- Joined
- Mar 27, 2013
- Messages
- 22,535
- Reaction score
- 14,942
Someone on FB was talking about how their old rocket's shock cord had become dried and brittle, and there's all kinds of suggestions on how to replace them with Kelvlar. While I don't fully agree with them, I don't fully disagree either.
Here's the rub...
The benefit of using the rubber shock cord is that it is the weakest material in the rocket. If the rocket gets caught up in a tree, the UV light will deteriorate it quickly. Thus you should hopefully get the cardboard and wood portion back with the least amount of damage.
Depends on the weather. If the cardboard is painted, that'll afford you some protection. Soak some thin CA around the inside of the top of the body tube, and that'll help things quite a bit. Use wood hardener on the inside,and you've got a nearly waterproof rocket. And the fins will likely hold up for a while, presuming that the winds aren't bashing the rocket too much.
I had a rocket that I literally filled with water, and launched under water (it didn't torpedo as planned). And after I allowed the rocket to dry completely, I was able to get the motor out (by unraveling it from the inside). That rocket has flown again, and is completely capable of flying to this day.
Here's some more to think about. The nosecone would likely survive a fall, even without a parachute, from a tree with little to no damage. The body tube likely will also do well in a fall (even better if you can have someone catch it). Parachutes are likely what will tangle in a tree, but they're easily replaceable. The cardboard and wood is where we invest most of our time in building a kit. Lose a parachute? No worries. Lose a nosecone, you can replace it. Lose the cardboard tube, fins, paint and decals? You're back at square zero.
The fragile nature of the rubber allows you easily cut it, and recover the hard to replace part quickly before weather damage occurs. If you can't recover the nosecone for a while, you might be able to replace it from another source. With a replacement for the rubber, a new parachute, and a recovered or replaced nosecone, you're back in business.
Given my preference for rockets that are too short to get a baffle, but not minimum diameter, I'd use a length of Kevlar with a loop on both ends, The line is passed alongside the motor tube, and the loop is "tied" around the outside of the motor mount (accessible from the bottom of the rocket). Tie a rubber shock cord to the other end of the line, with the junction just below the top of the body tube. You can then replace the rubber shock cord if it gets too old, and you can inspect the Kevlar for wear and tear by pulling it back along the motor mount. This way you get the best of both worlds. The benefits of the unrestricted "neck" of the body tube (preventing the parachute or streamer from getting caught inside), and the "If stuck in a tree" benefits of the weakness and replaceable nature of rubber.
Now, the best thing is not to get stuck in trees. However, if you do, a slingshot with a lead weight, a bow and arrow, or a crossbow can launch a Kevlar line up into the tree. and If you can catch the shock cord, you can "saw" thru it.
*I've got a high school buddy who is a double amputee (both arms) who had an encounter with a powerline as a kid. He's got one that was amputated below the elbow, and the other was removed at the shoulder. Be safe
Here's the rub...
The benefit of using the rubber shock cord is that it is the weakest material in the rocket. If the rocket gets caught up in a tree, the UV light will deteriorate it quickly. Thus you should hopefully get the cardboard and wood portion back with the least amount of damage.
Depends on the weather. If the cardboard is painted, that'll afford you some protection. Soak some thin CA around the inside of the top of the body tube, and that'll help things quite a bit. Use wood hardener on the inside,and you've got a nearly waterproof rocket. And the fins will likely hold up for a while, presuming that the winds aren't bashing the rocket too much.
I had a rocket that I literally filled with water, and launched under water (it didn't torpedo as planned). And after I allowed the rocket to dry completely, I was able to get the motor out (by unraveling it from the inside). That rocket has flown again, and is completely capable of flying to this day.
Here's some more to think about. The nosecone would likely survive a fall, even without a parachute, from a tree with little to no damage. The body tube likely will also do well in a fall (even better if you can have someone catch it). Parachutes are likely what will tangle in a tree, but they're easily replaceable. The cardboard and wood is where we invest most of our time in building a kit. Lose a parachute? No worries. Lose a nosecone, you can replace it. Lose the cardboard tube, fins, paint and decals? You're back at square zero.
The fragile nature of the rubber allows you easily cut it, and recover the hard to replace part quickly before weather damage occurs. If you can't recover the nosecone for a while, you might be able to replace it from another source. With a replacement for the rubber, a new parachute, and a recovered or replaced nosecone, you're back in business.
Given my preference for rockets that are too short to get a baffle, but not minimum diameter, I'd use a length of Kevlar with a loop on both ends, The line is passed alongside the motor tube, and the loop is "tied" around the outside of the motor mount (accessible from the bottom of the rocket). Tie a rubber shock cord to the other end of the line, with the junction just below the top of the body tube. You can then replace the rubber shock cord if it gets too old, and you can inspect the Kevlar for wear and tear by pulling it back along the motor mount. This way you get the best of both worlds. The benefits of the unrestricted "neck" of the body tube (preventing the parachute or streamer from getting caught inside), and the "If stuck in a tree" benefits of the weakness and replaceable nature of rubber.
Now, the best thing is not to get stuck in trees. However, if you do, a slingshot with a lead weight, a bow and arrow, or a crossbow can launch a Kevlar line up into the tree. and If you can catch the shock cord, you can "saw" thru it.
*I've got a high school buddy who is a double amputee (both arms) who had an encounter with a powerline as a kid. He's got one that was amputated below the elbow, and the other was removed at the shoulder. Be safe
Last edited:
