Creating Plugged Motors

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tmacklin said:
I voiced my opinion and for that I received a flurry of viscous, insulting and libelous insults .
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I get your feeling; They are some caveman thinking persons on the forum…… I suggest once we don’t need things like High power rules for low power to atract more peoples to the hobby , someone reply that we gone kill kids with those idea. I was referring at thing like flight cards inspection tables . In another tread about active stabilisation, someone say that some can use my idea to take down a plane …. I was thinking and still think a Gimbal active stabilisation.
 
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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Plugged motors work just fine. They are simply booster motors with a clay cap. Estes makes a certified D11-P when a minimum demand is met. https://www.nar.org/SandT/pdf/Estes/D11.pdf Estes made and certified an E9-P but there is no commercial market for it, but will make a production run for someone with the money to pay for the run. https://www.nar.org/SandT/pdf/Estes/E9.pdf

1.) Plugged motors are safe.
2.) Certified plugged motors can be flow at NAR/TRA/CAR launches.
3.) You can't make your own plugged motors.
4.) If you use a BP booster motor, it is not safe to use a sustainer ignition method that delays the sustainer ignition.
5.) There is no need to use electronics to ignite a second stage BP motor as they can be gap stage at separations of 1' using proper techniques.

Estes dropped the E9-0 booster motors because they do not develop enough velocity to properly stage a rocket, so your idea is not a good one and does not advance the hobby. Since a 2 stage rocket powered by a E9-0 booster does not provide sufficient velocity to stage properly, your idea to delay the second stage ignition is not safe so don't do it.

Estes does make a D11-P however again for a booster application in a 2-stage rocket, the Estes D12-0 and even the C11-0 motor use in the conventional BP motor staging method is the way to go. Neither motor develop sufficient thrust to make a delayed ignition safe so don't do it.

Bob Krech, NAR S&T Tech Officer
 
bobkrech said:
Plugged motors work just fine. They are simply booster motors with a clay cap. Estes makes a certified D11-P when a minimum demand is met. https://www.nar.org/SandT/pdf/Estes/D11.pdf Estes made and certified an E9-P but there is no commercial market for it, but will make a production run for someone with the money to pay for the run. https://www.nar.org/SandT/pdf/Estes/E9.pdf

1.) Plugged motors are safe.
2.) Certified plugged motors can be flow at NAR/TRA/CAR launches.
3.) You can't make your own plugged motors.
4.) If you use a BP booster motor, it is not safe to use a sustainer ignition method that delays the sustainer ignition.
5.) There is no need to use electronics to ignite a second stage BP motor as they can be gap stage at separations of 1' using proper techniques.

Estes dropped the E9-0 booster motors because they do not develop enough velocity to properly stage a rocket, so your idea is not a good one and does not advance the hobby. Since a 2 stage rocket powered by a E9-0 booster does not provide sufficient velocity to stage properly, your idea to delay the second stage ignition is not safe so don't do it.

Estes does make a D11-P however again for a booster application in a 2-stage rocket, the Estes D12-0 and even the C11-0 motor use in the conventional BP motor staging method is the way to go. Neither motor develop sufficient thrust to make a delayed ignition safe so don't do it.

Bob Krech, NAR S&T Tech Officer
Click to expand...

Thank you for your objective comments.
 
I come back since I don't have reply, An Aerotech or CTI motor with grease instead of BP is NAR, TRA and CAR certified motor. and you have way more choice.
 
Area66 said:
I get your feeling; They are some caveman thinking persons on the forum…… I suggest once we don’t need things like High power rules for low power to atract more peoples to the hobby , someone reply that we gone kill kids with those idea. I was referring at thing like flight cards inspection tables . In another tread about active stabilisation, someone say that some can use my idea to take down a plane …. I was thinking and still think a Gimbal active stabilisation.
Click to expand...

I think the story on that is in the very old Tripolitan magazine. George Gassaway is the man to talk to. I know it's sort of a been-there-done-that for him but I'm thinking with the advances there could be amazing possibilities. Email VernK and ask about KATE ;)
 
bobkrech said:
Neither motor develop sufficient thrust to make a delayed ignition safe so don't do it.

Bob Krech, NAR S&T Tech Officer
Click to expand...

