Creating Plugged Motors

I was browsing old archived websites the other day. One of them spoke of plugging booster motors with epoxy. It actually made sense to me. But what does the hive mind say? Would it be safe?

It depends. If you're flying a NAR sanctioned launch, plugging a motor with epoxy constitutes modifying the motor which is contrary to the NAR code. If you're flying by yourself and not expecting to be covered by NAR insurance you're on your own.

[video=youtube;wBO99FPxgGY]https://www.youtube.com/watch?v=wBO99FPxgGY[/video]

Peter Olivola said:

It depends. If you're flying a NAR sanctioned launch, plugging a motor with epoxy constitutes modifying the motor which is contrary to the NAR code. If you're flying by yourself and not expecting to be covered by NAR insurance you're on your own.

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Ditto! in spades!
In 40+ years of flying All kinds of Clustered -0 motor models, I've never ever seen a good reason to plug a motor with the possible exception of RCRG gliders. beyond those it's totally unnecessary and as stated in Peters post violates the NAR model Rocket safety code. Please don't do it.

tmacklin said:

[video=youtube;wBO99FPxgGY]https://www.youtube.com/watch?v=wBO99FPxgGY[/video]

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Looks fairly innocuous based on the video...

Your mileage may vary...

Kruegon said:

I was browsing old archived websites the other day. One of them spoke of plugging booster motors with epoxy. It actually made sense to me. But what does the hive mind say? Would it be safe?

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Apparently, the "hive mind" is all a buzz. I think it would be safe and apparently so did Estes, as they used to produce a small number of plugged motors in various sizes with the only real difference being the materials and methods used to form the plug. Then again, I'm not part of the hive. :wink:

If it's not plug it will not blast........ wait it's a rocketry forum not a rock blasting one, lol...... first rule when you do rock blasting is too put 2 bag of gravel over the dynamite stick in the hole, or else you gone have an ejection and not a blast..... why I’ talking about that……
fire in the hole, and if a rock is coming to you, don't run just avoid it......... same with rockets ......

tmacklin said:

Apparently, the "hive mind" is all a buzz. I think it would be safe and apparently so did Estes, as they used to produce a small number of plugged motors in various sizes with the only real difference being the materials and methods used to form the plug. Then again, I'm not part of the hive. :wink:

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Though I have never cut open a plugged motor, I have flown many. I do believe you are mistaken in your understanding of Estes commercially produced "plugged" motors. They do not have any sort of top charge. Regular Estes BP motors with delay have a top charge to deploy a recovery package. Booster -0 varieties have a top charge without delay to send fiery bits to ignite a sustainer motor. The plugged motors have no audible "pop" at the end suggesting a top charge exists.

As part of the "Hive mind", I'd say don't do it. When you start modifying motors you are getting out of the realm of "model rocketry".


Jerome

Well, how would you guys suggest I achieve a burn with no burn through and no ejection charge in an Estes BP motor?

I need to burn with no ejection charge. And for the project, it has to prevent burn through at the end. And it needs to be an E9.

A chunk of aluminum rod in the motor mount would be my suggestion. If you haven't built the mount yet, I'd get some 1" aluminum rod, sand it down, and epoxy it into the motor mount.

Kruegon said:

Well, how would you guys suggest I achieve a burn with no burn through and no ejection charge in an Estes BP motor?

I need to burn with no ejection charge. And for the project, it has to prevent burn through at the end. And it needs to be an E9.

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Plug away and fly on your own, the real world doesn't give a crap what you do as long as you don't interfere with their iPhones or mess with the kids soccer... I've been pouring in epoxy plugs for years, never had any problems like a burst or anything like it. Just don't try to find a minimum thickness of epoxy, that would defeat the purpose

So explain your project in detail if you want a solution. (I have plenty of time, I don't receive my order of hard drives so I'm pay all the night doing nothing )

The theory is to use a plugged E9 as the launch motor, then use a timer to fire a second set of E9 motors at the same time. One of the second E9s will provide the ejection charge. The other second E9 will be plugged as well. The basic design is based of the old Flying Why rocket. Just think of it but the upper pods will have motors as well.

The first motor would burn through to the timer. Can't have that. And the balance for the second firing requires the first motor to stay in the tail.

Its not the most sound design since it requires this, but pushing the limits if design and advancement us what keeps the hobby advancing.

As Dave said plug it and don't give a crap or do it legit with an Aerotech or Cesaroni 24mm, you will benefit of more boost

If I had my own field I'd do just that. Unfortunately I have to launch with the NAR club.

NAR don't accept Aerotech E motors ?

This.

https://www.rocketryforum.com/showthread.php?123625-Plugged-motors-question&highlight=plugged+motors

There is no delay grain in an end burning black powder booster motor, just one solid slug or "grain". That is why there is a zero at the end of the designation as in B6-0, C6-0, C11-0, D12-0 etc. A factory "plugged" motor is nothing more than a booster motor with the addition of a pressed clay plug which blocks combustion gases and forces them to exit only out of the nozzle. This ain't "rocket science" but it is what it is.

The bees are sleeping right now but they'll be buzzing around again after sunrise, stinging anyone who threatens the hive. :duck:

No, this issue is that in NAR you can't modify a motor, unless allowed by the manufacturer (such as drilling a delay grain for CTI) Once you plug a estes booster motor, it becomes a EX launch, so then you need to be at a Tripoli launch and be a Level 2 to fly it with insurance.

What you're hearing is that you can do it without problems. The only real hang up is where you can fly it and what you gotta be certified.

