Richard,
Interesting you mention the Punisher drag race. If memory serves it was a fresh
batch of motors that had the higher CATO rate for reasons unrelated to storage.
Perhaps I am mistaken. I happened to pull an older K1440W from my stash.
Figured I dodged a bullet that day. My one and only CATO was on a 38mm for my
first L1 attempt at 2013 ROCStock ... go figure. I had built the motor the
night before and left the rocket out in freezing temperatures overnight... not
good for o-rings as history tells us.
On Apr 5, 2021, at 12:19 PM, Michael Kramer <mike@xxxxxxxxxxxx> wrote:
Quick survey, Think about this for EACH failure you may have had.
On 54mm motors or larger,
1) Have you ever had a motor fail in flight (for ANY REASON, no ejection
charge, cato low power, Punisher drag race collateral damage)
if yes, all failures are not due to storage, Same problem may happen if the
motor sat for an extended time.
A) was it in a motor that used a reload less than 2 years old that was loaded
into the case less than 2 months before flying?
If yes, not a storage problem.....
B) Was the reload older than 2 years BEFORE being put into the case
if yes, was there ANY evidence of grain swelling, liner discoloration, O-ring
degradation, um, did you 'fix' the motor?
If yes, could the problem be the reload age not the storage time (ignoring
storage condition / sealed bag/ trunk of car etc.)?
C) Was the reload loaded and stored for over 2 months?
If yes,
i) were the treads loosened?
Did you have a failure caused by an o-ring failure?
did you have a failure caused by ejection charge getting past an o-ring?
ii)Were the ends capped / dry?
iii) Was it a leap year, solstice, black cat involved?
Just thinking.... If it was stored, and failed, the failure may have had
nothing to do with the method of storage.
On 4/5/2021 11:15 AM, Dave Peterson wrote:
Good stuff. I tend to accumulate upper stage motors that were not started
for various reasons. They may go years before another attempt, so they are
often “decertified” for upper stage use. A great source of long burn motors
for the Wocket! My storage method is to loosen the forward closure and
rubber band plastic freezer bags over the aft and forward ends of the case.
That gets put back into the reload case stored horizontally. I normally have
electronic recovery, but come to think of it; would a delay grain stored
that way in a forward closure be subject to any degradation? Maybe grease
migrating to fill the touch hole etc.?
On Apr 5, 2021, at 10:37 AM, Andrew Wimmer <xenonrocket@xxxxxxxxx> wrote:
I *think* one of the historical reasons folks suggest loosening the
closures is for Aerotech motors with paper liners. Compressing the o-ring
in Aerotech motors requires that the liner be compressed as well, and the
concern is that the cardboard may slowly deform, leaving the o-ring
effectively floating and not sealing. This would mostly be a concern on the
hobbyline motors that do not have a full grain stack. It's not a concern on
phenolic liner Aerotech motors or motors that seal by putting the o-ring
between a closure and the case (CTI, any snap ring hardware, etc).
-Andrew
On Mon, Apr 5, 2021 at 10:31 AM Jason Muckenthaler
<dmarc-noreply@xxxxxxxxxxxxx> wrote:
Thanks Richard - i appreciate all of the feedback. “Just give you the
motors...” that was good!
Sent from my iPhone
On Apr 5, 2021, at 10:28 AM, richard dierking <applerocketry@xxxxxxxxxxx>
wrote:
So, I bet you could loosen the threads (not now of course) or keep the
threads tight when you can’t use a motor. To be safe, I think you should
give me the motors Jason and I’ll test them for you.
Sorry, just kidding and looks like there is yet another controversy that
will probably never die. :-)
But, I’m curious, what would AT say?
Richard
On Apr 4, 2021, at 10:26 AM, Kurt Gugisberg <kurtgug@xxxxxxxxx> wrote:
I agree with Rick. I've not released pressure on the O rings for motors
that sat for a year under compression. No failures. Put the cap on the
end of the nozzle and you have a sealed system that keeps out moisture.
No problem.
Kurt
On Sun, Apr 4, 2021 at 10:22 AM Rick D. <rocketrick@xxxxxxxxx> wrote:
Ron,
I respectfully disagree. O-ring seals are designed to remain under
compression indefinitely. Loosening and re-tightening them is a recipe
for disaster, as those are the moments where the O-ring has a chance to
get damaged.
Just sitting there forever under compression is what they are designed
to do. Let them do it.
Cheers,
Rick Dickinson
On Sun, Apr 4, 2021, 9:07 AM Ron McGough <rrmagoo7@xxxxxxxxxxx> wrote:
There is one thing that wasn’t mentioned concerning this post. If a
flier is unable to fly due to current weather or the latest (and
longest issue) pandemic closure and said flyer has assembled reloadable
motors that can’t be used it is always wise to loosen the closures just
a bit to remove compression from the orings. Just be sure to retighten
them when you’re actually ready to fly them.
Ron McGough
Sent from Mail for Windows 10
From: Jason Muckenthaler
Sent: Saturday, April 3, 2021 3:58 PM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: AT Motor Loaded pre-COVID
That all sounds prudent - I left my motors in a cool, dark place in the
garage cabinets.
On Apr 3, 2021, at 3:44 PM, DAVID ROBB <robbdm@xxxxxxxxxxx> wrote:
Last year, I attended a large March launch that was impacted by wind.
I was not able to launch two Aerotech K456DM, two J800T, one J460T,
three G138T, J350W and one L1040M. When I returned home, I
disassembled, placed all the gains in freezer bags and sealed away
for another day. I was concern about the ability of white
lightening and blue thunder to quickly ignite since they are used in
two stages and air starts. Another launch came up in October. I
assemble as normal (regressed) and flew without a problem.
Good luck.
==================
David M. Robb
On 04/03/2021 12:32 PM Jason Muckenthaler
<dmarc-noreply@xxxxxxxxxxxxx> wrote:
I have had a few 75mm Aerotech motors loaded since January of 2020 -
one is a K and the other is an L. Now that we have a launch
opportunity, I’m curious if these motors are safe to launch. I plan
to open the motors and re-grease the O-rings - do folks have any
experience with motors packed for a long time prior to launch?
Thanks,
Jason
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