Estes BP motor overpressure CATO failure mode "priority"?

[SolarYellow]

It came up in hypothetical discussion yesterday, and I'm not sure of the answer, so I'm posing the question to the experts here.

Are Estes BP motors designed such that in an overpressure CATO event, it will blow out the lower nozzle or upper portion of the propulsion grain, delay grain, ejection charge and clay cap before the paper case splits? In other words, is there any reasonably expected risk of it bursting sideways like a firecracker before the ends blow out?

 

[DigBaddy]

C6-5

 

[mh9162013]

C6-5

View attachment 626774

Holy scha-moly...

I don't recongize the label on the engine, though. Is that an older engine?

 

[Art Upton]

Specs are for Model Rocket motors to fail axially rather then split. But some times they split, BP and AP.

I'd rather have the aft blow out rather then the fireball out both ends, but BP tend to do it out both ends.

I have had AP fail and the Aft blow out and I can generally fix that, but not all the time; they can blow both ways also.

 

[DigBaddy]

Holy scha-moly...

I don't recongize the label on the engine, though. Is that an older engine?

Yeah, older. Mid 90s...I think. Was stored with a few dozen others and every other one worked perfectly. Poop occurs.

It still shot a flaming slug out the front too. Got video somewhere....

 

[DigBaddy]

View attachment C65- Failure~2.mp4

 

[prfesser]

Watched as one of the old E15s CATOed. Nozzle, forward clay, propellant were not to be found. And crazily, it also split down the side---in a straight line, looked as though a Skilsaw had been taken to the case.

 

[bjphoenix]

The last 2 E12s I saw CATO both blew the delay grain out the front.

 

[Daddyisabar]

Estes cases are "over built" to avoid dangerous lateral splits. I have only seen it happen three times in 17 years at club launches.

Out the top, out the bottom, but never out the side on kiddie motors!

Bog Boy AP, now that's a different story.

 

[Back_at_it]

In all of the CATO's I've seen there has only been one that split the case but when it did so it was spectacular. Blew all three fins completely off the rocket and turned the lower part of the rocket into confetti. The sound was also amazing as it didn't sound like a motor at all. If I didn't see the case come out of the rocket afterward I would have sworn that someone had an M80 in the rocket.

Generally the cases don't split and you simply get a fireball out the top and bottom of the motor case.