CTI 3G case with stuck spacer

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astronut69
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CTI 3G case with stuck spacer

Postby astronut69 » Sat Jul 29, 2017 4:26 pm

I flew a CTI P29 3G case with a 56F31 for AYRC last week and was not able to remove the motor that afternoon. The ejection cap had forced through the 2 spacers (which were the right way around and sitting in the correct position when loaded) and stopped in the roll at the top of the case. When I finally was able to remove the ejection cap and the motor, I was left with one spacer stuck in the case. The other spacer has a damaged top - the roll has been compressed, but it did come out.
Any thoughts on removing the remaining spacer without damaging the case?

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Re: CTI 3G case with stuck spacer

Postby kopius » Sun Jul 30, 2017 7:17 am

Can you take a couple of pictures and post them please


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Re: CTI 3G case with stuck spacer

Postby astronut69 » Sun Jul 30, 2017 4:02 pm

Attached are pics of the motor after it was removed, the lower spacer with it altered top lip, and the case from top and bottom showing the upper spacer stuck inside.
Attachments
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20170730_155052.jpg (89.72 KiB) Viewed 935 times
20170730_155033.jpg
20170730_155033.jpg (75.41 KiB) Viewed 935 times
20170730_154958.jpg
20170730_154958.jpg (71.38 KiB) Viewed 935 times

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Re: CTI 3G case with stuck spacer

Postby Digit » Sun Jul 30, 2017 6:45 pm

Your casing actually looks to already be damaged mate, is that a bulge about 10mm above the sticker about where the spacers would have been touching?

As for getting it out you could try freezing the whole lot over night and then running ambient temperature tap water over the outside of the casing to expand it off spacer and then try tapping it out.

Unless Aus Rocketry needs it as is to show CTI?
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Re: CTI 3G case with stuck spacer

Postby astronut69 » Sun Jul 30, 2017 9:41 pm

There are two bands where the spacers have slightly deformed the case. I can send it down if you like as I don't know that it would be reusable even if I can get the spacer out. It would be an interesting one for a rep to see.
Everything was checked before we loaded the case into the rocket and it is the first time the case has been used, so I am not sure what happened. We did have a long delay happen on that flight at AYRC, past what we drilled it to (drilled from 12 sec to 6 sec from memory but the video suggests it took somewhere around an extra 5 sec for the chute to get out)....thought we were going fencing for a moment!
BTW - AYRC was a great day.

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Re: CTI 3G case with stuck spacer

Postby SpaceManMat » Mon Jul 31, 2017 9:29 am

You don't normally see the liner melt down like that on such a small reload. I'm thinking the forward seal leaked somehow but must have been only slightly due to not melting the case at that point. Weird that it melted higher up at the spacer. Take the whole thing including reload and packaging if you have it to Blake. Also you should file a mess report, perhaps after having Blake look at it.
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Re: CTI 3G case with stuck spacer

Postby Viking » Mon Jul 31, 2017 5:24 pm

Wow, that's impressive. To me it looks like the lower spacer has bellmouthed the bottom of the upper spacer into the case. A bit like a swagelok fitting but in reverse. Good luck getting that out!
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Re: CTI 3G case with stuck spacer

Postby SpaceManMat » Mon Jul 31, 2017 9:36 pm

Viking wrote:Wow, that's impressive. To me it looks like the lower spacer has bellmouthed the bottom of the upper spacer into the case. A bit like a swagelok fitting but in reverse. Good luck getting that out!

Don't bother trying to remove it, case is damaged and no longer in spec. It should not be used even if you could remove the spacer, would most likely lead to more failures. As I said before Blake may have some insight into what has occurred, follow up with a MESS report here http://www.motorcato.org/MESSForm.aspx if there are manufacturing issues then CTI will see it in the statistics.
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Re: CTI 3G case with stuck spacer

Postby kopius » Wed Aug 02, 2017 9:01 pm

That is an interesting result with the motor. If you could please send it back to us (Australian Rocketry, PO Box 84, Browns Plains QLD 4118), we can have a closer look and discuss it with CTI.
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Re: CTI 3G case with stuck spacer

Postby astronut69 » Thu Aug 03, 2017 1:28 pm

I'll send it down

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Re: CTI 3G case with stuck spacer

Postby SpaceManMat » Thu Aug 03, 2017 5:52 pm

Reread your original post. I think you had a forward closure failure late in the burn or at burnout.
The forward closure sheared off against the first spacer and was forced up into the lip where it lodged firm. The first spacer and the forward closure where then forced part way into the second spacer which was forced to expand slightly damaging the case and deforming the lip. I suspect there was not any or at least very little damage due to excessive heat, closer inspection should confirm this. What does the inside of the first spacer look like? Is it sooty or burnt?
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Re: CTI 3G case with stuck spacer

Postby astronut69 » Fri Aug 04, 2017 7:09 am

Yes, it was granular sooty material that was difficult to remove.

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Re: CTI 3G case with stuck spacer

Postby SpaceManMat » Fri Aug 04, 2017 9:20 am

astronut69 wrote:Yes, it was granular sooty material that was difficult to remove.

Difficult to remove implies it was still burning, the other thing I think happened was that the force and subsequent deformation of the case and spacers may have actually resulted in the motor being resealed.
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 10,849 feet
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

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Re: CTI 3G case with stuck spacer

Postby Oldboy » Fri Aug 04, 2017 11:22 pm

"As sands through the hourglass, so to are the
anomalies of our hobby ?
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Re: CTI 3G case with stuck spacer

Postby SpaceManMat » Tue Aug 08, 2017 9:10 am

Oldboy wrote:"As sands through the hourglass, so to are the
anomalies of our hobby ?

Well I don't think sand is a likely explaination :lol:
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 10,849 feet
Largest Motor: CTI 1115J530 IM
Current Project: X Wing


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