Swollen or Expanded grain?

Fuddrucker

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First let me say that I will be testing one by placing the case in the ground and test firing. So with that said I’d still like to hear some options or experiences anyone has had with swollen or expanded grains like the examples I am showing below.

i came across several packs of these D9’s and all of the grains in all of the packs are swollen or I guess a more accurate term is expanded as shown in the photos. I can easily squeeze the grain and insert it into the liner and it looks normal so I am wondering if they are still good to use or if anyone has experienced this issue and has used them with no issue.

Fudd
 

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Sandy H.

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Wow! I've never seen one that expanded. If you can still fit it in the tube, as you show, I'd assume they would be fine. They might be hard to light (not sure which propellant D9's are. If white lightning, probably hard to light, but if they are blue, maybe they will be easier). Possibly be concerned about the delay as well. When you ground test, maybe film it on your phone and go back to see how long it took the delay to burn.

I look forward to hearing about your test!

Sandy.
 

Fuddrucker

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The delays look fine but good idea about filming and seeing if the delay is really 7 sec. They are White Lightning.

Fudd
 

Sandy H.

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The delays look fine but good idea about filming and seeing if the delay is really 7 sec. They are White Lightning.

Fudd

Interesting. Most of the White Lightning I have that is old has a lot of white pock marks sitting proud of the surface. Not sure what form of oxidization it is, but I think that's what it is. Yours look very uniform. I have to usually sand the oxidization off and put in a hot igniter to get them to light, but yours may have been stored in totally different conditions.

Sandy.
 

Fuddrucker

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They did have the usual white oxidation on them but I lightly sanded them to clean them up for the pictures to try and avoid the usual comments like ”those look pretty oxidized you may want to sand them“ etc etc etc. ;)

Fudd
 

Sandy H.

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They did have the usual white oxidation on them but I lightly sanded them to clean them up for the pictures to try and avoid the usual comments like ”those look pretty oxidized you may want to sand them“ etc etc etc. ;)

Fudd

Heh. . . glad I brought it up then. . . DOH!!!!

Sandy.
 

Fuddrucker

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Aerotech D9W for RMS 24/40 case.

Maybe drop Aerotech an email with these photos.
They are still sealed in their original packing but I don’t expect them to do anything about them as they are so old. If anything else Aerotech will be at LDRS next month so I suppose I could just show them and ask if this it normal aging for these. I’m just more curious if they are still flight usable or more suitable for a little excitement at the fire pit. They are basically the same as an Estes D12.

Fudd
 

Fuddrucker

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Heh. . . glad I brought it up then. . . DOH!!!!

Sandy.
No worries. You know how some of these threads go off the rails pretty quick at times. You ask a question and post a pic and then someone notices and comments on something completely unrelated in the pic and that is now the subject of conversation. I try and avoid that when I can is all.

Fudd
 

T-Rex

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I have several F-24 in a similar condition. They were old when I got them for a song. The ends are now domed from expansion. I had one that was assembled and stored a little too long from the same stash. It chuffed and the rocket flew less than a quarter of simulated altitude, lawn darted and I still have no replaced the tube.

Long story, I intend to just burn them in a fire in the back yard since it is legal for me to do so.
 

Sooner Boomer

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I don't think they're oxidized. My bet is that they have absorbed moisture from the air, and undergone an irreversable chemical reaction. Even if you packed the swolen grains in a vacuum, they would not go back to original size. My experience is that the grains will be hard to light, and very likely to chuff.
 

waltr

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They are still sealed in their original packing but I don’t expect them to do anything about them as they are so old. If anything else Aerotech will be at LDRS next month so I suppose I could just show them and ask if this it normal aging for these. I’m just more curious if they are still flight usable or more suitable for a little excitement at the fire pit. They are basically the same as an Estes D12.

Fudd
Did not ask you to have Aerotech replace them but to get Aerotech's opinion of whether this should be used.

Last couple of posts highly recommend not to fly them.
 

prfesser

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I don't think they're oxidized. My bet is that they have absorbed moisture from the air, and undergone an irreversable chemical reaction. Even if you packed the swolen grains in a vacuum, they would not go back to original size. My experience is that the grains will be hard to light, and very likely to chuff.
Yes, this is what has happened. One or more of the metal powders in the propellant has reacted with atmospheric moisture to form that metal oxide. Nothing can be done to reverse the reaction.
 

CoyoteNumber2

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One thing is certain: the core dimensions have changed. I don't know if it's enough to cause a cato, but if you plan to use the reloads, run an emery board through them to square up the C-slot.
 

Reinhard

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I once launched an E18 or F24 that I had laying around in similar condition. I cleaned up excess material until everything fit again as expected. Multiple copperheads were not enough to ignite it. Adding a sliver of Blue Thunder did the trick. The motor chuffed for ages before it came up to pressure and even then I seem to remember it "farting" on the way up. That was by far the lowest flight I ever had, 38m (125') if I remember correctly. Thankfully the parachute made it out in time, although only barely so.

Reinhard
 
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