Thank you for the info. What must be understood here is that the booster is not in line with the second fire motors. The timer is planned to be set to ignite just prior to burnout of the booster. Thus there will be no delay in burn. The question had nothing to do with feasibility of the build or staging of the motors. I have absolutely no doubt that the design will work. Just wanted to know if I could or could not plug the motor.

And the info I received answered it well and then some. Yes I CAN plug the motor. NO it is generally not recommended. NO it can not be flown at a NAR launch if I do.

I've also been given some alternatives to consider. And I thank you all for it.

Please feel free to continue the debate. I'm getting a lot of good views on how its looked at from different people. Just because its against NAR rules does not mean it us unsafe nor ill advised. Remember, since upon a time ALL rocketry was experiment and technically unsafe. But through failure, advancements are made. Through risk discoveries are achieved.

So my next question is this... is modifying a commercial motor in this fashion considered experimental by TRA rules or is it also prohibited?
 
Kruegon said:
Thank you for the info. What must be understood here is that the booster is not in line with the second fire motors. The timer is planned to be set to ignite just prior to burnout of the booster. Thus there will be no delay in burn. The question had nothing to do with feasibility of the build or staging of the motors. I have absolutely no doubt that the design will work. Just wanted to know if I could or could not plug the motor.

And the info I received answered it well and then some. Yes I CAN plug the motor. NO it is generally not recommended. NO it can not be flown at a NAR launch if I do.

I've also been given some alternatives to consider. And I thank you all for it.

Please feel free to continue the debate. I'm getting a lot of good views on how its looked at from different people. Just because its against NAR rules does not mean it us unsafe nor ill advised. Remember, since upon a time ALL rocketry was experiment and technically unsafe. But through failure, advancements are made. Through risk discoveries are achieved.

So my next question is this... is modifying a commercial motor in this fashion considered experimental by TRA rules or is it also prohibited?
Click to expand...

I just read the Tripoli rules as posted online and could find no definitive answer to your question. The rules appear to be vague regarding what constitutes a "modification" and are thus open to interpretation. Perhaps it would be helpful if you could post a picture or drawing of your proposed rocket design. I know it would help me visualize what you are trying to do. If you can find a suitable piece of land where you can safely perform both static and actual flight tests that would be a good thing. :handshake:
 
Haven't been in Tripoli for a while, but as I remember 'research' is all about making your own motors (read that propellant) rather than modifying commercial ones. I can't say if plugging is considered modifications, but rendering a certified motor non certified is a no-no.
 
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yrs ago I flew my Vaughn Bros Lil Wild Thing with 1 C-6-7 and 6 epoxy plugged A-10-3s LOL when the ejection goes It blows the nozzle out and it sounds like firecrackers going off if the air Gets everybody's attention quickly
 
rstaff3 said:
Haven't been in Tripoli for a while, but as I remember 'research' is all about making your own motors (read that propellant) rather than modifying commercial ones. I can't say if plugging is considered modifications, but rendering a certified motor non certified is a no-no.
Click to expand...

That has changed actually. Quoting from the FAQ on the Tripoli site:
"13. I want to ‘kit-bash’ some commercial motor parts to create a ‘custom’ motor is this allowed at a TRL?
Yes, this is considered a Research motor. However, this is not allowed at non- TRLs since the motor is not certified."

The document is located at https://www.tripoli.org/Resources/tabid/344/Default.aspx
 
bobkrech said:
4.) If you use a BP booster motor, it is not safe to use a sustainer ignition method that delays the sustainer ignition.
Click to expand...

That's not always true. It is probably not a good idea for something boosted by an E9. However, in a properly designed rocket, using up some of the velocity coasting between stages will get you a higher altitude if that's what you're going for.
 
Len B said:
That has changed actually. Quoting from the FAQ on the Tripoli site:
"13. I want to ‘kit-bash’ some commercial motor parts to create a ‘custom’ motor is this allowed at a TRL?
Yes, this is considered a Research motor. However, this is not allowed at non- TRLs since the motor is not certified."

The document is located at https://www.tripoli.org/Resources/tabid/344/Default.aspx
Click to expand...

Thanks for straightening me out on this. That wasn't the case in the past....and I wish it had been. But then, MDRA has spoiled me on that account.
 
