Tag Archives: Pratt & Whitney Turbo Wasp

26 October 1958

Pan American World Airways’ Boeing 707-121, N711PA, Clipper America, at Idlewild Airport, New York, 26 October 1958. (Pan American World Airways)

26 October 1958: Pan American World Airways opened the “Jet Age” with the first commercial flight of an American jet airliner. Pan Am’s Boeing 707-121 Clipper America, N711PA, departed New York Idlewild (IDL) on an 8 hour, 41 minute flight to Paris Le Bourget (LBG), with a fuel stop at Gander, Newfoundland (YQX). (The actual flight time was 7 hours.) The distance was 3,634 miles (5,848 kilometers). Aboard were 111 passengers and 11 crewmembers.

A Pan Am company publication explained the need for the stop at Gander:

The Jet could not be fully loaded with fuel before takeoff because of weight restrictions imposed at Idlewild. Fuel capacity of the jet is 17,398 gallons, allowing a cruising range of 4,400 miles. But with a full pay load of passengers, only 9,731 gallons could be taken aboard in New York.

Pan American Clipper, Vol. XV, No. 11, November 1958, Page 6, Column 5

The Boeing 707 was developed from the earlier Model 367–80, the “Dash Eighty”. It is a four-engine jet transport with swept wings and tail surfaces. The leading edge of the wings are swept at a 35° angle. The airliner had a flight crew of four: pilot, co-pilot, navigator and flight engineer. The 707-121 is 145 feet, 1 inch (44.221 meters) long with a wing span of 130 feet, 10 inches (39.878 meters). The top of the vertical fin stands 42 feet, 5 inches (12.929 meters) high. The 707 pre-dated the ”wide-body” airliners, having a fuselage width of 12 feet, 4 inches (3.759 meters).

The first versions were powered by four Pratt & Whitney Turbo Wasp JT3C-6 turbojet engines, producing 11,200 pounds of thrust (49,820 kilonewtons), and 13,500 pounds (60.051 kilonewtons) with water injection. This engine was a civil variant of the military J57 series. It was a two-spool axial-flow turbojet engine with a 16-stage compressor and 2 stage turbine. The JT3C-6 was 11 feet, 6.6 inches (3.520 meters) long, 3 feet, 2.9 inches (0.988 meters) in diameter, and weighed 4,235 pounds (1,921 kilograms).

The airliner’s empty weight is 122,533 pounds (55,580 kilograms). Maximum take off weight (MTOW) is 257,000 pounds (116,573 kilograms). At MTOW, the 707 required 11,000 feet (3,352.8 meters) of runway to take off. Its maximum speed is 540 knots (1,000 kilometers per hour). It had a range of 2,800 nautical miles (5,185.6 kilometers).

The Boeing 707 was in production from 1958 to 1979. 1,010 were built. As of 2011, 43 707s were still in service.

Boeing delivered N711PA to Pan American on 17 October 1958. The airliner was named Clipper America,  but was later renamed Clipper Mayflower. It was leased to Avianca (Aerovías Nacionales de Colombia S.A.) from 1960 to 1962. In April 1965 the 707 was upgraded to the –121B standard. This included a change from the turbojet engines to quieter, more powerful and efficient Pratt and Whitney JT3D-1 turbofans, producing 17,000 pounds of thrust. The wings were modified to incorporate changes introduced with the Boeing 720, and a longer tailplane installed. Pan Ayer of Panama purchased Clipper Mayflower 21 February 1975. It was later leased to Türk Hava Yolları, the Turkish national airline, and went on to serve with Air Asia Company Limited (an Air America aircraft service unit) and E-Systems. After 26 years of service, in August 1984 Clipper America was scrapped at Taipei.

Pan American World Airways’ Boeing 707-121, N711PA, Clipper America, arriving at Aéroport de Paris – Le Bourget, Paris, France, 27 October 1958. (Photograph © Jon Proctor. Used with permission.)

© 2018, Bryan R. Swopes

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15 April 1952

The Boeing YB-52 Stratofortress, 49-231, takes off from Boeing Field at 11:09 a.m., 15 April 1952. (Robert F. Dorr Collection)
The Boeing YB-52 Stratofortress, 49-231, takes off from Boeing Field at 11:09 a.m., 15 April 1952. (Robert F. Dorr Collection)

15 April 1952: At 11:09 a.m., Boeing’s Chief of Flight Test, Alvin M. “Tex” Johnston, and Lieutenant Colonel Guy M. Townsend, U.S. Air Force, ran all eight turbojet engines to full power and released the brakes on the YB-52 Stratofortress prototype, 49-231.

With an awesome eight-engine roar, the YB-52 sprang forward, accelerating rapidly, wings curving upward as they accepted the 235,000-pound initial flight gross weight. At V2 (takeoff speed) the airplane lifted off the runway, because of the 6-degree angle of incidence of the wing, and at 11:08 a.m. we were airborne. The initial flight of the YB-52 had begun.

Tex Johnston: Jet-Age Test Pilot, by A.M. “Tex” Johnston with Charles Barton, Smithsonian Books, Washington, D.C., 1992, Chapter 13 at Pages 397–398.

