Are "PLUGGED" Motors Legal To Fly ?

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Ez2cDave

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So, a basic question . . .

Are "PLUGGED" motors ( using Epoxy ) legal to fly under the Model Rocket Safety Code ?

NOTE : I am talking about BP Motors & Single Use APCP motors of "G" impulse and below.

Dave F.
 

prfesser

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If they're plugged from the manufacturer...yes, perfectly legal, though I'd assume there's a requirement for electronic ejection.

If they're plugged by the user, that makes them research motors, and we all know what that means.

Best -- Terry
 

heada

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If you leave the ejection charge and cap in place and add epoxy on top of that, I'd say it was legal but that just my opinion.
 

Ez2cDave

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If you leave the ejection charge and cap in place and add epoxy on top of that, I'd say it was legal but that just my opinion.
What about Booster motors ?
 

prfesser

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Just my opinion: altering the motor by adding epoxy likely constitutes a change to a research motor. NAR ain't agonna let ya. Tripoli will, though.
 

heada

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What about Booster motors ?
Same. If all you're doing is adding epoxy and not removing anything or modifying the thrustcurve, it doesn't change the performance or any function of the motor. Not really any different than installing a bulk plate in the BT. Again, that's just me and my opinion.
 

Ez2cDave

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I was always under the impression that the "tampering" being referred to was more pointed at something like "porting" an end-burning BP motor to increase its initial thrust . . . Like making your own B14's.
 

UhClem

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NFPA 1122 is pretty clear on the matter so no. The NAR is making the word "tamper" do a lot of work so there is no way to tell what the NAR safety code means. But NAR policy since 2006 is that all NAR ranges observe the NFPA codes so that doesn't matter.
 

Ez2cDave

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I have been searching online and found a video by Tim Van Milligan of Apogee Rocketry . . . Has anyone seen this before ?

 

Ez2cDave

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My independent source of information says that 1,623 people have seen this before.
My, how observant you are . . . How many of them are on the Forum ?
 
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CoyoteNumber2

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So, a basic question . . .

Are "PLUGGED" motors ( using Epoxy ) legal to fly under the Model Rocket Safety Code ?

NOTE : I am talking about BP Motors & Single Use APCP motors of "G" impulse and below.

Dave F.
I've been doing this for decades and have yet to be thrown off a range.

Aside: I would NOT plug a black powder motor that has an ejection charge - only -0 booster motors.
 

Ez2cDave

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I've been doing this for decades and have yet to be thrown off a range.

Aside: I would NOT plug a black powder motor that has an ejection charge - only -0 booster motors.
What about removing the ejection charge ? That way, you would still have the Tracking Smoke from the Delay Train.
 

Stefan2k4

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What if the motor manufacturer tells you to plug the motor? Would that be considered legal?


Aerotech sells a plugged foreward closure for the RMS 18/20 motor system, but they also mention in the documentation for the RC reloads, that you can plug the regular forward closure with JB Weld.

• Do not modify the motor in any way, except asdescribed herein (addition of JB Weld epoxy to forwardclosure ejection well
And they tell you how to go about doing this.

Assembly Instructions (numbers refer to item numbers on drawing):

1.To prevent hot gas from escaping from forward end of motor, fill the ejection well of the forward closure (9) with JB Weld epoxy(10)and allow to cure before proceeding with step 2.
Of course, it would probably just make more sense to buy the plugged forward closure, such that you could still use the motor with normal reloads, but if the manufacturer says it's okay, that should be legal, right?
 

cerving

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If the manufacturer says you can do it, then it's OK. If they do not, then you can't. When it comes to motors, that which is not specifically allowed is prohibited...
 

CoyoteNumber2

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What about removing the ejection charge ? That way, you would still have the Tracking Smoke from the Delay Train.
From a black powder motor? Now that I would consider modification of the motor. Chipping out the clay cap is way different than peeling a paper disk.
 

bobby_hamill

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NEVER EVER use a knife to scratch out the Bp ejection charge !!
A hard plastic part maybe . But I would advise not to do it.

I am 61 and in my younger years ( late 60s ) I got the same idea to remove the ejection charge
from a motor and things did not go to well. Luckily I did not have the motor end pointed
in the direction of my face.

What happened was when I was using a hobby knife to scratch out the ejection charge the ejection charge ignited and started the propellant charge to burn backwards from top of motor to nozzle .Before the propellant had completed burning the Estes paper case ruptured and split down the side.

