meters). Its maximum speed was 412 miles per hour (663 kilometers per hour) at 25,800 feet (7,864 meters). The test pilot reported that the engine was unable to produce full power during these tests. It was determined that it had a cracked cylinder head, resulting in a loss of 2.5–4% of its maximum rated power. Also, the XP-47B was painted in camouflage, resulting in a slight loss of speed.

It could climb to 15,000 feet (4,572 meters) in just five minutes.

The Thunderbolt was armed with eight Browning AN-M2 .50-caliber machine guns, four in each wing, with 3,400 rounds of ammunition. It could also carry external fuel tanks, rockets and bombs. The structure of the P-47 could be described as “robust” and it was heavily armored. The amount of damage that the airplane could absorb and still return was remarkable.

 

Republic XP-47B Thunderbolt 40-3051, 4 May 1941. (U.S. Air Force)
Republic XP-47B Thunderbolt 40-3051, 4 May 1941. (Republic Aviation Corporation)

During a test flight, 4 August 1942, the XP-47B’s tail wheel was left down. The extreme heat of the turbocharger’s exhaust set fire to the tire, which then spread to the airplane’s fabric-covered control surfaces. Unable to control the airplane, test pilot Filmore L. Gilmer bailed out. The prototype Thunderbolt crashed into Long Island Sound and was destroyed.

The third production Republic P-47B Thunderbolt, 41-5897, at Langley Field, Virginia, 24 March 1942. The door-hinged canopy of the XP-47B has been replaced by a rearward-sliding canopy, requiring that the radio antenna mast be moved.(NASA)
A Republic P-47B Thunderbolt in the NACA Full Scale Tunnel, 31 July 1942. (NASA LMAL 29051)

A total of 15,683 Thunderbolts were built; more than any other Allied fighter type. In aerial combat, it had a kill-to-loss ratio of 4.6:1. The P-47, though, really made its name as a ground attack fighter, destroying aircraft, locomotives, rail cars, and tanks by the many thousands. It was one of the most successful aircraft of World War II.

¹ Data from Pilot’s Flight Operating Instructions, Technical Order No. 01-65BC-1, 20 January 1943

© 2018, Bryan R. Swopes

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6 May 1935

Curtiss-Wright Model 75, NX17Y. (Ray Wagner Collection, San Diego Air & Space Museum Archives)

6 May 1935: At Buffalo, New York, the prototype Curtiss-Wright Model 75, NX17Y, serial number 11923, made its first flight.

Designed by Donovan Reese Berlin, the airplane was a modern design of all metal construction, with fabric covered control surfaces. The Model 75 was a single-seat, single-engine low wing monoplane with retractable landing gear.

In its original configuration, the Model 75 was powered by an air-cooled, supercharged 1,666.860 cubic inch displacement (27.315 liter) Wright Aeronautical Division GR1670A1 two-row 14-cylinder radial engine. The GR1670A1 was a developmental engine with a compression ratio of 6.75:1. It was rated at 775 horsepower at 2,400 r.p.m. at Sea Level, and 830 horsepower at 2,600 horsepower for takeoff, burning 87-octane gasoline. The engine was 3 feet, 9 inches (1.143 meters) in diameter, 4 feet, 4–25/32 inches (1.341 meters) long, and weighed 1,160 pounds (526 kilograms). The GR1670A1 drove a three-bladed Curtiss Electric constant-speed propeller through a 16:11 gear reduction.

The GR1670A1 was also used in the Seversky SEV-S1, NR18Y, a record-setting experimental variant of the rival Seversky P-35.

Registration issued 1 June 1936, cancelled 26 April 1937.

Curtiss-Wright Model 75, NX17Y. (Ray Wagner Collection, San Diego Air & Space Museum Archives)
Curtiss-Wright Model 75, NX17Y. (Ray Wagner Collection, San Diego Air & Space Museum Archives)
Curtiss-Wright Model 75, NX17Y. (Ray Wagner Collection, San Diego Air & Space Museum Archives)

The Curtiss-Wright Model 75 would be developed into the P-36 Hawk fighter for the U.S. Army Air Corps. France ordered it as the H75A-1, and in British service, it was known as the Mohawk Mk.I.

