[INNOVATIONS] CHUTE WORKS
T e Evolution Behind the Plane with the Parachute; An Interesting Application for Synthetic Materials and Wire Rope.
Over the past few decades, airplanes have evolved much like automobiles, integrating engineering design and technological innovation into a machine that provides more capability, and most importantly, an experience that is the safest ever encountered. Aircraft manufacturers have continued to evolve products that promote both protective and preventative safety measures in an attempt to save lives, and one company based in Duluth, Minnesota, has developed a proven winner. Cirrus Aircraft has been in the business of building single-engine piston aircraft since the 1980s. Co-founders and brothers Alan and Dale Klapmeier imagined a modern aircraft that combined performance, safety, comfort and innovation that had been lacking in the industry for some time. While many of the features of the composite-designed aircraft were state-of-the-art, the most recognizable and signifi cant was the inclusion of an entire airframe parachute. After the FAA certifi cation approval of the fi rst Cirrus SR20 in 1998, the “plane with the parachute” was now a reality. For the last decade, Cirrus has held the unique advantage of being the world’s best-selling aircraft in its class.
both weight and speed can be controlled, the idea to use an entire parachute for an aircraft as a safety net meant that engineers had to design a system that would be successful in a wide range of conditions of fl ight – fast or slow, and with varying amounts of weight and aircraft attitudes. According to Tim Timmerman, Director of
SR2X Engineering at Cirrus Aircraft, having a parachute attached to an airplane is unique to begin with, but the design criteria made the implementation of the entire system even more diffi cult. T e parachute needed to open quickly when at low speeds in order to preserve a minimum loss of altitude, but be strong enough to sustain the forces when used at high speeds without failing. T ese are two very diff erent design criteria and diffi cult to meet in a single parachute design. As Fallows puts it in Free Flight,
Kevlar webbing straps used in the Cirrus Aircraft Parachute System. Photo Courtesy of Cirrus Aircraft
T e Cirrus Aircraft Parachute System, or CAPS, as it is more commonly known, was not an easy task. While parachutes have been used in a myriad of ways for centuries, as author and pilot James Fallows noted in his book Free Flight, “the problem with a whole-airplane parachute is that no one had made it work in quite this way before.” Unlike static parachute drops where
30 MAY-JUNE 2014 WIRE ROPE EXCHANGE
“A way of slowing the deployment of the chute, so that its shock force was spread over several seconds rather than hitting all at once, [Cirrus Chief Engineer Paul] Johnston applied [Ballistic Recovery Systems’] concept of a “slider ring.” T is was a device that encircled the lines leading from the parachute canopy to the plane. When the chute fi rst deployed and the plane’s speed through the air was at its greatest, wind force on the ring itself would keep it near the top of the lines, where it would allow the chute to open only part way. Over the next few seconds, as the drag from the partly opened chute began to slow the plane, the slider ring would move farther down the shroud lines – allowing the chute to open more fully, which would slow the plane more, which would let the ring move farther down until within a few seconds the chute was fully deployed.”
According to Cirrus’ website, pulling the red CAPS handle on the ceiling inside the cockpit deploys a solid-fuel rocket out a hatch that covers the concealed compartment where the parachute is stored. As the rocket carries the parachute rearward from the back of the airplane, the embedded CAPS airplane Kevlar harness straps
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