A color transparency of the Boeing XB-15 in flight near Floyd Bennett Field, Long Island, New York, circa 1941. (Rudy Arnold Collection, National Air and Space Museum)
30 July 1939: Major Caleb Vance Haynes, Air Corps, United States Army, with Captain William D. Old, Master Sergeant Adolph Cattarius and Staff Sergeant William J. Heldt, flew the Boeing XB-15 experimental long range heavy bomber to a Fédération Aéronautique Internationale (FAI) World Record for Greatest Payload Carried to a Height of 2,000 meters. The XB-15 carried 14,135 kilograms (31,162 pounds) to an altitude of 2,000 meters (6,562 feet) over Fairfield, Ohio.¹ The flight set a second record by carrying 10,000 kilograms (22,046 pounds) to an altitude of 8,228 feet (2,508 meters).² Both records were certified by the National Aeronautic Association, the American organization representing the FAI.
Major Caleb V. Haynes, Captain William D. Old, Master Sergeant Adolph Cattarius and Staff Sergeant William J. Heldt, crew of the record-setting Boeing XB-15. (FAI)Boeing XB-15 35-277 at NACA Langley Memorial Aeronautical Laboratory, 13 September 1938. (NASA)Boeing XB-15 35-277
The Boeing Model 294, designated XB-15 by the Air Corps, was an experimental airplane designed to determine if a bomber with a 5,000 mile range was possible. It was designed at the same time as the Model 299 (XB-17), which had the advantage of lessons learned by the XB-15 design team. The XB-15 was larger and more complex than the XB-17 and took longer to complete. It first flew more than two years after the prototype B-17.
Designers had planned to use an experimental 3,421.194-cubic-inch-displacement (56.063 liter) liquid-cooled, supercharged and turbosupercharged Allison V-3420 twenty-four cylinder, four-bank “double V” engine. It produced a maximum of 2,885 horsepower at 3,000 r.p.m. The engine was not available in time, however, and four air-cooled Pratt & Whitney R-1830 (Twin Wasp) engines were used instead. With one-third the horsepower, this substitution left the experimental bomber hopelessly underpowered as a combat aircraft. (The Douglas XB-19 was retrofitted with V-3420s in 1942, and re-designated XB-19A.)
Boeing XB-15 35-277, a prototype long-range heavy bomber. (U.S. Air Force)Boeing XB-15 35-277. (U.S. Air Force)
The XB-15 was a very large four-engine mid-wing monoplane with retractable landing gear. It was of aluminum monocoque construction with fabric-covered flight control surfaces. The XB-15 had a ten-man crew which worked in shifts on long duration flights.
The prototype bomber was 87 feet, 7 inches (26.695 meters) long with a wingspan of 149 feet (45.415 meters) and overall height of 18 feet, 1 inch (5.512 meters). The airplane had an empty weight of 37,709 pounds (17,105 kilograms) and maximum takeoff weight of 70,706 pounds (32,072 kilograms)—later increased to 92,000 pounds (41,730 kilograms).
A ¼-scale model of the Boeing XB-15 inside the Full-Scale Wind Tunnel at the National Advisory Committee for Aeronautics (NACA) Langley Memorial Aeronautical Laboratory, Hampton, Virginia. The model has a wingspan of 37.3 feet (11.37 meters). (NASA)
The XB-15’s wings used a symmetrical airfoil and were very highly tapered (4:1 from root to tip). They had an angle of incidence of 4½° and 4½° dihedral. The total area was 2,780 square feet (258.271 square meters). A contemporary aeronautical publication wrote, “The airfoil provides constant center of pressure, minimum profile drag with flaps up and high maximum lift with flaps down.” The XB-15’s wings were adapted by Boeing for the Model 314 Clipper flying boat.
