Plugging Estes Booster Engines?

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Darian Rachal

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Is it against one of the rocketry rules to plug a booster(ex. with epoxy) for certain applications where you want to limit exposure to the heat of the BP burning through? I know that one is not supposed to modify an engine, but was wondering if this counted?

Thanks,
Darian Rachal
 
Officially, according to the rules, yes...

Has it been done, or is it done-- also yes...

If something happens on the flight can the insurance coverage not indemnify (cover the damages) due to the flight using "modified" motors, therefore being in contravention of the Model Rocket Safety Code... yes... if they find out.

Just FYI...

Later! OL JR :)
 
IANAL. I do hear that it's easier to plug regular motors than -0s. If one scrapes out the ejection charge, the delay grain remains. When delay grain burns, it produces a lot less pressure than the BP in a -0 motor. So your plug needs to withstand less pressure and is less at risk of failing. Just what I hear.

Also... Estes casings nest: 24mm fits in a 29mm, 18 fits in 24 etc. I wonder if you take a spent casing, plug its nozzle and then friction-fit that into your booster motor... if that constitutes a case modification.

Ari.
 
Estes 24mmmotors do NOT fit inside Estes 29mm motors. You would need to peel away the inside of the 29mm motor.

The others all nest.


Scraping out the ejection charge is clearly modification of the motor.


The easiest method: Buy plugged motors.

A10-PT

When available: D11-P, E9-P

https://www.rocketryforum.com/showthread.php?59787-Who-wants-Estes-D11-P-motors

iter said:
IANAL. I do hear that it's easier to plug regular motors than -0s. If one scrapes out the ejection charge, the delay grain remains. When delay grain burns, it produces a lot less pressure than the BP in a -0 motor. So your plug needs to withstand less pressure and is less at risk of failing. Just what I hear.

Also... Estes casings nest: 24mm fits in a 29mm, 18 fits in 24 etc. I wonder if you take a spent casing, plug its nozzle and then friction-fit that into your booster motor... if that constitutes a case modification.

Ari.
Click to expand...
 
Thanks for all the responses. I was just thinking of a project where a couple of plugged engines(in a cluster) would be appropriate.
 
Darian Rachal said:
Thanks for all the responses. I was just thinking of a project where a couple of plugged engines(in a cluster) would be appropriate.
Click to expand...
If it's not a scale model, leave the motor alone and put vent holes in the motor mounts to dispose of the gas produced by the booster motors.

If there's room to put a motor into a larger casing, there's also room to put the vent holes into the centring rings, or instead of rings, to use strips of balsa whose thickness equals the difference between the motor mount outer radius and body tube inner radius. The gas can then vent out of the back between the strips.
 
You can hold most of the gases back by using a dowel and o ring like this:

P1010028.jpg

It's removable so it's not modifying the motor. You do need solid motor retention for it to work. As a bonus you get a little extra total impulse:

graph.jpg
 
billspad said:
As a bonus [when using a plug] you get a little extra total impulse:

attachment.php
Click to expand...

Thanks, Bill. I notice we get that extra impulse with the epoxy plug, too ;)

Doug

.
 
Last edited:

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