Kruegon said:

I was browsing old archived websites the other day. One of them spoke of plugging booster motors with epoxy. It actually made sense to me. But what does the hive mind say? Would it be safe?

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Actually, the original post merely asked a question: "Would it be safe?"

dave carver said:

Plug away and fly on your own, the real world doesn't give a crap what you do as long as you don't interfere with their iPhones or mess with the kids soccer... I've been pouring in epoxy plugs for years, never had any problems like a burst or anything like it. Just don't try to find a minimum thickness of epoxy, that would defeat the purpose

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Same here!
For a D12-0 1/4" of 5 minute epoxy Put a disk of masking tape on top of the exposed propellant first.

All we need is Estes to start making some plugged -0 motors, or a note saying pour in some epoxy!!!

All you need to do is insert a square or two of FP wadding in the forward end of your -0 motors to keep the burn thru from singing your booster. I generally add a layer or two of Stainless tape to the Booster bulk head as well. if your worried about the burn thru pressure kicking out the booster motor casing just add 3 or 4 open slots in the booster motor/airframe centering rings to pass the gas out the aft end of the booster stage.
There is NO NEED to plug the booster motor at all.

Since your flying at sanctioned NAR launches the POOR advise given by others should be ignored. The No alterations to motors" rule is one of the reasons we've enjoyed 50+ years of Safe flying. Lets not let the new-age basement bombers ruin that record with Ill advised "Hey y'all we can do this" Crap.
It is perfectly true on your own land, in your own private moments, without other unsuspecting persons around one can do almost any Stupid, Careless or dangeous thing one likes. But NOT where Other persons and/or property are involved.
{edited by mods}
Safety first ALWAYS. Think before you act or advise! Go ahead...Flame away... you know I'm Correct!

The solution is quite simple , just don't put the BP ( but if you ask be I will use CTI 24mm, of course it cost more)

[video=youtube;mcHvMpUaXzg]https://www.youtube.com/watch?v=mcHvMpUaXzg[/video]

Looks to me like there's no need to flame someone who has already set them self ablaze. :neener:

Kruegon said:

The theory is to use a plugged E9 as the launch motor, then use a timer to fire a second set of E9 motors at the same time. One of the second E9s will provide the ejection charge. The other second E9 will be plugged as well. The basic design is based of the old Flying Why rocket. Just think of it but the upper pods will have motors as well.

The first motor would burn through to the timer. Can't have that. And the balance for the second firing requires the first motor to stay in the tail.

Its not the most sound design since it requires this, but pushing the limits if design and advancement us what keeps the hobby advancing.

Click to expand...

The solution should be obvious, unless this is a scale model or unless you later plan to remove the timer and fly the same rocket with regular motors. If you can't plug the motor, plug the motor mount instead.

I'd make the mount a bit longer than necessary to accomodate the motor, e.g for a 3.75" long E9 motor, perhaps make the mount tube about 4.5" - 5". Fit a thrust ring, Estes clip, or whatever else you want to make sure the motor doesn't move. Ahead of the thrust ring, drill a couple of holes so the ejection gas has somewhere to go. At the top of the tube, fit the plug to prevent the ejection charge from hitting your timer.

Rules - "At this point, what difference does it make"...

Rules - Only for the "little people"...

Rules, edict, decree, rulers, king, despot, despotism, tyrant, tyranny, et al...

Just have fun guys and don't kill, hurt, impale, pierce, pucture, perforate, lance, prick, or otherwise disfigure anyone...

Here is what I did instead -
https://www.rocketryforum.com/showthread.php?120890-patriot-build-for-deployment-experiments

I have not flown it yet but did ground test the venting and it works quite well.

Kruegon said:

I was browsing old archived websites the other day. One of them spoke of plugging booster motors with epoxy. It actually made sense to me. But what does the hive mind say? Would it be safe?

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Once again I will refer to the original post by Kruegon who essentially asked; Would it be safe to plug a booster motor with epoxy? That question remains unanswered. For what it is worth, my opinion is that if properly mixed epoxy is poured into the recess at the head of a black powder booster motor and allowed adequate time to cure thereby creating a plugged motor, it is safe to do so. As proof, I linked a YouTube video of an actual test which supports that view. I voiced my opinion and for that I received a flurry of viscous, insulting and libelous insults from Micromister. Accordingly, a formal complaint has been filed against the offender.

EDIT: The post directly above appeared while I was composing mine. My comments are not directed at tmaclin, but to the OP.

John (Micromeister) is mostly right. Certainly there are alternate solutions, which have been amply suggested already. Since you're launching at NAR sanctioned events you'll need to use one. Plugging a motor may be the technically best solution all else being equal, but one must also abide by applicable laws and regulations, in this case the safety code. Engineering - from flying models to satellite launches to skyscrapers and bridges - is all about finding the best compromise among competing goals and requirements, and that usually includes laws and regulations.

Most of the things one might do to a commercial engine - like drilling a hole in the side of the case to create spin or adding a bit of loose BP to augment the hot sparks for staging - are dangerous and stupid. That said, there's no reason to dismiss any and all modifications as universally stupid, or all those who try them as "basement bombers." Experiments can be conducted with proper caution and consideration. Just not at NAR sanctioned launches.

I can't imagine anything dangerous about a well formed epoxy plug on top of a -0 motor. I wouldn't hesitate to launch one when launching on my own, nor to stand next to you with my daughter in tow while you launch yours, if only you had a place to do it.