Articles

Highest Step in the World

In Uncategorized on November 21, 2017 by hillermuseum

Parachuting From Extreme Altitudes
By Jon Welte

Between the end of World War II and the dawn of the Space Age, aircraft performance led pilots to ever higher altitudes and faster speeds. The stresses on both pilot and aircraft were extreme, and the consequences of a pilot being forced to eject from an aircraft were dire.

In 1958 the United States Air Force launched Project Excelsior. The mission plan for Project Excelsior was outwardly quite simple: launch a helium-filled balloon to extreme altitude, and have the pilot within exit by parachute. Parachutes had been used since the 1780s, but a jump from 100,000’ or more is daunting. At altitudes above 60,000’, air pressure drops to a point at which water boils at human body temperature. Depressurization results in unconsciousness in seconds, and death in minutes.

The pilot for Project Excelsior was Air Force Captain Joseph Kittinger. Kittinger traveled to altitude in an unpressurized balloon gondola, wearing a pressure suit and multiple layers of insulating clothing. The first jump, from 75,000’, took place in November 1959. A series of mishaps during exit caused Kittinger’s drogue chute to open early. The chute tangled around Kittinger’s neck and he entered a spin of over 100 rpms. Kittinger lost consciousness in the 20 g spin, and the tangled drogue was unable to extract the main parachute aas planned. Kittinger survived only through the automatic deployment of his emergency parachute. Many modifications were made, leading to an uneventful second test just one month later.

Excelsior III was the final jump in the series, and intended to reach the highest altitude. Riding the balloon to an officially recorded altitude of 102,800’, Kittinger stepped out into the void—Air Force crew had emplaced a plaque at the foot of the balloon’s egress port helpfully stating “This is the highest step in the world”. Kittinger fell for over four and a half minutes, reaching a speed of Mach 0.9 – nearly the speed of sound – in his rapid descent.

The Excelsior III gondola held its billing as the world’s highest step for over half a century. Earth’s atmospheric pressure at 100,000’ is about the same as the mean atmospheric pressure on the surface of Mars, and accidental depressurizations proved fatal for two would-be record breakers in the 1960s. This altitude—some 20 miles above sea level—is well below the internationally-recognized line at 62 miles considered to be the boundary to space, or even the 50-mile limit at which NASA and the United States Air Force issue astronaut wings to pilots and flight crew. Nonetheless, the low atmosphere pressure poses many of the same challenges faced by astronauts working in space.

It was not until 2012 that Joe Kittinger’s record was finally broken. Professional skydiver Felix Baumgartner joined the Red Bull Stratos project in 2010 with the goal of breaking the altitude record. Unlike Project Excelsior, Stratos involved an ascent in a pressurized balloon gondola. This added complexity to the balloon system, but meant that the pressure suit need only provide primary life support for a span of minutes, not hours. The concept was demonstrated successfully in a pair of test jumps in early 2012. In October 2012 Baumgartner successfully jumped from an altitude of 127,800’. During nearly 4 minutes of free fall Baumgartner reached a maximum descent speed of Mach 1.25—jumping without a drogue chute to stabilize his descent allowed a faster free fall. Despite some stability problems early in the jump, Baumgartner maintained control and landed safely.

While the Red Bull Stratos project was under development, Alan Eustace became intrigued with the concept of exploring the stratosphere by balloon and descending via parachute. Eustace partnered with Paragon Space Development in Roswell, New Mexico, to develop a system capable of supporting a record-breaking launch and descent in a new project named StratEx. Unlike Excelsior or Stratos, StratEx did away with the balloon gondola altogether. Like Kittinger, Eustace would be protected by his pressure suit for the entire mission. Unlike either Kittinger or Baumgartner, Eustace would not need to exit a gondola. Suspended directly from the balloon, just beneath the balloon’s avionics bus, Eustace would start his descent by simply firing explosive bolts to separate his pressure suit from the balloon assembly. This simplified the mission profile and removed appreciable risk: in 1962, Soviet test pilot Pyotr Dolgov was killed in a jump from over 90,000’ when his helmet faceplate impacted part of the balloon gondola during exit, causing a lethal depressurization of his pressure suit.

Eustace’s flight began at dawn on October 24, 2014, as he was lifted in a face-down position from a launching platform. It took over two hours for Eustace and the StratEx balloon to rise to the mission’s maximum altitude of over 135,000’, nearly two miles higher than Baumgartner’s previous record and more than six miles higher than Kittinger’s mark from Project Excelsior. Following separation, Eustace returned to Earth in just 15 minutes, free falling for over 120,000’.

Despite its apparent daredevil aspects, extreme skydiving has had the practical effect of boosting access to the stratosphere for both scientific and commercial purposes. Paragon Space Development has leveraged its experience with StratEx to support World View, an organization focused on providing high altitude balloon flights for both research missions and private sightseeing flights. With operational flights planned for later in 2017, World View expects to offer missions to 100,000’ in gondolas containing two crew and up to six passengers. During recovery, the entire gondola will separate from its balloon, descending to land beneath an enormous parawing parachute.

Resources

http://www.paragonsdc.com/stratex/#twentyeight , downloaded 2 February 2017

http://www.redbullstratos.com/ , downloaded 1 February 2017

http://stratocat.com.ar/artics/excelsior-e.htm , downloaded 1 February 2017

http://www.worldview.space/voyage/ , downloaded 2 February 2017

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