mdross

My Feedback: (4)

Hi;

Out of the last 10 Estes C6-5 I've fired four of them have misfired meaning the rocket motor exploded out the top and bottom of the rocket tube. These motors were less than two weeks old and were taken out of the package and stored in a zip lock bag prior to launching. Is this normal or is there something I can do to prevent it?

Thanks
MDR

skyhawkjock

The misfires are a troubling indication of a loss of quality control at Estes. In the past I have launched hundreds for these motors without a single problem.

The first thing you should do is contact the National Association of Rocketry,(800-262-4872 or 319-373-8910) a national model rocket association and tell them what happened. They can check with their members to find out if this is an increasing problem. They may also want to investigate the problem themselves or they may suggest that you document what happened and return the damaged cases and the remaining motors to Estes. In the past these motors were assembled in the U.S., I do not know if that is still true.

John H.

scottrc

Keep the packages and the motors to get the lot numbers and date codes. A few years ago Estes let out a series of C and D engines with bad clay causing CATOS, which is what happened to you. They were having the motors made off shore and have since pulled production back their Colorado plant. This is also known as poopy clay and from time to time would show up in lots. If Estes had a large lot of bad clay, then NAR and NMRA should have a notice on their website. Or you may have bought old inventory.

MJD

My Feedback: (1)

Except that clay has absolutely nothing to do with blowing out the top of the motor. The clay cap on the ejection charge has no role in holding the motor together under chamber pressure, it is pneumatically pressed at low pressure to retain the ejection charge only, whereas the nozzle, propellant and delay are pressed hydraulically at high pressure. Scrape out the top clay and the motor still works as before, except some or most of the ejection charge will likely fall out. You could replace it with a wad of toilet paper for all it matters.

If this motor blew out the top and bottom it was another defect. Domestic production is not perfect either - bad runs or individual bad motors can occur. Four out of ten sounds like something was off for a whole shift or more. Several production factors could cause this.

Same for the C&D catos - sounds like BS designed to blame a third-party supplier versus the manufacturer. If the clay was bad they would puke nozzles and road flare out the nozzle end. Think about it - bad clay? Either the whole nozzle would fracture and puke, or the nozzle throat would erode away lowering chamber pressure, not raising it. How else would it cause a failure?

In this case it does not matter - these are clearly defective engines and warranty is due. This is not normal. 1 out of 100 maybe. 4 out of 10? No way.

46u

My Feedback: (3)

Never heard of any problems with the C6-5 but have heard of plenty of problems with then E12-4 and E12-6. If you are having that much problem you need to fill out a form with the NAR. Have you contacted ESTES? With the E12-4 and E12-6 it is taking out the whole rocket.