(SOLVED) Are there any plugged 18mm Motors?

[TeslaPenguin1]

I am building a linear-3 cluster rocket. The two side engines are 18mm (A/B/C) but the center is a single 24mm (D/E) motor. I only want the ejection charge on the center motor to fire. Are there any 18mm motors without a delay charge? (I know that the -0 motors don't have a delay charge, but I am specifically asking about plugged motors)

 

[dhbarr]

The 18mm Aerotech reloadables can be plugged by using the RC forward.

 

[James Duffy]

The Aerotech C3.4-P is a plugged 18mm motor designed for the AT 18/20 RMS casing.

https://www.nar.org/SandT/pdf/Aerotech/AT_C3.4_2015.pdf

(The six-second delay version of the motor is a single use motor, not a reload.)

James

 

[CoyoteNumber2]

You can drip some epoxy into -0 motors to plug them.

 

[8thPaladin]

Used an Aerotech 18mm D10-PW that was plugged at Hellfire. It was a lot of fun for the Quest Planet Probe!

 

[vcp]

I printed a moderately tight fitting plug that seemed to work pretty well.

 

[TeslaPenguin1]

So, which of these are single-use? I'm relatively new to model rocketry (read: approx. 1 week) and haven't gotten the hang of assembling reloadables yet.

 

[kuririn]

If you're new, I would suggest sticking with black powder motors for a cluster, rather than composites. They are more difficult to simultaneously ignite. Use a 12 volt automotive battery. The extra amperage makes a difference. You can make your own plugged motors, like coyote said, by gluing some epoxy over the forward end of the propellant on booster motors. The only black powder plugged motors being currently produced that I know are the 13mm A-10PTs for the Estes rocket cars.
Ignitors are critical. I wouldn't use Estes starters for a cluster. See if you can borrow some Quest Q2G2 ignitors from a rocket buddy who might have a stash. Otherwise order some aftermarket ignitors for greater reliability.

 

[TeslaPenguin1]

If you're new, I would suggest sticking with black powder motors for a cluster, rather than composites. They are more difficult to simultaneously ignite.

Yes, exactly as I was saying. Due to the fact that I am new, I was looking for a simpler solution than composite motors.

Also, I read another thread where someone tried putting epoxy in the end but the heat of the epoxy setting made the motor go off (and incinerate itself). Is there anyway I can prevent this from happening?

 

[rharshberger]

The biggest question is what delay is the center motor, if its the longest for that motor available then you have an issue with the other delays in the cluster, if however its the shortest like a C6-5 then use longer delays for the outer motors (like C6-7's), that way the center motor will have already ejected the laundry (parachute), and the outer motors delays are just firing out a hollow tube. Modifying an commercial motor via plugging with epoxy puts it into the realm of Research/EX motors and it cannot be flown at a NAR launch.

 

[CoyoteNumber2]

Modifying an commercial motor via plugging with epoxy puts it into the realm of Research/EX motors and it cannot be flown at a NAR launch.

LOL, are you serious?

 

[CoyoteNumber2]

Also, I read another thread where someone tried putting epoxy in the end but the heat of the epoxy setting made the motor go off (and incinerate itself). Is there anyway I can prevent this from happening?

Run-of-the-mill epoxy will not exotherm anywhere close enough to ignite black powder.

 

[rharshberger]

LOL, are you serious?

Yes, I am, modifying a motor in any manner not specified by the manufacturer makes it EX. Granted most people just ignore the fact its a little bitty LPR motor and do it anyways. If someone is caught flying a modified motor at our clubs launches on a non-research event it could very well mean a permanent ban.

https://www.nar.org/safety-information/model-rocket-safety-code/

Number 2: 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.

And the Tripoli Research Safety Code specifically prohibits non-commercial black powder motors.

So a modified, and yes plugging a -0 motor is modification since the manufacturer did not make it that way.

NAR and TRA representatives feel free to weigh in.

 

[burkefj]

Yes specifically for RC rocket gliders, plugging motors with epoxy is done sometimes, I asked the nar board to contact Estes and ask them if plugging a motor with epoxy would be manufacturer approved modification and estes declined to approve that. However leaving an ejection charge out of a composite reloadable motor or a single-use motor is not a modification.

 

[TeslaPenguin1]

The biggest question is what delay is the center motor, if its the longest for that motor available then you have an issue with the other delays in the cluster, if however its the shortest like a C6-5 then use longer delays for the outer motors (like C6-7's), that way the center motor will have already ejected the laundry (parachute), and the outer motors delays are just firing out a hollow tube. Modifying an commercial motor via plugging with epoxy puts it into the realm of Research/EX motors and it cannot be flown at a NAR launch.

