My First Rocket Project - a Rocket Oven in stages

Hi folks, this is my first thread on Permies, not my first post mind you, but my first thread.  I am going to move or should I say copy (with help from one of the efficient moderators) my rocket oven posts from Daron's (of WildHomesteading Fame) thought provoking rocket oven thread.  I inadvertently hijacked his thread with my posts which was unintentional.  I just got excited sharing my progress and got a bit carried away.  Sorry Daron.

Before I posted any more rocket oven progress and design mods, I told him in the tread that I would start my own thread.

As soon as I got the low resolution version of the Permies/Paul Wheaton/Tyler Morrison kick starter video, I was off to the races, procuring drums, bricks, clay, misc refractory materials, etc.

This will not end up being an inexpensive rocket oven, but it will be a slick one when finished.  The oven is almost ready to begin testing. Tyler's oven from the video is a 2 barrel oven, but this will be a 2-1/4 to 2-1/2 barrel oven as it requires one more or half of one more steel drum.

The rocket engine is in its final stages of assembly and it will be tested as a stand alone piece first. Hopefully this will happen in the next week or so.  The stand for this oven is massive with work tables on either side of the oven and mounted on six heavy-duty casters.  It is made of 3/4" steel tubing and is presently being sanded and spray painted when weather permits.  Thank goodness for my neighbor, Greg, who is an expert welder whose welding skills made the stand possible.  I cut most of the metal, but he welded it and used his years of experience to make it come out gorgeous in spite of a couple cocktail napkin miscalculations on my part.

The changes which are shown in Daron's (WildHomesteading) Rocket Oven thread are Rev. 1.0 and 1.1 which is the basic oven as built in the Permies video, with the addition of a 3/16" steel griddle plate for the floor of the oven.  I may place a pizza stones directly on the plate as well as one on a shelf for cooking pizzas and/or bread.  The griddle can be used with the door open and all but the top shelf removed to make eggs, pancakes or whatever you want to fry up. Phil Stevens made a great suggestion on Daron's thread (which will have to wait till I have verified my other mods) to add a direct port from the engine to heat the griddle directly.  Thanks Phil!

Mods 2.0 & 2.1 beef up the insulation a bit and redirect the exhaust airflow and these mods excced the scraps of metal left over of the first 2 steel drums.  Enter steel drum number 3. Mod 2.0 adds a small panel below the hinge, constructed similarly to the insulated door assembly and fills that space with rockwool insulation.  With this mod in place the only part of the front panel which is not insulated is the 1" wide strip between the door and the new lower insulated panel.  It also makes a door support which holds the door at precisely 90 degrees to the drum when the door is open  It also provides gives a bit of a work surface if using the griddle plate to make pancakes or whatever.

Mod 2.1 uses the rest of the steel drum lid from barrel number 3 that was left over from mod rev. 2.0 and it is mounted about 2 to 2.5 inches behind the rear wall of the oven in the exhaust compartment.  The concept is that it forces all the hot exhaust gases to wash over the rear wall of the oven which should make for more even heating of that surface than the current design.  In the current design the exhaust gases exit from the outer drum though the rectangular cutout into the exhaust chamber where they then stratify and the coolest gases exit through the chamfered stove pipe.  In the mod 2.1 design. the gasses exit through the rectangular slot and wash down past the top 80 percent or so of the rear wall of the oven and then exit into the new smaller exhaust stratification chamber and similarly the coolest gases exit thorugh the stovepipe.

Other mods and progress photos will be in future posts on this thread.  For those who made it this far in my litany, I thank you for your patience and persistence.

Sincerely,

Ralph

My stove, not quite ready for prime time, but mostly completed except for the rock wool insulation and outer shell.


The second photo is with the door open showing the 3/16" steel plate griddle.  Rocket Oven 1.1.

The first substantive mod 2.0 is insulating the area below the door.  The third photo shows this in progress and the fourth photo with it complete, and the fifth photo showing that the height is adjusted to provide a door rest that holds the door at 90° when open.  This of course means that my rocket oven is a 3 barrel oven to provide the cover under the door, but.......

The next part of mod 2 is using the piece of the cover that was cut out to make the lower door cover and using it to direct the hot air thru the oven to wash the back of the oven with the hot air.  The plate is mounted about 2-1/2" behind the rear wall of the oven. When it gets near the bottom it will obviously migrate to the top of the rear area before three cooler air which has been displaced to the bottom  goes out the exhaust.  This is shown in the final photo as R.O. 2.1.