The tenth production P-36 was modified with a liquid-cooled Allison V-1710 V-12 engine to become the prototype XP-40.

1st Lieutenant Benjamin Scovill Kelsey in the cockpit of a Curtiss-Wright P-36A Hawk, circa 1938. (U.S. Air Force)
1st Lieutenant Benjamin Scovill Kelsey, Air Corps, United States Army, with a Curtiss Wright P-36A Hawk, Air Corps serial number 38-2, at Wright Field, Ohio, circa 1938. (Ray Wagner Collection/SDASM)
Curtiss-Wright P-36B 38-020. (U.S. Air Force)
Curtiss-Wright P-36B 38-020
Curtiss-Wright P-36C camouflage test, Maxwell Field, 1940. (Ray Wagner Collection, San Diego Air & Space Museum Archives)
Curtiss-Wright P-40 Warhawk, 55th Pursuit Squadron, Oakland, CA, 1941 (IWM FRE11437)

© 2018, Bryan R. Swopes

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26 April 1939

Curtiss-Wright’s Chief Test Pilot, H. Lloyd Child, in the cockpit of a P-40 Warhawk, circa 1940. (Rudy Arnold Collection/NASM)

26 April 1939: The United States Army Air Corps placed an order for 524 Curtiss-Wright P-40 Warhawks. This was the largest production order for any U.S.-built fighter since World War I. The total cost was $12,872,398.¹

The order was authorized by the Air Corps Expansion Act, approved by Congress 3 April, and signed by President Roosevelt on 26 April 1939.

The Curtiss-Wright Corporation Hawk 81 (P-40 Warhawk) was a single-seat, single-engine pursuit, designed by Chief Engineer Donovan Reese Berlin. It was developed from Berlin’s radial-engine P-36 Hawk. The P-40 was a low-wing monoplane of all-metal construction and used flush riveting to reduce aerodynamic drag. It had an enclosed cockpit and retractable landing gear (including the tail wheel). Extensive wind tunnel testing at the NACA Langley laboratories refined the airplane’s design, significantly increasing the top speed.

The first production Curtiss-Wright P-40 Warhawk, 39-156. (U.S. Air Force)

The new fighter was 31 feet, 8-9/16 inches (9.666 meters) long with a wingspan of 37 feet, 3½ inches (11.366 meters) and overall height of 9 feet, 7 inches (2.921 meters). The P-40’s empty weight was 5,376 pounds (2,438.5 kilograms) and gross weight was 6,787 pounds (3,078.5 kilograms).

The P-40 was powered by a liquid-cooled, supercharged, 1,710.597-cubic-inch-displacement (28.032 liter) Allison Engineering Co. V-1710-C15 (V-1710-33). This was a single overhead cam (SOHC) 60° V-12 engine designed by Harold Caminez, Allison’s chief engineer. The V-1710-33 had a compression ratio of 6.65:1. It was rated at 930 horsepower at 2,600 r.p.m. at 12,800 feet (3,901 meters), and 1,040 horsepower at 2,800 r.p.m. for takeoff, burning 100-octane gasoline. The engine turned a three-bladed Curtiss Electric constant-speed propeller through a 2:1 gear reduction. The V-1710-33 was 8 feet, 2.54 inches (2.503 meters) long, 3 feet, 5.88 inches (1.064 meters) high, and 2 feet, 5.29 inches (0.744 meters) wide. It weighed 1,340 pounds (607.8 kilograms).

Allison Engineering Co. V-1710-33 V-12 aircraft engine at the Smithsonian Institution National Air and Space Museum Steven F. Udvar-Hazy Center. (NASM)

The cruising speed of the P-40 was 272 miles per hour (438 kilometers per hour) and the maximum speed was 357 miles per hour (575 kilometers per hour) at 15,000 feet (4,572 meters). The Warhawk had a service ceiling of 30,600 feet (9,327 meters) and the absolute ceiling was 31,600 feet (9,632 meters). The range was 950 miles (1,529 kilometers) at 250 miles per hour (402 kilometers per hour).

