Core burner rockets storage

[Aspirina]

I want to make some 15mm and 19mm (1Lb) rocket motors but I dont know how much time can storage this stuff (To prevent CATO). The idea is make it to use the 23th of this month. When is the best moment to make it? 1 week before? 2 dyas? 1 day?

I make it with no moisture in the fuel.

 

thanks for all.

Edited June 3, 2019 by Aspirina

[justvisiting]

My nozzleless BP rockets are generally made with 2% wax in the BP, dissolved in Coleman fuel (naphtha). They can be stored for years. Recently, I've been playing with moistened BP (2- 2 1/2% water). The water stays in the motor after pressing, even after several weeks. They press solidly and easily. I'd try it if I were you. BP rockets pressed dry have the greatest chance of CATO, IMO.

[Aspirina]

My rockets are pressed with dry fuel, never have a problem. Im not have to much time to experiment (add wax or water), so, any recommendations?

[justvisiting]

As I said, the moisture stays in the rocket. It doesn't need to dry out. Also, I wax my tubes. That reduces friction on the tube when loading, so it's less likely to CATO after storing. I'm only mentioning things I do that work. If you don't have any problems, maybe you don't need to change anything Myself, I find that making rockets with dry powder in a dry tube is a less pleasant way to make rockets, that could result in less pleasant results. I press all my rockets.

 

If you don't want to try my suggestions (no problem), then my next suggestion would be to store the propellant and the tubes in the same sealed container for a few days, and then make the rockets. That way the moisture levels in both items are as similar as possible. I'd then store the rockets in a place without crazy temps or humidity until firing.

Edited June 3, 2019 by justvisiting

[Arthur]

Commercial rockets made in China could easily be six months to two years old before they are fired by the consumer.

[Aspirina]

As I said, the moisture stays in the rocket. It doesn't need to dry out. Also, I wax my tubes. That reduces friction on the tube when loading, so it's less likely to CATO after storing. I'm only mentioning things I do that work. If you don't have any problems, maybe you don't need to change anything Myself, I find that making rockets with dry powder in a dry tube is a less pleasant way to make rockets, that could result in less pleasant results. I press all my rockets.

 

If you don't want to try my suggestions (no problem), then my next suggestion would be to store the propellant and the tubes in the same sealed container for a few days, and then make the rockets. That way the moisture levels in both items are as similar as possible. I'd then store the rockets in a place without crazy temps or humidity until firing.

Thanks for all your tips, after 23th I will try your recommendations. Until the date I must use techniques that I'm sure is going to work.

[Aspirina]

Commercial rockets made in China could easily be six months to two years old before they are fired by the consumer.

Yep, good observation but im sure that the chinese workshops dont press with dry fuel hehe.

 

Thanks for your answer!

[justvisiting]

I didn't know 1lb Chinese rockets were commercially available. I was just talking about amateur stuff. The teeny little whistling bottle rockets are the only ones I've seen.

[Tim1877]

I store my rockets in a zip lock bag and put the sticks on when I'm going to use them haven't had any problems yet

[Bigmark]

I press my rockets with 1% to 2% water. And have had some stored for 4 to 5 months. Fired off a few couple weeks ago worked

just fine.

[Aspirina]

I press my rockets with 1% to 2% water. And have had some stored for 4 to 5 months. Fired off a few couple weeks ago worked

just fine.

I'm little afraid to use water in the composition, if I use it, how much time have to pass to evaporate? I can change water for alcohol?

[Aspirina]

I store my rockets in a zip lock bag and put the sticks on when I'm going to use them haven't had any problems yet

You press your rocket fuel dry?

[BetICouldMake1]

Using 1-2% water you don't need to let them dry. In fact, like just visiting said, they don't dry. It doesn't affect performance in an appreciable way. It does eliminate dust while pressing and create a very dense fuel grain.

[Aspirina]

okey thanks, I will try

[justvisiting]

I pressed a 3lb nozzleless rocket with straight 75-15-10 moistened with 2 1/2% water. I stored it for 22 days before flying, tracking the weight each day. It lost just under half a gram, coming in at 351.6 grams. I did the same with 1lb rockets, but only stored them for up to a week.

 

Also, another pyro told me he presses damp propellant to 3800psi instead of the 'usual' 6500-7500. He makes big rockets, and says it works fine. I made 2 more 3lb rockets with leftover damp BP I had. One was pressed at 3750psi, the other at 7500psi (double the force). The one pressed at higher force only had 8% more propellant. Both propellant grains were like stone. Both were tested on the Acme test stand. The one pressed with less force got about 13% less lifting power. That may sound like a loss, but before I was pressing damp, I was getting 10-15% less propellant in the rocket anyway. So, it's basically a wash.

 

Pressing with less force (if it does the job) is preferable to me. It eliminates compression of the tube during pressing, and allows for the use of cheap, readily available materials for tube supports. I wax my tubes to facilitate pressing, and I use tube supports made out of a sheet of mylar, cut to the appropriate height. I've made plenty of 1lb and 3lb rockets this way. Adding the water is just another lesson in my rocket education

 

Perfectly dry black powder will absorb some water from the atmosphere. By adding the water during pressing, the black powder becomes more stable (neither absorbing or losing water). The propellant grain is hard as a rock, and can't be scraped with a fingernail. I've taken apart Estes rocket motors, examined the grains, and tested the density. It's my opinion that they are pressed damp. These are nozzled end burners I refer to. I've flown Estes motors that are 20 years old.

