Baffle? I have been baffled by the baffle?

I have been reading alot about baffle this and baffle that recently, but what exactly is it, how does it work, and what exactly is it's purpose?

A baffle is a device that replaces Dog Barf, wadding or chute protectors. Primarely used on low andmid power rockets.

There are several different designs but they all basically block direct access to the chute from the deployment charges hot gasses and burning bits of materiel. The pressure wave is channeled through a series of direction changes so that what eventually blows the chute out is cold enough not to burn/melt your recovery device.

Ok, so does it entirely eliminate the need for wadding?

How is one constructed?

Can it be added to an existing rocket? Or do I need to put it in when I start building?

It's like a car muffler....

Sadly I don't entirely know how to build a car muffler....
Thanks anyway?:eyeroll:

boomtube said:

A baffle is a device that replaces Dog Barf, wadding or chute protectors. Primarely used on low andmid power rockets.

There are several different designs but they all basically block direct access to the chute from the deployment charges hot gasses and burning bits of materiel. The pressure wave is channeled through a series of direction changes so that what eventually blows the chute out is cold enough not to burn/melt your recovery device.

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This statement is not entirely true. A baffle that causes direction changes in the pressure flow does not cool the hot gasses created by the ejection charge.

Imagine you have just launched a rocket that is using a baffle, and that baffle is using three internal half moon plates to redirect the hot pressurized gas created by the ejection chrage.

When that rocket left the launch pad, the air that's filling the recovery gear compartment and the baffle is aprox. the same temp. as the cool air you are breathing.

This already "cool" air has to go somewhere when the hot ejection gasses are pressurizing the tube and and looking for the path of least resistance to escape.

All of the following happens like dominos falling:

the hot pressurized gasses travel up and thru the baffle
particulate in the ejection gasses strike the plates in the baffle and fall out of the air stream
as hot pressurized gasses travel up and thru the baffle it's pushing out the "cool" air that's already in the baffle and parachute compartment (remember this "cool" air has to go somewhere)
when the nose cone is blown off it is followed by the recovery gear, which is still surrounded by the "cool" air that went up with the rocket at lift off.

That is why no wadding is absolutly needed.

It's like the up stroke of a piston.
Eh?

Now That makes sense!

Very helpful indeed, Thanks so much!!

Now as to how to make it, Where to place it, what to make it out of, DIY or buy from somewhere, if so where, best hole shape, how many layers, oh gosh that's a lot of questions...

nute said:

Sadly I don't entirely know how to build a car muffler....
Thanks anyway?:eyeroll:

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They are extremely simple devices. Sorry, thought you'd have a rudimentary idea of how they work.

Fred Garvin said:

They are extremely simple devices. Sorry, thought you'd have a rudimentary idea of how they work.

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Sorry, that was kinda harsh on my part.

No worries Nute.....Baffles are really simple and once you dig in a bit you'll see....how effective they are....well, that can be up for debate and design.....

Well as with most rocketry things I would assume a large part of it is up to the builder and designer to determine its effectiveness.

Is there any minimum or maximum BT diameter that they work best with?

nute

One other thing a baffle does is block burning chunks of propellant from hitting recovery gear. When a BP motor blows, everything inside can blast up and out. I've seen fairly large bits of burning debris come out of 24mm BP engines

Here is a 3 part post in a blog on how to build your own baffle by the master.

https://www.modelrocketbuilding.blogspot.com/2010/08/do-it-yourself-baffle-part-1.html
https://www.modelrocketbuilding.blogspot.com/2010/08/make-baffle-part-2.html
https://www.modelrocketbuilding.blogspot.com/2010/08/do-it-yourself-baffle-part-3.html

I followed these steps and added a baffle to a Big Bertha I'd built a year earlier and it works GREAT! No wadding at all, and the chute comes out just fine.

Many companies also make baffle kits for the different tube sizes. The steps above show how to build one type of baffle, but there are others. The one above has holes that don't line up, other kinds include the half circle shapes that alternate which side of the tube they're on. Pretty much anything that gives the pressure of the ejection to escape but blocks the burning pieces should work.

Here is a drawing of the baffle I used in my Vagabonds. It was made from 1/16" ply and a tube coupler.

Nute here is one I made for a BT60
I'll bring it tomorrow so you can see it, simple to make View attachment 139399View attachment 139400View attachment 139401

Fliskits sells them as kits you can add to your rocket...

