Reload Casings

[Marlin523]

I've built some Mid-power rockets this winter and want to order some motors to launch them. I've never used anything beyond Estes D-12. I purchased a 24/40 case and have selected some reload kits to order. My real question is how many times can I re-load before I have to clean the thing? If I go to a launch, should I take more than one motor case?

 

[Buzzard]

Actually, you would need to clean it after each firing. Disassemble, remove the nozzle and the liner from the casing, and wipe it down. I use Wet Ones towellettes. You do not have to make it squeaky clean to reload, but do a thorough cleaning after a day's flying.
A second casing is useful if you are only going to make a couple of flights and have limited time. Again it only takes a couple of minutes to wipe the fired motor down and to get it ready to reload.

Chas

 

[DM1975]

Yep, clean after each flight. I use baby wipes and give my casing a quick scrub down to get most everything out of it and then reload it. You can also make a chamber out of a capped PVC pipe (got the idea off of a website somewhere) and a rubber expandable plug, put the casing in, add some cleaning solution, and cap and shake, take out and wipe off.

Every night after a launch I take my casing hardware and soak it in Windex, or another amonia solution to neutralize any corrosive material left over on the casing.

 

[troj]

When cleaning, nothing more exotic than hot water with dish soap is required.

The only time I've had this not work is on very large cases where Dow 111 was used, or bearing grease that was then allowed to sit for months before cleaning.

I've cleaned an M motor 2 months after it was fired, using nothing more than dish soap and a brush. Works like a charm.

-Kevin

 

[ScrapDaddy]

Thhis is kinda off topic but how long do the casings last?

 

[NAR29996]

You'll lose it first. That's what finally happened to one of my 24 mm cases after 15+ years and a hundred+ firings.

A buddy eventually found it a few months later, after it had been run over by a lawn mower. Now, I just have to replace the casing.

 

[The EGE]

This is kinda off topic but how long do the casings last?

With proper care and feeding, a long long time. I'm pretty sure that there are folks here with casings that have survived 50+ flights. They're made of strong aluminum and can take a lot of abuse.

That said, however, most casings die eventually. Certain catos will completely strip the threads of one or both closures, or blow right through the side of the case. (Fortunately, that doesn't always happen). The threads will wear out, eventually, after a large number of flights. I've even heard of them being eaten by farming equipment :eyepop:

However, the most common fates are simply disappearing with the rocket into the wild blue yonder, hanging in trees, and disappearing into low grass following failure of motor retention.

As for cleaning, for my smaller casings, I have a lunchmeat container of half vinegar, half water. Just soak the casing for 10 minutes after removing all the spent propellant crap and all that, then clean well with paper towels. Use a toothpick to clean out the ejection charge hole, and grease with petroleum jelly.

 

[MarkII]

I have heard about the vinegar and water method. I know that vinegar works great to remove black powder soot, too. One of its effects is to neutralize the corrosive components in the residue. Does either vinegar or ammonia have that effect on APCP residue?

MarkII

 

[troj]

You'll lose it first. That's what finally happened to one of my 24 mm cases after 15+ years and a hundred+ firings.

A buddy eventually found it a few months later, after it had been run over by a lawn mower. Now, I just have to replace the casing.

Depends... I know people who've left them soaking in vinegar, and come back to find a pitted, worthless case.

-Kevin

 

[troj]

I have heard about the vinegar and water method. I know that vinegar works great to remove black powder soot, too. One of its effects is to neutralize the corrosive components in the residue. Does either vinegar or ammonia have that effect on APCP residue?

Does it truly neutralize it (meaning the residue is a base), or does it just remove it?

I'd want to hear the chemical analysis behind that, before accepting it as gospel.

-Kevin

 

[MarkII]

Does it truly neutralize it (meaning the residue is a base), or does it just remove it?

I'd want to hear the chemical analysis behind that, before accepting it as gospel.

-Kevin

This is what I have been told. Having very little knowledge of the subject of chemistry, I can't evaluate that claim in depth. But it has something to do with neutralizing an alkaline environment, I believe. I do know from experience that it works like nothing else that I have ever tried in removing BP residue from launch rods, blast deflectors and motor retainers. There is a strong and very obvious reaction that occurs when the vinegar contacts the BP residue, and it is one that doesn't appear on any other portion of the object. After a brief period of exposure, the product of the reaction just rinses off, leaving behind no trace of the BP residue behind. So although I can't explain the chemistry behind it, the method seems to be quite effective.

MarkII

 

[ScrapDaddy]

Ahhh Tim Has this mentioned in one of his peak of flight articles just give me a minute to pull up the link......

 

[mkadams001]

I use the windex towelettes for cleaning. One area not to miss is that little hole in the forward closure. Debris from the ejection charge builds up and will restrict or close off the hole.

