ANOTHER CATO...

Discussion in 'Propulsion' started by JARED S JAYNES, Mar 28, 2019.

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  1. Apr 11, 2019 #91

    DavidMcCann

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    If it's just a confidence boost... then I'm right and it's unnecessary. I maintain unless you're testing a specific thing, a check flight is a waste of time. You're changing the CG/CP, so it's not a stability check. You're not pushing it as hard, so it's not a stress test. If you're gaining experience doing X or Y, it's not a test of the bird, it's a test of you.

    Checkflights are dumb...and no one has yet provided a reason to do one that pertains to the actual rocket.
     
  2. Apr 11, 2019 #92

    Steve Shannon

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    Nobody claimed it only pertains to the actual rocket. Rockets don’t fail nearly as often as rocketeers.
    But if the rocket does fail with a lower impulse motor it almost certainly would have failed during the higher impulse flight. Also, with a lower impulse motor it may be possible to better observe the entire flight and learn from it something that helps the certification flight succeed. But if all it does is make a flyer feel more confident that’s okay too. It’s okay to fly more rockets.
     
    Last edited: Apr 11, 2019
  3. Apr 11, 2019 #93

    Glasspack

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    Steve that sucks...……… My friend and I were just talking about CTI Pro29 starter set vs Aerotech RMS.
    I have both Pro38 and Pro29 although haven't used the 29 case yet. My friend was leaning towards the CTI Pro29.....

    I should show him this...….
     
  4. Apr 11, 2019 #94

    Charles_McG

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    Don't be hasty. All motor systems fail occasionally. I had an Estes C11 shoot a fuel grain through the rocket a couple years ago. But I still want more. A single Pro29 3G Vmax report doesn't fall into the same circle as the 5-6 Pro38 1G Blue cluster we've been talking about. The statistician in me knows that clusters can happen and mean nothing. The modeler in me who's doing the repairs will ask for a nice G79 Smokey as a replacement.

    Still, that's a lot of 1G Blues in a short time.
     
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  5. Apr 11, 2019 #95

    Mike Haberer

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    I think there are two factors to consider. First, there is a reason you have to have a cert rocket examined by an experienced, certified rocketeer. A good reviewer will ideally catch deficiencies that would pose problems or be hazardous. That said, you could have a bad reviewer or someone too accommodating. In that case a test launch is a good idea.

    Second, it depends on the experience of the builder. I've been building LPR and MPR for over 50 years and am going for my L1 this year. I've had my share of Catos in 50 years so I tend to overbuild. As long as I have a solid Rocksim or Openrocket sim I'm very confident that I can launch my L1 on it's initial flight.

    So, like anything in life, it depends. I would like to see clubs have their own set of rigorous cert review standards which include a verified sim (e.g., verify the weight, CP and CG).
     
  6. Apr 11, 2019 #96

    djs

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    You mistyped "Vmax" there...

    G79 has a low initial thrust..I'd go for the G115WT instead.

    Clusters of events can be deceiving when it comes to "identifying a pattern", but it definitely seems like more than just reporting bias.

    Truthfully- I think this would be less of an issue if CTI was more "present". @SCEtoAux had a CATO on a G78 almost a year ago, and hasn't heard squat from them.
     
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  7. Apr 11, 2019 #97

    SCEtoAux

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    Date code on mine was 09/27/2017 btw.
     
  8. Apr 12, 2019 #98

    pondman

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    Your opinion David. Again, if the flyer wants to do it then fine; it is a personal thing. I didn't do it for my L3 and I am not going to recommend or require an L3 flyer to do it.
     
  9. Apr 13, 2019 #99

    DavidMcCann

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    Presented of course as my opinion. I'm not saying people shouldn't do them. Simply that they should realize it's not required/standard practice/needed and actually sit down and consider what precisely they are attempting to test, and consider the risk vs benefits. There seems to be a trend of " gotta check flight stuff" and it being done with no supporting reasoning or process. Apollo had little joe II , and saturn I, IB, and V. If theres reason, by all means it makes sense.
     
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  10. Apr 13, 2019 #100

    Steve Shannon

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    I didn’t intentionally do it for my L3 cert flight, but when my shear pins sheared at apogee and my main came out at apogee during my first attempt, that flight literally became my shakedown flight.
    I learned a couple of things:
    1. My shear pins were inadequate,
    2. Although I had powered up my redundant electronics, I had forgotten to remove the disarming pin (G-Wiz altimeter).
    I agree that shakedown flights shouldn’t be required, but smart flyers may wish to do a dry run to see what they may have forgotten, what steps must happen in a different order, which switch cannot be reached when the rocket is on the rail, etc. It’s amazing how many flyers get a rocket vertical on the rail only to realize they cannot reach a switch and they didn’t bring a ladder.
     
