Finocyl Propellant Segments Fired

Rick Maschek successfully conducted a static test of the small test motor which used a finocyl core geometry for the SStS project. This is exciting because of the possibilities that complex core geometries open up. Many of the most impressive small sounding rockets utilize a monolithic grain segment with a complex core geometry. Arguably on of the earliest and most successful is the Loki dart which could deliver a small payload to 34 miles despite being only three inches in diameter. It used a simpler cruciform core design.

Photos and video courtesy of Rick Maschek.

Finocyl grain testing

The Sugar shot project has begun testing finocyl grain geometries. Rick Maschek is doing a great job of actually casting the segments. Rick has managed to remove the mandrels with ease , something that is notoriously difficult with complex cores, by cooling it first by running nitrogen through the center of the mandrel. Ed at true-core fabricated the mandrel designed by Richard Nakka. I supplied a short 2 segment casing to work with the Blast Tube Motor that I designed to test ablative samples. Really interesting work that I wish I could be more involved with.

Pictures of last months launch

My friend James took some great pictures of the zinc/sulphur rockets at last months RRS launch. Zn/S rockets typically leave the ground like they're being shot out of a cannon, so many photos I've seen only include a column of smoke but no the rocket.

You can see the rest of Jame's photos from the day on his Picasa site here. The day was pretty overcast and there were some really cool cloud formations late in the day. James captured a great panorama of the approaching storm clouds that he posted on his blog here.

Two Wheeled Rocket

The other day a friend at work rode in his friends Ducati Desmosedici RR, and I got an opportunity to look over this awesome machine in person. Not a true rocket, but an incredible machine none the less.

Great Weekend!

I attended the RRS launch this weekend. It was a great launch and I had tons of fun. Rick Maschek and I fired a motor that was part of ongoing testing for the Sugar Shot to Space project. There were at least 12-13 small Zn/S rockets flown, a 4000lb thrust LOX/kerosene static test, and a variety of other flights and tests.

PACS-1 Ejection Motor

I recently got this small rocket motor. It's about the size of a large coffee can. The base says PACS-1 Ejection Motor with a logo underneath that I believe is the Atlantic Research Corporation logo. My guess is that it's from the 60-70's based on the hand engraved serial numbers, coffee stained base, and light patina that had accumulated on the nozzle half of the motor. It did clean up pretty well though as seen in the above photo. It looks like a large central nozzle surrounded by the four smaller nozzles (two of which are canted 45 degrees and all the smaller ones are plugged). I'm guessing the the nozzle consisted of at least a couple of parts and that the convergent section and throat were recessed. Those sections are not included so the visible divergent section is only part of the nozzle included. The two halves unscrew and the gold anodized half is lined with rubber and has a variety of inspection stamps. There is also a central threaded "neck" were the igniter is likely intended to go. I'll post some more pictures when I get a chance.

How Much Inhibitor?

On the Sugar Shot project we've been talking about, among other things, how much inhibitor is actually necessary to inhibit the propellant surface. I suspect that it's less than what most of us would guess. A few years back I made several motors that were designed around a readily available source of casting tubes, ie paper towel and toilet paper rolls. The motors worked great and have been fired with Fructose, Sorbitol, and Xylitol based propellants. These "casting tubes" with a wall thickness of just 0.020" seemed to do the job quite well. It makes me wonder just how thin one could go. In the last photo, the kraft paper casting tube can be seen inside of the red rosin paper used as insulation. I was expecting to be able to use a bit more insulation, but in practice the fit was tighter than I was expecting. I considered making slightly smaller diameter casting tubes to allow more insulation, but that goes against the original design intent. I then considered switching to a different insulation, but with the relatively thick casing wall and short burn time the casings on this motor seem to come through a firing none the worse for wear. There are other thin insulation material that I may try in this motor in the future.