Captain Charles W. Stark, Jr., 35th Pursuit Squadron, 8th Pursuit Group, climbing from the cockpit of a Curtiss-Wright P-40 Warhawk, 39-188, at Langley, Field, Virginia, 1941. Note the single .30-caliber machine gun visible on the left wing. (Rudy Arnold Collection/NASM)

The fighter (at the time, the Air Corps designated this type as a “pursuit”) was armed with two air-cooled Browning AN-M2 .50-caliber machine guns on the engine cowl, synchronized to fire through the propeller, with 380 rounds of ammunition per gun. Provisions were included for one Browning M2 .30-caliber aircraft machine gun, with 500 rounds of ammunition, in each wing.

The first production P-40 Warhawk, 39-156, made its first flight 4 April 1940. The 8th Pursuit Group at Langley Field, Virginia, was the first Army Air Corps unit to be equipped with the P-40.

Curtiss-Wright P-40 Warhawks of the 8th Pursuit Group at Langley Field, Virginia, 1940. (Unattributed)

After 200 P-40s were produced for the Air Corps, production was interrupted to allow Curtiss-Wright to build 100 Hawk 85A-1 export variants for the French Armée de l’air, then engaged with the invading forces of Nazi Germany. When France surrendered 22 June 1940, none of these airplanes had been delivered. The order was then assumed by the British Royal Air Force as the Tomahawk I.

U.S. Warhawk production resumed as the improved P-40B, and the remainder of the P-40 order was cancelled.

¹ Equivalent to $229,542,638.49 in 2018

© 2018, Bryan R. Swopes

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7 April 1943

First Lieutenant James Elms Swett, United States Marine Corps Reserve. (U.S. Naval Institute)

The President of the United States takes pleasure in presenting the MEDAL OF HONOR to

FIRST LIEUTENANT JAMES E. SWETT
UNITED STATES MARINE CORPS RESERVE
 

for service as set forth in the following CITATION:

For conspicuous gallantry and intrepidity at the risk of his life above and beyond the call of duty, as a division leader in Marine Fighting Squadron TWO TWENTY-ONE in action against enemy Japanese aerial forces in the Solomon Islands Area, April 7, 1943. In a daring flight to intercept a wave of 150 Japanese planes, First Lieutenant Swett unhesitatingly hurled his four-plane division into action against a formation of fifteen enemy bombers and during his dive personally exploded three hostile planes in mid-air with accurate and deadly fire. Although separated from his division while clearing the heavy concentration of anti-aircraft fire, he boldly attacked six enemy bombers, engaged the first four in turn, and unaided, shot them down in flames. Exhausting his ammunition as he closed the fifth Japanese bomber, he relentlessly drove his attack against terrific opposition which partially disabled his engine, shattered the windscreen and slashed his face. In spite of this, he brought his battered plane down with skillful precision in the water off Tulagi without further injury. The superb airmanship and tenacious fighting spirit which enabled First Lieutenant Swett to destroy eight enemy bombers in a single flight were in keeping with the highest traditions of the United States Naval Service.

/S/ FRANKLIN D. ROOSEVELT

James Elms Swett was born at Seattle, Washington, 15 June 1920, the first of three children of George Elms Swett, an electrical engineer and U.S. Marine Corps reservist, and Nellie Emily Burns Swett. He grew up in San Mateo, California, where he attended San Mateo High School and the College of San Mateo. While in college, Swett learned to fly through the Civilian Pilot Training Program.

Swett enlisted in the United States Navy as a Seaman 2nd Class, 26 August 1941. Swett was 5 feet, 11 inches (1.803 meters) tall and weighed 154 pounds (69.9 kilograms). He had brown hair and blue eyes. Seaman Swett was assigned to flight training as an Aviation Cadet at NAS Corpus Christi, Texas. While in training, Sweet elected to serve as a U.S. Marine Corps officer. On completion of flight training, James Swett was awarded the gold wings of a Naval Aviator and commissioned a Second Lieutenant, United States Marine Corps Reserve, 1 April 1942. He was then sent to MCAS Quantico at Quantico, Virginia, for advanced training.

