United Air Lines’ Boeing 247, NC13304, over Chicago, Illinois, 1933.
10 October 1933: A United Air Lines Boeing 247, civil registration NC13304, was on Trip 23, a scheduled transcontinental flight from Newark, New Jersey to Oakland, California, with intermediate stops at Cleveland, Ohio, and Chicago, Illinois. The airliner, which had been in service only six months, was carrying a crew of three with four passengers.
While enroute from Cleveland to Chicago, NC13304 exploded in mid-air. It crashed near Jackson Township, approximately five miles southeast of Chesterton, Indiana. There was a second explosion after the crash. All seven persons aboard were killed.
Boeing 247 NC13304 (Boeing)
NC13304, serial number 1685, was the fourth Model 247 to be built. The Boeing 247 is considered to be the first modern airliner because of its all-metal, semi-monocoque construction, cantilevered wing and retractable landing gear. It was 50 mph faster than its contemporaries, and could climb on one engine with a full load. It carried a pilot, co-pilot, flight attendant and up to ten passengers.
The Boeing 247 was powered by two air-cooled, supercharged 1,343.80-cubic-inch-displacement (22.021 liter) Pratt & Whitney Wasp S1H1 nine-cylinder radial engines with a compression ratio of 6:1. The S1H1 was a direct-drive engine. It had a Normal Power rating of 550 horsepower at 2,200 r.p.m., at 8,000 feet (2,438 meters), and 600 horsepower at 2,250 r.p.m for takeoff. The engine was 3 feet, 6.94 inches (1.091 meters) long, 4 feet, 3.75 inches (1.314 meters) in diameter, and weighed 864 pounds (392 kilograms).
The Boeing 247 had a maximum speed of 200 miles per hour (320 kilometers per hour) with a cruising speed of 188 miles per hour (304 kilometers per hour). It had a range of 745 miles (1,200 kilometers) and a service ceiling of 25,400 feet (7,260 meters).
United Air Lines Boeing 247 NC13304 loading cargo at Chicago, Illinois, 1933.
The investigation determined that the airliner’s tail had been blown off by a nitroglycerin bomb which had been placed in the baggage compartment.
The pilots had closed both throttles, turned off the magneto switches and pulled the master switch prior to impact.
This was the first proven case of a commercial aircraft destroyed by sabotage. No suspects or motive for the crime were ever discovered.
Boeing XB-52 Stratofortress 49-230 takes off for the first time, at Boeing Field, Seattle, Washington, 2 October 1952. (LIFE Magazine via Jet Pilot Overseas)
2 October 1952: The Boeing XB-52 Stratofortress prototype, 49-230, made its first flight at Boeing Field, Seattle, Washington, with test pilot Alvin M. “Tex” Johnston in command. Lieutenant Colonel Guy M. Townsend, U.S. Air Force, acted as co-pilot.
The first of two prototype long-range, high-altitude, heavy bombers, the XB-52 had been damaged during ground testing and extensive repairs were required, which delayed its initial flight. The second prototype, YB-52 49-231, made the type’s first flight nearly six months earlier, on 15 April 1952.
Alvin M. “Tex” Johnston, test pilot, after the first flight of the Boeing XB-52 Stratofortress prototype, 2 October 1952. (LIFE Magazine via Jet Pilot Overseas)
The prototype Stratofortress the largest jet aircraft built up to that time. It was 152.7 feet (46.543 meters) long with a wingspan of 185.0 feet, (56.388 meters) and 48.25 feet (14.707 meters) to the top of the vertical fin. The leading edges of the wings were swept back 36° 54′. The XB-52 had an empty weight of 155,200 pounds (70,398 kilograms) and its maximum takeoff weight was 390,000 pounds (176,901 kilograms). Fuel capacity was 27,417 gallons (103,785 liters).
