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 !Does not appear that the date code "a 07 14 17" was on the CATA list.
Yes, this suspected bad motor list...CATO List?
thanks for reposting that.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)."
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.....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.
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.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.....
E16s do not have a reputation for CATOing. But any motor can CATO:Estes is going to replace my E12's with a pack of E16's. Hopefully those work OK.
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.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.
That’s just it. If we knew how many catoed and how many total flew at a launch we’d have a better understanding.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.
Well um... I had a CATO from it a few days agoCurrently building a Super Big Bertha with plans to launch with on Estes E12 black powder engines. These engines are cheap (E12-4 cost $6) and readily available locally. But reading through the Rocketry Forum I came across the CATO list. The list was full of E12 black powder engines. Now I don't know if my original plans were misguided. I wanted a nice slow dramatic (affordable) launch on a 13 ounce rocket and the E12 was a good match. But are E12s reliable? Are they on the CATO list because more people can afford to use them, or because they are more likely to CATO?
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And your motor was modified as well, yes plugging is a modification.Well um... I had a CATO from it a few days ago
Updated List 2019-10-10Does not appear that the date code "a 07 14 17" was on the CATO list.