If you’ve ever flown round-trip across the United States (or to Asia or Europe), you may have noticed that the trip is longer in one direction than the other.
Eastbound flights have a tail wind; westbound ones are effectively swimming against a current. That current is the jet stream, not (directly at least) the rotation of the Earth. Jet streams are “fast flowing, narrow, meandering air currents in the atmosphere.”
On 22 July 1933, Wiley Post (1898-1935) “dropped through the cloud cover” at Floyd Bennett Field in New York where he was greeted by 50,000 people. Seven days, 18 hours, and 49 ½ minutes earlier, Post had climbed into his Lockheed 5C Vega, Winnie Mae, en route to becoming the first person to fly solo around the world. West-to-east, 15,596 miles.
Two years earlier, Post and his navigator, Harold Gatty, had set the record for aerial circumnavigation, also in the Winnie Mae. The previous record of 21 days had been set by the German airship Graf Zepplin. They did it in less than nine.
For his solo flight (89 years ago), Post had modified the Winnie Mae for “long-distance, high-altitude operation.” Part one: an autopilot. Part two: pressurization for high altitude flights. Working with the B. F. Goodrich Company, Post designed the world’s first pressure suit.
On 05 September 1934, Post reached an altitude of 40,000 feet above Chicago.
On March 15, 1935, Post flew from Burbank, California, to Cleveland, Ohio, a distance of 2,035 miles, in 7 hours, 19 minutes. At times, the Winnie Mae attained a ground speed of 340 miles per hour, indicating that the airplane was indeed operating in the jetstream.
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During its high-altitude flight research, the Winnie Mae made use of a special tubular steel landing gear developed by Lockheed engineers Clarence L. “Kelly” Johnson and James Gerschler. It was released after takeoff by the pilot using a cockpit lever, thus reducing the total drag of the plane and eliminating its weight. The Winnie Mae would then continue on its flight and land on a special metal-covered spruce landing skid glued to the fuselage.
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This early full-pressure suit is the direct ancestor of full-pressure suits used on the X-15 research airplane and manned space voyages. The Winnie Mae, its jettisonable landing gear, and Post’s pressure suit are in the collection of the National Air and Space Museum.
Because Post recognized that his ground speed exceeded air speed, “he can be credited as the first person ‘experiencing’ the jet stream first hand.”
In 1935, Post “planned to explore an air route to Asia and Europe from the United States through Alaska and Siberia.” His friend Will Rogers would accompany him. They left from Renton, Washington (south of Seattle) on 05 August 1935. Both died in an airplane crash in Alaska 10 days later.
About jet streams
Jet streams are located about five to nine miles above sea level. The strongest jet streams are the polar jets. Their hot-and-cold boundaries “are most pronounced in winter” (regardless of hemisphere). Although jet streams flow west-to-east, they are shaped more like a wave than a straight line.
In December 2021, the Washington Post reported that the jet stream was “reaching speeds of close to 200 mph at 34,000 feet,” the altitude of commercial jet airliners. It had an impact on flight times.
As of 7:15PM CDT… @united flight 182 from Denver, CO to Frankfurt, Germany is traveling as one of the fastest on Earth right now.
Currently 35,000 feet over SW Wisconsin – this Boeing 787-9 Dreamliner is nearing a crazy speed of 797 MPH!
Extremely fast jet stream aiding this. pic.twitter.com/gTyTib4YJo
— Noah Bergren (@NbergWX) December 28, 2021
It’s important to note that the jet did not break the sound barrier. While its ground speed superseded the published speed of sound, the aircraft wasn’t traveling any faster through the surrounding air. It’s like the moving walkway at the airport — even though your translational speed may be through the roof as you walk with the belt, your actual walking speed remains the same.
Commercial airlines take jet streams into account when planning routes. However, they are not without risk.
Clear air turbulence
Clear air turbulence (CAT) happens when a slow jet stream and a fast jet stream collide, resulting in erratic air currents. It’s invisible to pilots and can cause “violent shaking of the aircraft.”
One major CAT accident occurred on board United Airlines flight 826 from Tokyo Narita to Honolulu International in 1997 – the exact route on which jet streams were first used on a commercial route. Sudden CAT caused the aircraft to fall 100 feet, causing severe spine and neck injuries to 18 passengers. One passenger, who wasn’t wearing their seatbelt, died due to the sudden turbulence.
In 2019, dozens of passengers were injured on a Turkish Airlines flight en route to New York from Istanbul encountered CAT and made an emergency landing John F. Kennedy International Airport. The turbulence occurred about 45 minutes prior to landing.
Researchers estimate that global warming could increase CAT frequency by 170%, making it riskier to pilot these paths. Because “some areas could experience several hundred percent more turbulence,” the rate of injuries may triple by 2050.
Almost 3,000 flights cross the North Atlantic on an average day.
It’s the world’s busiest overseas flight corridor, and flights crossing the ocean in this region are typically exposed to the polar jet stream for the duration of their flight, particularly during the winter.
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Since airliners cruise in the upper troposphere to lower stratosphere, the study shows that they may be buffeted by greater wind shear in the transition zone between the higher winds there and weaker wind speeds just below
Read Will Rogers on “trickle up” economics
#scitech, #science (183/365)
📷 Smithsonian
Daily posts, 2022-2023