 

[DM1975]

Vinegar can etch metals pretty badly. I used to use boiling vinegar to etch certain parts on AK-47's when I was trying to replicate the gray color on some of the parts. After each treatment the OD of the parts were a little less each time, not much, but it did take off metal and I will not use it to soak any metal in besides for my igniter clips with some baking soda.

Some oven cleaners will eat aluminum like it is styrofoam, so these things should be avoided. Aluminum also will suffer galvanic corrosion from dry lubes such as graphite and certain other material, even if anodized. Not sure the anodizing used on reload casings, but it looks like a Type I anodizing, which is pretty lightweight and will only offer minimal protection against some of these things.

As for ammonia, in the gun community, using older rifles with corrosive primers, windex is often used by many to neutralize the corrosive materials left behind in the barrels. This is a long time practice, and one I have used for many years.

While warm soapy water might be all you need, I will continue to spray my casings down with windex after every launch day. Less than 5 minutes of work is worth the piece of mind for me.

This is just my worthless two pennies.

 

[aerostadt]

I use the baby wipes for cleaning. The motor lasts indefinitely.

I think that the 24/40 case is a challenge to put together. Even harder than the big motors. You may find the last few turns of the end closure difficult to complete. I use a rag to grasp the end and turn. I think this motor can be assembled a day or two ahead of time of a launch without any problem. I am now tempted to thread an igniter into the grain at the time of assembly, although this might be considered a safety issue. Keep in mind that it is difficult to thread an igniter through the small nozzle throat into the slot grain after it is assembled. This motor is a lot of fun! I have several. The hardware is somewhat expensive for its size. I don't trust the delay time given on the F39. You will see a 6 and/or a 9 sec given. I would assume that the time is the 9 sec. You can drill the delay time to reduce it.

Bob

 

[DM1975]

I agree on the delay time, it is off most of the time, and the closures being hard to close (I use my shirt or jacket). I have never had a problem inserting igniters tho. I have built my motors on the spot between launches and have had them sit for over a year already built and have had no trouble either way. I have even assembled them in close to zero temps and while snowing, which I do not reccomend. I prefer to do it the night before a launch though, and think that proper preperation and cleaning will keep your casings life to the longest extent possible.

 

[The EGE]

The 8 bucks for the little metal wrench for the 24mm and 29mm hobby casings is well worth it. Much easier on my hands.

 

[GregGleason]

The 8 bucks for the little metal wrench for the 24mm and 29mm hobby casings is well worth it. Much easier on my hands.

I agree. I also use gripper mat (cut to a useful size) to help break things loose a little more easily. Sometimes I also use wooden dowels to "encourage" things to get it or come out.

Greg

 

[MarkII]

Vinegar can etch metals pretty badly.

Wow, I didn't know that. I have never used it on reload motor casings, though, just on blast deflectors, launch rods and homemade retainer rings, and I did use it with baking soda (forgot to mention that before). That's why I was asking about it's usefulness for cleaning up composite residue. I have seen posts in which people mentioned using diluted vinegar on their cases. But from what you say, I think that I'll go with something else for my RMS cases. It is amazingly good at removing soot from bare steel, and I haven't noticed any etching. But the vinegar I use is in contact with the steel for only a few seconds, because that's all it takes to do the job. I have never soaked any metal in it, just washed it on and then off. The next time that I do some etching, I'll have to try using it on the plates. It will certainly be cheaper and easier to handle than the hydrochloric acid that is normally used. I wonder why none of my art teachers ever mentioned this? My experience with reloadable motors has mainly been with Pro38s, and there was no cleanup required with them. I have used dish soap and water on my RMS motors, which worked OK.

You mentioned a weak solution of ammonia (such as Windex) - that was the other method that I was wondering about. I was curious about whether some everyday product would work through a chemical process to remove soot, versus simply scrubbing it off (mechanical removal). Vinegar is too caustic, so I'll give glass cleaner a try. Interesting thing about ammonia - it works great to dissolve stains from fountain pen ink. (I know, who uses fountain pens anymore? I do; collecting fountain pens is one of my other hobbies.) Whenever I get ink stains on my fingers, a couple of quick sprays with Windex gets them right out.

MarkII

 

[DM1975]

You mentioned a weak solution of ammonia (such as Windex) - that was the other method that I was wondering about. I was curious about whether some everyday product would work through a chemical process to remove soot, versus simply scrubbing it off (mechanical removal). Vinegar is too caustic, so I'll give glass cleaner a try. Interesting thing about ammonia - it works great to dissolve stains from fountain pen ink. (I know, who uses fountain pens anymore? I do; collecting fountain pens is one of my other hobbies.) Whenever I get ink stains on my fingers, a couple of quick sprays with Windex gets them right out.

