The fuel is the most important part of a rocket. Without it, it is simply an elaborate tube with a pointed end.
This is where most of our time has been spent; perfecting the fuel mixture. We started out with 60/40 oxidizer/fuel mixture (I literally eye-balled the KNO3 & Sugar into a solo cup) and actually got a really fast burn rate. This was before I had the rocket project in mind and really just liked the idea of making rocket fuel to lite off in a parking lot.
With this goal an actual goal in mind, we started measuring everything. We have actually had less success with getting a satisfactory burn test until a few days ago.
I've said this before and I want to reiterate: I have no training in chemistry or aerospace...anything. I saw a YouTube video and got excited. Please correct me if I misquote or state incorrect facts! I am learning as I go...
Our current fuel mixture is:
KNO3 : Dextrose : Sucrose
4.25 : 2 : 1
Our average batch is 153 grams total and it makes about 4 grains depending on loss during the cooking process. We have Red Iron Oxide on order and will add in at 1-2% depending on batch size.
Now that we have the thrust meter (mostly) working, we can really start to dial in the fuel mixture. The final issue we are working out is the best method to pack the warm, gooey fuel, into the grain form. We have had an issue with air bubbles and that causes CATO almost 70% of the time.
We are all meeting again tonight to get the thrust meter attached to the arduino. This will give us very specific readings and allow much more accurate measurements to use for the final adjustments.