Lieutenant Colonel Guy M. Townsend, U.S. Air Force. (Jet Pilot Overseas)
The XB-52 was powered by eight Pratt & Whitney YJ57-P-3 turbojet engines, with a normal power rating of 8,700 pounds static thrust at Sea Level (38.700 kilonewtons). The prototype bomber had a cruising speed of 519 miles per hour (835 kilometers per hour), and a maximum speed of 611 miles per hour (983 kilometers per hour) at 20,000 feet (6,048 meters). The planned bombing altitude was 46,500 feet (14,173 meters) and it had a service ceiling of 52,300 feet (15,941 meters). The XB-52 had an initial rate of climb of 4,550 feet per minute (23.11 meters per second) at Sea Level. Its maximum unrefueled range was 7,015 miles (11,290 kilometers).
Pilot’s cockpit, Boeing XB-52. (Boeing)Boeing XB-52 Stratofortress 49-230. (U.S. Air Force)Boeing XB-52 Stratofortress 49-230 with a North American F-86 Sabre chase plane. (U.S. Air Force)Boeing XB-52 Stratofortress 49-230. (U.S. Air Force)
In its original configuration, the XB-52 was armed with two .50-caliber machine guns in a turret in the tail, with 600 rounds of ammunition per gun, though these guns were not installed on 49-230. The XB-52 was designed to carry a single 25,200 pound (11,431 kilogram) T-28E2 Samson bomb, or other conventional or nuclear weapons.
XB-52 49-230 was used in flight testing for its entire service life. The airplane was scrapped in the mid-1960s.
744 B-52 bombers were built by Boeing at Seattle, Washington and Wichita, Kansas, with the final one, B-52H-175-BW 61-0040, rolled out 22 June 1962.
75 B-52H Stratofortresses are still in service with the United States Air Force.
Boeing XB-52, with Tex Johnston and Guy Townsend in the tandem cockpit. (Boeing)Boeing XB-52 Stratofortress 49-230 with two Pratt & Whitney J75 turbojets in single-engine nacelles on the outer pylons, circa 1959. (U.S. Air Force)
An American Airlines Boeing 707-023B Astrojet (720B) at Los Angeles International Airport, 26 December 1962. (Photograph courtesy of Jon Proctor)
15 August 1962: American Airlines’ Captain Eugene M. (“Gene”) Kruse set two National Aeronautic Association Class C-1 records for Speed Over a Commercial Air Route, East to West Transcontinental, when he flew a Boeing 720B Astrojet from New York to Los Angeles, 2,474 miles (3,981.5 kilometers), in 4 hours, 19 minutes, 15 seconds, at an average speed of 572.57 miles per hour (921.46 kilometers per hour). 61 years later, these records still stand.
The National Aeronautic Association has placed Captain Kruse’s records on its “Most Wanted” list: long-standing flight records that it would like to see challenged. Rules require that a new record exceed the old by at least a 1% margin. The performance needed to establish a new record would be 578.30 miles per hour (930.68 kilometers per hour).
The Boeing 720 was a variant of the Model 707, intended for short to medium range flights. It had 100 inches (2.54 meters) removed from the fuselage length and improvements to the wing, decreasing aerodynamic drag.
The Boeing 720 was operated by a flight crew of four and could carry up to 149 passengers. It was 136 feet, 2 inches (41.25 meters) long with a wingspan of 130 feet, 10 inches (39.90 meters) and overall height of 41 feet, 7 inches (12.65 meters). The airplane had an empty weight of 103,145 pounds (46,785 kilograms) and Maximum Takeoff Weight of 220,000 pounds (100,800 kilograms).
The Boeing 720 was powered by four Pratt & Whitney Turbo Wasp JT3C-7 turbojet engines, a civil variant of the military J57 series. The 720B was equipped with the more efficient P&W JT3D-1 turbofan engines. The JT3C-7 was a “two-spool” axial-flow engine with a 16-stage compressor (9 low- and 7 high-pressure stages), 8 combustion tubes, and a 3-stage turbine (1 high- and 2 low-pressure stages). It was rated at 12,030 pounds of thrust (53.512 kilonewtons) for takeoff. The JT3D-1 was a dual axial-flow turbofan engine, with a 2-stage fan section 13-stage compressor (6 low- and 7 high pressure stages), 8 combustion chambers and a 4-stage turbine (1 high- and 3 low-pressure stages). This engine was rated at 14,500 pounds of static thrust (64.499 kilonewtons) at Sea Level, and 17,000 pounds (75.620 kilonewtons), with water injection, for takeoff (2½ minute limit). Almost half of the engine’s thrust was produced by the fans. Maximum engine speed was 6,800 r.p.m. (N1) and 10,200 r.p.m. (N2). It was 11 feet, 4.64 inches (3.471 meters) long, 4 feet, 5.00 inches (1.346 meters) wide and 4 feet, 10.00 inches (1.422 meters) high. It weighed 4,165 pounds (1,889 kilograms). The JT3C could be converted to the JT3D configuration during overhaul.
