Apologies for the vapid update, but I'm hoping to keep this current, and today is my deadline for over 50k', so no time like the present.
Three weekends ago, Manny and I totaled 4 hours of sleep, and it took four days to reach that total (Friday-Monday). I added 860 miles of driving on top of that, but that's all in the rearview because we got all the New Mexico propellant made.
Last Monday, I was able to get some time on my buddy's dedicated propellant chop saw, and pulled an all nighter taking advantage of it to get all 103.4 pounds of propellant cut. The 10" saw was too small for my 4.475" OD grains, so it took a few passes with the requisite half-cut approach (tweaking the Harbor Freight saw exhaustively to be accurate to the tenth of a degree and disobeying the "approximated" factory square settings; small deviations from square are magnified in a half-cut arrangement, and with my particular motor design square grain faces are absolutely critical). I lost 9/16" of propellant total over the eight grain faces getting this right, meaning it took me roughly 1/16" of material per grain face to get it perfect. Not too bad, especially for doing it on my knees on my buddy's back porch with a floodlight at 4am on a Tuesday morning. The perfectionist in me is annoyed at the lost impulse. Oh well. I'll more than likely have surgery over the holidays, and the launch will be under our noses right after the New Year, so it was imperative to get as many time-intensive operations (like mixing and cutting the propellant) as possible done. Feels great to have that whole thing off the table.
In the meantime, my friend has finished printing the pin drilling jig, and it's been sent to Charlie for test fitting over the motor case (which is currently serving as the mandrel for the tube Charlie is making):
Pin ring (fore and aft) designs, as well as closure and nozzle design, was finalized last Wednesday and manifested in a series of dimensional drawings and CAD renders. Two separate machinists (graphite and non-graphite) will be making the parts sequentially since all of my stock is in one place - Dan P. will be making the aluminum parts, and once he's finished, Arcesio can get going on the nozzle. The hardware design is a natural progression from what worked on Sunday Silent, focusing on areas where it was felt that further mass reduction could be realized. Same thing with the propellant - the formula is tailored to accommodate my desire for improved volume loading as compared to Sunday Silent, but with the same underlying principles that worked well on SS in both geometry and formulation. The propellant physically looks awesome (good density), so this motor should be pretty solid (85%, to be specific, hah):
Half of my motor chilling with Randito's motor:
In other news, I caught a flight to an MDRA launch a few weekends ago to assist my dad with a years-long initiative that the time had come to try. It had been a while since I'd seen Randito, so he made the trip down to hang out and even fly a rocket. Just for kicks, we talked on the phone a few days before and decided he'd make a downscaled version of the Sunday Silent motor (formula/geometry) and fly it in his Extreme Wildman that has over 50 flights on it. Every other 4700 load he's flown in that rocket got 11.5, he got 13.5 with the SS formula and accompanying increased vol loading. A 17% performance increase in a small motor. That gap will be magnified in a larger motor, and it was cool to see the concepts scale so well, especially with all the residence time pundits around the hobby EX community. Nice flight, Randito.
As I recover from surgery, the one objective will be to get the fincan done. I plan to use the same approach that worked on SS, but I'll have to find a way to do it without the benefit of my equipment, since surgery and subsequent recovery will be in the New York area. Minor detail, I'll figure it out.
If I can emerge on 1/1/16 with a completed fincan and completed motor parts, all I'll have to do in the first two weeks of the new year is assemble the motor (a b!tch with the single use pinned design, but it could always be worse) and cobble together an av bay using the Sunday Silent electronics. Still toying with the idea of flying a camera but we'll see, maybe the camera mass would be better assigned to Nemo in his quest to become the world's first stratospheric fish.
This timeline is a layup, I kinda like it.
-s