Question on AT J510W - A Close Call or Normal Operation?

I flew an AT J510W for the first time last month and it made some loud chuffing sounds during the burn that gave the impression of chunks of material blocking the nozzle and then getting ejected. Is this typical; or a close call that indicates I might not have assembled the motor correctly? The J510W has rubber ring spacers between the grains (first time I have seen that) and I am wondering if those were what was getting ejected. Or is it something else? There are some spikes in the axial acceleration that suggest very brief interruptions in thrust.
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Here is a video where you can hear the sounds during the burn.
[video=youtube;Q3IE2sUYqxY]https://www.youtube.com/watch?v=Q3IE2sUYqxY[/video]

What you are hearing are the remains of the casting tubes getting blown through the nozzle.
You will see that on long motors unless you glue in the grains.

JD

it sounds normal to me.

Ditto, Casting remnants blowing out the end. I've flown 5 of these, Sometimes I hear it, sometimes I don't. Nice flight incidentally. I envy you
Westerners wide open spaces. Kurt

This was the one I burned.... didn't have the pops.
https://youtu.be/28_wEDGHnb0?t=45s

Like JD said, likely just liner spitting out.

the rings are spacers to make sure the ends of the grains all start right at the beginning of the burn

Not the liner... otherwise the casing would meltdown.


JD

DizWolf said:

This was the one I burned.... didn't have the pops.
https://youtu.be/28_wEDGHnb0?t=45s

Like JD said, likely just liner spitting out.

the rings are spacers to make sure the ends of the grains all start right at the beginning of the burn

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JDcluster said:

Not the liner... otherwise the casing would meltdown.

Click to expand...

Yea casting tube. I just spell it funny.

Thanks everyone for the replies. Sounds like the chuffs are normal operation, which is good to hear. I will be flying more J510W motors soon... they are pretty awesome.

WoShuGui said:

Thanks everyone for the replies. Sounds like the chuffs are normal operation, which is good to hear. I will be flying more J510W motors soon... they are pretty awesome.

Click to expand...

Yes, this normal. I have not flown the J510, but have flown a bunch of J570 and they too do this.

If you look at many longer motors thrust curves you can see evidence of this.

The last one I flew spit a casting tube or two. Guess it's normal.

top here is a J510