CTI 38mm CATO Report

At the weekend launch I was just at, there were 4 CATOs on 38mm Cesaroni motors. Three of them (all within about 3 hours) were 2G H225s, and one (the next day) was a 3G I, I believe either the I175 or I345. Two of the H's took out L1 cert rockets, and the I finished the job on one that had been rebuilt overnight. One of the H's and the I will get MESS reports. All three H's had date codes within a month of 9/1/15. I don't know about the I.

On all four motors, the rocket got about 10 feet off the pad when the nose cone blew off and a wide flame came out the top of the rocket. The motors were not ejected. The recovered motors had a ~1" diameter hole where the delay grain used to be. No touch hole for the ejection charge or anything. It looked like the entire assembly was burned out at the diameter of the glue ring that holds the delay grain in. Initial looks said that there was a little more burning on one side, so maybe the burn-through started there. The forward o-ring was intact and undamaged.

That said, people in our group flew 38mm 2G red and blue with no issues, and I flew a 5G pink with no motor issues. I'll get pictures of the damage as soon as I can.

Did any of the casings burn out where the threads are?

We had a larger launch where we had 3 out of 3 H123-SK from the same charge 09. September 2015 cato.
All showed the same defect blowing out through the delay grain.
I have a highspeed video of one of the catos.

A vendor recently told me that no Cesaroni warranties will be honored until they are back in full production.

I am not sure who or what to believe at this point.

watermelonman said:

Did any of the casings burn out where the threads are?

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No, the casings were undamaged on the threaded end. A 2G load in a 3G case with spacer did weld the spacer to the inside of the case, so it's now an extra-long 2G case.

Those failures were depressing to watch. I felt really bad for the L1 candidates on Saturday; that's a rough way to watch your big cert flight end up.

boatgeek said:

No, the casings were undamaged on the threaded end. A 2G load in a 3G case with spacer did weld the spacer to the inside of the case, so it's now an extra-long 2G case.

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Good to hear; I had two 38mm3G casings in a row now disintegrate at the threads, about 1/3 of the circumference.

I just did a post mortum on a Pro38, 6G , I believe the dealer said it was a vmax load. It blew the aft closure out the back and burned through the fwd and consumed it the flame. All I had was a totally undamaged case and the liner burned in two about 1/3 down from the fwd. The liner pieces were all bubbled up at the area of separation. Liners slid right out and the case cleaned up.

Photo of said failure.

That happens to the liner a lot. Dr.J told me most the melting like happens after motor burn out. The liner did its job when motor was burning and melted after motor burn out. As long as case is fine the liner did its job.

I once had an on-site dealer tell me that the liner mostly gets eaten away by the delay burn.

I've only flown maybe a handful of CTI motors myself and I don't recall the liners being eaten away too badly but I have seen plenty of roasted AT liners. AT Redline and Mojave Green loads tend to roast liners.:wink:

Donaldsrockets said:

I once had an on-site dealer tell me that the liner mostly gets eaten away by the delay burn.

I've only flown maybe a handful of CTI motors myself and I don't recall the liners being eaten away too badly but I have seen plenty of roasted AT liners. AT Redline and Mojave Green loads tend to roast liners.:wink:

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And cases:

AT Mohave Green H250 And a few others had this type of failure also. Kurt

watermelonman said:

Good to hear; I had two 38mm3G casings in a row now disintegrate at the threads, about 1/3 of the circumference.

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What was the resistance like screwing it in? I've taken to pulling the rear closure, shoving the load in as far as I can, then using a flipped spacer to seat the liner all the way in, then screwing in the rear closure.

I have flown nothing but CTI Pro38 classic loads and the original Smokey Sams. Never had a failure, only slight bubble in some liners in long loads. Shorter liners come out perfect on the outside. Isn't happening more with the faster loads?

Specifically on 38mm cases, I have been told that a huge percentage of the CATOs occur when the liner is bound up as a result of it not being in position before the thrust ring/nozzle is tightened down. The binding creates tiny gaps between the liner and the o-ring and gasses leak through. These result in aft end CATOs and generally there is pretty bad burn damage to the case which in turn leads to the nozzle being blown out.

I have been told, and have not had problems since doing this, that you should detach the nozzle. so that the bottom end of the liner is visible. use the aft side of a spacer to push the liner into place and make sure it is tight instead of relying on torqueing down the thrust ring/nozzle. Then screw on the thrust ring/nozzle assembly.

And as with any motor, you have to make sure the igniter is all the way forward. If it isn't then you ignite the fuel in both directions instead of just from the top down. Then you over-pressurize, and BOOM.

The I motor was the I170 Classic. Date code was 9/22/2015. I'm gathering more details and have photos of the delay burn throughs. I refuse to speculate at this time, but I will say the sequence has many of us scratching our heads right now. I'll just gather data and get it into the hands of smarter people than I, and wait to see what comes from any investigation.

I was one of the participants at the actual event we've been talking about this weekend who experienced one of the CATO's. Myself and my friend drove up together and both attempted our level 1 cert after a years worth of research, building and meticulous preparation. It was devastating to witness all our efforts ending in this way. We knew it COULD happen, just didn't expect it on our very first attempt. And for BOTH of our rockets to have this happen, made it all the worse.

All that said, the details (from our perspective) are as follows: We prepped our motors by basically unwrapping them form the packaging, inspecting the outside for any damage and loading them into the case by threading them all the way in and loading them in the rockets. We did not disassemble or adjust them in any way. No delay adjustments were necessary, as we were both using electronics. The motors were both Cesaroni Pro-38 H225's, and they both had manufactured dates of 18 Sep 2015. They both looked fine, and were purchased weeks before from the same distributor. Both CATO's happened in the same manner, the rockets were ignited and launched of the pads and almost immediately separated at the lower body tube ebay point (as if our rear ejection charge had deployed) and huge flames came bursting from the lower body tube. It was pretty apparent the upper motor delay had failed and the motor was burning out of both ends. Our rockets were recovered with the forward ends in tact, but the lower body tubes were complete losses. (all that fin fillet work...).