Kruegon said:
I have absolutely no doubt that the design will work. Just wanted to know if I could or could not plug the motor.
Click to expand...
I'm not here to dispute that or discourage you, but I'd like to point out something you should consider (just in case, maybe, you haven't already.) There's a good deal of talk on the forums about models boosted by E9s, especially 2 stagers with E9-0s, not getting sufficient speed off the launch guide for good flights. The D12 does a better job of this. With the weird- no, odd- no, interesting shape of your design, I'd want lots of speed off the guide.

I present for your consideration the Aerotech E15-P. It's a 24x70mm single use motor, it will give you lots more speed off the guide than the E9 or the D12, and it's plugged from the factory, all nice and certified.
 
Kruegon said:
Thank you for the info. What must be understood here is that the booster is not in line with the second fire motors. The timer is planned to be set to ignite just prior to burnout of the booster. Thus there will be no delay in burn. The question had nothing to do with feasibility of the build or staging of the motors. I have absolutely no doubt that the design will work. Just wanted to know if I could or could not plug the motor.

And the info I received answered it well and then some. Yes I CAN plug the motor. NO it is generally not recommended. NO it can not be flown at a NAR launch if I do.

I've also been given some alternatives to consider. And I thank you all for it.

Please feel free to continue the debate. I'm getting a lot of good views on how its looked at from different people. Just because its against NAR rules does not mean it us unsafe nor ill advised. Remember, since upon a time ALL rocketry was experiment and technically unsafe. But through failure, advancements are made. Through risk discoveries are achieved.

So my next question is this... is modifying a commercial motor in this fashion considered experimental by TRA rules or is it also prohibited?
Click to expand...

For what it's worth, I say build it, test it and fly it wherever you can safely do so. And I agree with you that through failure advancements are to be made. (It's the Basement Bombers' Creed. :wink:)
 
jqavins said:
I present for your consideration the Aerotech E15-P. It's a 24x70mm single use motor, it will give you lots more speed off the guide than the E9 or the D12, and it's plugged from the factory, all nice and certified.
Click to expand...

That's an interesting idea. I'm at work and can't research the info easily. Is this motor BP or APCP? One of the goals was to achieve this complex setup on old fashioned bp motors.
 
Kruegon said:
Thank you for the info. What must be understood here is that the booster is not in line with the second fire motors. The timer is planned to be set to ignite just prior to burnout of the booster. Thus there will be no delay in burn. The question had nothing to do with feasibility of the build or staging of the motors. I have absolutely no doubt that the design will work. Just wanted to know if I could or could not plug the motor.

And the info I received answered it well and then some. Yes I CAN plug the motor. NO it is generally not recommended. NO it can not be flown at a NAR launch if I do.

I've also been given some alternatives to consider. And I thank you all for it.

Please feel free to continue the debate. I'm getting a lot of good views on how its looked at from different people. Just because its against NAR rules does not mean it us unsafe nor ill advised. Remember, since upon a time ALL rocketry was experiment and technically unsafe. But through failure, advancements are made. Through risk discoveries are achieved.

So my next question is this... is modifying a commercial motor in this fashion considered experimental by TRA rules or is it also prohibited?
Click to expand...
Now on the other hand, if you fill the top of the BP booster motor with dog barf to prevent the hot gases from the motor from scorching a forward bulkhead at the top of a motor tube, and use standard motor retention components to retain the motor, you have not modified the motor and yet met your objective.

Bob
 
Kruegon said:
One of the goals was to achieve this complex setup on old fashioned bp motors.
Click to expand...
Ah, well then... No, it's composite. If you want to stick with BP then you're stuck with the E9 and D12.

If I were you, unless you've already done so, I would simulate a simple 3FNC that has the weight of your design including the two airstart motors, and look at the speed off the guide with the E9 and again with the D12. (I'm not suggesting this is good for anything except the guide departure speed, but weight and the thrust profile are all you need to simulate that much.) With the D12 you should get in the ballpark of 25 to 30 percent more, and that could be worth taking the hit in other ways if it helps ensure the flight is successful.
 
bobkrech said:
Now on the other hand, if you fill the top of the BP booster motor with dog barf to prevent the hot gases from the motor from scorching a forward bulkhead at the top of a motor tube, and use standard motor retention components to retain the motor, you have not modified the motor and yet met your objective.

Bob
Click to expand...