In July 1942, 2nd Lieutenant Swett was placed under arrest for a period of ten days for “diving and zooming over traffic” below 500 feet (152 meters), along U.S. Route 1. He was then transferred to an air station in Florida.

Swett was next assigned to Marine Fighting Squadron 221 (VMF-221), Marine Air Group 21 (MAG-21), 1st Marine Air Wing, Fleet Marine Force. In March 1943, the squadron deployed from Hawaii to the South Pacific aboard the Bogue-class escort carrier USS Nassau (CVE-16), arriving at Espiritu Santo, New Hebrides, in late March. VMF-221 then flew on to Henderson Field, Guadalcanal, in the Solomon Islands.

Grumman F4F Wildcat fighters at Henderson Field, Guadalcanal, 1943.

On the morning of 7 April 1943, Lieutenant Swett led a four-plane flight of Wildcats on a patrol, then returned to refuel at Henderson Field. While his fighter, Grumman F4F-4 Wildcat, Bu. No. 12084, was being serviced, word came of a large group of enemy aircraft approaching from the north. Swett and his flight joined a number of other fighters to intercept the attacking enemy aircraft.

Near the Russell Islands, about 30 miles (48 kilometers) northwest of Guadalcanal, the American fighters came in contact with an estimated 150 enemy aircraft. Swett, in combat for the first time, quickly engaged three Aichi D3A Type 99 (American reporting name, “Val”) dive bombers. He shot them down. Becoming separated from his flight, he continued to engage the enemy, shooting down several more. His right wing was damaged by American anti-aircraft guns, but he continued. Having shot down seven Vals, he engaged an eighth. The Val’s gunner fired his two 7.7 mm machine guns in defense. By this time, Swett was running out of ammunition, but his final bullets killed the enemy gunner and set the Aichi on fire. Machine gun bullets fired from the Val damaged his windshield, punctured an engine oil cooler and set the Wildcat on fire.

Aichi D3A Type 99 dive bomber, Allied reporting name, “Val”. (San Diego Air and Space Museum Photo Archives)

Unable to make it back to Henderson, Swett ditched in the ocean near Tulagi. The airplane quickly sank. It was about 25 feet (7 meters) down before Swett was able to escape from the Wildcat’s cockpit. He was picked up by a U.S. Coast Guard patrol boat. Lieutenant Swett was listed as wounded in action.

During only fifteen minutes, 2nd Lieutenant Swett destroyed seven enemy aircraft and damaged an eighth.¹ He had become an “Ace in One Day.”

This Grumman F4F Wildcat on the sea floor near Tulagi may be Lieutenant Swett’s F4F-4, Bu. No. 12084. (Dive PlanIt)

Swett was promoted to 1st Lieutenant and transitioned to the Chance Vought F4U-1 Corsair. He shot down four Mitsubishi G4M “Betty” twin-engine medium bombers and an A6M Zero, before being shot down again near New Georgia, 10 July 1943. He returned to combat in October, shot down two more Val dive bombers and a Kawasaki Ki-61 Hien Type 3 fighter, known to Allied forces as “Tony.”

During a ceremony held at Espiritu Santo, 10 October 1943, Major General Ralph Johnson Mitchell, commanding the 1st Marine Air Wing, presented First Lieutenant James Elms Swett, United States Marine Corps Reserve, the Medal of Honor.

In 1944, Captain Swett was returned to the United States, and was training with VMF-221 at MCAS Santa Barbara, California. He would meet President Franklin D. Roosevelt at the White House during the Spring.

Oakland Tribune, Vol. CXL, No. 20, Thursday, 20 January 1944, Page 14, Columns 5–7

Captain Swett married Miss Lois Aileen Anderson 22 January 1944 at St. Paul’s Episcopal Church in Burlingame, California. They would later have two sons, both of whom would go on to become Marine Corps officers.

After retraining in Southern California, VMF-221 returned to the War, assigned to the Essex-class aircraft carrier USS Bunker Hill (CV-17) in the western Pacific.