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  11. Apr 14, 2019 #101

    rharshberger

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    Just witnessed another CTI 38mm 1-grain motor CATO, this time it was a G69 Skid. The nozzle end blew out taking the Aeropack retainer with, and post mortem of the motor showed that the rear closure had been blown off, and the threaded section of the casing was belled slightly outward, most pieces were recovered and the flier will file a MESS report and see about warranty claim. The igniter was a CTI igniter, the case was either a 2 or 3-grain with the appropriate spacers. The I know the igniter was factory as I did the RSO on the rocket prior to the attempted launch. The launch was at TriCities Rocketeers today and the flier was an experience HPR flier, Dave has had quite a few successful flights with us in the past. Beyond the Aeropack being ripped off, and the upper rail button being dislodged, the rocket was remarkably lightly damaged.
     
    Last edited: Apr 15, 2019
  12. Apr 14, 2019 #102

    Banzai88

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    Have there been enough of these yet to have any kind of date code correlation or is this just normal variation?
     
  13. Apr 14, 2019 #103

    Steve Shannon

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    Thanks Rich. I’m glad you paid such close attention. I’m also glad the flyer is filing a MESS report. I wish I could be more helpful, but nobody at CTI has responded to me on this subject.
     
  14. Apr 15, 2019 #104

    djs

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    Thanks for following up on this Steve. One thing that I've noticed is that almost everyone i know (including myself) who's flown a G78BS needed to try with several ignitors before it lit. Part of me wonders if this has caused some sort of shock on the grains, even if the motors never lit.
     
  15. Apr 15, 2019 #105

    Steve Shannon

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    Interesting. I don’t know. The BP pellet is there to facilitate immediate and easy ignition using an electric match. Were you using igniters or electric matches for your repeated attempts?
     
  16. Apr 15, 2019 #106

    djs

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    Can't speak to other people, but I've used both.
     
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  17. Apr 15, 2019 #107

    Charles_McG

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    In my misfires, I also used both. I think the root cause of my misfires was inserting the ematch or igniter too far into the motor. The starter pellet on the G78 is drilled, and when I opened up the motor to look at it (after the misfires and before the CATO) the soot markings were on the grain face above the starter pellet. I had drilled the delay, and I think I had the misfortune of threading the ematch/igniter all the way up, through the starter pellet and into the delay.

    So, I plan on changing my prep practices. I plan on threading the ematch up the motor before putting it in the case, so I can see (and mark) how far up it should go. Then inserting to that mark (and no further) when out on the pad. I had been doing it all by feel.
     
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  18. Apr 15, 2019 #108

    Steve Shannon

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    I think that’s a good process improvement and an interesting analysis.
     
  19. Apr 15, 2019 #109

    Faroutspacenut

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    Rich, could this have been me you're referring to? Saturday at Lucerne? (EDIT: had I read your post closely I would have seen this was a different incident - similarities are uncanny) The same thing happened to me w/ a Pro38 G69 Skidmark. It was in a 1 grain case - no spacer. I took 3 seconds off the delay, other than that, everything seemed to be by the numbers. Rear closure/nozzle blew out, taking my aeropack retainer with it (ripped it right off the motor tube). Found the un-burnt grain about 6 feet from the pad. The motor case was up inside the rocket body tube. Here are a few photos attached (sorry I realize now that I didn't get the important stuff on the motor packaging).

    My question is about the warranty. What does CTI typically replace (if anything)? Just the motor? Motor and case? (I haven't checked the threads carefully but it seems like the case is still usable). Is there any compensation for the rocket? I think it can be repaired, but I'm out an aeropack retainer and them ain't exactly cheap...

    Finally, do I have to go through the vendor I actually purchased it from, or can I use my local vendor? I'm pretty sure I bought this at last year's LDRS, but not sure which vendor...


    UNADJUSTEDNONRAW_thumb_160b2.jpg UNADJUSTEDNONRAW_thumb_160b3.jpg UNADJUSTEDNONRAW_thumb_160b4.jpg
     

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    Last edited: Apr 15, 2019
  20. Apr 15, 2019 #110

    djs

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    Normally they would replace the case + motor (assuming of course, you can get a response from them). I don't think you'd get anything else on the rocket replaced.

    Note- I've never reused anything from a case after a cato, as it may look ok, but be weakened in a way you can't see.
     
  21. Apr 15, 2019 #111

    Faroutspacenut

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    That's a very good point. If they're willing to replace it (fingers crossed) I'll certainly "retire" the other one. Should prob. do that anyway...
     
  22. Apr 15, 2019 #112

    Ez2cDave

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    I use slivers of Blue Thunder, CA'd to the E-Match wires, just below the head . . . Lights every time !
     
  23. Apr 15, 2019 #113

    Ez2cDave

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    How "convenient" for CTI . . .
     
  24. Apr 15, 2019 #114

    Steve Shannon

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    While that helps with many composite motors, the black powder pellet in the CTI Pro38 motors should not require that. I’d be especially concerned about adding a pressure spike in a small one grain case.
     
