Ventris Baffle

I'm attempting to build my first ejection baffle for an Estes Ventris. I cut out three circles out of 1/4" plywood with a hole saw and cut two for half moons (little more than half a moon) and left one whole for the shock cord mount. I attempted to drill 8 holes in the shock cord mount circle but the wood broke off at the edges. I don't have a drill press so the holes were hard to get consistent. I cut another baffle and drilled only 4 holes this time. I'm going to coat all the pieces with 30 minute epoxy before mounting inside the coupler. It's not pretty but I'm wondering if this baffle will hold up sufficiently to the ejection gas pressures with only the 4 holes or am I likely to see this baffle blow out?

I would do 3 "half moons", instead of 2 "half moons" and a perforated disk. It will still trap the vast majority of the flaming bits. Also, makes it easier to clear the baffle.

Greg

GregGleason said:

I would do 3 "half moons", instead of 2 "half moons" and a perforated disk. It will still trap the vast majority of the flaming bits. Also, makes it easier to clear the baffle.

Greg

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If I go with a third half moon, how should I attach the shock cord?

What I do is attach the cord around the motor mount behind the forward centering ring, then run it up through the center hole left by the hole-saw. I might have a picture of it , I'll have to look though.

Hmmm ...

If you have an eyebolt and another piece of wood (call it "anchor wood"), like about 3/4" x 3/4" x 1/3rd.baffle.length, you could glue the piece between the upper and middle plate, with one side flush against the baffle. That way there would be lots of surface contact on the side. Then screw the eyebolt into the top plate, where the centerline of the eyebolt is in the middle of the "anchor wood" end. You might want to pilot drill a hole first to minimize the risk of the wood splitting. I hope that makes sense. There are lots of ways to do this.

Greg

I like to duplicate the Aerotech system with a Chore Boy and a perforated disk. This is the easiest to construct.

I also like the Semroc baffle: One tube facing back, one tube facing front. Air needs to turn 180 deg two times.

I never did well with moons and disks. Still burned the chute. Try to make a very tortuous path for airflow:3 half+ moons and a perforated disk!

This is how I did my VENTRIS. I think it was 4 half moons, works very well without adding a lot of weight.

JJSR said:

This is how I did my VENTRIS. I think it was 4 half moons, works very well without adding a lot of weight.

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Just got my Ventris today and I'm thinking about a baffle... Which section did your baffles go in? The coupler or the upper body tube? What sort of gap did you leave between them? Did you make them yourself or buy them? Cut them with a hole saw? How have they stood up so far? What kind of cord is that? It looks ... beefy.

And do you just rest your 'chute on top of the baffles? Wad it up and hope for the best?

(all of this said, I kind of like the idea of a Semroc-style baffle, which sounds like it works like a car muffler. Lots of parts and delicate assembly, but it seems like it would work really well.)
Thanks!

ActingLikeAKid said:

Just got my Ventris today and I'm thinking about a baffle... Which section did your baffles go in? The coupler or the upper body tube? What sort of gap did you leave between them? Did you make them yourself or buy them? Cut them with a hole saw? How have they stood up so far? What kind of cord is that? It looks ... beefy.

And do you just rest your 'chute on top of the baffles? Wad it up and hope for the best?

(all of this said, I kind of like the idea of a Semroc-style baffle, which sounds like it works like a car muffler. Lots of parts and delicate assembly, but it seems like it would work really well.)
Thanks!

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I used the coupler, cut with a hole saw. Since I didn't have the exact size hole saw for them to fit right in the coupler, I cut them in half so I didn't have to sand them too much to fit. I divided the coupler into forth's glueing the inner ones first and worked my way out. Used a wire to fish the Kevlar (not sure what size 1/4"?) cord through it and glued coupler in the BT's. The Kevlar cord is heavier then is needed I used what I had on hand.
Little dog barf down in there, chute on top and its good to go. its held up just fine no burns in chute so far, couldn't say how many flights I've done lost count after the first 10 or so :wink:

Perfect, exactly the info I needed. Thanks.

If you don't have the tools or materials to cut your own baffles, https://www.balsamachining.com/ has them available. They're not listed on the website but if you email them they have them. I ordered a couple for several other Pro Series builds I have including another Ventris. For my Ventris baffle I used two half moons in the coupler aft and center and a full circle bulkhead with holes drilled around the outer edge and a center hole for an eyebolt to attach the Kevlar cord. I flew it with just a single sheet of wadding and the bundled chute just inside the body tube and she worked fine. This is the Kevlar I use for most of my builds https://www.amazon.com/dp/B008ROSCX8/?tag=skimlinks_replacement-20