ANOTHER CATO...

[JARED S JAYNES]

so my last thread was about cesaroni single grain g78 i attempted to fly a scratch build in preparation for a cert flight. ended with a overpressure cato. so a week ago i received a new single grain case and after alot of reassurance from the folks on the forum and my dealer the other reloads looked safe to fly and proceeded to prep a very flight worthy rocket. took about 7sec off the delay grain. verified that the cesaroni supplied ignitor was touching the top and in the correct position. first ignitor was a miss fire. replaced it with another cesaroni ignitor and boom destroyed the rocket and case. please keep in mind i have flown alot of composite motors never had a issue with Aerotechs so little frustrated with cessaroni at this point.

pictures to follow.

 

[JARED S JAYNES]

Pictures of the motor

 

[Andrew_ASC]

Ooooooof. That’s harsh.

 

[Andrew_ASC]

I personally don’t waste my time with a precert flight as you see now it’s an added risk before the cert. The way I feel about it is just shove the high power motor into it and go for it. Any brand can Cato.

 

[JARED S JAYNES]

I personally don’t waste my time with a precert flight as you see now it’s an added risk before the cert. The way I feel about it is just shove the high power motor into it and go for it. Any brand can Cato.

2 motors in a row? Personally I think that is unacceptable. I have flow at least 30 areotech gmorors with zero fatalities...Pre cert with a scratch built vehicle, not a kit is wise.

 

[Steve Shannon]

Jared,
There was another thread last week by a guy who had two catos in one grain Pro38s.
Need help
https://www.rocketryforum.com/index.php?threads/Need-help.151613/

It looks a lot like this. Please be sure and turn in a MESS report.
There’s nothing wrong with flying a shakedown flight. It’s no riskier than any other flight.

 

[Andrew_ASC]

I view a precert flight as a potential to lose the rocket total loss before ever attempting the cert. At least if you shove your certification motor into it you’re attempting the cert before the rocket is destroyed at worst. And that’s just how I view it.

With student project launches we never did shakedown flights because the loss of a scratch build rocket sustainer or booster stage was a serious risk to completing objectives on a time table. We simply used the airframes to max performance and they either passed or failed. My opinion.

 

[Steve Shannon]

I view a precert flight as a potential to lose the rocket total loss before ever attempting the cert. At least if you shove your certification motor into it you’re attempting the cert before the rocket is destroyed at worst. And that’s just how I view it.

With student project launches we never did shakedown flights because the loss of a scratch build rocket sustainer or booster stage was a serious risk to completing objectives on a time table. We simply used the airframes to max performance and they either passed or failed. My opinion.

Andrew,
That’s silly. A certification flight should be just another flight, but with more impulse. The value of a “shakedown flight” is that it allows you to test your checklist, practice your preparation, and double check yourself, in a less stressful situation and with a rocket that flies to less altitude, before your cert flight. Many people feel perfectly comfortable skipping a shakedown flight because they are experienced, but flying one introduces no more risk than any other flight.

 

[cbrarick]

I echo what Steve said. I also wonder if this type of attitude is part of what's caused so many student flight failures. If you are new or old to our hobby, each flight adds to your knowledge base. I've been L3 for a while and am still trying out new things - there's so many ways to do what we do. I can tell you now I don't do things the same way I did my L3
Even the big boys don't just wing it - look at the tests for Falcon9 or now the Hopper.....

 

[djs]

I had the same problem with a G78 last year at MWP, as well as a friend of mine who had the same issue earlier in the year with the same motor. To be honest, I didn't bother filing a MESS report or contacting CTI, because I know they won't do anything about it.

 

[SCEtoAux]

Yup I had the same issue with a G78 last April. Blew out the bottom of my Wildman Jr. I’m still waiting on a replacement motor and casing from them. Not terribly pleased.

I suppose if I get one, I’ll just trash it. At least I’ll get my 3 grain case replaced! I’m disappointed with their warranty service. I put in a warranty request with Aerotech this Monday and I’ve alreay heard back from them. Thinking of going all AT in the future.

David

 

[Steve Shannon]

I had the same problem with a G78 last year at MWP, as well as a friend of mine who had the same issue earlier in the year with the same motor. To be honest, I didn't bother filing a MESS report or contacting CTI, because I know they won't do anything about it.

The MESS reports have nothing to do with warranty replacements, but instead provide the certifying organizations (TMT, NAR S&T, CAR MCC) their only way of learning about common failure modes that may indicate a manufacturing problem. This is the main reason we have the MESS Report system. Please, please, please, always submit MESS reports to help other people if for no other reason.

 

[JARED S JAYNES]

Link to slowmo video of Cato, skip to 0.35 to see failure.

https://drive.google.com/file/d/1N8YSWJLpv0PsALZQCxQGC7Acq9D_P-Iw/view?usp=drivesdk

 

[JARED S JAYNES]

Kinda sad really this rocket had flown 10 times on 29mm g64 aerotech motors flawlessly one of my favorites, going to just send the remaining 3 g78 motors back to the dealer.

 

[Bat-mite]

I feel your pain.

 

[djs]

The MESS reports have nothing to do with warranty replacements, but instead provide the certifying organizations (TMT, NAR S&T, CAR MCC) their only way of learning about common failure modes that may indicate a manufacturing problem. This is the main reason we have the MESS Report system. Please, please, please, always submit MESS reports to help other people if for no other reason.

Hi Steve,

It's not that I expect the MESS reports to be a way to get a replacement, but I was always under the impression that the data was shared with the manufacturers so that they know about general problems.