All of this happened while the motor was IN MY HAND !!! The results were a slightly sunburned hand that throbbed for a few hours and stopped . No fingers lost thank god it was a small "C" motor . The only damage was to my pants and drawers !

So please be safe out there sometimes even the simplest things can hurt you ,

Bobby
 

John Kemker

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NEVER EVER use a knife to scratch out the Bp ejection charge !!
A hard plastic part maybe . But I would advise not to do it.

I am 61 and in my younger years ( late 60s ) I got the same idea to remove the ejection charge
from a motor and things did not go to well. Luckily I did not have the motor end pointed
in the direction of my face.

What happened was when I was using a hobby knife to scratch out the ejection charge the ejection charge ignited and started the propellant charge to burn backwards from top of motor to nozzle .Before the propellant had completed burning the Estes paper case ruptured and split down the side.

All of this happened while the motor was IN MY HAND !!! The results were a slightly sunburned hand that throbbed for a few hours and stopped . No fingers lost thank god it was a small "C" motor . The only damage was to my pants and drawers !

So please be safe out there sometimes even the simplest things can hurt you ,

Bobby
<In my best Hank Hill voice>"What the hell, Bobby?!"
 

Charles_McG

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In past threads, the opinion has been expressed that if the plug is reversible, it’s not a modification. So dog barf and tape would be ok, epoxy not. Also ok would be a bulkhead sealing the motor tube.

But that was still only opinion. I don’t think there’s a path to an official answer other than ‘no’. And a consensus answer probably wouldn’t be worth the trouble.

Take it up with your RSO, or fly on your own an accept the risk.

I second the advice to plug booster motors. I recently plugged a pair of 1/2A 13mm motors for a ground test, and was surprised at how loud and energetic the charge was when it blew out the nozzles.
 

Ez2cDave

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As for the clay cap, adding a drop or two of water or alcohol might soften the clay, making it easy to remove . . . Just some thoughts .
 
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bobby_hamill

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I was 16 at the time and thought I knew what I was doing NOT !

I am much better now :)
 

burkefj

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Tripoli does not allow research bp motors so no.

Just my opinion: altering the motor by adding epoxy likely constitutes a change to a research motor. NAR ain't agonna let ya. Tripoli will, though.
 

burkefj

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I have contact ESTES and NAR and both said an epoxy modification to a bp motor was a motor modification, not approved by the mfg and so no allowed. A single use composite motor where you simply remove the ejection charge is not considered a modification by the mfg or the NAR. Of course if you aren't flying under tripoli or nar insurance at a sanctioned launch and are covered by your own liability I don't know if it would matter to you.
 

HVArcas

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I have made several rockets where the ejection charge vents harmlessly to the atmosphere, sometimes backwards through drilled centering rings. Works great.

of course i realize this does not work in every situation, but worth pondering
 

prfesser

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Tripoli does not allow research bp motors so no.
Good point. Two reasons that research BP motors are not allowed are: the perceived hazard in construction of such motors; and the failure rate of large homemade PB motors. But if a *commercial* BP motor was modified in such a way as to not constitute a significant hazard, e.g. plugging the forward end of the motor with epoxy, would such a motor be allowed as a research motor? I'll bring it up for clarification to the BoD and TRA list.

Best -- Terry
 

aerostadt

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Before I knew that modified plugged motors did not have NAR sanction, I plugged an Apogee F10 with epoxy for my 4xOT Orbital glider. It worked fine. Having become aware of this ruling these past few months, I decided to modify my Blue glider to use the reloadable 32 mm plugged motor with an F13-RCT. I think that this option will work fine.
 

UhClem

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What if the motor manufacturer tells you to plug the motor? Would that be considered legal?
NFPA 1127 was revised to allow modification of high power reloads but there is no such provision for single use or model rocket motors. The justification for that change was user adjustable delays but the rule is broader than that allowing any manufacturer approved modification.
 

Ez2cDave

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Before I knew that modified plugged motors did not have NAR sanction, I plugged an Apogee F10 with epoxy for my 4xOT Orbital glider. It worked fine. Having become aware of this ruling these past few months, I decided to modify my Blue glider to use the reloadable 32 mm plugged motor with an F13-RCT. I think that this option will work fine.
Question : Since the F10 is an Apogee motor and Tim Van Milligan, owner of Apogee, is actively plugging single-use motors on YouTube, can plugging be considered as an "approved procedure" by the Manufacturer ?

Motors. I will use only certified, commercially-made model rocket motors, and will not tamper with these motors or use them for any purposes except those recommended by the manufacturer.
 
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