Fins n things

After having my composite sheet fail to cure because of the cold weather, I decided to go with 1/8" Lexan sheets for my fins. I got all of the stuff, and then spent the evening making them.

The Lexan Sheet


I cut the sheet into 4" strips, and marked out the angled cuts.


All cut and ready to shape and sand.


After about an hour of tedious shaping, sanding, and giving them a frosted look, this is the result. I made 10- 4 for each rocket, 2 in case of breakage or something.


I still really don't know how to attach them to the rocket. I was thinking of getting some aluminum C-channel and screwing it to the rocket body, but that would add a lot of weight. I want to use some kind of solvent glue, so I made a test piece with some leftovers and some PVC glue. I have no idea how well that will adhere the Lexan to the body, so I might have to try some acrylic glue or epoxy. If that doesn't work, then it's back to the drawing board.


I also got the two body tubes cut. The PVC is SDR 26, so it is more likely to flex and less likely to shatter than Schedule 40.


I wasn't ready to quit for the evening, so I started work on the launchpad. It is going to be a 12" concrete paving stone attached to a stand so it can be angled. I have an old CB antenna that will work great for the launch rod.

Here's drilling out the aluminum plate that will go on the bottom:


When I get the bracket done, it will be bolted to the bottom of the stone, like this:


And that's all that I got done tonight. Now to clean up the shop- I don't even remember using half of that stuff!

Goodness gracious, great balls of fire!

The first propellant test is done! I was actually rather impressed with the strength of the rocket candy. The force of the burning alone was enough to make the little pellet of fuel in the first test dance around, and it shot the big cylinder of burning rocket candy out of the pipe in the second test.

Anyways, below is the production process:

Start with:

• 65g of Potassium Nitrate (KNO3)


• 35g of Sucrose (table sugar)


• 40ml of hot water (H2O)

Get your hotplate and pot ready:



Mix all of your stuff together, and heat it up. Don't freak out if it starts bubbling, that's good. Just keep the heat down and let the water boil off.



You will begin to get a pasty looking blob, keep heating until there is no sizzling and it starts to get brittle. Like this:



Then, roll it into a little cylinder and have fun!

Plans- Mark 1

Ok, so I got some plans done.

Right Here

Still no idea what to do for the recovery system.

Of propellants and explosives

So, my order from skylighter came! I now have a pound each of Zinc powder, Sulfur, Potassium Nitrate, and Sucrose. Should be fun...

I think that I might do a test of stump remover (ghetto saltpeter) versus the actual potassium nitrate to see if it is really worth the extra money. If I don't need to buy pure chemicals, that means that I can get more zinc.

Right now, I am thinking of replicating the two best propellants from Rocket Boys. That would be "rocket candy" (saltpeter and sugar) and "zincoshine" (zinc powder, sulfur, and alcohol). Those look to be some really easy choices. After I get some nozzles machined, then I might try an Ammonium Nitrate composite propellant.

I am going to do a propellant test tonight- vids and pics will be up then.

The grand beginning

So this blog will chronicle my building of a large rocket over the next few weeks. This is what happens when you bite off too much for a science fair project.