After our launch attempts, another gentleman from our club attempted his level 1 cert with the exact same motor and the exact same rocket (Madcow Torrent) and his launch CATO was a MIRROR image of ours! His motor (after inspection and comparison) showed the exact same failure traits as ours, and was produced a month after ours in OCT 2015.

In the end, I'd like to say...absolutely everyone at the event was AMAZING! Everyone was so helpful, concerned and understanding. That was the main impression that I walked away with at the end of the day. This is definitely a community that I am proud to call myself a member of, even though we didn't get certified. I am very glad to have found my home in rocketry again (I am a B.A.R.) and couldn't be more pleased with the folks around this experience. I am grateful for the lesson and the time we had. I have already ordered a new rocket and will plan on attending the September launch for my Level 1.

boatgeek said:

The motors were not ejected. The recovered motors had a ~1" diameter hole where the delay grain used to be.

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I had a similar failure a couple of years ago with a Pro24 3G--I think F50. I can dig up some photos when I get home. Destroyed a glider entirely by torching the inside.

Ari.

Maybe a CTI dealer can chime in on this post. And give some info of want may have happened to your reloads. CTI is still shipping motors so I would think your dealer should be able to get you a replacement reload. It might not be the H225 but something close.

Here are two pictures of what happened. The first is the actual CATO the second is a comparison of another members successfully fired CTI Pro-38 compared with one of ours that failed. Ours is (obviously) the lower one that is all melted and blown out.

I was there and felt really bad for you guys, two in a row on the same rack no less...looked like something found it's way forward and burned from both ends...I didn't see or know about the third one...

Frank

burkefj said:

I was there and felt really bad for you guys, two in a row on the same rack no less...looked like something found it's way forward and burned from both ends...I didn't see or know about the third one...

Frank

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Thanks for the kind words Frank!

Regardless of how hard it was to watch our rockets CATO :y: and think about it afterwards :bang: the people and atmosphere at the event were wonderful. Everyone was incredibly friendly and enjoying each other's successes while feeling the pain of someone's mishaps. I was too distracted to gather contact information from the folks I ended up talking to but a fellow next to us (Robert) got his level 2 cert. which was awesome to see. Again great people all around and I'm looking forward to giving it another go in September!

Altdelhistory said:

Regardless of how hard it was to watch our rockets CATO :y: and think about it afterwards :bang: the people and atmosphere at the event were wonderful. Everyone was incredibly friendly and enjoying each other's successes while feeling the pain of someone's mishaps. I was too distracted to gather contact information from the folks I ended up talking to but a fellow next to us (Robert) got his level 2 cert. which was awesome to see. Again great people all around and I'm looking forward to giving it another go in September!

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COULD NOT AGREE MORE!!

Flyfalcons said:

Those failures were depressing to watch. I felt really bad for the L1 candidates on Saturday; that's a rough way to watch your big cert flight end up.

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Thank you for the sentiment. We couldn't agree more. LOL!

burkefj said:

I was there and felt really bad for you guys, two in a row on the same rack no less...looked like something found it's way forward and burned from both ends...I didn't see or know about the third one...

Frank

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+1, I felt the same way as I watched the 3 rockets damaged by CATOs of normally reliable motors, especially in L1 attempts. Seems like quite a few of us were observers to this series of Catos.

crossfire said:

Maybe a CTI dealer can chime in on this post. And give some info of want may have happened to your reloads. CTI is still shipping motors so I would think your dealer should be able to get you a replacement reload. It might not be the H225 but something close.

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What is there to say? I have warrantied x number of this failure, from date codes all over the place. The issue (if I remember right) was the bond between the potting and the closure isn't holding up. This allows the motor to blow by and torches out the front closure.

As Thomas said above, we had a bunch of H123-SK (38mm) all with charge no. 9 sept. 2015
3 of them showed the same behaviour: Burnt-through delay grain.
The abovementioned catoed H225 had a date of 18 Sep 2015, just 9 days later, and October 2015.

After two H123-SK motors got destroyed we inspected the remaining reloads, and could not find any flaws, they looked ok.
As we planned to launch a big cluster with 6 of these H123-SK in it, we wanted to be sure and launched another one of these reloads, as we smelled that there could be a problem with these reloads.
And guess what: It ended also in a cato, the same failure, the delay grain burnt through.
We choose then to take other reloads from older charge dates, which worked ok, the big project flew without problems.

As far as I know, we did not get any reaction from the dealer, we still have 6 of these reloads, and do not know what to do with them.

Here is some video I made from one of the CATOs, first in realtime then 5 times slowmotion:
[video=youtube;yMwt9CXPTF0]https://www.youtube.com/watch?v=yMwt9CXPTF0[/video]
The camera is stationary and the rocket was safely recovered far away from any persons.

I had a group of flyers from a college travel to one of our launches this spring. They all flew the H225 in L1 cert flights. One suffered a forward closure burn through. It burnt the center right through. It burned the shock cord and inside of the body tube. The flyer was able to repair his rocket and fly another flight, which was successful. His second attempt was also done using the H225.
I filed a MESS report and sent supporting information to Apogee, who responded the very next business day with information for how to report the failure to CTI. The person who bought all the motors followed up with CTI.


[emoji1010] Steve Shannon [emoji1010]