I can fill one out, I guess the question is- what do the certifying organizations use as a determining factor for "common failure modes"? What do they do with this info if they determine there's an issue?

 

[Bat-mite]

Hi Steve,

It's not that I expect the MESS reports to be a way to get a replacement, but I was always under the impression that the data was shared with the manufacturers so that they know about general problems.

I can fill one out, I guess the question is- what do the certifying organizations use as a determining factor for "common failure modes"? What do they do with this info if they determine there's an issue?

Steve will give the official answer, but to my understanding, it can lead to banning certain motors, or even decertifying them, if there are numerous reported problems. Right now, VMAX motors with motor deployment are banned at NAR and TRA launches, and now CTI has stopped making them.

When the 38mm forward closure failures were reported, CTI sent all their dealers replacement forward closures to hand out with the motors.

 

[Charles_McG]

Kinda sad really this rocket had flown 10 times on 29mm g64 aerotech motors flawlessly one of my favorites, going to just send the remaining 3 g78 motors back to the dealer.

Can you share the production code on failed motors? Or on the the remainder?

 

[djs]

it can lead to banning certain motors, or even decertifying them, if there are numerous reported problems.

I'm just thinking about the infamous Estes E12 issues- which didn't seem to create any movement?

FYI- my failure was the back end was blown off- wasn't a forward closure issue.

 

[grouch]

Timely, I was just considering picking up a CTI 38mm case for funzies. I sold all of mine years ago for one reason or another. I think when it comes to CTI, I'll just stick with their 24 and 29mm motors. Don't trust those plastic nozzle closures on the 38s at all.

 

[jqavins]

Andrew,
That’s silly... flying one introduces no more risk than any other flight.

Not exactly true. On any flight, something can always go wrong. While it's true that the shakedown flight is not more dangerous any other single flight, it is an additional danger. Andrew's point, in short, is that if you go right to the cert flight then you need one success, but if you add a precert flight then you have to go two for two.

That said, I do plan to do a shakedown flight when I (eventually) get my L2 rocket ready.

 

[Steve Shannon]

Hi Steve,

It's not that I expect the MESS reports to be a way to get a replacement, but I was always under the impression that the data was shared with the manufacturers so that they know about general problems.

I can fill one out, I guess the question is- what do the certifying organizations use as a determining factor for "common failure modes"? What do they do with this info if they determine there's an issue?

Because they don’t know production numbers all they have to go on are trends. If they see an uptick in similar types of failures they notify the affected manufacturer. Occasionally they might see a spike that they must address by issuing some sort of ruling. The only one I was aware of was the requirement that Vmax motors be flown with electronics rather than relying on motor deployment.
Our manufacturers are usually the first to announce any kind of recalls or advisory.
It’s an imperfect solution.

 

[JARED S JAYNES]

Not exactly true. On any flight, something can always go wrong. While it's true that the shakedown flight is not more dangerous any other single flight, it is an additional danger. Andrew's point, in short, is that if you go right to the cert flight then you need one success, but if you add a precert flight then you have to go two for two.

That said, I do plan to do a shakedown flight when I (eventually) get my L2 rocket ready.

Most if not all my rockets are built with the intention of flying on non L1 motors I have a nice field by my house and can fly anytime the weather permits so the above comments are welcome but I build, fly, repeat almost daily. If the only time I launched was at club events I would have quit rocketry along time ago. I will take pics of the packaging with dates and post.

 

[dr wogz]

I wasn't nervous when I did my cert flights. Its a flight like any other. I've planned for it, and I know what to expect. I see people always getting nervous when thy do their cert flights, and to me, I don't understand it.

This is what I tell the few students who come up for their 'shakedown' and to those flying a cert flight:

"It's no different than any other flight. just a little louder and more flames"
"Every flight is a test"

As for Jared's original comment, this is a motor issue, and one that may need to be looked at for quality assurance, reliability, and consistency.

 

[Steve Shannon]

Steve will give the official answer, but to my understanding, it can lead to banning certain motors, or even decertifying them, if there are numerous reported problems. Right now, VMAX motors with motor deployment are banned at NAR and TRA launches, and now CTI has stopped making them.

When the 38mm forward closure failures were reported, CTI sent all their dealers replacement forward closures to hand out with the motors.

Actually I think you did a better job of explaining than I did!

 

[Bat-mite]

Actually I think you did a better job of explaining than I did!

Thanks.

 

[JARED S JAYNES]

Date stamp, all engines have same date

 

[crossfire]

Steve will give the official answer, but to my understanding, it can lead to banning certain motors, or even decertifying them, if there are numerous reported problems. Right now, VMAX motors with motor deployment are banned at NAR and TRA launches, and now CTI has stopped making them.

When the 38mm forward closure failures were reported, CTI sent all their dealers replacement forward closures to hand out with the motors.

There are a few other reasons why CTI has stopped making V Max motors. Not all because of forward closure problem.

 

[rharshberger]

I'm just thinking about the infamous Estes E12 issues- which didn't seem to create any movement?

FYI- my failure was the back end was blown off- wasn't a forward closure issue.

Whats the issue with E12's, the E9's were the ones famous for CATO's afaik?

 

[Steve Shannon]

I just received this from CTI:

Steve,

We have not received any reports of these incidents. It would really help if we did. This is the link.

https://www.pro38.com/pdfs/ProX_Warranty_Form_V1.0.pdf

Thanks.

Cesaroni Technology/Cesaroni Aerospace