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  25. Apr 15, 2019 #115

    Banzai88

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    I discussed this very thing face to face recently with 2 national level dealers and one by email that 38mm and 54mm warranty claims that they've had in for over a year are STILL outstanding on motors and cases.....not looking good for the home team.
     
  26. Apr 15, 2019 #116

    WILDMANRS

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    This issue has been investigated and solved .
    There is a public statement coming very soon .
     
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  27. Apr 15, 2019 #117

    djs

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    Thanks for the update Tim!
     
  28. Apr 16, 2019 #118

    WILDMANRS

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    Pro38 BULLETIN 1G Failures April 15, 2019

    It has been brought to the attention of Cesaroni Technology Inc over the past week that there has been a high failure rate on Pro38-1G Blue (141G78-15A). We have been looking into this matter and have verified the anomaly which stems from an over-pressurization at ignition resulting in nozzle blowouts.

    Upon investigation it appears the cause is primarily due to a significantly faster burning ignition pellet. Furthermore, CTI has discovered it stretches beyond just the 141G78-15A and this issue has implications throughout the entire Pro38-1Grain lineup.

    These pellets have not been manufactured in-house at CTI for the over three years, and have since been outsourced to a 3rd party company. Unfortunately it appears the most recent lot/batch of Pro38 pellets we received in 2018 have a higher burn rate then nominal. Due to this, our recent Pro38 reloads have been experiencing an elevated pressure during the initial ignition transient as the grain is being ignited. Since the Pro38-1G motors use the smallest throat diameters within this lineup they are proportionately the most drastically affected by this increase.

    It appears these first pellets may have been introduced into circulation as early as May 2018. We have been in contact with the manufacturer of the pellets and they have identified the issue. Going forward all new pellets will have this issue resolved so that any reloads manufactured by CTI from Apr 12, 2019 onward will be fine.

    However to address all the affected reloads currently in circulation CTI has developed a small “in-field” modification to reduce this ignition pressure spike. This modification can be done easily by the end-user during preparation for launch and simply involves trimming the pellet to a smaller size. CTI has successful conducted an entire series of motor testing on all the Pro38-1G lineup with this modification applied. For verification CTI is in the process of formalizing this testing information/data and will be distributing it in the coming days.

    A copy of the in-field modification instructions can be found on our website and will be distributed to the dealers for public distribution. We also hope that if any end-user of these affected reloads does not feel comfortable conducting this modification themselves they can seek the assistance of any ProX dealers at the launch site during preparation for flight.

    CTI recommends that ALL Pro38-1G reloads within the affected date range have this modification done before flight.

    As reassurance, we recommend adopting this in-field modification to any reloads purchased back to Apr 2017. Please note this is NOT the propellant manufacturing date, but the date when reloads where shipped from our facility. The “propellant date” stamped on the outside of the reload is independent of the pellet manufacturing date

    2561 Stouffville Rd Gormley, ON, L0H 1G0 Telephone: 905-887-2370 Fax: 905-887-2375


    (for which there is no identification). Additionally, please note that different pellets are used within the Pro24, Pro29, & Pro54, and therefore this issue is exclusive to the Pro38 lineup.

    Furthermore although no failures have been reported to date regarding the Pro38-2G lineup, CTI is also recommending that these changes be applied to some of the Pro38-2Grain lineup for due-diligences. CTI has conducted several motor tests of various reloads all of which have been successful, but the data did show a heightened ignition pressure as well. Therefore this modification should be applied to the smaller nozzle size reload which include;  Blue Streak (276H152-15A)  Classic (266H125-12A)  Red Lightning (261H120-14A)  Skidmark (232H123-14A)  White (269H110-14A)

    Dealers Inventory

    To address the dealers current inventory of motors (Pro38 1G & 2G) that are affected but not yet sold to the general public CTI is asking all dealers to place a label on the affected reload packaging identifying it as requiring the “in-field modification”. CTI can supply any dealers with either an electronic copy of label details for immediate printing or CTI can ship the label direct for them to be applied (at our cost). Please inform your CTI representative of which method works best for your time/schedule.

    In addition, all future Pro38-1G & Pro38-2G manufactured by CTI after Apr 12, 2019 will have an additional label placed on the packaging identifying it as not requiring the in-field modification. This will be done in an effort to reduce confusion between future reloads. We will keep this identification process in place for the next 3 years (or longer if deemed necessary).

    We sincerely apologize for any inconvenience or hobby rockets that have been affected by this issue. For any hobby rocket failures in flight that occurred as a result of this forward closure issue please follow the regular warranty process by contacting your ProX dealer. The dealers will then provide all the details to CTI so we can ensure you receive the appropriate warranty.

    Sincerely,

    Cesaroni Technology Inc

    2561 Stouffville Road Gormley, Ontario L0H 1G0 Phone: 905-887-2370 Fax: 905-887-2375 Web Site: www.cesaroni.net www.pro38.com
     
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  29. Apr 16, 2019 #119

    WILDMANRS

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  30. Apr 16, 2019 #120

    Charles_McG

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    Thanks Tim.
     

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