Are Estes E12 black powder motors unreliable?

Discussion in 'Propulsion' started by Underdog, Jul 30, 2019.

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  1. Sep 1, 2019 #31

    Underdog

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    With all this anicdotal evidence I may have to adjust my strategy. Maybe I fire the least expensive (easiest to replace) rockets on bp first.
    I ran bp (and E18w) sim on the Super Big Bertha (easy to replace/repair):
    flight  time.JPG
     
  2. Sep 1, 2019 #32

    Gerald

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    Just amazing that this question would be posted today, when just yesterday this all happened to me !
    Estes E12-4 a pack of 3 and two of them CATO !
     

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  3. Sep 1, 2019 #33

    Underdog

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    Does not appear that the date code "a 07 14 17" was on the CATO list.
     
    Last edited: Sep 1, 2019
  4. Sep 1, 2019 #34

    cwbullet

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    CATO List?
     
  5. Sep 1, 2019 #35

    Gerald

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    I think it can happen to any black powder engine, the engines get packed too hard (see photo of crack in casing) or the shipment gets dropped, or left out in the warehouse all summer, and winter and the hot, cold cycle causes problems. Or could be age of them from store. I just don't know. My Space Monkey V-2 $49 kit is all crap now !
     
  6. Sep 1, 2019 #36

    Underdog

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    Yes, this suspected bad motor list...

    shreadvector had an insightful response on the subject recently:
    He tested hundreds of D12-4 motors. And identified a weakening of the mechanical bond of the propellant to the casing wall as an issue;
    "When the flame front reaches the wall of the casing, it can propagate up the sides of the propellant grain - resulting in a HUGE overpressure. This will blow the grain out the top like a Roman Candle. It can also blow the nozzle as the pressure gets very high. IF the delay train is bonded really good, and the nozzle stays bonded good, then the excess pressure has nowhere to go and the casing splits (pretty loud). That would happen with some of the Estes BP E15 motors and some of the Year X C5 motors.

    Now, how does the flame get to the propellant wall "too soon" after ignition and what makes the propellant to casing bond fail?
    Temperature Cycling. The cardboard and propellant expand when they get hot (sitting in a hot garage/car/USPS truck/etc.). The propellant is nice and solid and it expands in length and diameter. It stretches the cardboard casing which is made of wood fibers with some glue. When the motor cools, the propellant returns to it's original size, but the casing may not shrink back at the same rate or it may stay slightly stretched. This can compromise the propellant to casing mechanical bond, which allows the flame to propagate up the inside.

    The nozzle to propellant interface also expands at different rates, so there is a small crack that forms around the outside of the nozzle to propellant interface. This allows the flame to reach the wall shortly after ignition and before it normally would get there (at the time of peak thrust at the top of the thrust-time curve)."
    https://www.rocketryforum.com/threads/suspected-bad-motor-list.150501/page-4
     

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    Last edited: Sep 1, 2019
  7. Sep 1, 2019 #37

    BRS Hobbies

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    My brother at NARAM-61 had at least one E12-4 engine failure. One didn't have any ejection charge. The other one didn't pop the nose cone so it was either a really weak ejection charge or it might have been packed too tight with dog barf. Either way, two rockets bit the dust which was a Broadsword and a BIg Daddy.
     
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  8. Sep 1, 2019 #38

    cwbullet

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    Another E12 Cato. Unsure of lot number.
     
  9. Sep 1, 2019 #39

    cwbullet

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    04 02 12 Cato . E12
     
  10. Sep 2, 2019 #40

    shreadvector

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    thanks for reposting that.

    D12-5 (there is no D12-4)

    And for all the people posting about dropping the motors, that does NOTHING. You would need to lay them flat on concrete and smash them with a hammer to get the grain to crack from shock. If a no hammered motor grain has a crack, it would have come from a strange manufacturing defect, such a the centerbore "pintle" malformed creating a sharp point that cracks as the motor cures (they are pressed moist and dry out or "cure"). It could also come from a bit of debris in the propellant, like a stray bit of cardboard casing - but that is very rare from Estes. Very, very, very rare.
     
  11. Sep 2, 2019 #41

    shreadvector

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    Big Daddy was probably not the motor at all. They have a history of not deploying. The nose started to pop off, and stops as soon as the HUGE bevelled area is free and all the ejection gas can leak out. Many people fill in the bevelled area. Usually after crashing one.....
     
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  12. Sep 2, 2019 #42

    Underdog

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    Some folks make a modification to Big Daddy's nose cone. Attaching a bulkhead plate to the bottom of the nose cone that a slips in the airframe.
    rharshberger posted these links....
    http://www.rocketryforum.com/showthread.php?67909-My-First-Big-Daddy!-My-First-Lawn-Dart!&p=736301
    http://www.rocketryforum.com/showth...ame-a-Lawn-Dart&highlight=Big+Daddy+Nose+Cone
    http://www.rocketryforum.com/showthread.php?118211-big-daddy-recovery-problems&highlight=Big+Daddy+Nose+Cone
     
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  13. Sep 2, 2019 #43

    BDB

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    Sorry about the outcome...but great pics!!!
     
  14. Sep 2, 2019 #44

    Underdog

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    What camera are you using to get shots like this?
     