The maximum cruise speed was 611 miles per hour (983 kilometers per hour) and maximum speed was 620 miles per hour (1,009 kilometers per hour). Range at at maximum payload was 4,370 miles (7,033 kilometers).
Boeing built 154 720 and 720B airliners from 1959 to 1967.
The last flight of a Boeing 720 was on 9 May 2012, when a 720B aircraft used by Pratt and Whitney Canada as a test aircraft was placed in the National Air Force Museum of Canada at Trenton, Ontario.
The speed-distance record-setting crew of the Boeing XB-15 experimental long range bomber, left to right: Major Caleb V. Haynes, U.S. Army Air Corps, with Captain William D. Old; Walter G. Bryte, Jr.; A.C. Brandt; Master Sergeant Adolph Cattarius; Technical Sergeant Daniel L. Spicer; Staff Sergeant James E. Sands. (FAI)
2 August 1939: The Boeing Model 294, designated by the U.S. Army Air Corps as the XB-15, serial number 35-277, flown by a crew led by Major Caleb Vance Haynes, set a Fédération Aéronautique Internationale (FAI) World Record for Speed Over a Closed Circuit of 5000 Kilometers With 2000 Kilogram Payload, when they flew the experimental long range heavy bomber a distance of 3,109 miles at an average speed of 267.67 kilometers per hour (166.32 miles per hour) while carrying a payload of 2,000 kilograms (4,409.25 pounds).¹
The other members of the XB-15 crew were Captain William D. Old, Walter G. Bryte, Jr., A.C. Brandt, Master Sergeant Adolph Cattarius, Staff Sergeant William J. Heldt, Technical Sergeant Daniel L. Spicer and Staff Sergeant James E. Sands.
The Boeing XB-15, 35-277, flies past the Wright Brothers National Memorial at the Kill Devil Hills, Kitty Hawk, North Carolina. (U.S. Air Force)
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.
The Boeing Model 294 (XB-15) at Boeing Field, Seattle, Washington, circa 1937. (The Boeing Company)
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 at NACA Langley Memorial Aeronautical Laboratory, 13 September 1938. (NASA)
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).
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.
Boeing XB-15 in flight. (U.S. Air Force)050406-F-1234P-053
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).
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.
The Boeing XB-15 experimental long-range heavy bomber flies in formation with a Boeing YP-29 pursuit. (U.S. Air Force)
The flight crew of the FAI World Altitude Record-setting Boeing Y1B-17A. Left to right: Captain Pearl H. Robey, Captain Clarence S. Irvine and R. Swofford. (FAI)
1 August 1939: Captains Clarence S. Irvine and Pearl H. Robey, United States Army Air Corps, used the Boeing Y1B-17A Flying Fortress (Model 299F), serial number 37-369, to set a Fédération Aéronautique Internationale (FAI) World Record for Altitude with a 5,000 Kilogram Payload. The bomber climbed to 10,371 meters (34,026 feet) with a payload of 11,023 pounds.¹ ²
On the same day, Irvine and Robey flew the Y1B-17 from Dayton, Ohio to St. Jacob, Illinois, setting an FAI World Record for Speed Over 1,000 Kilometers with a 5,000 Kilogram Payload, averaging 417.46 kilometers per hour (259.40 miles per hour).³
The flight crew of the FAI World Speed Record-setting Boeing Y1B-17A. Left to Right: Captain Carl J. Crane, P.G. Miller, Captain Clarence S. Irvine and Captain Pearl H. Robey. (FAI)
The single Y1B-17A (Boeing Model 299F) was originally ordered as a static test article, but when that was determined to be unnecessary, it was used as an engine test aircraft. It was equipped with four 1,823.129-cubic-inch-displacement (29.875 liter) air-cooled, supercharged, Wright R-1820-51 (Cyclone G59) single-row nine-cylinder radial engines. Moss/General Electric turbo-superchargers were installed, initially on top of the wings, but were moved to the bottom of the engine nacelles.
