Estes F Class BLack Powder Cato Risk v. Composite

[Tom Zachman]

Understand Black Powder motors are inherently more risky (subject to containment breach) than Ammonium Perchlorate motors given equal handling, storage care, motor size, and age.

However does anyone have an estimate of flight tested failure rates for each motor class? Looking specifically for F Class motor data.

 

[Nytrunner]

Fliers are highly encouraged to file MESS reports with each CATO, but I'm not entirely sure if that data is collated somewhere public

 

[Steve Shannon]

Fliers are highly encouraged to file MESS reports with each CATO, but I'm not entirely sure if that data is collated somewhere public

Unfortunately it’s not. The problem we have is that we don’t know enough information to calculate a failure rate. If we see that X motor failures are submitted twice as often as Y motors and we publish that, we don’t have any way of telling if that’s because twice as many X motors are bought, burned, or manufactured.

 

[Tom Zachman]

Interesting! Thanks for your replies.

 

[shreadvector]

Understand Black Powder motors are inherently more risky (subject to containment breach) than Ammonium Perchlorate motors given equal handling, storage care, motor size, and age.

However does anyone have an estimate of flight tested failure rates for each motor class? Looking specifically for F Class motor data.

There are virtually no failures reported of the Estes 29mm E16 and F15 motors. They are extremely reliable.

By "virtually no failures reported", I mean that all of the discussion forums that are common have seen maybe 1 or 2 reports and hundreds if not thousands of these motors have been flown or observed being flown by forum posters.

 

[DankMemes]

The F15 has been a good motor for me, it gets my super big Bertha just high enough I can still fly it at the soccer complex... I believed the E9s problem was a very restrictive nozzle that caused over-pressurization, relatively speaking the 29mm e and f motors have larger nozzles given the diameter so one would be left to the 29mm motors being less prone to this phenomenon, but that being said I have seen one f15 Cato, compared to many 24mm...

From my own experience in 29mm it’s more likely that a composite motor would chuff your rocket to death rather than an explosive Cato

 

[aerojacket]

Understand Black Powder motors are inherently more risky (subject to containment breach) than Ammonium Perchlorate motors given equal handling, storage care, motor size, and age.

However does anyone have an estimate of flight tested failure rates for each motor class? Looking specifically for F Class motor data.

I have never had an issue with the 29mm E and F motors from Estes. The only ones that I have had CATOs with have been the smaller E9 size motors.

 

[Andrew_ASC]

I flew two E12s this year then switched to Aerotech APCP RMS24-40 E18W for 24mm rockets. I think the APCP is more reliable in moist or cold climates. Takeeta airbags or whatnot also had problems In moist climates that they did not lab test for. Stay the heck away from Estes E9.

 

[Tyler P]

I've launched a bunch of E9s and haven't had any failures. I see people mentioning them in FB groups and on forums but have yet to see one fail in person.

 

[dr wogz]

Tyler, put a few in your garage this winter, then fly them next summer..

the reported problem is temperature cycling.. The BP core & the cases expand & contract at different rates, and the core becomes separated from the casing.. that's what I've understood, that's what I've been lead to believe..

I've had 2 happen so far..

 

[Anthony Claiborne]

I've had a cato with an E9 and won't fly them again. I am interested in flying with an E12. My impression is that E12s are much more reliable. What are forum members' experiences with E12s?

 

[Tyler P]

Tyler, put a few in your garage this winter, then fly them next summer..

the reported problem is temperature cycling.. The BP core & the cases expand & contract at different rates, and the core becomes separated from the casing.. that's what I've understood, that's what I've been lead to believe..

I've had 2 happen so far..

Maybe that's the difference. I keep mine in my shop. Moisture and temperature controlled.

 

[Steve Shannon]

Maybe that's the difference. I keep mine in my shop. Moisture and temperature controlled.

I leave Estes BP motors in my rocket trailer where they transition from -40° in the coldest days of winter to +100°F in the summer. I bought out the stock of a hobby shop that got out of rockets to give away. Many have been in my trailer for a decade. Our humidity changes little though. I’ve never had a cato on any of the ones I’ve given away. I have D and below.

 

[caveduck]

I've seen a lot of E9's cato, enough that I won't use them in anything I care about. They tend to blow out both ends and incinerate the model. E12s seem better but I've still seen a few failures. In another thread shreadvector said that Estes has phased out production of E9's in favor of the E12, and that E9 failures were pretty random on date codes. I've never seen a 29mm E16 or F15 fail, but I've seen far fewer of them flown. They don't have enough thrust for a lot of the rockets people are tempted to use them for.

 

[shreadvector]

Tyler, put a few in your garage this winter, then fly them next summer..

the reported problem is temperature cycling.. The BP core & the cases expand & contract at different rates, and the core becomes separated from the casing.. that's what I've understood, that's what I've been lead to believe..

I've had 2 happen so far..

You have the cycling backwards. Hot makes everything expand. When it cools, the casing does not shrink back as much as the propellant. This results in a loss of or weakened propellant to casing mechanical bond. Firing a cold motor that was exposed to temperatures 75 degrees hotter than it is at the moment can lead to failures.

Firing a hot motor that was once cold does not lead to failures.

If the motor is severely temperature cycled numerous times, it may fail at any temperature. i do not have the experimental data for that. Did anyone do an R&D report on that?

 

[dpower]

I've flown around 30 the E16/F15 motors, and have had 1 CATO (an E16). For AP, I've had no CATOs when flying RMS (24/40 or 29/40-120) motors. EconoJets have been trouble-free. Worst F motor failure rate for me are AT SU F25 motors (newer molded plastic case) - I won't fly those, except perhaps in a cardboard saucer.

 

[Tom Zachman]

I've flown around 30 the E16/F15 motors, and have had 1 CATO (an E16). For AP, I've had no CATOs when flying RMS (24/40 or 29/40-120) motors. EconoJets have been trouble-free. Worst F motor failure rate for me are AT SU F25 motors (newer molded plastic case) - I won't fly those, except perhaps in a cardboard saucer.

Interesting and informative. Appreciate your significant flight experience and wisdom.