Reflector Oven… Pizza and Muffins anyone?

Dan, great design! I don't understand how it works. Does it use the Sun's rays or do you put some kind of stove in there?

Good work, Dan. It's probably more efficient than aluminum, since titanium should hold the heat better. But how do you do pizza in that thing–little pizzettes? By the way, I love the little pizza delivery car in the photo.

OK I'm curious too. It looks good but I have no idea how it works. Do you put it in or near a fire, or is there a stove built in, or do you put a little stove inside it? Or does it actually close up and then you put it on top of a stove?

Great little Reflector Oven. How about some plans?
You set it near a wood fire.

Here is some info.
Mike

Sorry guys…

Yes, you place it in front of a fire, it only needs to be small, I was staggered when I first tried an aluminium prototype, it does not need a large fire….
I will draw up the dimensions if anyone is interested.
The little titanium tray in the picture is about 4" x 9" from memory, two pizzas that size is heaps for me!
Thanks all for the comments, I am glad you like it.

Any other questions, ask away!

Cheers, Dan.

Cheers for the link Mike, I have not seen that one and it explains it all perfectly.

Thanks Dan, that makes sense now.

Thanks Jason, and thanks for your site, great videos, great info.

Dan

Nice looking project Dan. What do you mean you were "staggered" when you first used aluminum?

Hi Keith,

I was staggered at how small a fire you can get away with and at how well it baked breads and cakes. a small camp fire, say 1' in diameter is plenty big enough, a fist sized damper (flour salt and beer – bread dough) cooks through in approx. 15 minutes, drizzled with butter… mmmmmmm! small pizza's of 6" diameter, cooked in 5-10 mins. You may like to turn the tray during the process to get an even browning of the item.

If you put reflector oven into google you will have plenty to read
Cheers, Dan.

I love that a great trail oven is made by a man named BAKER! Life is great!

-Tim

So, Dan, when are you making these for sale? :-)

Thanks all for the comments, I have not got any plans to make these for sale, I will over the next few days put together a pdf of the plans and you can all make your own…

I hope to see all improvements listed here on BPL! :)

Cheers,

Dan

Nice work, Dan.

> It's probably more efficient than aluminum, since titanium should hold the heat better

Gary, I'm not sure I follow you. The heat capacity of Ti is 0.52J/gK, and aluminium is 0.89J/gK. I suspect that the relative thermal conductivities might have an effect (22W/mK vs 235W/mK).

@Kevin: What I was thinking did relate to the lower thermal conductivity of titanium. I figured that titanium wouldn't allow the heat to escape as readily as aluminum would. But then I realized (after I posted) that sides are in fact aluminum, which might somewhat negate the heat retention of the titanium in the back. Probably all this means nothing, and I would think the device should work quite well. Great MYOG.

Guys

Thermal mass and thermal conductivity have little to nothing to do with it.
This oven works by radiation and reflection. The better the reflectivity in the IR band, the better it works. In fact, aluminium would probably be better than titanium for the reflector, except that the Al foil would be much weaker.

Cheers

> Thermal mass and thermal conductivity have little to nothing to do with it.

I'm aware that the thing relies on reflecting heat, but I suspected Gary was referring to the tray. You want the tray to be absorptive and conductive, so that it can absorb reflected heat and spread it out under the things it's cooking, such as pizza, preventing hot spots at the focal point. In which case, I'd suggest that thermal mass and conductivity are quite relevant.

It might be interesting to do some ray tracing analysis to see if a reflector can be devised that deliberately provides multiple foci over a central area to allow the food to be cooked evenly. You might also propose a central 'oven' chamber that sits at the focus and is absorptive and conductive to provide a more even heating than will result from the one-sided reflected heat (although the fire itself may heat the other side well enough for even cooking…).

> It might be interesting to do some ray tracing analysis to see if a reflector can be devised

The problem there is that the fire is a very large diffuse source. All ray tracing would do for you would be to confirm that the reflected energy is equally spread out. Hey – it works …

Cheers

Hi again all,

I made my initial trial version from Aluminium and it worked great, biggest problem (that Ti addressed) was storage and transport. The rear reflector is 535mm long and 300mm wide (approx) storage and transport involved a large sheet of aluminium as opposed to the rolled Ti, I toyed with the idea of hinging at the centre but have not tried it out.
I have used both side-by-side and have found no difference in cook time or reflectivity. The main concern with some reflector ovens is the need to rotate the dish during the cooking process to provide an even bake and even browning of the food.
With both units I turned a 'bread' (read- lump of coagulated mess) once during a 10-15 minute bake time for exactly the same result- uniform and even 'cookness'
So to summarise my long-windedness…

Ti and Al versions produced identical cooking results.
Ti is lighter and easier to store, carry and assemble.
Ti spokes and sides would make for a lighter oven, however Al sides give the unit a great rigidity for a negligible addition to weight and storage room.

Does any of that make sense?
Any further questions?

Cheers, Dan

I really like the idea of this oven for providing some flexibility in camp cooking. I am also planning to make myself the 1 oz. grill described here:

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=4446

However, I was wondering whether you could replace the baking shelf in this oven with a series of closely-spaced spokes or rods, similar to a regular oven rack. If they were spaced closely enough, they would support muffin papers, lumps of dough, or whatever.

Most importantly, you could then use those spokes and the titanium sheet in a different configuration, as a grill. Specifically, it seems that you could place the spokes vertically across the front of the oven as it's shown in Dan's pictures, then lay the oven down with the concave side up, stabilized by rocks or whatever, with the spokes forming the grill. Having the curved titanium bottom to reflect and concentrate heat would probably make the grill very effective with a small fire, and would essentially form a fire pan, which would make leave-no-trace easier.. You might have to roll the titanium sheet the opposite way from the reflector oven configuration, to avoid impacting the reflectivity with soot in the grill configuration, but it seems like this would work easily enough as the whole sheet seems to roll easily. Maybe it's also functional in this configuration (or with slight modification, such as moving the aluminum sides closer together on the reflector) as a wood stove over which you could boil water…? If so, it seems like that covers just about every cooking option from your home kitchen, short of a microwave, and doesn't add much weight over Dan's original concept.

I was pondering about using one of those metallised plastic bags used for cooking turkeys (to keep them moist) as the reflector. One side of the bag is clear, one side is meatallised.

You'd need something to form the curved shape, and something to hold the ends apart, but it could be compact and light…

If the side walls aren't essential (are they?), then all you need is a strip of springy metal that can be bent into a curve, and fixed with a spar across the opening. Then some means of fastening the bag to the curved strips, and holding the strips apart: spokes for instance?

Not sure how you'd support the tray, though…

On the other hand, could you not just wrap whatever you're cooking in the bag, and fettle the bag so the reflective side is at the back, and roughly focussed…?

Just thinking aloud…

I have been thinking about this too. I was also thinking it might be possible to make a wood stove/heater that could come apart and be the reflector and also a grate, or the top could come off and you could boil water on it. I'm still thinking on how to do this.

I want to get some thin stainless to experiment with before committing to the cost of TI.

Any of you stovies want to offer some advice on a multipurpose oven/grill/boiler/heater?

-Tim

I figured someone else was probably already going down this path…

Tim, here's a quick SketchUp of what I was envisioning:

The reflector oven is turned on its side with spokes across the opening for a grill. Then, the sides of the oven are mated with two additional pieces of aluminum to make a stove (these stove sides could also be used as a shelf in the reflector oven). I'm not sure how well the wood stove portion of this would work, but I imagine someone here could provide input on that, and it wouldn't be adding much at all in terms of weight. The curvature I put on the top of the extra stove sides makes them even with the tabs on the reflector oven sides, so a pot would sit directly on top, with some room for flames. There would obviously be a need to put holes in the right spots in both the oven sides and the stove sides.

Feedback?

Could another curved section form the top with a stovepipe for heating a shelter? I know there is a need for air to enter to feed the fire, this could be built into the side suports of the upper unit. The upper unit could be made of the thinnest ti sheet as it will be holding in heat, not weight.

To work the way you have draw would the unit have to be the same width and height for the grate rods to fit tightly in both uses?

-Tim

Having just spent the last hour and a half cursing at SketchUp (my first use), I admire what you've managed to achieve… I seem to be having trouble getting my head around how it thinks…

My main concern for a multi-use reflector/grill would be the loss of reflectivity caused by the use of fire within it. You might be able to use one side for the burning mode, and keep the other side shiny for reflective mode.