Chance Vought F4U-1D Corsair aboard USS Bunker Hill (CV-17), 6 May 1945. (U.S. Navy)

On the morning of 11 May 1945, Captain Swett was flying a combat air patrol in an F4U-1D Corsair, when the fleet was attacked by kamikaze suicide aircraft. Swett shot down a Yokosuka D4Y Suisei (“Judy”) dive bomber.

During this attack, Bunker Hill was hit by two successive kamikazes and suffered catastrophic damage. 346 men were killed in action, 43 missing in action and 264 wounded. The carrier would survive, but was out of action for the remainder of the war.

Unable to land aboard their carrier, Captain Swett organized the airplanes still airborne and led them to USS Enterprise (CV-6).

30 seconds after the first, a second Mitsubishi A6M Zero crashes into USS Bunker Hill (CV-17), 1005 hours, 11 May 1945. (U.S. Navy)

During World War II, Major Swett flew 103 combat missions. He is officially credited with 15.5 aerial victories.

Following World War II, Major Swett remained in the Marine Corps Reserve. In 1949, he took command of Marine Fighting Squadron 141 (VMF-141) at NAS Oakland. He was recalled to active duty during the Korean War, but was not sent to the war zone.

James Swett rose to the rank of Colonel. He retired from the Marine Corps in 1970.

In addition to the Medal of Honor, during his career in the Marine Corps, Colonel Swett was awarded the Distinguished Flying Cross with gold star (2 awards); Purple Heart with gold star (2 awards); Air Medal with 4 gold stars (5 awards); Navy Combat Action Ribbon; Presidential Unit Citation with 2 bronze stars (3 awards); Navy Unit Commendation Ribbon; Asiatic-Pacific Campaign Medal with 1 gold star and 1 silver star (6 campaigns); World War II Victory medal; and the Armed Forces Reserve Medal with silver hourglass device (20 years of service).

Colonel James Elms Swett, United States Marine Corps Reserve (Retired), died at Mercy Medical Center in Redding, California, 18 January 2009, at the age of 88 years. He was buried at the Northern California Veterans Cemetery, Igo, California.

Major James E. Swett, United States Marine Corps Reserve

The Grumman F4F-4 Wildcat was a single-engine, single place mid-wing monoplane with retractable landing gear, designed for operations from United States Navy aircraft carriers. The wings could be fold alongside the fuselage for storage.

The F4F-4 was 28 feet, 10-5/8 inches (8.804 meters) long with a wingspan of 38 feet, 0 inches (11.582 meters) and height of 12 feet, 1-3/8 inches (3.693 meters). The Wildcat’s wing had 0° angle of incidence. The fixed, inner wing has 0° dihedral, while the outer wing panels have 5° dihedral. There is no sweep. The width of the airplane with its wings folded was 14 feet, 6 inches (4.420 meters). The fighter’s empty weight was 5,895 pounds (2,674 kilograms), and the gross weight, 7,975 pounds (3,618 kilograms).

Grumman F4F Wildcat, circa 1942-1943. (U.S. Navy)

The F4F-4 was powered by an air-cooled, supercharged, 1,829.399-cubic-inch-displacement (29.98 liter) Pratt & Whitney Twin Wasp SSC7-G (R-1830-86) two-row, fourteen cylinder radial engine with a compression ratio of 6.7:1. The R-1830-86 was rated at 1,100 horsepower at 2,550 r.p.m. at 3,500 feet (1,067 meters), 1,000 horsepower at 2,550 r.p.m. at 19,000 feet (5,791 meters), and 1,200 horsepower at 2,700 r.p.m. for takeoff, burning 100-octane gasoline. The engine drove a three-bladed Curtiss Electric propeller with a diameter of 9 feet, 9 inches (2.972 meters) through a 3:2 gear reduction. The R-1830-86 was 5 feet, 7.44 inches (1.713 meters) long, 44 feet, 0.19 inches (1.224 meters) in diameter, and weighed 1,560 pounds (708 kilograms).

The F4F-4 Wildcat had a maximum speed 275.0 miles per hour (442.6 kilometers per hour) at Sea Level, and 318.0 miles per hour (511.8 kilometers per hour) at 19,400 feet (5,913 meters). Its service ceiling was 34,800 feet (10,607 meters), and it had a maximum range of 765 miles (1,231 kilometers).