As built, the XB-15 was equipped with four air-cooled, supercharged, 1,829.39-cubic-inch-displacement (29.978 liter) Pratt & Whitney R-1830-11 (Twin Wasp S1B3-G) two-row 14-cylinder radial engines with a compression ratio of 6.7:1. The R-1830-11 was rated at 850 horsepower at 2,450 r.p.m. and 5,000 feet (1,524 meters), and 1,000 horsepower at 2,600 r.p.m. for take off. They turned three-bladed controllable-pitch propellers through a 3:2 gear reduction. The R-1830-11 was 4 feet, 8.66 inches (1.439 meters) long with a diameter of 4 feet, 0.00 inches (1.219 meters), and weighed 1,320 pounds (599 kilograms).
Boeing XB-15 35-277
The experimental airplane had a cruise speed of 152 miles per hour (245 kilometers per hour) at 6,000 feet (1,829 meters), and a maximum speed of 200 miles per hour ( kilometers per hour) at 5,000 feet (1,524 meters). The service ceiling was 18,900 feet (5,761 meters) and maximum range was 5,130 miles (8,256 kilometers).
The bomber could carry a maximum of 12,000 pounds (5,443 kilograms) of bombs in its internal bomb bay, and was armed with three .30-caliber and three .50-caliber machine guns for defense .
Only one XB-15 was built. During World War II it was converted to a transport and re-designated XC-105. In 1945 35-277 was stripped and abandoned at Albrook Field, Territory of the Canal Zone, Panama.
U.S. Army Sikorsky H-34A Chocktaw, 56-4303, MSN 58-671. (Sikorsky Archives)
12 July 1956: Starting at 5:29 a.m., 12 July 1956, a Sikorsky H-34 Chocktaw, the U.S. Army variant of the S-58, flown by Captains Claude E. Hargett and Ellis D. Hill, near Milford, Connecticut, set three Fédération Aéronautique Internationale (FAI) world records for speed: over a 100 kilometers (62.1 statute miles) without payload, 228,39 kilometers per hour (141.92 miles per hour/123.32 knots);¹ 500 kilometers (310.7 statute miles) without payload, 218,89 kilometers per hour (136.01 miles per hour/118.19 knots);² and 1,000 kilometer (621.4 statute miles) circuit without payload, 213,45 kilometers per hour (132.63 miles per hour/115.3 knots).³ Captain Hargett was awarded a bronze oak leak cluster in lieu of a second award of the Distinguished Flying Cross. Captain Hill was awarded the Legion of Merit.
Captains Claude E. Hargett and Ellis D. Hill, U.S. Army, with a Sikorsky H-34A Chocktaw. (FAI)
The Dothan Eagle reported:
“RECORD HOLDERS—Captain Claude E. Hargett (left) of New Bern, N. C., and Ellis De. Hill of Birmingham [Alabama], both stationed at Fort Rucker are shown in the cockpit of an Army H-54 Sikorsky helicopter which they piloted to break three world speed records last month in a closed-circuit course at Milford, Conn. Both pilots, assigned to the Continental Army Command’s Board No. Six, reside at Enterprise.” (The Dothan Eagle)
Rucker Pilots Set 3 World Records
FORT RUCKER — The establishment of three new world helicopter records by Fort Rucker Army pilots was announced yesterday by the Department of the Army. Flying an Army H-34 Sikorsky helicopter on July 12, over a course bordering a section of the southern Connecticut shore, Army aviators set a new closed-circuit record for 100, 500 and 1,000 kilometers. The old record had stood for a period of 10 years.
The H-34, assigned to the Army Board Six of the Continental Army Command at Fort Rucker and piloted by Capt. Claude E. Hargett of New Bern, N. C., and Capt. Ellis D. Hill, Birmingham, set marks of 141.9 miles per hour for the 100 kilometer course, 136 for the 500 kilometers course, and 132.5 for the 1,000 kilometer course.
Previous records for the same distances are 122.7, set in 1949 by a Sikorsky S-55; 66.6 mph set by a French SE 3-120 in 1950 and 66.6 mph in a Sikorsky R-5 in 1946.
The special speed run was conducted by the Army under the supervision of Charles S. Logsdon, of the National Aeronautics Association in Washington, D.C.
The records are subject to confirmation and acceptance by the Federation Aeronautique Internationale which is represented in the U. S. by the NAA.
