RMS Questions

[Adam Selene]

I recently purchased 24 and 29mm Aerotech RMS cases. and several reloads. unfortunately when i went to use them we discovered that our field had been reduced in size and was no longer big enough. so i have several reloads that i won't get to use for awhile. maybe TRF 2004. so my question is: Aerotech says to not open the bags until you are ready to load and use the motors. i figure that this is mostly just so you don't lose the parts? they take up too much room in the bags so i want to store them in waterproof divided boxes. plano fishing tackle stuff. is there any problem with doing that?
TIA!

 

[Ryan S.]

there shouldnt be a problem, I store my loads in individual Ziploc bags. You just want to keep the sealed (so they stay away form moisture and too much oxidation)

 

[Adam Selene]

that's about what i figured.
thanks

 

[llickteig1]

AP propellant grains and delay grains are agroscopic. That basically means that they will suck moisture from the air. The delays are even worse than the propellant. There can be odization deposits on the surface of the grains that can be a real pain. Also the cardboard packing liners and phenolic liner tubes can change spec if they absorb moisture. This includes the moisture from the air.

This all means that you don't want any of the motor parts (except, I guess, the o-rings and nozzle) to be exposed to moisture, including humidity.

The plastic bags leave the Aerotech factory in airtight condition and your motors will be easier to assemble and to lignt if you keep them as absolutely dry as possibe from the time you purchase them until you burn them.

Now, unpackaging the motors won't ruin them per se, but I personally can't understand what might be gained by transferring them to another type of container. Also, you might be really careful, but if you grab too long a delay, or mix-up some o-rings, you risk one of the following: 1) CATOing a motor; 2) lawndarting a rocket; 3) zippering a rocket; 4) blow-through on a forward closure; and 5) possibly other failures. Some of those things are dangerous to property and people.

It wouldn't be worth it to me.

--Lance.

 

[Ryan S.]

I do it because it simply makes it much easier at a launch to grab a single bag with everything I need then a bag with a bunch of extra parts that I need to sort through. I dont know about Aerotechs bags being completly sealed. I have bought grains new and in perfect condition and in two weeks they had started to oxidizee

 

[havoc821]

Last Sunday (one week ago) I tried to launch a scratchbuild on a G64. I didn't get the motor to light and scrubbed the launch. Well, I came home and put the rocket back in its spot. I forgot to take out the motor and reseal it. It has been there for a week in my room exposed to air. I just now resealed it. Do you think I will have any problems with the motor?

 

[Ryan S.]

I really really doubt it. I have left grains laying around and nothing bad has happened. before you launch the G64 next time take some sandpaper and rub it up and down the C-slot (even the edge of your shirt will work) this will expose AP that has not oxidized and make lighting the motor easier

 

[havoc821]

"before you launch the G64 next time take some sandpaper and rub it up and down the C-slot (even the edge of your shirt will work) this will expose AP that has not oxidized and make lighting the motor easier"

Kinda hard to do after the motor is built. Thanks for the help though.

 

[Ryan S.]

then just unscrew a closure and pop out the grain....not to hard

 

[havoc821]

Black powder for ejcetion is also installed. This motor was flight ready and I tried to launch it but those stupid crapper heads or my stupid launch controller wouldn't work. You can't unscrew motors after ejcetion charge is in place. Well, you can, but you will have problems that I don't want.

 

[Ryan S.]

if the ejection charge is already installed just flip the motor upside down and unscrew the forward closure and make sure it stays upside down then take the Grain out. you just need to make sure the delay unit does not fall out. Or if you want you can empty the delay into the red cap, then clean your oring and forward closure. Either way it wouldnt be that hard and it is gonna be harder to light then to take apart. I wouldnt leave an ejection charge in a motor for a long period of time....I have heard that is not a good idea

 

[llickteig1]

havoc821,

You're right about the problems associated with disassembling motors that already have the BP installed. Best to avoid it if possible.

The motor being unsealed for 1 week shouldn't hurt it at all. No need to disassemble it or do anything else extra if you plan on firing it within the next month or two. It should light fine if you've sealed it in a baggie now. I would try to use a First Fire type of ignitor, rather than a Copperhead. More pyrogen = hotter, more reliable ignition.

Just keep it in the baggie until you're ready to burn it.

The only caveat to this is that if you don't think it will be launched for a few months, then do take it apart. The o-rings won't last forever in a compressed state and still be effective. If you didn't have the BP in there, you could just loosen the closures, but since you do, if the launch is a few months off, I would disassemble it completely and wipe off all BP residue from the motor case and o-rings.

HTH, --Lance.

 

[loopy]

Originally posted by Ryan S.
if the ejection charge is already installed just flip the motor upside down and unscrew the forward closure and make sure it stays upside down then take the Grain out.

I think you mean AFT closure - the one with the nozzle sticking out. Seriously -that's the best idea. Keep the ejection end pointed down, put your finger on the cap to make sure it doesn't fall off, unscrew the aft closure, remove the nozzle and o-ring, then pull out the propellant grain. You should at least loosen the closures anyway so the o-rings aren't kept under pressure. The only problem I think you'll have as far as the motor is concerned is getting it lit. Once it's lit, you'll be fine.

Loopy

 

[havoc821]

Well, it is sealed up and it will be burned in 1 week 5 days at the Manchester launch in Tennesee with HARA/MC2/ Knoxville group. I can't wait!