The F4F-4 was armed with six air-cooled Browning AN-M2 .50-caliber machine guns mounted in the wings with 1,440 rounds of ammunition.

Between February 1940 and August 1945, 7,898 Wildcats were produced by the Grumman Aircraft Engineering Corporation, Bethpage, New York, and General Motors Eastern Aircraft Division at Linden, New Jersey.

Grumman F4F-4 Wildcat. (U.S. Navy)

¹ Various reliable sources give different values for the number of enemy aircraft shot down by 2nd Lieutenant Swett on 7 May 1943, with the most common being five. Swett claimed eight destroyed, and this is reflected in his Medal of Honor citation. The intelligence officer who investigated determined that his claims were valid. The USMC History Division credits seven enemy aircraft destroyed: “Colonel James Elms Swett, of San Mateo, California, earned the Medal of Honor in World War II for shooting down seven Japanese bombers within 15 minutes.”

© 2018, Bryan R. Swopes

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6 April 1955, 18:00:04.1 UTC

Operation Teapot HA fireball, 6 April 1955. (U.S. Air Force)
Operation Teapot HA fireball, 6 April 1955. (U.S. Air Force)

6 April 1955: At 10:00:04.1 a.m. local time (1800 GMT), a Convair B-36H assigned to the 4925th Test Group (Atomic) at Kirtland Air Force Base, New Mexico dropped an atomic weapon from 42,000 feet (12,802 meters) over the Nevada Test Site, Area 1. The bomb was parachute-retarded to slow its fall so that the bomber could escape its blast effects.

The weapon was a test device to investigate its use as an air-to-air anti-aircraft missile warhead. It detonated at 36,620 feet (11,162 meters) with an explosive force of 3.2 kilotons. Because of the altitude of the explosion, there was no significant fallout.

“All test observers (with goggles) agreed that the fireball appeared more intensely bright than in events of similar yield fired at lower altitude.”United States High-Altitude Test Experiences by Herman Hoerlin, Los Alamos Scientific Laboratory, June 1976, at Page 12.

Captain William L. Hickey, USAF, pilot of a Convair B-36 Peacemaker very long-range heavy bomber during Operation Teapot, 1955. Captain Hickey is wearing a David Clark Co. S-2 capstan-type partial-pressure suit and K-1 helmet for protection at high altitude. (U.S. Air Force via Jet Pilot Overseas)
Captain William L. Hickey, USAF, pilot of a Convair B-36 Peacemaker very long-range heavy bomber during Operation Teapot, 1955. Captain Hickey is wearing a David Clark Co. S-2 capstan-type partial-pressure suit and K-1 helmet for protection at high altitude. (U.S. Air Force via Jet Pilot Overseas)
A smoke ring formed following the detonation of the Operation Teapot HA test. Contrails of the test aircraft are visible. (U.S. Air Force)
A smoke ring formed following the detonation of the Operation Teapot HA test. Contrails of the test aircraft are visible. (U.S. Air Force)

The test device was designed at the Los Alamos Scientific Laboratory (LASL) in New Mexico and was similar to the Wasp Prime device, which had been detonated earlier in the Operation Teapot test series. It used a spherical implosion device. The warhead was a 17-inch (43.2 centimeters) diameter sphere weighing approximately 125 pounds (56.7 kilograms). It was placed inside a Mark 5 bomb case which weighed 1,085 pounds (492.2 kilograms).

This was the only bomb dropped by parachute at the Nevada Test Site.

Flight crew of a Convair B-36 Peacemaker, 4925th Test Group (Atomic) during Operation Teapot, 1955. The crewmen are wearing David Clark Co. S-2 capstan-type partial-pressure suits for protection at high altitude. The two white helmets are early K-1 "split shell" 2-piece helmets, while the green helmets are later K-1 1-piece models. (U.S. Air Force via Jet Pilot Overseas)
Flight crew of a Convair B-36 Peacemaker, 4925th Test Group (Atomic) during Operation Teapot, 1955. The crewmen are wearing David Clark Co. S-2 capstan-type partial-pressure suits for protection at high altitude. The two white helmets are early K-1 “split shell” two-piece helmets, while the green helmets are later K-1 one-piece models. (U.S. Air Force via Jet Pilot Overseas)

The Convair B-36H Peacemaker was the definitive version of the ten engine bomber, with 156 B-36H/RB-36H built out of the total production of 383 Peacemakers. It is similar to the previous B-36F variant, though with a second flight engineer’s position, a revised crew compartment, and improved radar controlling the two 20 mm autocannons in the tail turret.