MarkII

Windex works great for taking out scuff marks from Corframs too (Any former Marines will know what that is )

When I clean my casings I do not really scrub anything, I wipe it all down with a baby wipe or two right after flight and most everything comes out. As mentioned, the flash hole for the ejection charge needs to be payed attention to, along with the threads.

When I get home I spray it all down with Windex and let it sit for a couple minutes and then rinse it off and dry it with a paper towel and I am done.

I have heard that ammonia can etch as well, but I am unsure of that. Windex is so mild that I doubt it would ever etch anything.

 

[bobkrech]

The only corrosive by-product of APCP combustion is hydrochloric acid which is initially formed as a gas. There can be some residual HCl in disolved in the liner, so it's smart to remove the liner and clean the casing immediately after use.

It's best to clean a casing with water with a pH between 4 and 8.5, and if necessary a detergent like DAWN, and then rinse it off with tap water. For stubborn greases, a non-aqueous solvent will remove greases, oils and organic residues without harming the anodization.

If a motor casing is left soaking in vinegar (5% acetic has a pH of 2.4) for a long time, the anodization (aluminum oxide) is attacked and will eventually dissolve, leaving bare aluminum metal behind which then will slowly dissolve in the acid.

If you have lost your casing, and later find it and it is covered with white crystals (aluminum oxide/hydroxide), soaking it in vinegar for several hours will remove the white crystals. Then rinse/soak the casing several times in plain water, and then immerse it in boiling water for a few minutes to seal the surfaces, and then dry the casing. It should be as good as new.

If a motor casing is left soaking in an ammonia solution (household ammonia has a pH > 12) for a long time, it will pit the casing if there are any breaks in the anodizing by dissolving the aluminum. Not a good idea.​

from https://www.corrosionsource.com/technicallibrary/corrdoctors/Modules/MatSelect/corralumin.htm

The corrosion resistance of aluminum is dependent upon a protective oxide film. This film is stable in aqueous media when the pH is between about 4.0 and 8.5. The oxide film is naturally self-renewing and accidental abrasion or other mechanical damage of the surface film is rapidly repaired. The conditions that promote corrosion of aluminum and its alloys, therefore, must be those that continuously abrade the film mechanically or promote conditions that locally degrade the protective oxide film and minimize the availability of oxygen to rebuild it.

The acidity or alkalinity of the environment significantly affects the corrosion behavior of aluminum alloys. At lower and higher pH, aluminum is more likely to corrode but by no means always does so. For example, aluminum is quite resistant to concentrated nitric acid. When aluminum is exposed to alkaline conditions corrosion may occur, and when the oxide film is perforated locally, accelerated attack occurs because aluminum is attacked more rapidly than its oxide under alkaline conditions. The result is pitting. In acidic conditions, the oxide is more rapidly attacked than aluminum, and more general attack should result.

Bob​

 

[DM1975]

Well, there is a good answer

 

[MarkII]

I have heard that ammonia can etch as well, but I am unsure of that. Windex is so mild that I doubt it would ever etch anything.

Yes, it's true - I forgot to mention that. A weak ammonia solution is sometimes used to clean fountain pens that have become extremely fouled with dried ink. Even then, it is used sparingly, because too much exposure can corrode the nibs (and break down the cements that are used in pen assembly).

MarkII

 

[MarkII]

Well, there is a good answer

Works for me. Thanks, Bob.

MarkII

 

[The EGE]

Useful stuff

Thanks. That makes a lot of sense.

I personally leave my casings in the 50/50 vinegar-water mixture for roughly 10 minutes before cleaning them dry. If I ever need to soak one for a while, I'll dilute it to around 10:1 water:vinegar or higher.

 

[Marlin523]

Thanks for all the input. I've learned a lot from all of you. Please don't think this means you should stop.

 

[dave carver]

I've used Hoppes Gun Cleaner on a rag. Seems to work pretty good.

 

[NAR29996]

The 8 bucks for the little metal wrench for the 24mm and 29mm hobby casings is well worth it. Much easier on my hands.

Another good solution, albeit more expensive, is this little gem from McMaster-Carr: 5555A55. We called these cannon plug pliers in the Air Force. I was lucky enough to get a couple from my last aerospace job.

 

[Marlin523]

Good call! I ordered a wrench.

 

[Mikus]

Thanks for all the input. I've learned a lot from all of you. Please don't think this means you should stop.

Simple Green, a bottle brush and a few q-tips for the ejection charge well.

Add water, a little elbow grease and a handy rag to dry them and they come back sparkling. :2:

The bottle brush needs to be right size for the casing but with luck you can find one that tapers - mine does 38mm all the way down to 18mm casings.

Dang, I must have been the luckiest rocketeer in the world. I cannot seem for the life of me to be able to find a link to a brush that looks like mine. I guess I'll have to find it tonight and take a picture.