Boeing Y1B-17A 37-369. (FAI)
The supercharged Wright R-1820-39 (Cyclone R-1820-G5) engines of the YB-17s were rated at 805 horsepower at 2,100 r.p.m., at Sea Level, 775 horsepower at 14,000 feet (4,267 meters), and 930 horsepower at 2,200 r.p.m., for take off. By contrast, the YB-17A’s R-1820-51 engines were rated at 800 horsepower at 2,100 r.p.m. at Sea Level, and 1,000 horsepower at 2,200 r.p.m. for take off. But the turbochargers allowed the engines to maintain their Sea Level power rating all the way to 25,000 feet (7,620 meters). Both the -39 and -51 engine had a 16:11 propeller gear reduction ratio. The R-1820-51 was 3 feet, 9.06 inches (1.145 meters) long, 4 feet, 6.12 inches (1.375 meters) in diameter, and weighed 1,200.50 pounds (544.54 kilograms). 259 were produced by Wright between September 1937 and February 1940.
Boeing Y1B-17A 37-369. (U.S. Air Force)
The turbo-superchargers installed on the YB-17A greatly improved the performance of the bomber, giving it a 55 mile per hour (89 kilometer per hour) increase in speed over the supercharged YB-17s, and increasing the bomber’s service ceiling by 7,000 feet (2,132 meters). The turbo-superchargers worked so well that they were standard on all following B-17 production models.
Boeing Y1B-17A 37-369. (U.S. Air Force photo)
The Boeing Y1B-17A 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 (4.363 meters). Its empty weight was 26,520 pounds (12,029 kilograms). The maximum gross weight was 45,650 pounds (20,707 kilograms)
The Model 299F had a cruise speed of 230 miles per hour (370 kilometers per hour), a maximum speed of 271 miles per hour (436 kilometers per hour) at Sea Level and 295 miles per hour (475 kilometers per hour) at 25,000 feet (7,620 meters). The service ceiling was 38,000 feet (11,582 meters). The maximum range was 3,600 miles (5,794 kilometers). Carrying a 4,000 pound (1,814 kilogram) load of bombs, the range was 2,400 miles (3,862 kilometers).
The Y1B-17A could carry eight 600 pound (272 kilogram) bombs in an internal bomb bay. Defensive armament consisted of five .30-caliber machine guns.
Following the engine tests, 37-369 was re-designated B-17A.
The Boeing Y1B-17A in flight near Mt. Rainier on 28 February 1938. (U.S. Air Force)
¹ FAI Record File Number 8318
² This record-setting flight was dramatized in the motion picture “Test Pilot,” (1938, Metro-Goldwyn-Mayer) with Clark Gable, Spencer Tracy and Myrna Loy. This movie is now 80 years old and has a melodramatic plot, but is well worth seeing for aviation history enthusiasts.
10 October 1933: A United Air Lines Boeing 247, civil registration NC13304, was on Trip 23, a scheduled transcontinental flight from Newark, New Jersey to Oakland, California, with intermediate stops at Cleveland, Ohio, and Chicago, Illinois. The airliner, which had been in service only six months, was carrying a crew of three with four passengers.
NC13304, serial number 1685, was the fourth Model 247 to be built. The Boeing 247 is considered to be the first modern airliner because of its all-metal, semi-monocoque construction, cantilevered wing and retractable landing gear. It was 50 mph faster than its contemporaries, and could climb on one engine with a full load. It carried a pilot, co-pilot, flight attendant and up to ten passengers.