Later! OL JR

I'm building a Leviathan right now, and I'm debating building one or just ordering one. I need some Kevlar anyway....and the cost of a 3" coupler plus 2 bulkheads isn't much less than a pre-made baffle....so might as well....besides a couple bucks the only thing I'm losing is the satisfaction of building my own.

Mushtang said:

Here is a 3 part post in a blog on how to build your own baffle by the master.

https://www.modelrocketbuilding.blogspot.com/2010/08/do-it-yourself-baffle-part-1.html
https://www.modelrocketbuilding.blogspot.com/2010/08/make-baffle-part-2.html
https://www.modelrocketbuilding.blogspot.com/2010/08/do-it-yourself-baffle-part-3.html

I followed these steps and added a baffle to a Big Bertha I'd built a year earlier and it works GREAT! No wadding at all, and the chute comes out just fine.

Click to expand...

I came across that looking for his Saturn V build....I'm sure it's effective....but I can't help thinking that if you turn it over it will "moooo"......

The smallest diameter baffled rocket I'm aware of is the Bandit, and it uses a BT55 as its main body tube...

https://www.semroc.com/Documents/pdf/Bandit.pdf

For other baffle designs I found this:

https://www.apogeerockets.com/downloads/newsletter129.pdf

nute said:

I have been reading alot about baffle this and baffle that recently, but what exactly is it, how does it work, and what exactly is it's purpose?

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I have been using baffles in all my builds of BT60 tubes and larger.My good friend Jim aka as "qquake2k" showed me how to make one over a year ago.If you have hole saws of a circle cutter,they are very easy to make.3 half moons and a top plate.Works great with no barf of tissue.My chutes look brand new with no burns.

I have been using baffles in all my builds of BT60 tubes and larger.My good friend Jim aka as "qquake2k" showed me how to make one over a year ago.If you have Click image for larger version.

hole saws of a circle cutter,they are very easy to make.3 half moons and a top plate.Works great with no barf of tissue.My chutes look brand new with no burns.

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That's good to know!

I do hate using the wadding...

For other baffle designs I found this:

https://www.apogeerockets.com/downloa...sletter129.pdf

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Nice document there!!

That has many good designs!!

I saw some baffles for sale from Semroc. Those look like a possibility for me, If I can't build one (or am too lazy...)

The aerotech kits use a baffle that uses this type of material as a baffle.



There is a lot of debate on here as to whether they clog, but I have not had a problem (Yet :wink

luke strawwalker said:

Fliskits sells them as kits you can add to your rocket...

Later! OL JR

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That is pretty cool!
Will definitely have to check it out!

The aerotech kits use a baffle that uses this type of material as a baffle.
There is a lot of debate on here as to whether they clog, but I have not had a problem (Yet )

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I was looking at some Aerotech kits and I saw this, but for a rocket not designed for it (or otherwise) It looks to me like it could clog IMHO

JJSR said:

Nute here is one I made for a BT60
I'll bring it tomorrow so you can see it, simple to make View attachment 139399View attachment 139400View attachment 139401

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Great!!

Do you plan to go today? Weather looks iffy?

Aero Antics said:

Here is a drawing of the baffle I used in my Vagabonds. It was made from 1/16" ply and a tube coupler.


View attachment 139393

Click to expand...

Very Cool!
That seems like a good design!

Mushtang said:

Here is a 3 part post in a blog on how to build your own baffle by the master.

https://www.modelrocketbuilding.blogspot.com/2010/08/do-it-yourself-baffle-part-1.html
https://www.modelrocketbuilding.blogspot.com/2010/08/make-baffle-part-2.html
https://www.modelrocketbuilding.blogspot.com/2010/08/do-it-yourself-baffle-part-3.html

I followed these steps and added a baffle to a Big Bertha I'd built a year earlier and it works GREAT! No wadding at all, and the chute comes out just fine.

Many companies also make baffle kits for the different tube sizes. The steps above show how to build one type of baffle, but there are others. The one above has holes that don't line up, other kinds include the half circle shapes that alternate which side of the tube they're on. Pretty much anything that gives the pressure of the ejection to escape but blocks the burning pieces should work.

Click to expand...

Very nice websites!
That seems like a nice simple design. Maybe good for my Phoenix or Maxi Alpha 3?

FlisKits has baffles for BT-20, 50, 55, 60, & 70 tubes.

The 2 smallest use the half-moon style baffle plate while the others use a pair of perforated plates (see attached image)

You can find all of our baffles on our misc components page (on the bottom of the page) here: https://fliskits.com/products/components/misc.htm

Hope this helps