How long do Motor Reloads last ? ? ?

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>More seriously, the biggest problem you might have is oxidation on the grains (esp if they are white lightning loads). Before flying them, sand some of the surfaces just a little bit to help them light.[/QUOTE]

Everybody who has tried to fly an old AT White Lightning motor is familiar with the phenomenon, but I'm not sure that it is oxidation. The entire propellant grain is packed with oxidizer (AP) so why does it just happen at the surface? My current thinking is that it is related to the slightly hygroscopic (sucks up water) nature of AP, and involves some interaction between water, AP and maybe the metals in the propellant. The product, whatever it is, occupies more volume than the propellant that was there before (it swells), and that goober is dang hard to light, which is why "they" all recommend sanding or cutting it off before loading the motor. The involvement of water would explain why some old WL reloads are much more severely affected than others: The sealed plastic bags may suffer from small nicks or cuts, or they may experience light-induced depolymerization that would make some bags break down in one persons' storage area and not in another.

Alan Whitmore
Carrboro, NC
 
How long do Motor Reloads last ? ? ?

according to thrust curve
a G 79- 1.4 seconds
an H242- 1.1 seconds
an I300-1.4 seconds
a J90 -6.9 seconds
a K550 3.9 seconds
an L850 4.4 seconds

:facepalm::kill:
 
Two separate things: the scale that builds on the surface, and the swelling. I've definitely seen scaling without swelling, and that's where I recommend a good scuffing. If they've swelled much (i.e. more than a paper wrap or so) I dispose of them.
 
Really? Interesting.

I know I've flown about 3-4 (J1999) of these successfully - all in a custom 3" fiberglass rocket - The "Fuzzy Bee."


Do NOT fly that J-1999..remember the drag race at LDRS that used those guys? Every single rocket [including mine] blew up spec-tac-u-lar! They were recalled. Find a decent dealer and you may even be able to trade it for the replacement version.

Fly it & almost a certainty you will destroy whatever it's in.

Others have answered old motor usage. Most propellents are fine. White and red will absorb moisture & swell if you live in high humidity climate. Even then with some work you can usually light them . The REAL problem is delays chemical degrading over time. If flying with altimeters your fine. Motor eject ...any discolored or marbleized forget about it!

When in doubt, you can always fly iffy reloads in saucers ....blow one of those up and you don't really lose much...lol
 
Here are two 24mm reloads that have swelled almost shut. One is still in plastic bag. Think they are still usable?

reload2.jpg

reload1.jpg
 
Here are two 24mm reloads that have swelled almost shut. One is still in plastic bag. Think they are still usable?

I flew three like that a couple months ago. First I sanded out the slot and leveled off the muffin top using drywall screen.
The motors burned just fine. The delays were several seconds longer than labeled.


Steve Shannon
 
Here are two 24mm reloads that have swelled almost shut. One is still in plastic bag. Think they are still usable?

That C- Slot is such that it would be very difficult to fit an igniter in. You would to open it up a bit, but after that I would think it should work ok.
 
On this same note - I've got a lot of old 29/40-120 loads. Can you get just the delay grains? I would feel much better replacing them
 
On this same note - I've got a lot of old 29/40-120 loads. Can you get just the delay grains? I would feel much better replacing them
Yup, just look for hdk's at your favorite rocket vendor.

I've a mostly-complete reference which can be found by searching for "dhbarr hdk"; always double-check vs. the official Aerotech instructions.
 
Everybody who has tried to fly an old AT White Lightning motor is familiar with the phenomenon, but I'm not sure that it is oxidation. The entire propellant grain is packed with oxidizer (AP) so why does it just happen at the surface? My current thinking is that it is related to the slightly hygroscopic (sucks up water) nature of AP, and involves some interaction between water, AP and maybe the metals in the propellant. The product, whatever it is, occupies more volume than the propellant that was there before (it swells), and that goober is dang hard to light, which is why "they" all recommend sanding or cutting it off before loading the motor. The involvement of water would explain why some old WL reloads are much more severely affected than others: The sealed plastic bags may suffer from small nicks or cuts, or they may experience light-induced depolymerization that would make some bags break down in one persons' storage area and not in another.

I'm not discounting this possibility.... however, swelling is much more prevalent in old WL than say, old blue thunder. and then there's greens but they never want to light anyways.
 
Here are two 24mm reloads that have swelled almost shut. One is still in plastic bag. Think they are still usable?

I posted earlier that at NSL in May I used some 24/40 reloads from the early 90s. They showed similar swelling. I scraped them with a pocket knife to open the slot, enough that I could get the igniter installed. I did replace the delay (HDK-XX Hobby Delay Kit), since I heard they can go bad. (Bad meaning erratic or fast burning, not bad meaning they do not work at all).

Rocket flew just fine.
 
What would extend the usable lifetime of reloads? I keep mine bagged in zip-lock baggies (the ones with the real zipper), in an ammo can with an o-ring seal. They're either under the bed or in the bedroom closet, so there are no wild temp swings. Would dessicant or O2 displacer help?
 
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