Assembled, but Unused RMS

The local air traffic control tower lowered our waiver at the last minute this past weekend. Now I have two assembled AT RMS motors (H165 and G64). How long will a RMS motor be good for after it is assembled in the case? Our next club launch is Dec 17th. Next closest launch is Dec 10th.


Thanks,


Alan

Make sure one of the closures is loosened so there is no load on the o-rings. Once that is done toss it in a ziploc bag with a note that says "REMEMBER TO TIGHTEN BEFORE USE!" then seal it up. That will normally keep for a couple of months.

A

you ought to disassemble the delay grain from the H165, so the redline propellant doesn't react with the delay grain over the storage time. there is an issue with that, it's why the delay grain was packaged separately from the propellant. not an issue with your white lightning G64.

This season I was caught with a rolled G104 and a G64. I keep the aft enclosure loose until just ready for flight, the tighten it down and add the ejection charge. These two motors sat in my range box for over four months before I was able to fly them, no problems what so ever.

Originally posted by skip_dye
The local air traffic control tower lowered our waiver at the last minute this past weekend. Now I have two assembled AT RMS motors (H165 and G64). How long will a RMS motor be good for after it is assembled in the case? Our next club launch is Dec 17th. Next closest launch is Dec 10th.


Thanks,


Alan

Click to expand...

I've used a 29mm H motor five weeks after assembly, and
I've used an I211 three weeks after assembly, both without loosening. The o-rings keep their compression very well. After all, they are used in single use motors as well.

Of course, you should do whatever garoq (aerotech) says.

I went 15 months on an assembled F40 w/o loosening or anything.

Yeah, definitely take the delay elemant out of the redline motor. Otherwise you should be good.
Reed

This raises a question; do SU motors use O-Rings, and if so, what is different in a SU vs. an RMS that it's shelf life is virtually indefinite?

Originally posted by Hospital_Rocket
Make sure one of the closures is loosened so there is no load on the o-rings. Once that is done toss it in a ziploc bag with a note that says "REMEMBER TO TIGHTEN BEFORE USE!" then seal it up. That will normally keep for a couple of months.

Click to expand...

Basically good advice, but before you do any closure loosening, make certain that the black powder IS NOT already in the ejection charge well in the aft closure. Loose black powder will foul the o-ring seal and you could suffer a blow-by -- hard on RMS cases, killer to rockets. If you indeed launch these motors before the end of the year (Dec 10 or 17), you don't need to loosen anything, just put them in a baggie, squeeze out the air, and tie/zip it. Do it again in a second bag. Should be fine. Certainly, if the black powder isn't already added, no problem loosining the closures, just don't forget to retighten them. Far worse to fly with loose closures than with "compressed" o-rings, IMHO.

I just flew a K550 that had been assembled for about 9 months and a J420 after about 6 months. Nary a hiccup. I can't say I've ever heard of a failure attributable to an RMS motor being assembled too long, although I suspect it's possible.

HTH, --Lance

I always loosen the nozzle end for the above reason. too many itsy bitsy things that can make you go boom at the other end....

I also keep a bag of those little dessicant pillows that come with stuff shipped from overseas. I toss one in the bag with the motor just as a belt and suspenders approach.

I do wish at this point someone like Gary Rosenfield would chime in with a bit of advice.

Come on Gary I can hear your breathing out there...

I fired off both motors at the ROSCO launch in Orangeburg this past weekend. Both motors ignited without any problems.

Thanks for all the suggestions.

Here is what I did for storage:

G64-> Loosened the aft closure. Sealed the motor in a plastic bag.

H165--> Removed forward closure (with delay installed) and double sealed it in plastic bag. Taped off the forward end of the casing, then doubled sealed it in a plastic bag. Taped bags to each other so I would not lose them.

Just before launch, I re-greased the 0-rings.


Alan

At the https://www.aerotech-rocketry.com/ page click on "help" in the left menu. Then go to the "see if your question has already been answered in our FAQ area" page. Scroll down to their "How long can I store a fully assembled RMS. motor" section.

Also take a look at the warranty to see that it is voided if you assemble the motor more than 12 hours before the launch.