new board for 3rd oeinter

If you are thinking about building a DAQ from scratch... don't bother.

So I started this month's ago. Fully aware that I would have to put in all the time that I skipped during my first rocket build, I knew that it would be a challenge. Now I know, I had no idea.
Don't bother.
Pre-TLDR just buy a usb NI-DAQ 600X on ebay for less than $250. Set up your load cells, collect your data, and get it over with.

Now back to don't bother... I tried everything. I bought every arduino known to man. Then I hooked them all up and created archaic forms of multi-core multi-threaded processors with amplifiers and signal conditioners, one Chinese microcontroller + 2 months of shipping at a time. I spent a whopping $50 so far for a box of basically useless micro controllers that I have been able to get down to 497hz refresh rate. What a joke.
I have been building headers and bit banging by code over to a windows and then a Linux cpu. I have NI fpga's, computational servers, professional licenses for LabView and Matlab, experience writing Java and C This, among other resources at my disposal for prototyping and I'm telling you now... 16 bit resolution at 200k samples per second is all you need and if not, reconsider what you are doing.
I bought the biggest and best micro processors and then coded them from scratch. The 2, 3, $400 dollars that NI costs is so worth it. I wish I could tell you I'm biased because I'm doing a review but no. It's just the truth, don't reinvent the wheel. There are no wheels in a rocket. And @NationalInstuments Please give me a sponsorship.

Limited time, limited materials

I've found that the most difficult part of this project has been my lack of machine tools. Trying to find which type of pvc pipe fits which size wooden dowel isn't something you can google. You have to get out there and do it. Fortunately, I have made some progress with sourcing all the things I need to get this done.

I was able to recrystallize (purify) the potassium nitrate stump remover by dissolving it in near boiling water. You will be surprised how much can be dissolved before saturation. Then I let it cool VERY slowly over several days to get some sizable crystals thereby confirming the purity.

Recrystallized KNO3

The sulfur was a whole different monster. To separate it from the 10% filler, which I am assuming is a Bentonite Clay (which is used to make the hydrophobic elemental sulfur "wettable"). I had to boil very small amounts in Toluene. Then perform the same crystallization process to purify the sulfur to, what I suspect is near 98%. This was excruciatingly time consuming because even in boiling Toluene Sulfur is only fractionally soluble. Regardless in the end, I ended up with enough ingredients to mill out ~1/2 kg of black powder (green milling powder). So the correct proportions of super dry, screened ingredients went into my grounded rubber tumbler barrel with double 0 buck shot lead that I emptied from a box of shotgun shells. This was put outside and embanked in case anything went haywire. 2-3 hours later... I had my first batch of powder to test.

Sourcing the Components for Solid Rocket Fuel

The search began where every search begins. Google.
Searching for each of the 3 primary ingredients Potassium Nitrate (KNO3), Charcoal and Sulphur, I found that Charcoal is very easy to make. Willow is the wood of choice but pine works well too. Potassium Nitrate is a common stump remover but also works as a fertilizer.
Sulphur is where things get a little complicated. To start there are a variety of forms of sulphur and its -ites and -ates but I need pure elemental sulphur of which there are a variety of states but that can go on and on. What I know is that I need to find a source of crystalline sulphur or a sulphur containing product that I can purify without having to melt the sulphur (MP= 239.4F=115.2C) (changes the state/flavor to something undesirable).

With a vague idea of what I was looking for I hit the stores first to make charcoal because its the easiest. I grabbed a paint can, put a hole in the top, loaded it with pine shims, sealed it up and cooked it for about 2 hours.

The shims are convent since they are fairly consistent in their shape and cook evenly.

Next I went on the chemical component hunt.

Turns out Spectracide Stump remover says it is 100% Potassium Nitrate but I think there is some sort of binder in it that keeps it powdery so I will recrystallize it to purify it. I tried every big box store out there before I was able to find the stump remover it was only in one place that I would rather not advertize for but their name starts with an "L" and ends with an "owes". Anyway that was the only chain type store that kept it in stock.