Alvin M. "Tex" Johnston, test pilot, after the first flight of the Boeing XB-52 Stratofortress prototype, 2 October 1952. (LIFE via Jet Pilot Overseas)
Alvin M. “Tex” Johnston, Boeing Chief of Flight Test, after the first flight of the Boeing XB-52 Stratofortress prototype, 2 October 1952. (LIFE via Jet Pilot Overseas)

The YB-52 remained over the Seattle area for approximately 40 minutes while Johnson and Townsend ran through a series of systems checks. When completed, they climbed to 25,000 feet (7,620 meters) and flew the new bomber to Larson Air Force Base at Moses Lake, Washington, where they stayed airborne for continued testing. The Stratofortress finally touched down after 3 hours, 8 minutes—the longest first flight in Boeing’s history up to that time. Johnston radioed that the airplane performed exactly as the engineers had predicted.

Boeing YB-52 Stratofortress 49-231. (Boeing)

The YB-52 had actually been ordered as the second of two XB-52s, but modifications and additional equipment installed during building resulted in enough differences to warrant a designation change. The first XB-52, 49-230, should have been the first to fly, but it was damaged during ground testing.

Boeing XB-52 Stratofortress 49-230. (U. S. Air Force)

The Boeing XB-52 and YB-52 were prototypes for a very long range strategic bomber. Both were built with a tandem cockpit for the pilot and co-pilot, similar to the earlier B-47 Stratojet. The wings were swept and mounted high on the fuselage (“shoulder-mounted”). The eight turbojet engines were in in two-engine nacelles mounted on pylons, below and forward of the wings. This had the effect of preventing the airplane’s center of gravity from being too far aft, and also provided cleaner air flow across the wings. The B-52’s landing gear has four main struts with two wheels, each. They can turn to allow the airplane to face directly into the wind while the landing gear remain aligned with the runway for takeoff and landing. With the landing gear under the fuselage, the wings could be constructed with greater flexibility.

Boeing YB-52 Stratofortress 49-231. (U.S. Air Force)
Boeing YB-52 Stratofortress 49-231. (U.S. Air Force)

The YB-52 was 152 feet, 8 inches (46.533 meters) long with a wingspan of 185 feet, 0 inches (56.388 meters). The prototype’s overall height was 48 feet, 3.6 inches (14.722 meters). The vertical fin could be folded over to the right so that the B-52 could fit into a hangar. The total wing area was 4,000 square feet (371.6 square meters). The wings’ leading edges were swept aft to 36° 54′. Their angle of incidence was 6° and there was 2° 30′ dihedral. The YB-52 had an empty weight of 155,200 pounds (70,398 kilograms) and gross weight of 405,000 pounds (183,705 kilograms).

The YB-52 was powered by eight Pratt & Whitney Turbo Wasp YJ57-P-3 turbojet engines. The J57 was a two-spool, axial-flow turbojet developed from an experimental turboprop engine. It had 16-stage compressor section (9 low- and 7-high-pressure stages), 8 combustors and a 3-stage turbine section (1 high- and 2 low-pressure stages). The YJ57-P-3s had a continuous power rating of 8,700 pounds of thrust (38.70 kilonewtons). The YJ57-P-3 was 183.5 inches (4.661 meters) long, 41.0 inches (1.041 meters) in diameter and weighed 4,390 pounds (1,991 kilograms).

The YB-52 had a cruise speed of 519 miles per hour (835 kilometers per hour) and maximum speed of 611 miles per hour (983 kilometers per hour) at 20,000 feet (6,096 meters). Its range was 7,015 miles (11,290 kilometers).

The two prototypes were unarmed.

Boeing YB-52 Stratofortress 49-231

The B-52 was produced by Boeing at its plants in Seattle and Wichita from 1952 to 1962, with a total of 744 Stratofortresses built. The last version, the B-52H, entered service with the Strategic Air Command in 1960. The final B-52, B-52H-175-BW Stratofortress 61-0040, was rolled out at Wichita, Kansas, 26 October 1962. This airplane remains in service with the United States Air Force. The newest B-52 in service, 61-0040 is 56 years old and has flown more than 21,000 hours.

All previous versions, B-52A through B-52G, have long been retired to The Boneyard and scrapped. Of the 102 Boeing B-52H Stratofortress bombers, 76 are still in the active inventory. One, 61-007, known as Ghost Rider, was recently taken from Davis-Monthan and after an extensive restoration and update, returned to service.

The YB-52 prototype was retired to the National Museum of the United States Air Force in the late 1950s. By the mid-60s it was determined to be excess and was scrapped.

Captain William Magruder (standing) Boeing Chief Test Pilot Alvin M. Johnston (center) and Lieutenant Colonel Guy M. Townsend with the Boeing YB-52 Stratofortress 49-231. (Boeing)
Left to right: Captain William Magruder, USAF; Boeing Chief Test Pilot Alvin M. Johnston; and Lieutenant Colonel Guy M. Townsend, USAF, with the Boeing YB-52 Stratofortress, 49-231. (Boeing)

© 2019, Bryan R. Swopes

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