18/20 RMS Question here.



AeroTech will extract it from you anyway.
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Jerry Irvine, Box 1242, Claremont, California 91711 USA
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On Sun, 12 Jun 2005 13:27:21 -0700, David Erbas-White

This has been my experience too.
On the HP reloads, the disc sticking depends on weather you have grease or BP on the surface the disc has to stick to or not. Obviously if you are in the not catagory the disc sticks. I almost always need to use masking tape.
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Phil Stein wrote:

I'm always very careful about making sure that no grease gets on the end of the closure, and 'tapping' it to get any of the grains of BP off the face, before putting the disc on. I also dry my hands carefully before handling the discs, and try to handle them just be the edges. Out of curiousity, I have occasionally touched the face of the discs to try and see how good the adhesive is. The discs just don't seem to have much (or very good) adhesive. I'm sure they're some kind of standard 'label', but I'm relatively sure they use the 'temporary' adhesive instead of a 'permanent' adhesive. In other words, I know that some address labels made by Avery are removable, and some aren't. This adhesives seems to be in the "aren't" category <G>.
David Erbas-White
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On Sun, 12 Jun 2005 15:43:41 -0700, David Erbas-White

I think I'm being careful - even when it doesn't stick. A piece of tape is good insurance.
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Phil Stein wrote:

I probably should have been clearer -- I ALWAYS put the masking tape on top of the white tape disc. I simply find that putting the disc on first (instead of using JUST masking tape) helps to keep the top end sealed.
David Erbas-White
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On Sun, 12 Jun 2005 17:00:27 -0700, David Erbas-White

The best method that I've discovered is to place the disc in position, then run 3/4" or 1" masking tape *around* the ejection well, forming a tape cylinder that extends half on and half off the ejection well, and then fold it over onto the tape disc, like you're closing up a roll of coins.
Easy to do, and pretty much guarantees that your ejection charge doesn't go anywhere until it's ignited. Also, screwing up and failing to clean off a small bit of grease on the ejection well doesn't keep it from sticking, as the tape sticks fine to itself, especially if you wrap it tightly.
Over-the-top masking tape reuires that the sides of the well be perfectly grease-free, otherwise the tape will come off. The wrap method doesn't have that particular failure mode. I've used motors I prepped several months before with no problems, and no spilled ejection charges, despite rattling around in a plastic bin in the back of my truck for the intervening time.
- Rick "tape sticks well to tape" Dickinson
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I put the little paper disk on and then tape it.....always.
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Joe Michel
NAR 82797 L2
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Hi,
Whaddya you use. A hammer to smash the thing in? In the reload kit of the D12-7W I have, there is at least 1.6cm of distance between the end of the alleged "collar" and the beginning or the ejection charge cup. From the end of the so called "cup" to where I can see BP is 2.5cm. That is way the heck too far for the smoke delay to ignite a charge through the paper. Tell me one thing. Am I supposed to smash, bash, screwup, hack, hit with a hammer and physically pour the BP into the end bulkhead of the 18/20 engine and tape it up? If so, I will find a way to get the galdanged powder out and Aerotech be damned.
Best regards, Kurt Savegnago
Phil Stein wrote:

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David Erbas-White wrote: I really wish the tape discs were

If you buy cards from a Hallmark store, they'll usually give you some "gold crown" stickers. Sometimes they'll give you some extras if you ask for them. They're supposed to be used as a fancy "seal" on the envelope but I think most people just throw them away. Anyway, they're bigger than the AT stickers, and have better adhesive. That's what I've been using for the past few years.
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David Erbas-White wrote:

