[FFT] Plugging Estes or Quest BP motors



Yes.
Point.
--
Jerry Irvine, Box 1242, Claremont, California 91711 USA
Opinion, the whole thing. <mail to: snipped-for-privacy@gte.net>
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Jerry Irvine wrote:

And what "real world tests" did you do?
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On Sun, 17 Apr 2005 22:15:48 GMT, Dave Grayvis

The ones that resulted in his Big Fine.
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Aren't you in more danger of blowing out your (Estes-type I would assume) body tube by doing this? Unless you can assure a gas-tight seal between the motor and plug, I think this could be a problem.
Is kicking the motor an option? Would be far simpler, just block off the MMT with a bulkhead and loosely friction fit the motor.
Another option would be to vent the gases, perhaps you could have a section of BT ahead of the motor with a simple baffle and small holes in the airframe to vent the gases evenly in all directions.
My thoughts are that if you want to avoid modifying the motor, there may be more ways to skin the cat (or something like that ;) ).
HTH.
--
Niall Oswald
================================
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-----snip-----
and
that
-----snip-----
MMT
section
I'm personally not a fan of motor ejection because I once had one actually hit my shoulder in a one-in-a-gazillion chance. Made me worry about lightning strikes, too.
Two 1/4 in diameter vent holes 180 degrees apart below the solid bulkhead will vent the ejection charge nicely.
John<==wearing hard hats at launches now
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Usually, ejecting motors is frowned upon. Most clubs use some type of farm land and motors can be a hazzard to livestock or machinery, so leaving motor liter all over the place from dozens of launches, isn't a good thing. I've flown them so that either way was an option, depending on the field and who I'm flying with. Some will say there is also a fire hazzaed but fire is more of a problem at liftoff, than from a fallen burned out booster.
On the other hand, if these conditions are not an issue, a falling A-D type engine doesn't pose too much of a threat, they tend to tumble quite a bit and 999 times out of 1000, arch away from the launch area. To date, I've made over 50 flights where the engines ejected and never had a problem of any kind. I like the idea of lightening the chute load AND ejecting can make spent engine extraction easier. Ever had an engine get stuck in your favorite rocket?
If you want to fly a bird that ejects it's engine, you can scotch tape a short piece of orange caution tape to it. That will allow you to track it as it falls and locate it later.
Randy http://vernarockets.com /
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john:
I'm not sure venting the ejection charge gases is what I am after... I was hoping to use the ejection charge gases, whether it blows out the nozzle or not, as a secondary source of energy.... to get some additional altitude.... If I vent then I have potentially 2 problems:
1. the vented gases may cause some instability as it is exhausted.. 2. drag due to 2 holes in model..
I guess I might as well go ahead and give "the rest of the story"....
Instead of using a microtimer as I posed in the 1st post, what I am actually considering doing is making my own delay train/ejection charge module.... and having the "real" ejection charge ignite the add-on delay train...
I figure that I only need 3-4 more seconds to give me an actual 6-7 delay time...
the idea is that with the A3-4T or A10-3T motors is their delay times are way too short for altitude..
I figure that a small delay/ejection charge module like this should not weight more than 2 grams max... and it would give me the effective 6-7 s delay time that I am looking for.
shockie B)

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shockwaveriderz wrote:

actually
module....
train...
delay
are
not
6-7 s

Have you considered using a 1/4A3-3T as your delay/ejection module? If mounted inside the body tube the thrust will be inefective-old timers call that the Krushnic effect, there is a newer term that escapes me. It does weigh 5.6 grams though
Dale Greene SPAAR 503
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avilable.
motor
I
in
the
actually
lightning
bulkhead
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This had got to be one of the most crazy ideas I've seen on RMR in years.
The ejection charge will still fire, and the "plug" will just be fired into the internals of the bird. (friction fit?)
If you don't want an ejection charge, you got ways to correct for it:
1) buy the motor you really need 2) vent it's charge 3) talk to Gary and get him to issue a press release that none of the testing groups have approved as to "motor modifications". (gary might do it, even though it's BP! He wants sales and happy people....) 4) put the bird on the shelf, as it can longer be flown.
What if I had a bird that used the "short" motors from Estes? (the original Midget comes to mind...) is it Ok for me to cut the casing to the proper length? (heck, it's only cardboard I'm cutting!!) What happens if I make the 6pm news when doing this, as a spark hit the ejection charge? (Model Rocket motor and bandsaw burns down house, more at 11!)

a
want
of
when
the
exhausted
the
failure
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AZ Woody wrote:

