AT AP in rockets with baffles

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TALON

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When I moved up to Mid Power, the rockets I built did not have a baffle. The 1st one with a "baffle" was the AT Arreauxbee-Hi, with the standard wire mesh. Then I scratch build a 24MM ARCAS and I installed a Semroc baffle w/ the holes in the bulk heads. Due to covid they are both awaiting their maiden flights. Then I was watching a video and there was a comment about the plastic ejection cap how it can damage the baffle and or get stuck in the body tube between the baffle and the motor mount. Now I think it will not be a problem in a AeroTech, but a rocket with a baffle will have issues. The solution in the video, suggested removing the plastic cap and using tape. Now if this is the best remedy, how hard is it to remove it without spilling the powder, and what would the ideal tape be. And is there any other way to avoid this issue. Many thanks to anyone who can help me with this issue.
 

dhbarr

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You can use a sticker, as with older AT reloads. Or you can use masking tape. I wouldn't recommend electrical or duct tape on a reloadable case as that would just be more goo to clean off.
 

mikec

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I've had the Semroc baffles completely blow out of the rocket when flown with AT motors, so I suggest using less BP if possible.

Masking tape works fine with most AT RMS motors but I've always used the plastic cap with the Hobbyline motors since the well is very small.

Are we talking about AT SU motors or reloads?
 

TALON

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I've had the Semroc baffles completely blow out of the rocket when flown with AT motors, so I suggest using less BP if possible.

Masking tape works fine with most AT RMS motors but I've always used the plastic cap with the Hobbyline motors since the well is very small.

Are we talking about AT SU motors or reloads?
Reloads, I forgot to mention that SU would solve that issue of the cap. Were you using SU or reloads when you had the baffle blow out? The baffle will be subjected to 24MM charge. Less BP for the charge and tape woild be a solution for the semroc baffled rocket.
 

Bowman

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SU E20 in a BT-60 rocket with a Semroc baffle. https://www.erockets.biz/semroc-ejection-baffle-kit-conical-fiber-bt-60-sem-eb-60/

In all honesty, I'd just not use the baffle myself.
I have had good luck with baffles.
You just need to be resigned to cleaning-out the mesh periodically.
Don't use the red caps, usually too-much space in them anyhow that you should take-up with some flameproof wadding.
BTW, tape will clog the mesh too.
Not that big a deal to replace it periodically if you build it right.
 

BEC

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I like baffles in everything I build BT-55 and larger. As such I’ve had a few blow out....and not just with Aerotech motors. I have a 24mm-mount-equipped Big Bertha that’s had the Semroc baffle blown out by an Estes D12. Maybe that just says something about how well I get them installed. And short models, where the baffle has to be close to the motor mount in order for there to be room for the recovery system are more of a challenge.

I can’t imagine that the plastic caps on an Aerotech reload would do that, though I suppose it is possible. Getting it out after a flight is just a matter of shaking the model until the the cap (or the rubber plug from an SU motor) bounces out via the motor tube.
 

shawn_rocket

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When I moved up to Mid Power, the rockets I built did not have a baffle. The 1st one with a "baffle" was the AT Arreauxbee-Hi, with the standard wire mesh. Then I scratch build a 24MM ARCAS and I installed a Semroc baffle w/ the holes in the bulk heads. Due to covid they are both awaiting their maiden flights. Then I was watching a video and there was a comment about the plastic ejection cap how it can damage the baffle and or get stuck in the body tube between the baffle and the motor mount. Now I think it will not be a problem in a AeroTech, but a rocket with a baffle will have issues. The solution in the video, suggested removing the plastic cap and using tape. Now if this is the best remedy, how hard is it to remove it without spilling the powder, and what would the ideal tape be. And is there any other way to avoid this issue. Many thanks to anyone who can help me with this issue.
Ground test it if you can. My first AT Arreauxbee-Hi lawn darted. I believe I didn't have the mesh stretched out enough or nose cone was not tight enough or both. I now ground test any new rocket or design to insure the ejection mechanism/baffle works properly.
 

Sooner Boomer

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You can build your baffles so they're almost impossible to blow out.

 

Back_at_it

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I've not had issues with baffles blowing out yet but I haven't flown anything larger than a G motor in anything. I do build my baffles with plywood or use manufactured version made of plywood. I'll also "paint" the complete baffle with thinned wood glue to offer up some fire protection. So far so good even on AT motors.
 

mikec

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I have had good luck with baffles.
To be clear, I have also had no problems with the Aerotech kit baffles, with the red cap, which is just loose after flight.

It's some styles of Semroc baffle that I have had blow out. YMMV.
 

Bowman

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To be clear, I have also had no problems with the Aerotech kit baffles, with the red cap, which is just loose after flight.

It's some styles of Semroc baffle that I have had blow out. YMMV.
Truth be told, I really prefer pistons over all. The big downside for me is the space required, even when built as small as practical.
You can t build them too small or they may cock and jamb in the body tube.
I do like them best though for protecting the recovery system.
I build them to slide on the strap and then tie a knot below to keep too-much strap from ending up on top of the piston.
So-far they have been very trustworthy when I use them.
 

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