Aerotech delay oxidation

[BlueNinja]

If I open the package of a G40 and store the motor in my range box(storing packages takes up a lot of space), will there be any oxidation on the delay, enough so it won't light and lawndart my rocket?



Blue

 

[r1dermon]

oxidation? do you mean moisturization? im not sure if the delay grains are hydroscopic, but i'd guess not, since i've had motors out in the open for almost a year and they've lit and ejected fine.

 

[BlueNinja]

Well, Doug's mentioned it before. I meant the delay being hard to ignite, exposed to the air for extended periods of time. I left some E30s out, but BT motors are so easy to ignite I figured those wouldn't be much of a problem.

 

[Ryan S.]

Originally posted by r1dermon
oxidation? do you mean moisturization? im not sure if the delay grains are hydroscopic, but i'd guess not, since i've had motors out in the open for almost a year and they've lit and ejected fine.

I am pretty sure he means oxidation When a motor oxidizes (not when burning) white stuff appears all over the surface and it makes the motor hard to light.

 

[BlueNinja]

Yeah, that's it.

 

[r1dermon]

ryan, would you care to explain this phenomena? i've personally never heard of "oxidization" of a propellent without it reducing. however, i HAVE heard of hydroscopic propellents, which was why i stated what i did, however, i am quite interested in some sort of explanation, or a reference where i can find out something about this. thanks

 

[jetra2]

There is a certain chemical in White Lightning propellants where, when exposed to atmosphere, will oxidise the propellant, like a piece of metal rusting, and as such, it makes the propellant hard to light. This is easily fixed on reloads because you can just use a piece of sandpaper to sand it off and make it almost brand-new, but you obviously can't do that with a SU motor. Your only option is to use a very hot igniter to get it going quick.

BN, my recommendation would be to put the two motor in a Ziploc baggy, but before you seal it, squeeze all the air out of it, then tightly wrap it up. That'll keep it from oxidising as much.

Jason

 

[n3tjm]

delay grains do "oxidize" over time, but not as fast as white lightning. This makes the delays on them burn longer than normal.

 

[xenon]

Are you worried about the delay oxidizing or the motor?
If it is the delay, you shouldn't have any problems. The delays are already very tough to light, sometimes it will take 10 seconds to light if you hold a match up to one in open air. There should not be any problems with it not lighting if it is stored like a normal motor. The heat from the motor should get it light. Even a bit of grease on the delay shound't matter. Once I purposly put about 1/8in of Super Lube on the delay for a E11, the motor still burned through the grease and light the delay. Not that I'd try that when you need ejection though, I still try not to get grease on them (and so should you), but in my experiance, they have ignited with a bit of grease on them.
If it is the motor, follow jetra's suggestions


EDIT: didn't see Doug's comment, maybe they do oxidize over time, I've never had it happen to me though. They should light if the motor lights though.

 

[r1dermon]

thanks jetra, i never knew that composite propellent could "oxidize" at any other time other than when its enflamed. heh.

 

[kgholloway]

OK, here's my 2 cents worth.

OXIDATION:

All Aerotech propellants and delay grains that I've used will oxidize. White lightning is particularily prone to this and if you examine a 4 or 5 year old reload kit you will find that all of the grains are coated with a loose, whitish coating. This makes them very hard to light. The cure is to lightly sand the surface of the grain where the ignitor will come into contact and also lightly sand the exposed surface of the delay grain.

HYDROSCOPIC PROPERTIES:

Blue Thunder reloads at least are hydroscopic to some extent. I had a BT grain from a 29mm motor that failed in the bottom of my range box for about a year. At the end of that time the grain ends had swollen so much that it looked like an hour glass. It would just barely fit in a 38mm casing!

PRECAUTIONS:

Because of the above I now store all of my motors/reloads in closed 50mm ammo cases with silica gel. Since I started doing that I've had only minimal problems with them.

Ken Holloway, NAR #78336, L-II

 

[artu]

Originally posted by Blue_Ninja_150
If I open the package of a G40 and store the motor in my range box(storing packages takes up a lot of space), will there be any oxidation on the delay, enough so it won't light and lawndart my rocket?



Blue

Hi Blue. An F60-9 loose in my range box bought in 1988 became a F60-15 when fired in 2003.

the motor guru's said that was normal for extreme aging on the motor propellent and delay grains.

 

[BHP]

I don't mean to be overlay pedantic (if you can be) but I noticed the word hydroscopic in this thread when it should be hygroscopic. It seems counter-intuitive with hydro meaning water and the concern here of absorbing (or should it be adsorb? I'm not sure.) it from the air. When something takes water from the air it is hygroscopic. A hydroscopic thing is a tool for looking into water.

I missed the hygro/hydro thing on an exam once so it jumps out at me. The members of this forum seem generally to be the kind of people that like to learn new things/ideas so I thought I'd toss it out here. No harm/disrespect meant to anyone.

Oh, yeah, I've seen this oxidation 'dust' on delay grains too. I think I just wiped it across my jeans and blew off the rest. No problem with the delay on launch. I have heard sandpaper is the tool of choice, however.

Pete