Hey,
That is good advice but I still don't understand. I find I have a red cap with a cylindrical connector that is 1 to 1.5cm long. Am I supposed to rip off the cylindrical connector and pour the black powder into the well of the 18/20 engine amd then tape it over? After reading all the advice here, I'd like to stick a piece of APCP up Aerotechs' arse for their lousy, unclear instructions. They have all the O ring things right and easily understandable for me but the danged ejection charge is really funked up. I had a cool launch but I think the ejection never occurred as I just topped the ejection charge "cup" over the end of the engine. I never did find the "so-called" end cap for the igniter. Screw them as I just use tape with good results. Cripes there was over 1 to 1.5cm between the cup and the well of the engine and I didn't even know there was a paper or whatever barrier. Call me ignorant and I will eventually figure it out but the instructions suck and you can forward that to Aerotech.
Best regards, Kurt Savegnago
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David Erbas-White wrote:

Hi,
I did that and there was still 2cm from the cuff of the plastic cup to the ejection charge powder. Am I supposed to fracture, bend, scrape, screw up, macerate and pour the raw BP into the well? If that is the case, then I will do it with the replacement casing I have ordered. Even though I lost the model and it was getting to end of life, it was still a cool flight. Am I bitter? Just a little bit, although if AT sent me a replacement case that would be nice. (Although that wouldn't happen in a thousand years.)
Best regards, Kurt Savegnago
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Go to this page:
http://www.aerotech-rocketry.com/customersite/theatre/index-RMS29-40.html
Click on the ejection charge video. If you still don't understand, post your SPECIFIC question here after viewing the video.
Note: while this is for the 29mm hobby case, the 18mm ejection charge assembly should work the same way.
David Erbas-White
Kurt wrote:

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[areo-tech ] don't have to have custom dies made..... hence the small gap when installed .....nuff said about that.......now the solution to your problem, which is really all you care about anyway.......having been in a similar situation here is what to do....get some common everyday wooden toothpicks......make sure the hole is clear......don't add the ejection powder until right before you fly ......you can pre-assemble the motor but don't add the ejection charge.....now right before you head to the pad ....seperate the two caps...pour a very small amount of powder into the ejection well take the toothpick and poke it [the powder into the hole ,this will make sure it comes into contact with the delay grain,insuring the ejection charge ignites] ......now slip the red cap, with the remainder of the powder over the well as instructed ......at this point, under no cicumstances turn the motor upside down.....install said motor in rocket by sliding rocket over motor ....this keeps the ejection charge in contact with the delay grain .....if you do tip it over the powder can "shift'' out of position due to the gap space in the cap and may not go back into contact with the de-lay due to the small size of hole.......this is not a problem with larger motors due to the larger hole size in the casing .....with such a small hole in the hobby size motors the powder grain size is such that it can jam together and not settle back into the hole .....kinda like when those 3 minute egg timers with the sand in them do.....you have probably seen that.... the sand clots together and you have to tap it,to get it flowing again... it sounds more difficult than it really is.....since using this technique, I haven't had a ejection charge fail to lite.....lighting on time though ,is another matter, which I'm sure, my brother rocketeers can relate to .......... just remember.....once the ejection charge is in....don't invert the motor or the rocket with installed motor....you shouldn;t have any further problems.....once again this seems to be a problem only with the smaller 18mm and 24mm casings, i haven't had it with the 29mm ..... the smaller they are the touchier they seem to be....hope this helps...... jim h
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Jeff's 38mm LOKI motors have a red cap that goes over their ejection charge well.
You pour the powder in, put wadding in the red cap to take up the difference, and snap it on.
I like it.
the wadding part is to make sure the powder stays in contact with the ejection charge.
Art Upton
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David Erbas-White wrote:

Embarassed to say I was the "true" idiot. Kurt Savegnago ;)
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The procedures are different for the model and HPR reloads. The model rocket reloads use the red cap to contain the ejection charge. Don't worry that it rattles around inside, that is normal. IMHO it's a more secure process than depending on the little tape dot to seal the ejection well.
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Hey,
I've cooled down. Thanks for all the advice for the ejection charge placement. Won't make the same mistake twice and it's best this occurred with a small engine and rocket. Replacement is on the way and I may going out looking in the fall when the vegetation is down.
Kurt Savegnago
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