[Aspirina]

I pressed a 3lb nozzleless rocket with straight 75-15-10 moistened with 2 1/2% water. I stored it for 22 days before flying, tracking the weight each day. It lost just under half a gram, coming in at 351.6 grams. I did the same with 1lb rockets, but only stored them for up to a week.

 

Also, another pyro told me he presses damp propellant to 3800psi instead of the 'usual' 6500-7500. He makes big rockets, and says it works fine. I made 2 more 3lb rockets with leftover damp BP I had. One was pressed at 3750psi, the other at 7500psi (double the force). The one pressed at higher force only had 8% more propellant. Both propellant grains were like stone. Both were tested on the Acme test stand. The one pressed with less force got about 13% less lifting power. That may sound like a loss, but before I was pressing damp, I was getting 10-15% less propellant in the rocket anyway. So, it's basically a wash.

 

Pressing with less force (if it does the job) is preferable to me. It eliminates compression of the tube during pressing, and allows for the use of cheap, readily available materials for tube supports. I wax my tubes to facilitate pressing, and I use tube supports made out of a sheet of mylar, cut to the appropriate height. I've made plenty of 1lb and 3lb rockets this way. Adding the water is just another lesson in my rocket education

 

Perfectly dry black powder will absorb some water from the atmosphere. By adding the water during pressing, the black powder becomes more stable (neither absorbing or losing water). The propellant grain is hard as a rock, and can't be scraped with a fingernail. I've taken apart Estes rocket motors, examined the grains, and tested the density. It's my opinion that they are pressed damp. These are nozzled end burners I refer to. I've flown Estes motors that are 20 years old.

Thanks for the long explanation! im very thankful

 

I must to try your tips, anybody try to granulate without binder the rocket fuel and then ramming it dry into the tube? like Ned Gorski?

[justvisiting]

Granulated fuel requires more pressure to properly consolidate. What I've also done recently is to make 'soft' BP pucks (density of 1.3g/cc) with 2 1/2% water, and force the fuel through a tough screen. This semi-granulation 'pre-densifies' the fuel, so that the difference between before-pressing volume and after-pressing volume is less. Again, less tendency for the tube to pull down. The fuel can be made ahead and saved in a sealed container in its moist state. This is just something I'm messing around with, playing off of the work of another pyro. It's labor-intensive to do, yes. But- my experiments have led me to making powerful rockets without milling complete black powder, without using a 'traditional$$$' tube support, and without having to set out fuel to dry.

 

The only reason NEPT tubes are 'required' for rockets is because of the high pressing forces needed to consolidate dry fuel.

[Mumbles]

Granulating and drying the fuel long predates Ned. Generally no binder is used and the fuel is dampened with either water or alcohol, but to the level one might if screen granulating Polverone or BP or something. Think more like pumped star level. Keeping it drier keeps the grains held together but not particularly hard. The primary purpose is to keep dust down and maybe give a little more consistency to volume scoops. Some have taken to adding various emulsifiers or things like wax or vaseline for somewhat similar purposes. There's a whole field of experiments that have been done. I don't think anyone has taken a more critical look at all the aspects that Just visiting though.

 

The same thing is often done with gerbs, shell inserts, etc. that contain coarse metals or components. If comp is mixed and stored in bulk as a dry powder coarser and finer components can separate and stratify.

[Arthur]

Proper BP is much to hard to press into a good rocket grain, but milled ingredients dampened with water and pressed through a mesh sieve works well because the dust of meal is kept under control and all the powder goes where you intend not into the atmosphere. It's a perfectly workable and cleaner way of working.

[Mumbles]

Just visiting, do you dry all your chemicals ahead of time for making bp? Black powder naturally absorbs some moisture. Do you think the prewetting just hits that sweet spot on it's own?

[justvisiting]

I don't dry all my chems, but I keep them in sealed containers. I make my black powder by hyper-milling the charcoal component, and milling the potassium nitrate and sulfur separately. I go on about it in other threads, so I won't elaborate here. The potassium nitrate would clump during milling if it was significantly damp. I've found my greenhouse grade to contain up to .2% water. Sulfur doesn't appear to take up water, so I've always assumed it to be perfectly dry. In the few times I've measured the water content of my charcoal, I've found it to contain up to 7-8% water.

 

From what I understand, commercial black powder contains about 1- 1 1/2% water. When I make pucks, the water content is in that range when they have dried to a stable weight. Perhaps the water is trapped due to the density. Perhaps the BP doesn't absorb more due to the density and/or glazing. Either way, I assume my screen-mixed black powder to have zero water content (even though that's probably not accurate), and add water from there.

 

As far as finding the "sweet spot", I think maybe it's more of a range than a spot Water content affects the speed of black powder, but for my purposes with rockets, a slightly slower product is preferable anyway. I'm not a hand rammer, but my guess is that hand ramming with damp BP would make a superior rocket.

 

The area where I live is not particularly humid. Somebody living in Louisiana might have different experiences than I've had

[MinamotoKobayashi]

Usually I store my dried granulated r-candy rockets inside an hermetic box containing some essicant bags.

They can be stored for years without issues.

 

If Your rocket is already mounted on a stick, it cannot be store in a box anymore, so I suggest to take a ball of cotton,

make an hole in the center (for the fuse), and press it inside the bottom of the rocket. This can reduce a lot

humidity issues.

Edited June 19, 2019 by MinamotoKobayashi