  15. Oct 8, 2019 #45

    deangelo54

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    When you search on E12 CATO you get a lot of hits. I started a thread recently in reference to 3 out of 5 engines CATOing. https://www.rocketryforum.com/threads/e12-4-catos.155151/

    Some people seem offended that I mentioned the problem I was having with the engines. Especially the cupcake guy. I think he took it personally. But after searching the forum I see that a number of people have had issues with E12's. Estes does not have any in stock at this time. I don't know if that means anything.

    Estes is going to replace my E12's with a pack of E16's. Hopefully those work OK. I must say that Estes does provide good customer service and stands by their products. They were willing to do more than I thought they should so I only asked for replacement engines. I ended up repairing the rocket good as new.
     
  16. Oct 8, 2019 #46

    Red7Fifty

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    I returned mine to HL, after matching up the same lot number of other reported CATO....I spend too much time on paint jobs... Will stick to D12-3 BP, and E and F Reloads.
     
  17. Oct 8, 2019 #47

    kuririn

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  18. Oct 8, 2019 #48

    deangelo54

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    From my experience and from what I see on the Rocketry Forum I must respectfully disagree. Enough of us that put a lot of time building and painting our rockets are not willing to take a chance.

    Feel free to use them and please share your experiences with us. If you achieve good results I will give them a chance on a rocket I’m willing to risk.
     
  19. Oct 8, 2019 #49

    kuririn

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    Reread my post. I'm talking about E16s, not E12s. In other words I'm in agreement with you.
     
  20. Oct 8, 2019 #50

    Wallace

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    Believe it or not I've had better luck with E 16s and E 12s than I've had with their F motors. All stored indoors/climate controlled in a sealed box. Who really knows how they were cared for before they fell into your hands?
     
  21. Oct 9, 2019 #51

    aerostadt

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    I was able to get an Estes black powder18 mm motor to have some kind of thrust anomaly back in 1965 from just one severe temperature cycling as part of a science project. Outside of this event I have never seen an 18 mm motor fail. ( The study won the Estes science project contest that year.) I put the motor in a plastic bag in a dry ice/alcohol mixture. I took the motor out of the bag and held a bulb thermometer next to the motor and placed the motor in a RDC recording static test stand. I figured the motor was about -10 Deg.F when it fired. The motor fired nominally for about a fraction of second and then the thrust went off-scale. When I repeated the test above -10 Deg.F., the failure did not happen. However, I did not have a large sample size.

    At the time I proposed that the extreme temperature difference between the flame front and the in-depth cold propellant caused propellant cracking, however, I am open to the idea of case/propellant de-bonding as put forth by Shreadvector. In either scenario the increased burning surface area will cause an anomaly. Black powder motors have an infamous failure history going back to at least the 1930's with Max Valier's Opel Rak rocket cars in Germany.
     

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  22. Oct 9, 2019 #52

    samb

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    You may already know this but you’re talking about motors with different diameters. E12s are 24mm and E16s are 29mm.
     
  23. Oct 9, 2019 #53

    lakeroadster

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    Yes.... E9's too
     
  24. Oct 9, 2019 #54

    deangelo54

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    I was thinking that I never had a CATO from an 18mm motor. I used to use E9's a lot and only had one CATO on me. I had two D12's CATO but I have to qualify that. They were very old and given to me by someone that had them since his youth, stored in his basement. We can give Estes a pass on those.

    Seems like some people get very defensive when you post problems with a certain engine type. Like we are insulting their child. I appreciate people sharing their experiences with rocketry products be it good or bad.

    In the past there were adults that made negative comments about my older son when he was a little kid. Now he is a college graduate making more money than they ever will. No CATOs from that kid. BTW he is the one that got me into rocketry when he was 8 years old.
    I'm not sure what that has to do with E12-4 engines but it makes for a good story. Never give up on your kids. They develop at their own pace.
     
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  25. Oct 9, 2019 #55

    aerostadt

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    This is good to know. I had big hopes for the return of my Double Shuttle earlier this year with two flights on E12-4's that hit the ground without separating. The "up" part was alright. I am now wondering if the delay charges were late or the ejection charges were weak. The internal pressurization tubing may now be compromised from the hard landings. In any case I am thinking of ground testing with ejection charges before launching again. If the Double Shuttle does pass a ground test, I will think twice before using E12's again.
     
  26. Oct 9, 2019 #56

    JohnCoker

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    It's hard to answer a question like that. We know that it fails (there are over 100 reported on motorcato.org). However, we don't know how many have been flown successfully.

    There have been reports lately of them failing, so it "feels" like they are unreliable, but a confident answer to that question is hard to give.
     
  27. Oct 9, 2019 #57

    Steve Shannon

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    That’s just it. If we knew how many catoed and how many total flew at a launch we’d have a better understanding.
     
  28. Oct 9, 2019 #58

    Yukon@K-9 Rocket Tech

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    Well um... I had a CATO from it a few days ago
    https://www.rocketryforum.com/threads/tvc-hold-down-test-cato.155319/
     
  29. Oct 9, 2019 #59

    rharshberger

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  30. Oct 10, 2019 #60

    lakeroadster

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    Updated List 2019-10-10

    Suspected Bad Motor List 2019-10-10 6-57 AM.jpg
     

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