Airframe Construction Shorty Core

Gerry Parent wrote:Seeing as how this shorty core does not have the need for a floor channel brings up the much higher risk of unintentionally plugging up the port with wood shoved too far back or from a falling piece of coal.

An idea came up....Perhaps an upside down U shaped piece of metal rod (approximately the width and height of the firebox port) could be mounted on a plate steel base and positioned about an inch or so before the port? The plate would be sized the same dimensions as the inside floor so it wouldn't move around and (if needed) a horizontal top spacer butting up against the top port brick to keep it from tilting.
Shouldn't interfere with gas flow any more than a stub would.
Yes, metal is going to spall, but still perhaps last long enough to warrant its advantages.
Any thoughts?

Sorry to say, most of these type of ideas are solutions looking for a problem. These heaters are radically different from "normal" woodstoves. It's only logical to have a different set of do's and don't's for each type. It did took a lot of work to banish all steel from the firebox' innards, why introducing new steel in there?

My solution, which has been in use for 9 seasons now: the fuel is much shorter (about 4") as compared to the maximum capacity of the firebox. I developed the habit to lay the fuel about 2" behind the threshold, so there's a space of 2" between fuel and rear wall of the firebox.
Plus a second habit: In 99.99% of the burns I use the upside-down method to light the thing. For those that aren't familiar with this: the firebox is loaded with the largest pieces at the bottom, the higher up the thinner the pieces. On top of or between the last pieces some kindling and a single barbeque lighter. So there's time enough to adjust pieces before lighting without the risk of scorching hands, and no fuel will be in the port. Lighting on top means the fire is slower to develop, but that isn't a disadvantage per se.

For those whom are accustomed to a specific length of fuel, the solution could be to build their firebox 4" deeper than the fuel's length so there will be enough space. Between the logs or whatever you have, very little space is required. All fuel front to back, no log cabin, tipi or criss-crossing style. This way, the pile of fuel is relatively compact, plus the required space in front, back and top is easy to achieve.

Peter van den Berg wrote:Sorry to say, most of these type of ideas are solutions looking for a problem. These heaters are radically different from "normal" woodstoves. It's only logical to have a different set of do's and don't's for each type. It did took a lot of work to banish all steel from the firebox' innards, why introducing new steel in there?

Being one of the beta testers of your creation, I don't see any point in veering off from the path you've chosen based on your findings.
Besides, there is plenty of work still to be done in other areas that need more attention rather than trying to fix a potential problem that has not even surfaced yet. Thanks for keeping the ship on course captain!

Peter van den Berg wrote:My solution, which has been in use for 9 seasons now: the fuel is much shorter (about 4") as compared to the maximum capacity of the firebox. I developed the habit to lay the fuel about 2" behind the threshold, so there's a space of 2" between fuel and rear wall of the firebox.
Plus a second habit: In 99.99% of the burns I use the upside-down method to light the thing. For those that aren't familiar with this: the firebox is loaded with the largest pieces at the bottom, the higher up the thinner the pieces. On top of or between the last pieces some kindling and a single barbeque lighter. So there's time enough to adjust pieces before lighting without the risk of scorching hands, and no fuel will be in the port. Lighting on top means the fire is slower to develop, but that isn't a disadvantage per se.

For those whom are accustomed to a specific length of fuel, the solution could be to build their firebox 4" deeper than the fuel's length so there will be enough space. Between the logs or whatever you have, very little space is required. All fuel front to back, no log cabin, tipi or criss-crossing style. This way, the pile of fuel is relatively compact, plus the required space in front, back and top is easy to achieve.

All great pointers Peter. Thank you for fleshing out the finer details.
I can see how for the most part (no matter how efficient or clean burning it is designed) a stove can only be as good as the person tending it.

Peter van den Berg wrote:...Plus a second habit: In 99.99% of the burns I use the upside-down method to light the thing. For those that aren't familiar with this: the firebox is loaded with the largest pieces at the bottom, the higher up the thinner the pieces. On top of or between the last pieces some kindling and a single barbeque lighter. So there's time enough to adjust pieces before lighting without the risk of scorching hands, and no fuel will be in the port. Lighting on top means the fire is slower to develop, but that isn't a disadvantage per se.

For any Permies community members reading this post and questioning the upside-down loading method that Peter uses... before I built my batch rocket I spent decades building my fires every day in conventional wood stoves using the log cabin style. I wasn't sure how this crazy idea of the upside down load was going to work until I tried it from the very first burn in the rocket. All I can say is follow Peter's method... it works and its faster and easier than any other method. Since the air flow in the firebox runs horizontally to the port in the rear it doesn't take long as the draft gets going and the dragon start roaring for it to simply burn from the top down... fantastic!

Peter van den Berg wrote:...For those whom are accustomed to a specific length of fuel, the solution could be to build their firebox 4" deeper than the fuel's length so there will be enough space.

My wood is all cut to 16" lengths so I did as Peter suggests and made the firebox deeper than his standard published depth to achieve the 2" gap front and rear. This is one dimension of the core that he will tell you is able to be adjusted to a reasonable degree. I've inspected the area beyond the port and I see virtually no buildup of ash in this area.

What is fitted around the bricks and steel frame we see in the photos?
Is there an open area, a 'drum'?

Hi John;
Not sure what you are asking.
There is no "drum".
Edit) But there is a "Bell'.

Hiya John
Perhaps you have not seen this thread.
https://permies.com/t/267527/Shorty-Core-bell

I believe this will answer your question.

please tell me system size and B number for this heater build, my bricks are 11.4 mm wide , roughly 4.5"

Hi Cerbu
This is a 6" Shorty.
I'm not sure what a "B" number is.

My firebricks are 9" x 4.5"
My clay bricks are 8x4x2.25

by B I meant base number, I  made a brick simulation, trying to copy Peter's, here are some pictures, it will require some few cuttings

Hi Cerbu;
Peter has not officially published Shorty's base number; I suspect that 6" Shorty is the same as a 6" first-generation batch.
He happily supplies anyone who asks him with plans.

In your simulation, I do not see a riser reduction on the lower level.  

the measured dimensions are roughly these in centimeters , the reduction is that the riser widens from 17 to 23 , above the fireboxes' roof splits replace  normal fire bricks
firebox width 23 cm, height 35 cm depth 60 cm ; riser23x 23 , bottom 17 x17 , height 60 cm;
port: height 23 to 27 cm , width 6.5 cm or 6, depth 11,4 cm, the airframe I think will fit

https://www.youtube.com/shorts/nbzOeZfeQuY  simulation in progress for a sidewinder shorty core, next I try to figure out last upper layers with the exit port