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Looking to build a baffle on a BT-80 based rocket

  • tlainhart
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3 weeks 3 days ago #11352 by tlainhart
I'm building a BT-80 based rocket, and decided now might be a good time to build an ejection baffle for it. Any tips?

Left to my own devices (which is typically problematic), I would take a BT-80 coupler I have lying around, close its ends with BT-80 motor mounts (after closing their center holes), and punch/drill non-aligning holes on either end. Maybe stuff it with porous steel wool?

Perhaps it's time to consult "The Handbook..."

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3 weeks 3 days ago #11354 by TimDawson
I use to be a baffle man, before I was a piston man.  A coupler with offset holes on each end, like I think you said, always worked well for me.  You can improve "filtering" by adding tubes to the holes, especially the upper/touching parachute holes.

After going to pistons, I don't think I'll ever build another baffle.

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  • DeltaVee
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3 weeks 3 days ago #11355 by DeltaVee
Here is a shot from my gallery post showing the guts of my favorite baffle design...  I've used this with good results... the one shown is in my bt70 three motor cluster...  my super Bertha uses the same design.  The main advantages are 1)you don't have to worry about moving parts possibly jamming 2) this design makes it very easy to shake out the bits of detritus that inevitably accumulate.

cmass.org/index.php?view=image&format=ra...omgallery&Itemid=300

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3 weeks 3 days ago #11358 by KennB
I think steel wool could be a problem. It may sustain glowing bits. Something like a Chore Boy scrubber, a thin ribbon of stainless steel tangled on itself, is what is comes with Aerotech models, but someone who has used this should confirm or correct me.

As Dr. Strangelove recommended, a bypass style is less prone to clogging. Here's a TRF thread on the subject with some good info and links to sources. Here's an eBay site for BT-80 baffles.

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  • tlainhart
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3 weeks 3 days ago - 3 weeks 3 days ago #11361 by tlainhart
Thanks Kenn. Those are great links. I knew that steel wool wasn't the right intermediary material, but lacking your and John's photographic memory, couldn't come up with the name of the wiry pot scrubber (scrubbing bubbles didn't seem right).

John - you'll have to explain to me your design on a call or the field. I'm not getting how the pressurized gases are transmitted from the picture.
Last edit: 3 weeks 3 days ago by tlainhart. Reason: typos

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3 weeks 3 days ago - 3 weeks 3 days ago #11362 by TimDawson
On John's baffle, the white tube fits up inside the red tube a bit. The "bulkhead/rings" are glued to each end of the coupler, which makes sure there is room for the gas to escape out of the white tube and around the red.  Gases have to go up > down > up.  Cool design, John.

I would think adding metal filtering material must add some weight.  Between the metal filter material and that Eyebolt on the EBay site baffle, holy crap!
Last edit: 3 weeks 3 days ago by TimDawson. Reason: up instead of down

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