Why smooth dome ? Why not multi sided stepped dome ?

[stoveup]

Re: Why smooth dome ? Why not multi sided stepped dome ?

I tend to think of a dome as a series of arches that all meet at the keystone at the top of the dome. There are many examples of corbelled arches built hundreds of years ago - especially on the Indian subcontinent and in the Moorish architecture of Spain.

I see no reason a corbelled dome would not work, but I am not sure it would be possible to maintain the relatively thin cross section of the dome shell and be structurally sound. Corbels are simply a series of increasingly projected cantilevers. For a cantilever to work, the weight of the unsupported section must be less than the weight of the supported section. As the corbels progress further and further out, more weight has to be added to the lower courses to support those above creating a thicker cross section and more thermal mass.

[Neil2]

Re: Why smooth dome ? Why not multi sided stepped dome ?

Domes are compression structures. I won't go into the engineering involved but all domes are smooth not stepped for a reason.

Besides, trying to build it "stepped" seems to be more complicated that the "normal" way (which has been in use for two thousand years or more).

[Tscarborough]

Re: Why smooth dome ? Why not multi sided stepped dome ?

Also points and corners will get hotter, faster than a smooth surface and may deteriorate quicker. There is still no significant reason why it won't work reasonably well, though.

[GianniFocaccia]

Re: Why smooth dome ? Why not multi sided stepped dome ?

I am merely paraphrasing directly from Wikipedia, but my brief inquiry into the properties of thermal radiation reveals that radiated heat acts in a linear, fluid manner, not unlike sound or light. Also, thermal radiation emitted by a body at any temperature consists of a wide range of frequencies, and the dominant frequency (or color) range of the emitted radiation shifts to higher frequencies as the temperature of the emitter increases.

Further, unlike conductive and convective forms of heat transfer, thermal radiation can be concentrated in a tiny spot by using reflecting mirrors. (This is how solar energy is concentrated).

I deduce from this that the discreet reflective surfaces of our hemispherical brick domes do indeed radiate heat directly at the center of our ovens, supporting dave s' theory as well as the gazillions of ovens built since the beginning of time!

[Tman1]

Re: Why smooth dome ? Why not multi sided stepped dome ?

I didn't tell her what I was doing, just to make some pizza dough. You already need the bricks, it's just a test version.


A good start to the addiction. A true pompeii is in my future.

[uk_exile]

Re: Why smooth dome ? Why not multi sided stepped dome ?

That's a wicked oven and so fast to build. Liking it ! ......however it won't meet with my CFO approval as she likes things to be 'tidy'. Bugger

[Tman1]

Re: Why smooth dome ? Why not multi sided stepped dome ?

You don't need to make it round... (check the link in my signature) but it sure looks better that way. I can confirm that it makes great pizza, and the next time I fire it I'm hoping for bread too.

[lwood]

Re: Why smooth dome ? Why not multi sided stepped dome ?

as you get closer to the top of the dome the gaps get bigger...or you have to make cuts. Did you look at laying the bricks on the face rather than the edge of the brick? More surface area to stick to. That looks like a very difficult build. Plus you only have 2" of fire brick, you need 4".

[Lburou]

Re: Why smooth dome ? Why not multi sided stepped dome ?

Didn't work as well as I hoped. Too many gaps

The other down side as depicted would be a lack of mass with 2.5 inch thickness. If I'm understanding you correctly, that would be a show stopper because it would not hold the heat.

Glad you have moved on.

[brickie in oz]

Re: Why smooth dome ? Why not multi sided stepped dome ?

Didn't work as well as I hoped. Too many gaps

Use half bricks on edge and turn them 90 degrees, there will always be big gaps using full bricks stretcher style..

[uk_exile]

Re: Why smooth dome ? Why not multi sided stepped dome ?

Didn't work as well as I hoped. Too many gaps

[uk_exile]

Re: Why smooth dome ? Why not multi sided stepped dome ?

Don't think that configuration will result in that much less cutting, especially towards the top of the dome.

But think about the ease of just stacking the bricks flat. Some support would be needed until the mortar sets on upper layers.

Perhaps structural strength and not any smoothness of airflow or smooth surface for reflected heat is the primary reason for the more labour intensive dome design used for centuries.

[lwood]

Re: Why smooth dome ? Why not multi sided stepped dome ?

Don't think that configuration will result in that much less cutting, especially towards the top of the dome.

[uk_exile]

Re: Why smooth dome ? Why not multi sided stepped dome ?

I might have a play in CAD to see what it would look like. Perhaps it gets would need to be a bit more cone like than squashed down cone / dome

[brickie in oz]

Re: Why smooth dome ? Why not multi sided stepped dome ?

you are going to have more brick hanging out than the part that supports it

Not if you only corbel each course 40mm you wont..

You would have to support the oven when building it, but once built it should be self supporting.