Thanks! I will try this and see if it works.

 

[vcp]

Yes, I am, modifying a motor in any manner not specified by the manufacturer makes it EX. Granted most people just ignore the fact its a little bitty LPR motor and do it anyways. If someone is caught flying a modified motor at our clubs launches on a non-research event it could very well mean a permanent ban.

https://www.nar.org/safety-information/model-rocket-safety-code/

Number 2: 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.

And the Tripoli Research Safety Code specifically prohibits non-commercial black powder motors.

So a modified, and yes plugging a -0 motor is modification since the manufacturer did not make it that way.

NAR and TRA representatives feel free to weigh in.

Good, I'm glad this came up because I was wondering where in this spectrum my printed plug would fit. It's a friction fit, with even a small 'handle' so that it can be finger removed. A small rim (makes it look like a top hat) clamps the plug between the motor and the engine block.

Edit: here's a used plug. It leaks a bit, but seemed to do the job.

 

[kuririn]

Thanks! I will try this and see if it works.

You mentioned a linear 3 engine cluster. I'm wondering if that means side pods, or are all three going into a central tube? If using side pods and motors with an ejection delay, provisions need to be made for the ejection gases. Blowing out the spent engine casings is not allowed at some launch meets. Venting to the central tube or nose cone blow with shock cord are options.

 

[Alan15578]

Good, I'm glad this came up because I was wondering where in this spectrum my printed plug would fit. It's a friction fit, with even a small 'handle' so that it can be finger removed. A small rim (makes it look like a top hat) clamps the plug between the motor and the engine block.

Edit: here's a used plug. It leaks a bit, but seemed to do the job.
View attachment 360008

Interesting. This a grey area in the sense that the answer depends on gets to do the interpretation, typically the RSO.
In addition, there is an old NAR competition rule that nothing may be "affixed" to a motor, and many people try to bring contest rulings into situations outside of sanctioned competition. So glue is not OK, but tape is OK. You cannot glue fins directly to a motor case in competition, although FSI had a kit where they recommended and required just that! For a brief time tandeming motors (gluing two motors end to end) was allowed, but was later disallowed. Plugging a booster motor with epoxy was never allowed, but you could plug it with a removable cork. I have never corked a motor, but I understand that it works. I have not read of this being disallowed, but I can't read everything and I may have missed it. Your plastic plug would be equivalent to the cork.

For the OP, it is not hard to vent the blow through gasses. It is not as powerful as an ejection charge. I've even seen cases where nothing was vented, and the motor was retrained, with no damage.

 

[TeslaPenguin1]

You mentioned a linear 3 engine cluster. I'm wondering if that means side pods, or are all three going into a central tube? If using side pods and motors with an ejection delay, provisions need to be made for the ejection gases. Blowing out the spent engine casings is not allowed at some launch meets. Venting to the central tube or nose cone blow with shock cord are options.

Yes, I am using side pods.

 

[kuririn]

Yes, I am using side pods.

O.K., that clears thing up. If you are flying at a sanctioned meet. you need to follow the sanctioning body's rules, be it Tripoli or NAR. That may mean no home made plugged motors, and no ejection of spent casings, although some meets do allow motor ejection.

If you are flying privately on your own you have more leeway, but it is advisable to still adhere to safety rules as stipulated in the NAR code. I assume you want to plug the side motors because you are looking for a simple solution of dealing with the blowby gases from the booster motors? The Hydra 7 uses a wooden block in the pod tube above the booster motor. The 6 pod motors are friction fitted with tape to prevent ejection, and the blowby gases go out the nozzle. I suppose you could get the same result with a glued in nose cone, but make sure it's securely glued because I've seen soot and charring on the outside from gases leaking past a glued nose cone. This is for booster motors only with no ejection charge.

 

[TeslaPenguin1]

O.K., that clears thing up. If you are flying at a sanctioned meet. you need to follow the sanctioning body's rules, be it Tripoli or NAR. That may mean no home made plugged motors, and no ejection of spent casings, although some meets do allow motor ejection.

By spent casings, do you mean the used up single use motors? Or only for reusables? Because I've seen quite a few rockets that eject their single-use motor after it is used up for featherweight recovery.

 

[kuririn]

Yup, spent casings are used up motors. And yes, there are kits that eject the motors, but some meets and RSOs do not allow this. Check with the RSO first. I think that is due to concerns about fire hazards and littering. Of course, if you are launching on your own, that's different. But still a good idea to pick up spent engines, wadding, and igniters before you leave. We try to leave the area as clean as when we arrived.

