- Jan 29, 2009
- Reaction score
Does anyone know how many grams of black powder is used for ejection charges in Estes 13mm, 18mm & 24mm motors?
As an aside, a few years ago I had a couple of 1/2A motors where the top clay cap was too thick, or maybe there wasn't enough BP, and the ejection charge vented though the bottom of the motor causing a deployment failure, closely followed by a lawn dart.
Bring back the days of the paper cap!
..I have some older AT single use 29mm motors where the paper caps adhesive has degenerated and there are BP particles in the package..Will have to remove the cap and refill the ejection charge bay if I intend to use those motors..
I'm not sure either, but I can imagine that it might be informative to know approximately how much "pop" they are packing these days. There has been a lot of talk in the past couple of years about the engines that Estes makes now having "shotgun" ejection charges. I know that there are BP calculators on the web that help HPR fliers figure out how much black powder to put into their ejection canisters for DD. If we knew how much BP Estes puts under the clay cap, then perhaps someone could use such a tool to figure out how much pressure it really does generate in a given airframe....
I am not sure why you are asking. ...
I have not had problems with "shotgun" ejection from any motors. In fact the only problems I've had is weak ejection. There seems to be a lot of reasons for this. One is nozzle erosion. I had one motor that ejected the nose cone, but not the chute after the C motor flew to an altitude I usually get on an A. When I got it back, the nozzle was over a 1/4" in diameter.
Discussing altering engines in any way violates the rules.
This thread should be immediately removed by the moderators, and is being reported.
Certainly, altering motors is a violation of the safety code. Gluing down the ejection charge to make a C6-plugged is a slippery slope. That is a tough one. How about a known failure? Let's say a C6-5 in a long rocket like a clone of an Andromeda. There are many cases where the ejection charge has not been enough to pop the cone off. Is it a violation to put a little more BP on top of the clay (or paper in the case of an old historic motor that we are legally using in the NAR motor testing case)? Is that a problem? I have a clone kit and I surely have heard that the standard charge has not been enough to pop the cone. Should I hold my breath and pray that maybe it happens? Or, should I "Heaven forbid!!" alter the motor by taping in another little bit of BP to get it off? Sometimes, I think people get a little hot to trot over reporting and such. Is this one of those cases?
They already revealed it in a patent application, so it is not proprietary any more. The current amount of .5 grams in 18mm engines has been fairly constant over the years. It is the same we used in the 60's. Remember, all black powder is not the same.It might be proprietary information that they don't want to reveal.
Personally, I don't see adding a little of your own BP in a rocket is altering the motor. You're just adding some additional BP and locating it where there will be the least delay between the motors normal ejection and the burning of your extra BP.
If I recall, there was a discussion of this on TRF 1.0 and the result was that this was sometimes done during NAR contests and was not considered to be altering a certified motor and therefore acceptable under contest rules. Not everyone agreed that this was safe and appropriate for rocket contests.
One of the avid contest folk could say for sure whether I am recalling this correctly.
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