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.
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>.
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.
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
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
"The radio business is a cruel and shallow money trench, a long plastic
hallway where thieves and pimps run free, and good men die like dogs.
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.
Phil Stein wrote:
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.
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.
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.)
Go to this page:
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.
[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
Jeff's 38mm LOKI motors have a red cap that goes over their ejection charge
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
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.
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD"
>>> To reply, remove the TRABoD! <<<
Kaplow Klips & Baffle: http://nira-rocketry.org/LeadingEdge/Phantom4000.pdf
www.encompasserve.org/~kaplow_r/ www.nira-rocketry.org www.nar.org
... One nation under surveillance, divisive, with liberty and justice for none.
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.
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