Recent reports indicate that Russia flew the 500-kilometer course at a speed of 116.2 miles an hour, approximately 20 miles an hour slower than the U. S. Army achieved.
The USSR claim for the “hound helicopter” has been authenticated by the FAI in Paris, the world wide governing body for sporting aviation. The stock production model, the record H-34, is known commercially as the Sikorsky S-58.
Capt. Hargett and Hill are presently stationed at Fort Rucker and both reside in Enterprise.
The two record holders said they started the run at 5:20 a.m. near Milford, Conn. They flew about five hours at a height of 50 feet, with ninety per cent of the run made over water. An additional 3,000 pounds of gas was aboard the craft during the run.
Both captains praise the Coast Guard which provided an auxiliary craft which followed the helicopter in the water as an added safety measure.
Both are veterans of World War II and Korea. Hill has logged approximately 3,500 hours of flying time, Hargett, approximately 3,000 hours.
A U.S. Army Sikorsky H-34A Cocktaw, s/n 54-2873, landing at Fitzsimons Army Hospital, Aurora, Colorado. (Vertipedia)
The H-34A Chocktaw is a U.S. Army variant of the Sikorsky Model S-58, which had been developed as an internal project by Sikorsky, using the company’s own money. It was a major improvement of the earlier Model S-55 (H-19 Chickasaw/HO4S). The S-58 (a U.S. Navy XHSS-1 Seabat) first flew 8 March 1954.
The S-58 followed the single main rotor/tail (anti-torque) rotor configuration pioneered by Sikorsky with the Vought-Sikorsky VS-300 in 1939. The helicopter was designed to be flown by two pilots in a cockpit above the main cabin. Like the S-55, the engine was placed in the nose, installed at a 35° angle, and driving the transmission located behind the cockpit. For maintenance the engine could be accessed through two large clam shell doors in the nose. The wheeled landing gear was conventional, with two main wheels forward, and a tail wheel.
The S-58 fuselage had been designed using wind tunnel testing. The helicopter was built primarily of aluminum but the fuselage incorporated magnesium skin panels. The helicopter would be equipped with Automatic Stabilization Equipment (ASE), an autopilot system specifically for helicopters.
Sikorsky S-58 three-view illustration with dimensions. (Sikorsky)
The production H-34A was powered by an air-cooled, supercharged, Wright R-1820-84 nine-cylinder radial engine with a compression ratio of 6.80:1. It was rated at 1,525 horsepower at 2,800 r.p.m. for takeoff; 1,425 horsepower at 2,700 r.p.m., 30-minute limit; and 1,275 horsepower at 2,500 r.p.m., continuous. The R-1820-84 was 4 feet, 4.00 inches (1.321 meters) long, 4 feet, 7.74 inches (1.416 meters) in diameter and weighed 1,405 pounds (627 kilograms). The engine required 115/145 octane aviation gasoline.
The R-1820-84 drove the transmission through a 0.5625:1 gear reduction. The transmission had a gear reduction ratio of 11.293:1. Maximum main rotor speed was 258 r.p.m. (2,914 engine r.p.m.)
A U.S. Army Sikorsky H-34A Chocktaw, s/n 54-3033, MSN 58386.
The H-34 had an empty weight of 8,400 pounds (3,810 kilograms), and maximum takeoff weight of 13,300 pounds (6,032 kilograms). Its fuel capacity was 307 U.S. gallons (1,162 liters).
The helicopter had a cruise speed of 84 knots (97 miles per hour/156 kilometers per hour), and a maximum speed of 126 knots (145 miles per hour/233 kilometers per hour) at Sea Level. Its service ceiling was 17,600 feet (5,364 meters), and the hovering ceiling, out of ground effect, was 9,900 feet (3,018 meters) at takeoff power. The range was 227 nautical miles (261 statute miles/420 kilometers).
In transport configuration the S-58 could carry 16 troops or 6 litters and medical attendant.
The S-58 was built in a number of military and civil variants. Sikorsky built more than 1,800 S-58 series helicopters. Another 600 were produced by licensed manufacturers.
