The Cirrus Airframe Parachute System (CAPS) is a whole airframe parachute that was developed by Ballistic Recovery Systems (BRS) specifically for the Cirrus. Started in 1980, BRS initially focused on parachute recovery systems for ultra lights and hang gliders. Boris Popov, the company’s founder, started the company after suffering a partial collapse of his hang glider. It was not until 1998, when used in the Cirrus SR20, that this system was used in a type certified aircraft. Again, the impetus for its development for the Cirrus was the result of a bad experience. Cirrus’ co-founder Alan Klapmeier helped push for the inclusion of the parachute system into the design of the first SR20 after having his own midair collision experience early in his career.
The design of the system was one of the first major hurdles to overcome in creating a system suitable for the Cirrus aircraft. Due to its weight it would need to have a very large surface area, but it would have to be compact and light enough to fit in the aircraft while still allowing enough room and weight for occupants. The other major challenge was the envelope of deployment conditions that it had to be designed for. Typically, parachutes are custom designed for a specific weight and deployment velocity. If you can imagine a skydiver parachute the conditions are fairly straightforward; the body types of skydivers do not vary more than 100 pounds and the terminal velocity of a human is fairly constant. Aircraft present a much larger envelope of conditions under which the parachute must function; weight can vary depending on fuel and passenger payload, but the velocity at deployment can vary tremendously; from a plane that is at the verge of stalling to one that is at max cruising speed.
How were these obstacles overcome? Several unique design concepts helped to create a system that could deploy at a wide range of speeds, deploy quickly, and also ensure the safety of the occupants.
1. Get the chute out quick. The surface area of the chute is massive to carry the load of the aircraft at speeds that will not injure the occupants. In order to deploy such a large mass of fabric, it was important to use an active deployment system. A rocket deployment system was chosen. The rocket allows the quick deployment of the chute so that the system can be effective from a mere 400’ above the ground. This system is very powerful. If untethered, the rocket could reach altitudes as high at 10,000 feet.
2. Make sure the chute doesn’t rip the wings off. If the parachute opens too quickly, the deceleration could tear the aircraft apart. To solve this problem, a sliding ring is used to hold the chute cords close together. As the chute fills with air, the ring slides down to let the material open wider. This simple system keeps the parachute from filling too quickly.
3. Keep the occupants safe. Cirrus utilizes special shock absorbing seat cushions and landing gear to further cushion the occupants from impact with the ground. The cockpit also features a carbon fiber roll cage and a slanted firewall to protect the pilot and passengers and further absorb impact energy.
The system does not end with the parachute itself though. Training even has a part to play in the success of the system. Pilots must be trained to recognize conditions that are acceptable for the system deployment and also realize the wide range of situations where deployment of CAPS should be considered. Surprisingly, one of the outcomes of the system being a part of all Cirrus aircraft are the times when the system is NOT used but could have been used to save the life of the pilot and passengers. One possible reason is that for the entire history of civil aviation pilots have been trained to react to emergencies without the option of having a parachute. Other theories suggest that pilots think they can save the aircraft if they attempt to make it to an acceptable landing site or back to the airport. Whatever the reason, Cirrus has taken the job of training pilots (and passengers) to use the system very seriously. Even over the past few years improvements continue to be made to training materials and checklists to help ensure that pilots are offering themselves and their passengers the safest transportation available in civil aviation today.