CTI K660 Total Destruction

I've flown Aerotech reloads since 1999, but a dealer in Manchester had a CTI 54mm 6 grain case (not brand new, but it looked flawless, except for some wear on the aft retaining ring anodizing). I believe in supporting the vendors that attend launches and bought the case even though I had always purchased new before. I also bought a K660 reload. I assembled it today following the instructions. I lightly greased the O-rings, and as I pushed the forward closure/grain assembly into the case I felt the resistance as the instructions said I would. I made sure the ignition pellet faced forward. I installed the aft closure/nozzle and pushed the assembly into its final position and screwed on the retainer. The retainer screwed on without any undue resistance and snugged up just fine. I remarked to myself how easy these motors were to assemble compared to my Aerotech reloads.I popped off the white cap and disposed of the black powder since I would be using dual deploy. I replaced the white cap and installed the engine. On the rail, I threaded the ignitor to the top of the motor.

On ignition, it was as if someone lit an M80 inside my rocket. The damage:
Motor case: 100% stuck inside the motor mount. The upper "lip" of the motor casing is bent back flat.
Propellant grains: 3 grains were ejected out the top of the case and never ignited. 3 (I assume) are still stuck inside the case.
Lower body tube: destroyed.
Upper body tube: damaged, but possibly repairable.
Aft centering ring and forward centering ring: broken in half and separated from the rocket.
Aft avbay bulkhead: broken into thirds,
Avbay 9V batteries: knocked out of their plastic battery holders despite their having been zip tied into place.
Fins: all sheared off except for one.
Lower shock cord: melted together in numerous locations.
Drouge chute: partially melted.
Launch pad: all four attachment bolts sheared off.

Obviously, a major malfunction. Any ideas?

You would think it was a chunk clogged the nozzle throat then kaboom.
What igniter did you use?
I would definitely have the vendor talk to CTI and send them photos of all the motor and grain pieces.
They would not need the unused grains but they may want to examine all the inert pieces of the reload.
Doesn't the reload assembly go into the case as 1 assembled unit then the aft closure? (I have only used the older 54's)
I have heard of some failures but I have had CTI motors since 2005 , 38s and 54s, luckily with no failures.

I have flew a lot of CTI never a problem. Did you install or slid in forward closure, liner with grains, nozzle in all at once. I have always taken the reload out of the package some times grease O-rings sometimes not. This is if I am not adjusting delay. Looks like you get to build a new rocket. I am sure CTI will take care of you. They would want to know what happened also.

I have never seen the front of a CTI case fail. The plastic, yes, but never the flange. Interesting.

You would think it was a chunk clogged the nozzle throat then kaboom.
What igniter did you use?

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I don't think the igniter was the issue because the throat of the nozzle was clear post event.

Doesn't the reload assembly go into the case as 1 assembled unit then the aft closure?

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That's exactly what I did. I greased the rings, put the forward closure on the liner/grain assembly and pushed them in as far as they would go. I then put the nozzle on the aft end of the liner/grain assembly and pushed it the rest of the way in. Everything seemed to fit together really well, with the forward closure fully against the rolled lip of the case and the screw-on retainer going on easily at first and then snugging up like you would expect.

Here's another picture of the forward end of the case (the first one was a head-on shot).

crossfire said:

I have flew a lot of CTI never a problem. Did you install or slid in forward closure, liner with grains, nozzle in all at once.

Click to expand...

I put the forward closure on the liner/grain assembly and slid them in first, then put the nozzle onto the aft end of the liner/grain assembly and slid them in the rest of the way. The overall length of the forward closure/liner-grain assembly/nozzle seemed exactly as I expected (even though I have never used a CTI motor before). When I screwed on the aft retaining ring, it went on easily at first and then snugged up against the nozzle, again, just as I would expect.

Sounds like you did things right. The only thing different than what I do is the whole reload goes in at once. I have never slid nozzle assembly in on its own. CTI will get back with Jeron makes post on this site.

Odd. I've assembled 54mm's just as you described and have never had an issue. I would expect they'll step up to warranty this in short order. I'm sorry your first experience with them was something like this. That really does suck to hear.


Later!

--Coop

Coop said:

Odd. I've assembled 54mm's just as you described and have never had an issue. I would expect they'll step up to warranty this in short order. I'm sorry your first experience with them was something like this. That really does suck to hear.


Later!

--Coop

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Thanks for the sympathy Coop. I was really depressed yesterday but am feeling better today. I know our hobby can result in the loss of a lot of hard work in just a split second, but this is the first time it has happened to me on a large/expensive rocket. I'll get over it.

I also wanted to say that I will use CTI motors again. I have an I100 for a two stage rocket that I have not yet flown. I am looking at their 75mm motors for my Level 3. I think CTI brings some really good products into our hobby and the competition/innovation is good for us all.

Wow never seen a CTI case do that. I would think if the motor is over pressure it would blow the rear closure and not do what it did to forward end. A grain core must have gotten plugged. CTI will make things right with you.

That is a clear case of over pressure by a large margin. Something clearly wrong with the motor.

Is it possible the used case you bought was a 6XL and not a 6G case? I only ask as this was your first time using CTI hardware, plus by putting the nozzle in separately you may not have noticed the gap?

Hello,

Sorry to hear and read about this failure. My first question would be the age of this reload. If it is older classic propellant (pre-2012) there could have been some crack formation in the propellant grains, depending on the storage conditions. Did you happen to inspect the grains?

We will honor this warranty of course. Your dealer will help you with that. Please try to save the packaging, so we can determine the lot#.

Regards,
Jeroen @ CTI

I sent you a pm.

Jeroen_at_CTI said:

Hello,

Sorry to hear and read about this failure. My first question would be the age of this reload. If it is older classic propellant (pre-2012) there could have been some crack formation in the propellant grains, depending on the storage conditions. Did you happen to inspect the grains?

We will honor this warranty of course. Your dealer will help you with that. Please try to save the packaging, so we can determine the lot#.

Regards,
Jeroen @ CTI

Click to expand...

Thank you so much Jeroen. I did not take the grains out to inspect them. I purchased this reload in September and it has been in my heated/cooled basement ever since save for a two day trip to south Georgia in February. I think I still have all of the packaging. I am going out of town tomorrow for several days so I will be in touch next week.

Thanks,
Eric

Jeroen_at_CTI said:

Hello,

Sorry to hear and read about this failure. My first question would be the age of this reload. If it is older classic propellant (pre-2012) there could have been some crack formation in the propellant grains, depending on the storage conditions. Did you happen to inspect the grains?

We will honor this warranty of course. Your dealer will help you with that. Please try to save the packaging, so we can determine the lot#.

Regards,
Jeroen @ CTI

Click to expand...

PM sent with info you requested.