For my schools rocketry program I have been assigned to the recovery team and we decided on using a combination of braided kevlar and nylon shock cord together to minimize stress on the shock cords, is this even a good idea or should I only do nylon or kevlar? If I end up doing both, what are yalls' suggestions for the length difference between the two cords, I can't find any info online about how much nylon shock cord stretches and Im at a loss for what cord I should longer. For context my rocket is using a L550 and we're breaking the sound barrier this year, it is 4 inches wide and 5 feet tall.