It is 162 feet, 1 inch (49.403 meters) long with a wingspan of 230 feet (70.104 meters) and overall height of 46 feet, 8 inches (14.224 meters). The empty weight is 168,487 pounds (776,424.4 kilograms) and combat weight is 253,900 pounds (115,167.1 kilograms). Maximum takeoff weight is 370,000 pounds (167,829.2 kilograms).

Three flight crewmen don their parachutes before boarding the B-36H Peacemaker for Operation Teapot HA, 5 April 1955. The automobile behind them is a 1955 Chevrolet Bel Air 4-door sedan. (U.S. Air Force)
Three flight crewmen don their parachutes before boarding the B-36H Peacemaker for Operation Teapot HA, 5 April 1955. The automobile behind them is a 1955 Chevrolet Bel Air 4-door sedan. (U.S. Air Force)

The B-36H has ten engines. There are six air-cooled, supercharged 4,362.49 cubic-inch-displacement (71.49 liter) Pratt & Whitney Wasp Major C6 (R-4360-53) four-row, 28-cylinder radial engines placed inside the wings in a pusher configuration. These had a compression ratio of 6.7:1 and required 115/145 aviation gasoline. The R-4360-53 had a Normal Power rating of 2,800 horsepower at 2,600 r.p.m. Its Military Power rating was 3,500 horsepower at 2,800 r.p.m., and 3,800 horsepower at 2,800 r.p.m. with water injection—the same for Takeoff. The engines turned three-bladed Curtiss Electric constant-speed, reversible propellers with a diameter of 19 feet, 0 inches (5.791 meters) through a 0.375:1 gear reduction. The R-4360-53 is 9 feet, 9.00 inches (2.972 meters) long, 4 feet, 7.00 inches (1.397 meters) in diameter, and weighs 4,040 pounds (1,832.5 kilograms).

Four General Electric J47-GE-19 turbojet engines are suspended under the wings in two-engine pods. The J47 is a  single-shaft axial-flow turbojet engine with a 12-stage compressor section, 8 combustion chambers, and single-stage turbine. The J47-GE-19 was modified to run on gasoline and was rated at 5,200 pounds of thrust (23.131 kilonewtons).

The B-36H was the fastest variant of the Peacemaker series, with a cruise speed of 234 miles per hour (377 kilometers per hour) and a maximum speed of 416 miles per hour (670 kilometers per hour) at 36,700 feet (11,186 meters) and 439 miles per hour (709 kilometers per hour) at 31,120 feet (9,485 meters). The service ceiling was 44,000 feet (13,411 meters) and its combat radius was 3,113 miles (5,010 kilometers). The ferry range was 7,691 miles (12,378 kilometers).

The B-36H has six remotely-controlled retractable gun turrets mounting two M24A1 20 mm autocannon, per turret. There is a tail turret, mentioned above, and another 2-gun turret in the nose.

The B-36 was designed during World War II, when nuclear weapons were unknown to the manufacturer. The bomber was built to carry up to 86,000 pounds (39,009 kilograms) of conventional bombs in two bomb bays. It could carry the 43,600 pound (19,777 kilogram) T-12 Cloudmaker, a conventional explosive earth-penetrating bomb, or several Mk.15 thermonuclear bombs. By combining the bomb bays, one Mk.17 25-megaton thermonuclear bomb could be carried.

This Convair RB-36D-5-CF, 49-2686, is similar in appearance to the B-36H used in Operation Teapot HA. (U.S. Air Force)
This Convair RB-36D-5-CF, 49-2686, is similar in appearance to the B-36H used in Operation Teapot HA. (U.S. Air Force)

© 2017, Bryan R. Swopes

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