So I attacked the KNO3 first by dissolving ~450 grams in 1L of boiling distilled water. KNO3 has a very high solubility/temperature correlation. I simmered it until I saw crystals start to crash out. Poured the solution into a Pyrex glass baking dish. Then I slowly cooled it in an oven over the course of a few hours. Next it went up on top of the refrigerator for a week or so and very large crystals formed. I filtered these out and rinsed them with ice water. Resulting in a VERY high purity product (>99% for sure).

Next I found this garden sulfur. The ingredients are 90% elemental sulfur 10% "inert ingredients". Which of course are proprietary on the MSDS. Considering the fact that sulfur is hydrophobic and insoluble in water apart from its tendency to form clumps in powder form, I figure the inert ingredients have to be some sort of binder that readily absorbs water giving their product the "wettable" property. This could be a number of things the most likely candidates are CaCO3 calcium carbonate or chalk OR Bentonite Clay which is basically kitty litter. I am fairly sure it is the clay so I have been researching how to separate the two but it is more difficult than I thought.

This time I have to take a different approach

My last rocket started with pencil and paper and ran from there. This one I have to see if 1st is it even possible? Making my own rocket propellant seems like it would be a quick way to get me on a watch list so I talked to some ATF and police friends. Here in the state of Florida, I really won't get in any trouble with anything up to about 50 pounds of black powder. Even then to get in trouble, I would have to parade around in the streets letting everyone know I have a black powder depot. I have no ambitions of storing that much of any explosive so I'm good there.

Next on the list, what is black powder? Do rockets even use that anymore?
That's yes and no. While I do feel that by the end of this I will be attempting solid rocket fuels like the rubberized emulsions of ammonium perchlorate and aluminum as seen in the Space Shuttle's SRBs, I want to start out with the most generic black powder formulation and work from there. Just like any recipe there are conflicting ratios of ingredients but at least the ingredients are all the same.

Black Powder is Potassium Nitrate, Charcoal, and Sulfur. Mixed at a variety of ratios. So many that I gathered several formulations and averaged them to decide on the composition I will aim for which is:

Potassium Nitrate	72%
Charcoal	24%
Sulphur	14%

Now I just have to find out where to get the ingredients.

And so it begins...

Well actually it has sort of already begun considering that this is my second blog about rocket engines. My first being the 50lbf Hollistar Liquid Rocket Engine. I have since moved on from the machine shop of my former race team and have spent the last year in Cape Canaveral developing telemetry and data analysis tools for rockets. Now I am starting to get the itch again. Truly, its a need to hear/feel/experience that completely indescribable sensation that causes even the earth itself to tremble when you walk the fine line of physical possibility.

Here at Cape Canaveral and Kennedy Space Center everyone within about 50 miles knows the thrill through the looking glass of SpaceX, ULA, Boeing...etc from our fairly regular launches. Though I have the priviledge of taking my lunch break to drive 5 miles across the cape and witness
1 million+ pounds of thrust launches from within the confines of the rockets "danger zone", there is still something missing. Maybe it is just the enormity that I can't comprehend... whatever it is I am going to go looking for it again. This time I am going back to basics.

I have felt limited and contained by not having access to a machine shop where I can just whip up any customized idea that comes to my imagination. Which made me wonder... how have people been building rockets since 904AD? They didn't have access to machine shops and all the tools that I had. In my 7 years of Aerospace Engineering study focused in propulsion, I found that I knew more about the history of chemistry and medical science than I did about rockets. This is where my new project begins.
My overly ambitious goal as of today is simple. Build a rocket that breaks the sound barrier. 
Sounds easy enough. If I wasn't trying to gain true insight and understanding, I could simply ebay some premade rocket, load it up with motors and fire it off for ~$300. But why would I make it that easy?

I'm going to attempt to build my rocket entirely from scratch without buying a single thing from a rocketry supplier. Even the blackpowder will be made from scratch and it will all be chronicled here! So please follow along!