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  #21  
Old 02-17-2012, 01:03 AM
luke strawwalker's Avatar
luke strawwalker luke strawwalker is offline
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Originally Posted by closet astronaut View Post
Hey Luke


One more question. I have a couple of E engines that have been packed away in a box up in my attic for about ten years, I'm curious as to how useable they might still be.

Any advice will be greatly appreciated.
Forgot your second question...

You said they were "E" motors and have been in the attic a long time... and the motors are about ten years old.

First, look at the motors... if they are an "E15-0,3,5,7" (or whatever... the "E15" is the important part) DO NOT USE THEM IN YOUR ROCKET! The E15's were NOTORIOUS for overpressurizing the paper case and catoing, (going BOOM!) Estes quit producing them after a VERY short time and a year or two later came out with a "de-rated" version called the "E9", which is the current E motor offered by Estes (though a somewhat uprated "E12" is soon to be released by Estes... hope they have a better result than the E15!) You CAN fly them if you want, but I wouldn't fly them in anything but a "junk rocket" or one made from cardstock or something (homemade) so that if they DO blow up, you haven't lost anything important (like you're shiny new QCC Explorer kit!) Or, conversely, you can keep them for posterity... there ARE folks who collect old motors that are no longer produced (and some even fly them!)

Second, what are conditions in your attic typically like?? Is it heated/air conditioned?? What's the climate like where you live?? Attics can get up to 100 degrees in the summer and well below freezing in winter, depending on the climate where you live, if they're unheated/un-air conditioned. This temperature cycling is VERY BAD for rocket motors, ESPECIALLY for the larger 24 mm diameter motors. What happens is, the paper casings and the pressed black powder propellant slug expand and contract at different rates as the temps fluctuate... when coupled with LARGE extremes of temperature (such as found in a blazing hot in summer/freezing in winter attic or garage or storage building or whatever) this can cause the propellant slug to actually separate a tiny bit from the paper casing, or to develop a hairline crack. When ignited, the propellant slug will start burning and will find ANY crack or gap (since the motor is pressurized at about 100 PSI or so) and IMMEDIATELY start to burn on the exposed surface of the black powder slug, which it is NOT meant to do... this causes TOO MUCH hot exhaust gas to be produced, which then cannot all get out of the nozzle fast enough, raising the pressure inside the paper casing to the bursting point-- the motor goes "BANG!" The effect CAN happen even with 18 mm motors, so basically ANY motor stored where it's exposed to extreme temperature differences is kind of risky to fly in a good rocket... I've flown some 20 year old motors that I had stored in a tacklebox under the stairs at my Grandmother's house, which is itself un-air conditioned in summer (which means in this Texas heat temps in the house in the high 90's to near 100 degrees) and heated only by propane room heaters (Dearborn heaters), and OCCASSIONALLY (when we were out of town) exposed to pretty cold conditions in the house of 40-50 degrees in winter (when we left only one small heater on to keep the pipes from freezing while we were gone). I haven't had any cato's BUT I mostly fly them in older rockets just to make sure...

I wouldn't throw them away... If nothing else, securely tape them to a long wooden dowel rod and make jumbo size bottle rockets out of them... either way they'll produce a good show...

Later! OL JR
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  #22  
Old 02-17-2012, 05:57 PM
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Quote:

Estes came out with a 24mm diameter "C" motor called a "C11-0,3,5,7" (choose one last number depending on the rocket and conditions..

OK...this explains it. The C motor this mod says it can use is 24mm, it does call for a C 11-3. The 6-5 is 18mm...unuseable.

As for the old motors, my bad...I just went and checked them and they're actually D 12-3's and in excellent condition. I live in Florida so temps in the attic are 100 in the summer and SELDOM below freezing in the winter.

That all makes since. Thanks for the education.
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  #23  
Old 02-17-2012, 11:53 PM
luke strawwalker's Avatar
luke strawwalker luke strawwalker is offline
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Quote:
Originally Posted by closet astronaut View Post
Quote:

Estes came out with a 24mm diameter "C" motor called a "C11-0,3,5,7" (choose one last number depending on the rocket and conditions..

OK...this explains it. The C motor this mod says it can use is 24mm, it does call for a C 11-3. The 6-5 is 18mm...unuseable.

As for the old motors, my bad...I just went and checked them and they're actually D 12-3's and in excellent condition. I live in Florida so temps in the attic are 100 in the summer and SELDOM below freezing in the winter.

That all makes since. Thanks for the education.
You're welcome! Later! OL JR
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