Brian Smith lived near my home where I grew up in Santa Rosa back in the 1960s and ‘70s. He built a 14-foot-tall classic diamond-shaped kite with the spine, spar and frame constructed of wood and a ballast tail that used an old canvas car cover cut in large bows.
When the winds were strong enough, he flew that kite in a broad open field near Mark West Elementary School with a tether made of braided green tuna line on a big wooden spool. The line was rated at 300 pounds of force before it would break. To fly this behemoth, he used thick leather welder’s gloves to prevent rope burns. I vividly remember that amount of pull this kite exerted on that tuna line as we helped him to bring the kite back in.
With that much force, we wondered, how high could a kite fly into the atmosphere?
To start, “A kite is defined as a tethered aerodyne deriving all its lift from ambient winds and unassisted by any ‘booster’ such as a rocket, balloon, gas, motor, electricity, explosives or other applied devices,” according to the American Kite Fliers Association.
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The most significant limiting factor for high-altitude flying is the aerodynamic drag on the tether line. You see, as the wind speed doubles, the force on the line quadruples. If the line is too thin it will break, but if too thick, its drag will keep the kite closer to the earth’s surface – a delicate balancing act indeed.
Well, for many decades, the world kite-flying altitude record stood at 12,471 feet, set in 1896 by A. E. Sweetland and Henry Helm Clayton. They used a Hargrave box kite with about 86-square-feet of sail that resembled the front wing of the Wright Flyer; they used piano wire with a breaking strength of 330 pounds for their tether line.
That record was broken by Richard Synergy on Aug. 12 2000, when he flew his delta wing kite named “Millibar Messenger” to an estimated 14,509 feet near the town of Kincardine, Canada, in a farmer’s wheat field. Millibar Messenger had a 30-foot wingspan with a total surface area of 270 square feet.
Robert Moore and his team broke that record 14 years later when his kite reached 16,009 feet above its launch point near Cable Downs on a sheep ranch in Australia on Sept. 23, 2014.
Depending on the atmospheric conditions that day and latitude, Moore’s kite may have reached the 500-millibars of pressure used to determine the atmosphere thickness. Let me explain:
Meteorologists estimate the thickness of the atmosphere by analyzing 500-millibar upper-level charts. In other words, this chart will tell you where the air density decreases by half. At our latitude, it usually varies around 18,000 feet. These are the altitudes where the jet stream or upper-level winds reside.
During the winter months, these winds can reach over 150 mph.
The kite Moore used to break the world record was also delta wing. It measured 21 wide and 12 feet high.
The kite carried a GPS unit to measure altitude. At the kite’s zenith, over 41,000 feet of high strength Dyneema braided line was reeled out and in from an electric winch on a trailer that could have been designed by Rube Goldberg.
A great place to learn about kites and the power of the wind will be at the Morro Bay Kite Festival this weekend.
“PG&E is proud to support the Morro Bay Kite Festival. The Wind is Power Competition allows us to pair that commitment with our focus on a clean energy future. By educating students on the importance of wind power, we can both inspire them, and provide them with valuable tools for making an impact in their local communities,” said Pat Mullen, Director of PG&E’s Los Padres Division.
To learn more, please visit morrobaykitefestival.org/.