That might be worth another static test but I'm about out of booster motors (engines, gas generating propulsion devices) for such purposes. :wink:


On the other hand, standard motor retention components might cause the gaseous combustion spike at the end of the booster's burn to rupture the motor mount/body tube if it is not vented. I think a properly plugged black powder motor or an APCP motor sans the ejection charge would be a better avenue. (I am assuming that the "timer" mentioned by the OP provides an electronic ignition for the "wing engines"?)
 
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tmacklin said:
(I am assuming that the "timer" mentioned by the OP provides an electronic ignition for the "wing engines"?)
Click to expand...

You are correct. The entire theory here is to only have the booster get the rocket moving. A measurable amount of thrust is lost to actually getting the rocket moving. The booster starts that and the dual mains get to slam it through the air with almost full thrust director as altitude with minimal loss of time and power.
 
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I think this chart, posted by billspad, illustrates what happens.

th March 2015, 11:26 AM #34 billspad's Avatar billspad billspad is offline
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Quote Originally Posted by ThirstyBarbarian View Post
But if the plug were not sealed to the grain, like maybe a solid bulkhead that acted as the motor block and had an air gap between the end of the grain and the bulkhead, then the unreinforced end of the grain would have the structural failure you described, and you would have all of the smaller burning particles, and that would mean a pressure spike as the remaining particles burned more quickly than an intact grain.

I believes this illustrates that:

Click image for larger version.

Name: graph.jpg
Views: 33
Size: 85.2 KB
ID: 258465

The removable plug was at the end of the casing and the epoxy plug was on the propellant.
Bill Spadafora https://www.billsplumbing.com
[email protected] [email protected]
 
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Kruegon said:
A measurable amount of thrust is lost to actually getting the rocket moving. The booster starts that and the dual mains get to slam it through the air with almost full thrust director as altitude with minimal loss of time and power.
Click to expand...
Umm, that's really not how it works. All the thrust "gets the rocket moving." All newton-seconds are created equal, and delta-V at low speed is the same as delta-V at medium or high speed. Your design is cool, but if this is the reason for the air start then you're wasting your time.
 
tmacklin said:
I think this chart, posted by billspad, illustrates what happens.

th March 2015, 11:26 AM #34 billspad's Avatar billspad billspad is offline
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Join Date
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Location
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Quote Originally Posted by ThirstyBarbarian View Post
But if the plug were not sealed to the grain, like maybe a solid bulkhead that acted as the motor block and had an air gap between the end of the grain and the bulkhead, then the unreinforced end of the grain would have the structural failure you described, and you would have all of the smaller burning particles, and that would mean a pressure spike as the remaining particles burned more quickly than an intact grain.

I believes this illustrates that:

Click image for larger version.

Name: graph.jpg
Views: 33
Size: 85.2 KB
ID: 258465

The removable plug was at the end of the casing and the epoxy plug was on the propellant.
Bill Spadafora https://www.billsplumbing.com
[email protected] [email protected]
Click to expand...
However if you pack dog barf tightly against the propellant grain, you do not have an air gap, so you shouldn't get the big spike. Furthermore, the compressed dog barf leakage will lengthen and attenuate any acoustic spike that could be generated. Any damage done by a booster engine to a distant bulkhead is due to the breakthrough of the propellant and the sudden release of ~100 psi chamber pressure into the void. The compressed dog barf prevents any sudden release of pressure.

Remember that gas escapes through the path of least resistance so the compressed dog barf isn't greatly different than an epoxy plug or thick clay cap. Without the plug or cap or dog barf, there is no resistant at the forward end of the motor and the full combustion pressure is applied to the bulkhead. With mass in the path, there's complete or almost complete resistance and the gas has no choice but to exit out the nozzle.

Bob
 
I don't see much difference between packing in dog barf, bentonite clay (kitty litter) or pouring in some epoxy ( a sure thing). No matter how you do it, it's putting stuff in a motor that aint supposed to be there. If dog barf is ok what is wrong with one of the others? Drilling delays was a no-no a few years back, now common.
Do you think Estes would give permission to plug a booster motor if asked?
 
rcktnut said:
Do you think Estes would give permission to plug a booster motor if asked?
Click to expand...

At the risk of sounding like Fred, why don't you call them and ask? Speculation from any of us about that is pretty much worthless.
 

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