See my old thread about plugged motors for r/c gliders here:https://www.rocketryforum.com/threads/question-on-plugged-motors.144038/

Good answers from knowledgable forum members there.

 

[BDB]

Why no just use -0 motors and drill small holes on the outside of the boosters to vent to the outside of the rocket?

 

[kuririn]

Why no just use -0 motors and drill small holes on the outside of the boosters to vent to the outside of the rocket?

That is an option. See my reply on this thread (post #4):

https://www.rocketryforum.com/threads/clustering-with-pods.147483/

External slots or holes will show charring or soot, may not be aesthetically desirable especially on a light finish.

 

[jmuck78]

Yes, I am, modifying a motor in any manner not specified by the manufacturer makes it EX. Granted most people just ignore the fact its a little bitty LPR motor and do it anyways. If someone is caught flying a modified motor at our clubs launches on a non-research event it could very well mean a permanent ban.

https://www.nar.org/safety-information/model-rocket-safety-code/

Number 2: 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.

And the Tripoli Research Safety Code specifically prohibits non-commercial black powder motors.

So a modified, and yes plugging a -0 motor is modification since the manufacturer did not make it that way.

NAR and TRA representatives feel free to weigh in.

Many composite motors have black powder wells with removable red plugs - removing the red plug, disposing of the black powder, then replacing the plug should not be considered modifying the motor - for the same reason that epoxying the ejection charge on a D12-0 is not considered modifying the motor. The intent of that rule is to preclude people from modifying the nozzle, the casing, or otherwise compromising the safety of the motor. Removing the black powder doesn't make the motor less safe.

 

[Alan15578]

Many composite motors have black powder wells with removable red plugs - removing the red plug, disposing of the black powder, then replacing the plug should not be considered modifying the motor - for the same reason that epoxying the ejection charge on a D12-0 is not considered modifying the motor. The intent of that rule is to preclude people from modifying the nozzle, the casing, or otherwise compromising the safety of the motor. Removing the black powder doesn't make the motor less safe.

There seems to be some misinformation above.

To be fair, in this brave new world of re-loadable motors and electronic ejection, the NAR has more acceptance of rocketeers using pyrotechnics, e.g. creative ejection charges that would have been prohibited ages ago. To safely deploy the recovery system, you could probably add some loose BP to the end of an Estes motor and just tape over it. I doubt Estes or the NAR would permit you to crack open the clay seal and remove some of the ejection charge. Removing all of it would NOT be safe in normal use. OTOH, if you are using old Estes motors with the paper end cap, they often come loose in storage and handling and need to be carefully repacked before use.

Peeling down a D12 case to fit into 21mm engine mount is hard work and a bad joke (Rick Gaff). I have long thought that rocketeers should be able to blueprint a motor. That is, take a poorly manufactured and delivered motor, and "modify" it back to its certified specs. But that is another can of worms.

 

[jmuck78]

There seems to be some misinformation above.

To be fair, in this brave new world of re-loadable motors and electronic ejection, the NAR has more acceptance of rocketeers using pyrotechnics, e.g. creative ejection charges that would have been prohibited ages ago. To safely deploy the recovery system, you could probably add some loose BP to the end of an Estes motor and just tape over it. I doubt Estes or the NAR would permit you to crack open the clay seal and remove some of the ejection charge. Removing all of it would NOT be safe in normal use. OTOH, if you are using old Estes motors with the paper end cap, they often come loose in storage and handling and need to be carefully repacked before use.

Peeling down a D12 case to fit into 21mm engine mount is hard work and a bad joke (Rick Gaff). I have long thought that rocketeers should be able to blueprint a motor. That is, take a poorly manufactured and delivered motor, and "modify" it back to its certified specs. But that is another can of worms.

Please be specific about the misinformation - i was referring specifically to single use composite motors that use red plugs to hold in the black powder ejection charge. Those plugs are not glued in place and are easily removable and replaceable without damaging the motor.

 

[dhbarr]

Please be specific about the misinformation - i was referring specifically to single use composite motors that use red plugs to hold in the black powder ejection charge. Those plugs are not glued in place and are easily removable and replaceable without damaging the motor.

I agree with: dumping loose powder is not usually considered a modification.

I disagree with: epoxying the top of a d12-0 is not usually considered a modification.

 

[TeslaPenguin1]

Please be specific about the misinformation - i was referring specifically to single use composite motors that use red plugs to hold in the black powder ejection charge. Those plugs are not glued in place and are easily removable and replaceable without damaging the motor.

I'm not using composite motors as I am pretty new to model rocketry.