L2 Cert Flight- CTI J760 CATO

cruck1000 · Jul 17, 2018

(First forum post! Woohoo!)

My L2 Cert Flight of a Wildman Extreme 4" kit flown with an extended upper body tube. Motor failure a few tenths of a second into flight on 7/14/18 at Michigan Intl Speedway. Enjoy my misery

blackjack2564 · Jul 17, 2018

More data??
Looks like the front end let go.
Pics of aftermath? Close up.
Did anything survive to be used again?

Welcome to the Forum & have some fun here!!!

djs · Jul 17, 2018

pictures of the aftermath of the motor? looks like the forward closure blew on it.

Steve Shannon · Jul 17, 2018

Please turn in a MESS report.

cruck1000 · Jul 17, 2018

Here's the rest of the post I neglected to add on...

Luckily, the RRC3's barely passed their arming altitude, so the main did deploy and the rest of what wasn't scorched returned intact. My certification overseer believes the insulation on the motor failed, causing the casing to separate 1-2cm above the aft closure and fly through the rocket. Pics below..

The bottom of the MMT definitely has heat damage, but with some rework the model should be flyable again!

More pictures: https://drive.google.com/drive/u/0/folders/1ovpZAoyRyQyy6AeYXSDJ-L-odMw9UUv3

Dipstick · Jul 17, 2018

Looks like you got a chute, did you cert? Or was the rocket not flyable?

Steve Shannon · Jul 17, 2018

Dipstick said:
Looks like you got a chute, did you cert? Or was the rocket not flyable?

From the rules for certification:
Non-certification
Any of the following will result in non-certification for a certification flight:

Motor Cato is listed first. Whether or not it’s the flyer’s fault doesn’t matter.

cruck1000 · Jul 17, 2018

Steve Shannon said:
Please turn in a MESS report.

I had to submit 2 because I didn't see the date code printed further down the cardboard container the 1st time, but I noted that in the comments (sorry!)

Steve Shannon said:
Non-certification
Any of the following will result in non-certification for a certification flight:

Motor Cato...

Sadly... :'(

Steve Shannon · Jul 17, 2018

cruck1000 said:
I had to submit 2 because I didn't see the date code printed further down the cardboard container the 1st time, but I noted that in the comments (sorry!)

Sadly... :'(

Nothing to be sorry about. You did the right thing. Thanks for filing a MESS report!
This falls under the caca occurs category.

blackjack2564 · Jul 17, 2018

Well hopefully most can be used again. I've had to hone out scorched tubes after a coupler disasters myself.

Good news is, you made your sacrifice to the rocket Godz....usually keeps them away for a season or 2....!

crossfire · Jul 17, 2018

Not good news at all. What was the date code on the motor? I just purchased the same motor from the WM.

cruck1000 · Jul 17, 2018

blackjack2564 said:
Well hopefully most can be used again. I've had to hone out scorched tubes after a coupler disasters myself.

Good news is, you made your sacrifice to the rocket Godz....usually keeps them away for a season or 2....!

Hopefully!!

crossfire said:
Not good news at all. What was the date code on the motor? I just purchased the same motor from the WM.

It was March 27, 2018, so pretty new. I'm hoping it was just a bad spot in the tubing or a bad o-ring as I've just placed my order for another J760! I'm not sure if I'm crazy or pushing my luck...

crossfire · Jul 17, 2018

I checked my motor and its dated April 2nd 2018. Not sure when i will use mine but I will let you know how it goes. If you would let me know how your new motor works out. I have flew a lot of CTI 54mm and I can not remeber the last time I had a problem.

Godd luck with your L2 flight

cruck1000 · Jul 17, 2018

I'll be sure to let ya know. Fingers crossed for it being an isolated issue, I really want to fly more Pro54 motors!

crossfire · Jul 17, 2018

Maybe a siily question were using a motor case with a space? A while back a guy flew a motor and forgot to use the spacer with same results.

Steve Shannon · Jul 17, 2018

Some people religiously epoxy the forward closure on CTI motors into the liner to prevent forward closure failures. Search for some posts by Jim Jarvis.

cruck1000 · Jul 17, 2018

Oh gheez.... forgetting a spacer? :| For reference here, brand new Pro54 3G case & aft closure. The failure occurred near the aft end, likely between the nozzle assembly and grain liner.

grouch · Jul 17, 2018

Sorry to hear. Good luck with the rebuild and 2nd attempt.

