Lifting shells

[Mumbles]

I know at least one person that had a rocket pop on them while they were ramming. We never figured out the cause, but my best guess would be static electricity. He was holding the rocket, so there was quite a bit of harm as you might expect. The majority of other incidents I've heard of typically are from removing the rammer from the spindle. Comp can get stuck or pinched there, and the friction of twisting off the rammer can occasionally set it off. This is more of an issue with whistle and strobe. Keep your rammers clean guys.

 

I'd still prefer a press and a shield. You can achieve higher pressures and better compaction with a press, and the results are more consistent and repeatable.

[dagabu]

Shoulda known it was coming but years prior to my accident, there was a rocket that went off at my table then the one right next to me the year after in manufacturing at PGI. Both were attributed to whistle and twisting the motor or rammer off the spindle.

 

I got home and made two different tools, one took me three years to finish it but I have two sets that "pull" the motor off, no twisting at all.

 

 

[CrossOut]

Ladies and gentlemen!! Lube your spindles!!!!!

I use just a touch of crisco on my spindle before i ram or press any rockets. i literally put just enough to lightly coat and make it slippery. then i wipe off excess with a paper towel . i dont notice any change in burn rate but it makes the rocket pop off with ease without any risk of breaking the fuel grain. (Ive only done this with BP rockets. not sure how itll affect whistles or strobes.)

 

I have seen an accident happen with hammering rockets.. particularly core burners. What happened is the guy stepped up to the next rammer a little early. The rammer impacted the tip of the spindle and ignited the little bit of comp that was on top of it. scared the shit out of all of us when it happened.. there was a small pop and the rocket burned straight up on the spindle.. no damages only a burnt the spindle.

 

I found weighing out every increment to be too time consuming. I now use a set of measuring spoons and that actually gives very consistent increments. I use Riced BP ~4F granules.

Edited September 13, 2016 by CrossOut

[Paradise]

Measuring spoons are what I use now. Riced fuel as opposed to powder seems like it would be easier to load consistent level spoons. Less tapping and not settling in the spoon? I put my fuel through a fine kitchen strainer once then rammed it then 2 in a row cato. I assumed poor consolidation due to granulated fuel and no press?? Otherwise I almost never get a Cato. Every now and then I'll have a motor bend very slightly. Whaling on it too hard maybe? I do try to be aware. Straightening it would maybe crack the fuel grain? Even if I still had an increment to ram? A sleeve then I guess is the solution. I use spiral tubes from phils gen store. I've read more hits using less force but.... Seems sketchy to tell when the increment is packed enough. Btw nice tooling. Om, what's your face shield like? Should it be fairly heavy duty in your opinion?

[CrossOut]

there's a few things there.

First off, ricing your fuel helps to give your loose fuel a little more uniform consistency when measuring by volume. It also helps to prevent you're tools from spraying the bp all over the place when ramming. Make sure you don't use any binder when you rice your rocket fuel. You want the grains to break up when you press. You shouldn't need to screen the bp before pressing.

 

Catos can be a number of things. Fuel ratios, spindle dimensions, not ramming enough, damage etc.

 

If your tube is bending that is definitely a bad sign that will cause Catos or potentially damage your tools. Make a good tube sleeve for your motor tubes. Get a piece of pvc pipe and cut it down one side of the pipe. You can slide the pipe around your motor and secure it with 6-8 pipe clamps. That should give out plenty of strength for ramming.

 

Those spiral tubes are definitely an issue. You are going to want to find some parallel wound or convaluted tubes. Phil should have them as well as other sources like pyro direct.

 

What size rocket are you making? For a 1# rocket, 4-6 hard wacks should do it. For bp your really can't over pack it.. just as long as you aren't breaking anything.

[NeighborJ]

When increasing the motor size I've found that the fuel needs to be slowed down a little. 1# is about when I switched to a non milled powder, only screen mixed, then granulated, for nozzled motors. And after testing a few I can gauge if I need to change the formula by adding charcoal. It sounds like you are hitting it too hard if you are bending Phil's tubes he has a good product but it will require at least the PVC support.

To add to what Crossout said, you can granulated without dextrin but you can add it after granulation and it helps with consolidation and binding.

[Mumbles]

How does adding a binder after granulation help with consolidation and binding if no additional water is ever introduced? I'm actually just curious. From the way I read that, I took that to mean you granulate sans binder and allow the granules to dry. Then from there dust or sprinkle the dry granules with dex?

 

I would generally agree that larger core burners with nozzles tend to need progressively slower fuels. At least they cannot handle as much pushing of the envelope. I've always considered 6:3:1 to be kind of the standard. It's not the best, but it will pretty much uniformly work. Slight detour, but 60:15:15:10 with 15 parts airfloat and 15 parts coarse charcoal is great too, and a bit hotter. Anyway, as you experiment you'll find you can probably get away with like 70:20:10 in 1lb rockets. 1/4" bottle rockets can handle straight milled meal in my limited experience. As you get into larger rockets you probably need to back things down back toward 6:3:1 or even a touch lower. They achieve higher chamber pressures and don't really provide as much wiggle room as the smaller ones.

[Arthur]

Having seen inside a rocket ramming shed from the UK in about the 60s the important feature is the ramming post that goes right through the floor and is standing in the ground. So the ramming post is hard timber about 8 feet long and 8" square. If you ram on a table you get a lot less effect per hammer blow.

[NeighborJ]

Mumbles, mabe I shouldn't have mentioned my use of dex on dry granulated bp. I have had problems with the absence of a binder, when the spindle is pulled, it would collapse the core no matter how hard I pressed or hammered. And when I granulated with dex, it would not compress enough and result in a Cato. So now I add 3% dex dry after granulation and the grain packs hard and solid every time. I realize it is an unconventional fix but the dex is able to be plasticized under pressure and works well for me in this instance. The only other option would be to use a sprinkle of water on dex bound bp, but this caused my nozzles to shrink just enough in storage that it would Cato anyway. I'd rather not need to ream every motor before launch. I'm sure there are other ways of making a solid grain but this was the solution I came up with and it does work.