Is this normal from a motor?

[debonairbear]

I recently had a fiberglass rocket cato and assumed I just need to improve my build skills. Getting the motor out of the case though was pretty tough. Had to knock it out with a rod. I haven’t had motors come out like this before, but very new still. Is it normal for CTI to burn through the side of the plastic housing?

 

[rharshberger]

As long as thats just liner material and no aluminum casing then its okay.

 

[debonairbear]

Right on!

thanks!

 

[rharshberger]

Right on!

thanks!

Did the casing look okay, no scorching on the outside of the casing?

 

[debonairbear]

Not on the outside, but I’ve got a lot to scrape off on the inside.

It’s the first time I had a motor not come out all at once so I was just curious if the Cato could have been something that was caused by a motor issue.

 

[rharshberger]

There is a difference between a CATO and a SHRED...

 

[debonairbear]

Ooh!

I think this must have been a shred then. All fins came off even after using rocketpoxy all over them.

Somehow, though, the parachute came off and the big red bee and chute release were both blown out.

 

[Voyager1]

Not on the outside, but I’ve got a lot to scrape off on the inside.

It’s the first time I had a motor not come out all at once so I was just curious if the Cato could have been something that was caused by a motor issue.

Don’t be too vigorous with your scraping on the inside of the motor tube. Let it soak in warm soapy water for a while to soften the residue. Then use a vinegar soaked rag on a length of dowel.

If that doesn’t move it, you can use some WD40 on a Jex pad. Works for me and it does’t damage the tube coating if done carefully.

 

[smstachwick]

Ooh!

I think this must have been a shred then. All fins came off even after using rocketpoxy all over them.

Somehow, though, the parachute came off and the big red bee and chute release were both blown out.

Yes, definitely a shred.

CATO implies a major motor malfunction caused by a manufacturing defect or incorrect assembly.

Shred typically means that the motor operates as designed but the rocket’s construction was inadequate for the demands placed on it. In-flight motor mount detachments and/or multiple fin detachments during the boost phase are the most common failure modes for a shred.

Both terms are extremely non-technical, though.