With the ever-increasing fees of maintaining our vibrant community (servers, software, domains, email), we need help.
We need more Supporting Members today.
Please invest back into this community to help spread our love and knowledge of multi-channel sound.
This is your chance to make a difference. Become a Supporting Member today:
Upgrade NowThat is probably because you are an elastic shock cord. Whaen it ejects it gets pulled or stretched out and it sprigs back on itself, usualy pulling the nosecone back in slingshot fashion and hitting the rest of the rocket. You could use a longer cord or replace it with a long non elastic cord.
+1. I like to use sewing elastic (1/8" or 1/4") because it still stretches but doesn't snap back as sharply. I also like to sew the ends around the mounting loop in the nose cone, rather than tie it...That way you don't get a big blobby knot that could get jammed in the mouth of the tube when you put the nose on. Whatever you do, longer is generally better.
That is probably because you are an elastic shock cord.
In the movie Pulp Fiction, at the end where the coffee shop is being held up, Pumpkin grabs the manager and starts giving him a hard time and asking him if he thinks he's a hero. The manager starts to talk but only gets out, "I am not a hero, I'm just a coffee shop...", and doesn't get to finish his sentence.
In the credits the actor is given credit as "Coffee Shop" instead of a character's name.
This problem used to be known as the "Estes dent". It's cause by elastic shock cords being too short on most kits. On my LPR rockets I fixed this by using non elastic shock cords at least 2.5X the rocket length.
Upon completing my second rocket kit ever, a SEMROC "Iris", I noticed on my very first recovery an odd crescent shaped indentation on the balsa nose cone. I was surprised at this, and filled it and painted the spot again.
On the second launch, it was not observed, but on the third time it happened again.
Finally, an old hand at the club launch mentioned it was known as the "Estes Smile" and that a longer shock cord would solve that. As I didn't know the amount of weight the rocket could handle nor if it would even impact the flight, I did nothing, but just moved onto additional rockets. Most all have blown plastic nosecones, I have noticed, but not the quality of that original IRIS. I still like balsa nosecones, cause.... I dunno....they just seem more classy and substanial.
But I've never had an Estes Smile or Dent with a plastic nose cone yet.
Micromeister - I would be interested in how you tie these off (pictures) along with part numbers.
Sent from my iPhone using Rocketry Forum
Kirk G:
It is perfectly OK to extend any LPR model's Shock-cord by adding 30 - 60'' of 1/8" oval elastic without worry about affecting the flight performance. I NEVER use the provided shock-lines in any KIT model replacing the Way TO Short Estes Rubber bands with as much as 6 feet of 1/8" oval elastic. The reason I stress Oval elastic is it holds up to the heat of ejection 10-to-1 over 1/8" Flat elastic. If you add the Kevlar or Stainless Anchor/Kevlar to the elastic shock-line system it will outlast the model
I agree that Estes supplied "rubber" shock cords are a waste of time. They are usually way too short. They also become brittle far too fast and can easily separate at ejection. More cord length is almost always better. I typically go for the 3x length of the rocket ratio.
There are a couple of observations of mine I would like to share.
First off, the old tried and true Estes "Tri-fold" attachment works just fine. Use carpenter's glue and let it dry for 24-hoiurs... If your mount breaks, then you had some other issue causing your failure and the mount placement wouldn't have mattered anyway. Using this method, you don't need a steel or kevlar leader. It is also very unlikely to zipper a model with your shock cord mounted this way!
Flat sewing elastic works just fine as well. Use the proper amount of wadding/"dog barf" and you will have no issues. This flat elastic is also less likely to zipper a tube. When stretched, it will lay flat against the tube distributing its force over a larger area. Round elastic is a pin-point wire like saw. Kevlar even worse!
Jerome
Flat sewing elastic works just fine as well. Use the proper amount of wadding/"dog barf" and you will have no issues. This flat elastic is also less likely to zipper a tube. When stretched, it will lay flat against the tube distributing its force over a larger area.
Jerome
Enter your email address to join: