New Trailer Build (Preplanning)

[jfluckey]

By trade I am a structural engineer.  I have at my disposal drafting and structural analysis software. That being said, I want to provide public plans and bill of materials for a rectangular (not a tank mod.) reverse flow smoker. I will be looking for feedback on these plans in upcoming months as my building funds won't be available for quite a while.  The smoker will be ~10' long (not including fire box) and 4' wide. The trailer will be wide enough to haul folding chairs and tables. I plan on a utility box for other tools and goodies on the hitch.

Is it out of convenience that everyone uses tanks to modify into smokers, or is there a benefit of a round tank over my design?

Not shown, but already calculated are counterweights on the doors for aid in opening, closing, keeping open, and keeping closed.

Take a look at my preliminary sketch and let me know your thoughts and maybe answer some of my questions.

 

[daveomak]

JF, morning and welcome to the forum.....  A friend of mine built a commercial smoker at his home that had some similar ideas built into it...

Below is a calculator to help with the critical measurements....

http://www.feldoncentral.com/bbqcalculator.html

The shelves on the left...   A 5x4 shelf full of meat will be heavy...  consider building them 5x2 and having doors on each side...  French Doors might be more forgiving also....  Shelves at eyeball height may be hard to manage...  

The smoker design is 1200 gallon equivalent..... That would feed 1000 people ....   Big smoker .....  You might consider a 3 axle trailer to haul it also....  

 

[bruno994]

Starting a catering business or restaurant?  Wow, this one's gonna be big.  On the tank question, round tanks (propane, air or old oil tanks are just more readily available and cut down on the fab work of constructing a box).  I do like the idea, but maybe not on such a grand scale. If and when I build another smoker, it will be an upright, but quite a bit smaller than your plans.  Don't forget about using the top of the RF plate as a water pan to steam the meat.  On the doors, either french door style on both sides of the smoker as Dave suggested or for sure gas shock assist.  gas assist would probably be better than counterweights.  With the french doors you will lose some space, but they will be much easier to work with.  As far as the depth, even with pull out grates, it's going to be hard to get to the back of a 4' deep grate to handle or pick up meat.  Even 3' deep would be a big stretch. 

 

[jfluckey]

Dave,

Thanks for the reply.  I guess I never calculated the size feeding that many people.  That is more than I will ever need.  Maybe I will scale it back to half that!

Your 5x2 french door idea: This would eliminate needing to crouch below heavy and hot doors if eye-level racks are not a good idea.  So (4) door panels with vertical hinges instead of (2) larger door panels with horizontal hinges?

The calculator: I had found that but I was a little confused.  Does the cooking chamber include the reverse flow chamber (i.e. 10'x4') or subtract the reverse flow (10'x3'-2")?  Also, the firebox volume confused me.  Should the volume of my firebox above the grates be what the calculator is calculating and the volume below the grates just need to be big enough for the required inlet openings and catching ash?  Finally, why is the chimney length calculated instead of just the exhaust area?  Is it calculating volume in the chimney, such that using (2) stacks with the same diameter would reduce the required chimney height by 2?

Bruno,

Water and steel? What do you do to the RF plate to keep it from rusting?  Just a high temperature paint sufficient?

Also, the racks will slide out.  That is part of the design that I have to do.  I will let them support their own weight even when slid out maybe 2'.  What is the consensus on weight per square foot? 200 lbs on the 5x4 rack would be 10 psf.  Is this enough?

 

[daveomak]

Dave,

Thanks for the reply.  I guess I never calculated the size feeding that many people.  That is more than I will ever need.  Maybe I will scale it back to half that!

Your 5x2 french door idea: This would eliminate needing to crouch below heavy and hot doors if eye-level racks are not a good idea.  So (4) door panels with vertical hinges instead of (2) larger door panels with horizontal hinges?  I thought French door would would be easier to access food and eliminate the counter weights....

The calculator: I had found that but I was a little confused.  Does the cooking chamber include the reverse flow chamber Yes (i.e. 10'x4') or subtract the reverse flow (10'x3'-2")?  Also, the firebox volume confused me.  Should the volume of my firebox above the grates be what the calculator is calculating and the volume below the grates just need to be big enough for the required inlet openings and catching ash? I would have to assume the firebox size includes ash removal area allowing for air flow also....   The firebox should be even with the reverse flow plate... I would slide the firebox inside the smoker 18-24" and use the top of it for part of the reverse flow plate...  That would reduce some of the heat loss from the firebox also...  Finally, why is the chimney length calculated instead of just the exhaust area? The chimney calculation is based on volume and the length is based on exposure to cold air.....  Is it calculating volume in the chimney, such that using (2) stacks with the same diameter would reduce the required chimney height by 2? I'm not sure if that double stack is a direct correlation... don't forget friction loss on the sides of the stack comes into play...

The calculator states a smaller firebox can be used but I would base all the calculations on originally recommended dimensions to insure proper air flow etc...  In a convection apparatus such as this smoker, air flow is critical for proper performance.....  

About the stacks.... I'm not sure if having them that low is a good idea.....  You might consider attaching the stack to the smoking chamber midway between the reverse flow plate and the top of the smoke chamber.... don't know why, just seems logical for some reason I can't explain.....  Dave 

 

[smoke_chef]

Jfluckey,

Thanks for the idea of providing plans and a material list. That would be crazy awesome!!

Also, just curious if you've seen the RF's with what some people call a "rib box" or a "warmer box"? I'm planning a build and I think I want it. I just thought I would get your opinion at this stage of your build.

Oh... somewhere I saw where someone had one of these rib boxes. He set it up to where he could smoke in the whole thing... or shut of the the horizontal part (the traditional part of a RF) and smoke in only the rib box. Seemed like a great design but now I can't find it. Maybe someone that reads this will know who's it was.

Good luck on this. I'll be watching.

Smoke_Chef

 

[jfluckey]

I was never quite sure what those boxes were for or how they were set up.  At one point I thought they were for cold smoking, but didn't know how the temperature would be regulated.  I still don't know how they are to be constructed... is it just a box that is separate from the smoke for keeping cooked items warm?

Sorry for the delay for anyone coming to this thread. I don't have much motivation to do the drawings as my budget won't allow this build for at least a couple years and I don't think anyone is waiting on this to be finished.  If you would like me to finish the design, let me know. I don't mind working on it, but like I said, if it is just for me I have a couple years.

I was thinking of designing the trailer, but I was also suggested to purchase a trailer. Anyone else have any thoughts on this?