Junior L1 build

Hey guys,
I haven't been too many places on this forum, having joined it late 2019, but because this is my largest project yet, I thought it would be a good idea to share it here, and mabye get some expert advice. It is being built on 4 inch cardboard airframe, and I plan to fly it on a Cesaroni - P38-2G Skidmark (H123). I will post the build images here, and I would appriciate any advice you guys have along the way.

Here goes nothing!

(this was posted in advance, I will probably have the first pics on saturday)

Sounds nice and straight forward.

Probably looking at 4-500m for a flight like that.

Have fun!

Sounds like a fun project!

You might need to change motors. I don’t think that people under 18 can fly sparky motors.

Sparky motors may be a problem. Check with your local NAR section before spending money on a motor you can't use.

Additionally, in effect starting this year, a written test is required. Info here.
https://www.nar.org/high-power-rocketry-info/formal-participation-procedure/

It would be in your best interest to check out a local club, and find a mentor to help you though the process. Good luck!

DuctTapeandRocketFuel said:

Sparky motors may be a problem.

Click to expand...

Where are you seeing this? I have a couple Jr. L1 candidates on the TARC team I am working with, and have reviewed the program & procedures at nar.org. I don't see any restrictions on propellant type for Jr L1 fliers.

Let me clarify that the use of sparky motors may be restricted at the club level, so checking with the club you would like to fly with important.

I have seen plenty of people fly sparky motors (skidmark, dark matter, etc.) at my club. Livermore unit of the NAR. I will of course check with them, but I don't think there are restrictions on sparky motors, at least at our high power launch location.

Looks like I was wrong and the sparky restriction is only HPR and not over 18 as well.

First day of build! Standing at roughly 7.5 feet tall, this is by far the largest rocket I have ever built.
I did CAD for the centering rings and fins, then laser cut them and epoxied them together
The nose cone, I ordered off apogee, and the tubing is standard 4 inch airframe, with a coupler in the middle.
The fin design is through the wall, with the fronts fitting over top of the slits. I will be adding a third plywood ring at the beck to make sure the flaps stay together. overall, a vey productive day!
I did realize today that I have a massive amount of space for a payload section, and other than messing around with dual deployment, I have no Idea wht I should put in there. Any ideas?
I also need a name for the rocket . . .

Howdy Oscar G.
The rocket looks great so far. Based on your pictures I'm guessing you are doing some of the construction at school - that's awesome!

You are right... there is a lot of 'empty space' in a really large rocket. If it were me, I would build the rocket with an Av-Bay to make it dual-deploy ready. That way you won't have to destroy the paint job when you decide to make it dual deploy in a couple of years. No-worries, you can fly motor deploy for the JR L1 cert with no problems.

You are off to a really nice start - and to confirm - the sparky motor won't be a problem. In Cali you'll be flying at a club launch under the guidance of the clubs OSFM Pyrotechnic Operator. Those guy's know all the rules and will help you every step of the way.

Good Luck!!

Hi Oscar, great rocket, best of luck on your flight. if I may ask, what did you use to laser cut the CRs? Dave.

Hi Dave,
I did the cuts on a 90W Full Spectrum P-Series (36"x24") Laser cutter, using 1/8 in plywood.

I think Oscar is allowed to use a sparky motor, as long as he is with his mentor when he launches it. My club mentor gave me the thumbs up to launch a J, and said that the motors a Junior can fly are limited to whay the mentor can fly.
That is a really tall rocket! Should be very stable. Good luck!

Also, are you the Fireworks guy from Rocket Emporium Discord server? LOL

One major thing to remember is that you want to know where the CP is. If you are using a simulation program it should show you.
As long as your rocket is the CG/CP should be no problem, but expect to be asked exactly where the CP is.

Second major thing I see is the volume of the body. A standard deployment charge that comes with the motor may not deploy reliably in flight. Converting the coupler to an electronics bay just ahead of the CG will shorten the effective body tube. You could also extend the motor mount tube to a forward centering ring. Either of these will stiffen the body and reduce the volume you need to pressurize.

You might want to use one of the online calculators to see how much pressure you can expect for the size of the body tube. Jut adding black powder may work, but brings up other issues.

You should have some of the folks at LUNAR review your project before you try to fly.