- This topic has 9 replies, 5 voices, and was last updated 11 years, 3 months ago by
Jack Matthews.
Jack Matthews.-
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Jack Matthews
Great time @ MHM – weather a little sketchy. On Sunday, I had a rocket prepped and on the pad (Cesaroni I170, 54 mm / 3gr) when the LCO got a tornado alert. Tried pushing the button, but popped the igniter, the waiver was cancelled, and scratched the launch.
Question – I’ve got that motor in a Cesaroni 3gr casing. I’m loathe to pull it out, figuring that the less I mess with it the better. Can I leave the load in the casing until the next launch? I don’t see why not, but maybe there’s some long term issue (moisture, spooky interactions at a distance, bad karma) I’m not aware of…
edward
I would take the motor apart and put it back into the container it arrived in. You don’t want to have the o-rings compressed for a long time and not perform next time.
If I have to take apart a motor and know I’m not going to fire it immediately I also replace all the o-rings and re-lubricate where needed. I figure it is prudent insurance for $3 in parts for the motor to perform next time.
Edward
Jack Matthews
Good point, Edward,,, how Feynman-like of you to think of that. That’s why we ask.
I’ll take it apart this evening…
edward
I don’t know how all the o-ring seals are designed, but most that I have encountered have been close to an industry standard for gland width and compression factor. Parker has an extensive manual on this. Even when they are designed properly the lubricants that we use could degrade the rubber over the long term and become cracked or brittle. I generally use 70D Buna-N because they are cheap and work well. I did not see a benefit to using an expensive o-ring that only needs to hold pressure for less than 60 seconds. If you use a smaller than required o-ring they will stretch and seal for the flight, but if you leave it together they will crack over time.
My preferred lubricant for o-rings is Slick 50 One Grease. It is a green color. Comes off easily after firing unlike some of the DOW products.
Edward
Kevin Osler
I thought he said this was for a Cessaroni which are already pre-assembled at the factory. Are you replacing the ring in the ejection charge and the nozzle?
I was talking to Joe about the same problem at MHM and he was suggesting I just wrap it back up in plastic like it came.
edward
They are pre-assembled, but not stored in the casing. I should clarify that I would take the reload out of the aluminum casing and store it back in the cardboard tube it came in. The reason to do that is concern about keeping the o-rings compressed.
Edward
Jack Matthews
That’s how I interpreted it, Edward. Thanks for the clarification, though. Going downstairs to get it all cleaned up right now…
Jeffrey Joe Hinton
Perhaps the motor should be removed from casing, perhaps not. I’ve left them loaded for months and not had a problem. However, regardless, the propellant should be protected from moisture by enclosing in a sealed plastic bag to prevent humidity and exposure to spider mites and other airborne microscopic issues. The black powder is sealed but also hydro-sensitive, if that’s the right word. It will absorb moisture and not work as well.
Rocketwhiz
I agree with Joe. I’ve had motors loaded, kept in a trash bag without problems. My only suggestion is to remove the nozzle. I can’t help but picture a high powered flame thrower zipping around the house. 😯
Jack Matthews
Got it – nozzle removed, wrapped in plastic, back in the original cardboard tube, packed safely away in a WWII-vintage ammo box.
Always wondered about the plastic, though – any issues with static discharge?
Jack Matthews
edward
Kevin Osler
Jeffrey Joe Hinton
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