A-N-D-R-E-W · Jul 17, 2018

Bummer about the CATO. However everything looked good before and after the failure! Keep us posted on your next attempt

markkoelsch · Jul 18, 2018

Is this motor one with a plastic liner or a phenolic liner?

cbrarick · Jul 18, 2018

sanding flapwheel is your friend. Find one about the size of the tube you gotta fix. Here's a few, but my Lowes has them in 1 inch increments thru 4 inches... https://www.homedepot.com/s/sanding%20%20flapwheel?NCNI-5

djs · Jul 18, 2018

These 54mm CTI issues have me nervous.. esp as I'm going to fly a 4-6 grain in a week at the WOOSH launch. Maybe I need to start investing in AT hardware?

Charles_McG · Jul 18, 2018

Steve Shannon said:
Some people religiously epoxy the forward closure on CTI motors into the liner to prevent forward closure failures. Search for some posts by Jim Jarvis.

Do you know, is that after adjusting the delay, or is this done when not using the motor eject at all?

tim cubbedge · Jul 18, 2018

Charles_McG said:
Do you know, is that after adjusting the delay, or is this done when not using the motor eject at all?

It has to be done after you adjust the delay, if you are in fact using the delay. Personally I remove the delay on most 54mm motors.
Here is the thread where they talk about epoxy & FWD closure:
https://www.rocketryforum.com/threads/small-bulge-in-rocket-motor-casing.144046/

Steve Shannon · Jul 18, 2018

timbucktoo said:
It has to be done after you adjust the delay, if you are in fact using the delay. Personally I remove the delay on most 54mm motors.
Here is the thread where they talk about epoxy & FWD closure:
https://www.rocketryforum.com/threads/small-bulge-in-rocket-motor-casing.144046/

Do not ever completely remove the delay grain; it seals the forward closure. Only the ejection charge powder should be removed and only if motor deployment is unnecessary. The reason I point out the difference is because last month we had a guy come to our launch who had “read somewhere about removing the delay” and literally did just that, removed the delay grain.
Thanks for posting the link. Jim Jarvis describes the procedure in posts #8 and #12.

tim cubbedge · Jul 18, 2018

Steve Shannon said:
Do not ever completely remove the delay grain; it seals the forward closure. Only the ejection charge powder should be removed and only if motor deployment is unnecessary. The reason I point out the difference is because last month we had a guy come to our launch who had “read somewhere about removing the delay” and literally did just that, removed the delay grain.
Thanks for posting the link. Jim Jarvis describes the procedure in posts #8 and #12.

Steve, I mispoke - I meant that I remove the BP, not the smoke/delay grain.

Steve Shannon · Jul 18, 2018

timbucktoo said:
Steve, I mispoke - I meant that I remove the BP, not the smoke/delay grain.

I was really sure that’s what you meant, but after the incident at our launch last month I didn’t want to assume. Thanks for clearing that up.

markkoelsch · Jul 18, 2018

cruck1000 said:
Here's the rest of the post I neglected to add on...

Luckily, the RRC3's barely passed their arming altitude, so the main did deploy and the rest of what wasn't scorched returned intact. My certification overseer believes the insulation on the motor failed, causing the casing to separate 1-2cm above the aft closure and fly through the rocket. Pics below..

The bottom of the MMT definitely has heat damage, but with some rework the model should be flyable again!
More pictures: https://drive.google.com/drive/u/0/folders/1ovpZAoyRyQyy6AeYXSDJ-L-odMw9UUv3

So, did the liner fail right at the liner/nozzle juncture, or was it above that point? Could you take a look at the nozzle- specifically the top portion that inserts into the liner. Is there evidence of blow by/ evidence of flow through this interface?

cruck1000 · Jul 18, 2018

markkoelsch said:
Is this motor one with a plastic liner or a phenolic liner?

IIRC it was a phenolic liner.

djs said:
These 54mm CTI issues have me nervous.. esp as I'm going to fly a 4-6 grain in a week at the WOOSH launch. Maybe I need to start investing in AT hardware?

I chose the Pro54 line as a nice size for large L1/Mid L2 flights and for the ease of use, I hope everything works well from this point on

markkoelsch said:
So, did the liner fail right at the liner/nozzle juncture, or was it above that point? Could you take a look at the nozzle- specifically the top portion that inserts into the liner. Is there evidence of blow by/ evidence of flow through this interface?

Honestly, with how messed up everything is I can't really tell; nor do I have any previous Pro54 nozzles to compare to. I'm certainly not an expert in the field of motor dynamics (maybe one day!), so I've added a few more pics to that drive folder if you want to take a look at it.

djs · Jul 18, 2018

cruck1000 said:
I chose the Pro54 line as a nice size for large L1/Mid L2 flights and for the ease of use, I hope everything works well from this point on

I've flown several Pro54 motors before (I thru K) and have never had any issues with them.. hopefully this is a one time glitch for you!

L2 Cert Flight- CTI J760 CATO

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