Inspired to design rockets again.

[crossbound]

It's been a very long time since I posted on the Rocketry Forum. Glad to see it's still a source of great inspiration. This past weekend my son, who is studying aerospace engineering and recently joined the Rocketry Club at school, informed me out of the blue that he is about to finish his first HP rocket built in order to get his Level 1. Mind you we haven't flown rockets in basically a decade when my kids were still little. We used to go to a rocketry club in our area to fly our little LPR's and enjoyed watching all the big boys rockets fly. The reason he joined the club was that one of the members asked him to be part of a large project that has the goal to send a rocket above the Karman line. As my son is also a chemistry major he was asked to be responsible for sourcing, developing and mixing propellant for the rocket. (man I wish I could be young again and be part of something like that!!)
Anyway.. To make a long story short, I got inspired to download OpenRocket again and start designing my own medium power/ high power rocket. The one thing I was wondering with these longer body tubes, does anyone every put a baffle half way down the tube to keep the parachute from sliding down the tube. The baffle would only be a stop and not meant to protect the parachute from the ejection charge. Attached picture shows the baffle right behind the parachute. I probably would drill maybe 5 holes through the baffle and attach an eye bolt in the middle of it. Does this make sense or am I overthinking this?

 

[pugachu]

Hello, and welcome back!

On larger low/mid power rockets, they use smaller dismeter 'stuffer tubes' extending through most of the larger tube to help keep the parachute near the top, as well as reduce the volume that the ejection charge needs to pressurize. That kind of looks like what you have going on.

On a lot of high power rockets, the tube separation happens near the middle, rather than at the nosecone.

Once your son gets his level 2 cert through Tripoli, he can be admitted into the 'research' sub-forum, where there are a lot of members here that would be happy to help him develop and mix the fuel for the schools rocket club.

 

[Hobie1dog]

back to the hobby

 

[Azamiryou]

Perfectly reasonable, and often called a "laundry shelf".

 

[KenECoyote]

Welcome back!

From my recall, TLP (The Launch Pad) kits often incorporated an extra centering ring higher in the bt to serve as a parachute shelf. They noted that it wasn't an ejection baffle and that you still need to use something to protect the chute from hot ejection gasses.

 

[lr64]

Welcome. Do you really have to be young to work on "something like that"? Serge Pipko is something like 60 and has a student group doing some pretty interesting things, despite living in a country that's been fending off an invasion for a few years now:
https://www.facebook.com/serge.pipko.5/?locale=ru_RU
(If I'm not mistaken, he's in Ukraine, NOT that other place)
---------
I think Richard Nakka is retirement age. I don't think he's working on anything to go above the von Karman line, but he's still got some interesting projects going:

and a wonderful web site:
nakka-rocketry.net

 

[crossbound]

laundry shelf.. I'll do a little search for that and see what others are doing.. Thx

 

[Capt. Eric]

If you are going to add an eye bolt to the shelf for the shock cord, I would be worried about the shelf being yanked out on deployment, especially for larger rockets. Were I doing it, I might add a coupler or ring above the shelf to help support it.

Also, I might put the eye off to the side where the tube walls will stiffen the structure more. The eye in the middle could pull the center out, depending on how large the holes around it are.

 

[4regt4]

It's been a very long time since I posted on the Rocketry Forum. Glad to see it's still a source of great inspiration. This past weekend my son, who is studying aerospace engineering and recently joined the Rocketry Club at school, informed me out of the blue that he is about to finish his first HP rocket built in order to get his Level 1. Mind you we haven't flown rockets in basically a decade when my kids were still little. We used to go to a rocketry club in our area to fly our little LPR's and enjoyed watching all the big boys rockets fly. The reason he joined the club was that one of the members asked him to be part of a large project that has the goal to send a rocket above the Karman line. As my son is also a chemistry major he was asked to be responsible for sourcing, developing and mixing propellant for the rocket. (man I wish I could be young again and be part of something like that!!)
Anyway.. To make a long story short, I got inspired to download OpenRocket again and start designing my own medium power/ high power rocket. The one thing I was wondering with these longer body tubes, does anyone every put a baffle half way down the tube to keep the parachute from sliding down the tube. The baffle would only be a stop and not meant to protect the parachute from the ejection charge. Attached picture shows the baffle right behind the parachute. I probably would drill maybe 5 holes through the baffle and attach an eye bolt in the middle of it. Does this make sense or am I overthinking this?

A baffle like that is what I use on anything long enough for all the goods to fit.

Hans.

 

[Bruiser]

I use laundry shelves with an eyebolt for the laundry on most of my "tallish" 2.6' and 3" builds. Got the idea from the Pro Series Patriot kit. I've only been doing mid power for 2-3 years but I haven't had one pull out yet. A lot of times I put them in the coupler. I'll epoxy them in and usually seal them with epoxy as well


Sometimes I'll add a piece of ply to them for the upper rail button attachment. This one also has the bottom coated with JB weld


Here's another in the coupler with the upper rail button attachment. This one uses a blind nut. The one above uses a flat head machine screw but you have to be carefull not to split the wood with them/ Pre-drill and I even have a screw that I turned into a "tap" to cut the threads. I like the Dubro blind nuts much better, ymmv...


-Bob

 

[crossbound]

If you are going to add an eye bolt to the shelf for the shock cord, I would be worried about the shelf being yanked out on deployment, especially for larger rockets. Were I doing it, I might add a coupler or ring above the shelf to help support it.

Also, I might put the eye off to the side where the tube walls will stiffen the structure more. The eye in the middle could pull the center out, depending on how large the holes around it are.

That makes sense, I was actually thinking about possibly adding a coupler to add strength

 

[crossbound]

I use laundry shelves with an eyebolt for the laundry on most of my "tallish" 2.6' and 3" builds. Got the idea from the Pro Series Patriot kit. I've only been doing mid power for 2-3 years but I haven't had one pull out yet. A lot of times I put them in the coupler. I'll epoxy them in and usually seal them with epoxy as well
View attachment 676086

Sometimes I'll add a piece of ply to them for the upper rail button attachment. This one also has the bottom coated with JB weld
View attachment 676088

Here's another in the coupler with the upper rail button attachment. This one uses a blind nut. The one above uses a flat head machine screw but you have to be carefull not to split the wood with them/ Pre-drill and I even have a screw that I turned into a "tap" to cut the threads. I like the Dubro blind nuts much better, ymmv...
View attachment 676087

-Bob

that looks good! definitely what I was envisioning