October sky

I watched October sky the other night and the special features. The comentary by Homer Hickam said they used Zinc/Sulfer propellant and alcohol as a binder. The film footage of the original launches showes them to burn for quite a while, zinc/sulfer also known as micro grain, burns very fast. I have no desire to make "Zincoshine" as they called it, but thaught it was interesting.

Were there motors similar to what we use today? Like Aerotech? Did they burn from forward end to aft? Did they have a core?

If you read the "About Us" on the Aerotech website https://aerotech-rocketry.com/about.aspx you will see that they do special effects for films, and October Sky is on that list. I imagine that the later rockets in the movie were simply WL propellant with a decorative bell nozzle on the back.

Zinc and sulfur was talked about a lot in Amateur Rocketry back in the 50's and 60's. I tried it in the 60's when I was in high school. Back then powdered zinc was cheap and so was sulfur. I believe powdered zinc or zinc dust now is very expensive. The powered zinc I had was so fine that it looked like gray flour. The stuff was cheap but the performance was poor. My own experience is that the grains were of very poor structural quality. There was a book by the name Amateur Rocketry Handbook by Brinley that goes into a lot of detail. There were two basic ways of putting the propellant in a tube. One way was putting the mixture in a tube and pressing it or tapping the sides of the tube to make the mixture settle compactly (called tamping). The other method was "cold casting" using acetone or ethyl alcohol. Hence, Homer Hickam investigated using alcohol from a moonshiner. In cold casting the slurry mixture was put into a tube and the alcohol or acetone evaporated making a grain. Burn-rates as high as 90 inches per second were reported for tamping, while burn-rates for cold casting were reported much lower at about 0.5 inches per second. In my experience the cold casted grains were very weak and would easily crumble back into powder again. (Density with cold casting was reported to be better than tamping. Tamped grains were end burners. Cold casted grains were generally tubular grains.) Brinely's book reports a specific impulse as I recall of around 40 seconds, which is very poor. Thermochemical computer runs may indicate a higher performance, but a performance "hit" must be taken because zinc sulfide condenses to solid particles in the nozzle preventing any further performance from gas expansion. Tripoli does not allow zinc & sulfur (or micro-grain) as an experimental propellant. I believe that there is some research society in California that still allows zinc and sulfur rockets.

..............and the safest way to tamp one:

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COrocket said:

If you read the "About Us" on the Aerotech website https://aerotech-rocketry.com/about.aspx you will see that they do special effects for films, and October Sky is on that list. I imagine that the later rockets in the movie were simply WL propellant with a decorative bell nozzle on the back.

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Ky Michaelson did the rockets for the movie and used AeroTech motors. At least I know that's true for the Miss Riley rocket at the end of the film. He had a slightly different version of the Miss Riley rocket for sale on the Rocketman site for a while. It looks like he's only selling recovery items now.

Reaction Research Society (RRS, www.rrs.com) has flown micrograin rockets out there for a while. They do everything including liquid propulsion--just check out the media page on their website. Several dramatic shots of some Z/S launches. I believe these were the "tamping" method. I've also heard that this method of loading the propellant results in a lot of the Z/S mixture simply being ejected from the motor before combusting--hence the dramatic exhaust plumes and low performance. Someone who really knows hard propulsion science can correct me

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rcktnut said:

..............and the safest way to tamp one:

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Cool! That's old school right there!!

For the movie they used I 211 motors as I remember; Ky or someone involved said so.


JD

I would say that the rockets they made in Coalwood where actual real rockets rather than just a motor in the bottom of a paper tube. They where more like motors with fins and a nocecone. I have an old newspaper article from about that time showing a couple of local guys out on a frozen lake attempting to launch their own rocket, pretty cool.

Too bad I don't have the CD of this movie. I still run the tape this time of year. The tape didn't have all the "special features". That would be nice to see. But for what it's worth, here's a photo of our little rocket shack we built just for our launches. Ignore the misspelling on the front. We were still kids learning how to.

Me: "Dave we're running a little late, we'll be to the MTA about 9 PM."
Dave: "Oh no problem, we'll leave the lights on. Hey could you do me a favor though? Unplug the drum mixer when you get there?"
Me: "Sure, what's in it?"
Dave: "Oh about two dozen pounds of micrograin for tomorrow."

I've never clenched so hard pulling an extension cord out of the wall.

Micro grain scares the bajeepers out of me! Major tight buns squeezing activity!

Micro grain scares the bajeepers out of me! Major tight buns squeezing activity!

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It is amazing how well zinc is oxidized by sulfur. If the zinc dust is fine particles (like I said zinc dust looked like gray flour) going into a mixture, a flame just lightly touching the mixture will set it off. There is a big poof and the stuff is gone (except for a large white cloud of zinc sulfide).

aerostadt said:

It is amazing how well zinc is oxidized by sulfur. If the zinc dust is fine particles (like I said zinc dust looked like gray flour) going into a mixture, a flame just lightly touching the mixture will set it off. There is a big poof and the stuff is gone (except for a large white cloud of zinc sulfide).

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And major 3rd degree burns.

I met Homer Hickam one of the first things he asked me was if I had all my fingers. If I was going to lose a finger it would be to a saw.



TA