SuperNova-Rocketry
Active Member
I wanted to figure out how I could deploy 2 parachutes from my nose cone on a high powered rocket, the first parachute would be a drogue and the second a main parachute (just a regular dual deployment).
I was considering options and have only thought of one: We have a fixed place divider between the parachutes. Both parachutes connected along one shock cord, tie a knot around 3 feet of cord before the main, the knot has to be big enough so that it cannot fit through a small ring on the side which the cord is threaded through. Drogue is ejected with a ejection charge on one side of the divider, it is fed shock cord attached to the main parachute until it reaches the knot. When we want to deploy the main we detonate the pyrotechnic bolts which are holding the ring to the rocket's air frame. This lets the knot pass through the released ring and the main can now freely escape. I'll have to test if the Kevlar shock cord will be strong enough to not break. There are 3 possibilities (im not including failures that can occur with any parachute here) :
1) Successful event
2) Drogue is pulled out but the knot breaks during the pyrotechnic bolt's release, in this scenario the secondary ejection charge then pushes out the main parachute and we lose the drogue but still land safely
3) Drogue is pulled out but after the pyrotechnic bolts release the knot is still stuck, secondary ejection charge pushes out the main parachute with the knot still stuck around the ring, so the main will only be 3 feet above the rocket (the 3 feet is the extra I left between the knot and the main) instead of the usual 6 or 7.
As you can see this is EXTREMELY complex for what could be done much easier with a normal dual deployment method, so I wanted to see if there were any other ideas.
I was considering options and have only thought of one: We have a fixed place divider between the parachutes. Both parachutes connected along one shock cord, tie a knot around 3 feet of cord before the main, the knot has to be big enough so that it cannot fit through a small ring on the side which the cord is threaded through. Drogue is ejected with a ejection charge on one side of the divider, it is fed shock cord attached to the main parachute until it reaches the knot. When we want to deploy the main we detonate the pyrotechnic bolts which are holding the ring to the rocket's air frame. This lets the knot pass through the released ring and the main can now freely escape. I'll have to test if the Kevlar shock cord will be strong enough to not break. There are 3 possibilities (im not including failures that can occur with any parachute here) :
1) Successful event
2) Drogue is pulled out but the knot breaks during the pyrotechnic bolt's release, in this scenario the secondary ejection charge then pushes out the main parachute and we lose the drogue but still land safely
3) Drogue is pulled out but after the pyrotechnic bolts release the knot is still stuck, secondary ejection charge pushes out the main parachute with the knot still stuck around the ring, so the main will only be 3 feet above the rocket (the 3 feet is the extra I left between the knot and the main) instead of the usual 6 or 7.
As you can see this is EXTREMELY complex for what could be done much easier with a normal dual deployment method, so I wanted to see if there were any other ideas.