That stage of the oven was done on Nov.10, more to follow.

Looks great Ralph! Your modifications are interesting and I hope you will post your results once it is completed. Thanks for sharing the pictures of your build!

You mentioned this is your favorite topic - what makes it so interesting to you?

More photos and more engineering changes.

R.O. 3.0

I didn't like the way any of the prior ovens were mounted.  It seemed like a real well..... oversight.  The oven is wrapped in rock wool, covered with metal and dropped into a sled of sorts.  Fortunately rock wool doors not compress horribly, but if you look at the photos off all the existing rocket ovens you can see the housing is compressed by the weight of the oven.  It is a quick and ready solution and it takes care is insulating the oven without a sneak path created by a mounting structure.    

I opted for a more rigid mounting structure with a minimal heat sneak path.  This is shown in the first photo R.O. 3.0.  Basically pop riveted some short pieces of angle and constructed two mounting brackets which will mount to the frame.  There will be rock wool insulation around the oven but inside the mounting brackets and the metal cover will attach to them also.  Then the whole oven assembly will bolt in place.  This part is done, but I do not have photos to show it off yet.   We drilled plus in angle brackets on the oven stand and welded nuts onto it so that it is easily removable to take the rocket engine in and out if necessary with minimal effort and no cob involved.

I am running out of battery so this will be short and sweet.  I am creating a bracket to over engineer the interface to the rocket engine.  The photos give a good idea of what is going on.  This was in process before the holidays and it had been on an extended delay.  It will all come together for initial testing in a couple weeks.

Daron Williams wrote:Looks great Ralph! Your modifications are interesting and I hope you will post your results once it is completed. Thanks for sharing the pictures of your build!

You mentioned this is your favorite topic - what makes it so interesting to you?

It is my first actual rocket stove type product that I will have built, but will not be the last.  I am an electrical engineer, rocket scientist so-called, but this is my first foray into more of a mechanical engineering type of project.  I always enjoy doing something where I can apply my skill set to a new problem.  This is a whole new class of problems.

Very interesting modifications - I'm looking forward to seeing it all completed! Thanks for sharing!

Ralph - have you thought about cutting into the inner drum so as to direct the full force of the heat riser at the griddle plate? Maybe there's a 4.0 in the offing, with a sliding panel that converts it from normal oven to superheated griddle operation.

Phil Stevens wrote:Ralph - have you thought about cutting into the inner drum so as to direct the full force of the heat riser at the griddle plate? Maybe there's a 4.0 in the offing, with a sliding panel that converts it from normal oven to superheated griddle operation.

I am all for brainstorming.  This post to you got delayed by things beyond my control.

I had said that I have enough problems trying to get this oven completed as it is without external help coming up with some GREAT ideas to assist me.  Implying that I do enough of this on my own.  

I have to get it tested and I am going to add deflectors to evenly distributed the heat before I get something like that.  I really think it is an interesting idea and have some ideas of my own kin how to implement it. I would mechanized it by making the baffle removable from inside the oven (under the griddle plate) and make it with a seal and possibly a clamping arrangement to keep the oven from becoming a black oven.

Keep the ideas coming.  This is all about creating a better mouse trap ... er rocket oven.

Thanks.

Ralph, I'm curious how the rocket oven turned out.  Did you start a new thread?

Hi Julia,

Sadly my inertia went to other projects and my rocket oven is waiting to be completed.  The oven and stand are done and the rocket engine was about 50% done.  My garden has taken precedence and in the midst of it all, my welder friend moved back to Dallas.  I hope to get back on it in the next few months.  It was/is so close.   My vermicomposting is going great guns.  Lol.  The rocket oven is on the back burner for sure but absolutely not forgotten.  Thank you for asking!

Sincerely,

Ralph

I hope you get back to it - for delicious pizza if nothing else!

Thanks for the encouragement Julia.  At the moment, my garden prep for spring and my worm bin expansion are taking precedence.  I am going to produce close to a cubic yard of worm castings this year have a very productive growing season.  When I can fit in some time I will finish the engine for my rocket stove.  

Sincerely,

Ralph

Now's a good time for finishing a rocket oven, doncha think?

Julia Winter wrote:Now's a good time for finishing a rocket oven, doncha think?

I understand the logic behind your thinking and can't argue with it, except for the major new cabin reno and expansion project that began in early December.  Once I move the oven to its new location it will stand a much better chance of being finished, don't anybody hold your breath.