For the first time (to the best of my recollection) in all my years on rmr, I'm turning the flamethrower on full blast.
Woody, pull your head out of your butt.
The rules regarding manufacturer recommended modifications has been on the books for eons. The entire POINT of modifications needed manufacturer recommendations is to allow for 'minor' tweaks that may (or may not) have been fully covered in other material and/or instructions, to allow for either safe operation or a wider range of operation. If, at any point, a manufacturer ABUSES that privilege, the certification organizations would theoretically have the right to ask for corrective action -- which might take the term of a request for clarification, a request for recertification, etc.
The entire POINT of this is that the manfacturer is the one who's butt is on the line in relation to liability issues, so they are very unlikely to 'recommend' modification that might create greater risk or liability.
Just because you've got a hair up your tail about this is no reason to jump on Gary -- he's done what the vast majority of Aerotech composite motors have been asking for for years -- and done it in a very thorough and professional manner.
To suggest that what Gary has done in relation to delay charge modifications is on par with folks 'experimenting' with plugging BP motors with epoxy suggests that you don't have clue one as to what is going on. In the case of delay modification, we have a situation that has been in place for quite some time with other manufacturers, that has no record of any problems, being made 'legal'. In the case of BP motor plugging, all of the folks who have done it are saying DON'T do it, because it's dangerous. For you to imply that what Gary did was in any way similar is unconscionable.
I look forward to hearing your apology (but I won't hold my breath)...
David Erbas-White
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The problem being real or perceived.
Gary is given wide discretion while others are harassed and expensed to death.

That was not the position taken on Kosdon Or USR or Vulcan or ACS ...
And these all had paperwork, so that excuse evaporates.
There is an OUTSTANDING problem. Different treatments of different vendors. Aerotech was given a pass. You and I agreee it was a good one. Fine. But CTI was not given the same pass on the same issue. Fact.
That fact is going to result in bad vibes from the "excluded class" while some revel in the ability to modify their monopoly sourced errortech motors.
Jerry

--
Jerry Irvine, Box 1242, Claremont, California 91711 USA
Opinion, the whole thing. <mail to: snipped-for-privacy@gte.net>
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Jerry Irvine wrote:

Should CTI have been given a pass on this? Frankly, yes! But, Gary did the SMART thing as a businessman -- he let somebody else blaze the trail and take the arrows, and once there was more history for it, he approved it for his own product. This, Jerry, is known as "conservative business practice".
David Erbas-White
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I apologize for the fact that you with born without an understanding of sarcasm!
Has S&T said anything new? Last I heard, was S&T was still looking at it (per John)

it,
What about the good old Ellis J350 mods? "Hey users, we got a problem and the way to fix it is to drill out the hole in the grain to 1/2"!" This was a mod that should have required a recert, as the J350 was no longer a J350! Hey, the Ellis J350 was one case, and the "red delay liner" was another......

And also required 3 certs of each delay grain, with various "adjusted" delays. And the tool to be modified to alow a finite number of adjustments.
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Don't forget to say NAR and TRA will go along with teflon-Gary on issues others have been refused over.
- Multiple subcontractors - modifications of already certified motors. - field modifications of primary propelling charges - to overcome and prevent recall of known manufacturing defects
Jerry
--
Jerry Irvine, Box 1242, Claremont, California 91711 USA
Opinion, the whole thing. <mail to: snipped-for-privacy@gte.net>
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Jerry Irvine wrote:

Poor pathetic psychotic jerry.
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AZ:
thanks for telling me this idea is crazy! Anyway, the ejection charge from the A3-4T motor would indeed "fire", with the idea that above the motor, a delay and ejection charge module of my own making. The idea is the hot particulate of the ejection charge will ignite this delay/ejection charge module. The module will not be blown upwards into the model, as there is a bulkhead above it.....the idea is to get 2-3 extra seconds of delay time so that my A3-4T functions like an A3-6/7-T.. the secondary ejection charge would then pop out the recovery system.
There are NO modifications or alterations made to the actual original A3-4T motor.
I may have to add some exhaust holes to help relieve the pressure and I may have to place the forward bulkhead up an inch or two of the delay/ejection charge module, so that the ejection charge pushes the delay/ejection charge module up these 2 inches and allows more space to pressurize to prevent nozzle blowout or a rupture of the casing....
shockie B)

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No, it's not "OK" to make your own short motors by sawing off an inch of empty casing. What I *HAVE* done many times, its take a used casing, saw it down, clean it out, and insert a "T" motor inside it. A standard 18mm casing makes a perfect adapter for them. And a shortened as above 18mm casing makes a perfect Shorty motor. And a cleaned out used D12 casing makes a perfect 18->24mm adapter. I just used one this weekend.
    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
It had become an universal and almost uncontroverted position in the several States, that the purposes of society do not require a surrender of all our rights to our ordinary governors; that there are certain portions of right not necessary to enable them to carry on an effective government, and which experience has nevertheless proved they will be constantly encroaching on, if submitted to them; that there are also certain fences which experience has proved peculiarly efficacious against wrong, and rarely obstructive of right, which yet the governing powers have ever shown a disposition to weaken and remove. Of the first kind, for instance, is freedom of religion; of the second, trial by jury, habeas corpus laws, free presses. -- Thomas Jefferson
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writes:
-----snip-----

it
casing
makes
And a cleaned out used D12 casing sawn into 1/4 in rings makes nifty spacers to hold an 18mm motor without adding excessive weight in the tail of the bird.
John<==if I glue the rings on, have I 'modified' the C6 ?
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http://nar.org/SandT/releases/r63.html

according to NAR S&T you have NOT modified the motor...
shockie B)
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