Fire Reflector Question

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william O

Joined
Feb 5, 2009
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Again, sorry for the silly question, but I was wondering if anyone ever compared the effectiveness of using a fire reflector 1. that is stacked, leaning back away from the fire, supported by two angled support beams, OR 2. stacked upright, sandwitched between two sets of two vertical beams? Just curious if the angle toward the camper would make any noticeable difference. Thanks! William
 
I don't have scientific proof one way or the other, but it seem that a reflector helps. I wouldn't think leaning it one way or the other would make a noticable difference. I just stack up staves, like an old time fense, on the side opposite where I'm sitting.
 
william O said:
Again, sorry for the silly question, but I was wondering if anyone ever compared the effectiveness of using a fire reflector 1. that is stacked, leaning back away from the fire, supported by two angled support beams, OR 2. stacked upright, sandwitched between two sets of two vertical beams? Just curious if the angle toward the camper would make any noticeable difference. Thanks! William
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Its not a silly question, but a perfectly valid one. When building a quick one ive used method 2 as a windwall and reflector. Like this one here which my 13 yr old stepson built.
4039608163_983eca1ef9.jpg


But ive used both methods to my back (behind me), and i feel an angled reflector behind me gives more heat. I think its because heat rises, and an angled reflector traps the heat for abit longer before it rises out. Kind of like a mini lean-to about 1 metres high.

EDIT: Forgot to add that ive used reflectors behind me when ive already got one in front of me. Like this one here, only the one behind me is much smaller than the one pictured.
call_97-5_fig1.gif
 
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The number one use for my cheapo space blanket(carry an amk bivy as well). Make a stick frame behind and tie off, rocks on the bottom.
It really does help, and I do angle it like above. or it catches wind like a sail.
 
It's actually a perfectly valid question, and one that's easily answered.

Heat, from any source (fire, etc.) is actually energy, the same as light is energy, and exhibits much of the same behavior. Heat radiates directionally the same as light would, and reflects (bounces off) from a reflector — in this case the log wall you have set up — exactly the same way light would. In other words, if your reflector wall is vertical, the heat will bounce directly back at the energy source (the fire). If, however, your reflector wall is angled back at 45 degrees, then the energy (heat) is going to be reflected straight up ... not back at you.

You can easily test this with a flashlight and a white card as a reflector. The angle of reflection is equal to the angle of incidence, or something like that.
 
dawsonbob said:
It's actually a perfectly valid question, and one that's easily answered.

Heat, from any source (fire, etc.) is actually energy, the same as light is energy, and exhibits much of the same behavior. Heat radiates directionally the same as light would, and reflects (bounces off) from a reflector — in this case the log wall you have set up — exactly the same way light would. In other words, if your reflector wall is vertical, the heat will bounce directly back at the energy source (the fire). If, however, your reflector wall is angled back at 45 degrees, then the energy (heat) is going to be reflected straight up ... not back at you.

You can easily test this with a flashlight and a white card as a reflector. The angle of reflection is equal to the angle of incidence, or something like that.
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:thumbup:

The mere fact of thermal mass provided by rocks is a more intense heat radiator than wood...

And having something at your back, either rock or wall, also increases heat reflection and thermal mass....

I prefer vertical, but I also prefer smaller fires so I can be closer to the radiant heat....
 
paleojoe said:
:thumbup:

The mere fact of thermal mass provided by rocks is a more intense heat radiator than wood...

And having something at your back, either rock or wall, also increases heat reflection and thermal mass....

I prefer vertical, but I also prefer smaller fires so I can be closer to the radiant heat....
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While I only addressed the question of reflectance, there is — as you pointed out — a lot more to the art of staying warm than just the angle of a backdrop.

Even a small fire will help keep you warm if you're between two different reflectors, and then there's radiance: hot rocks, rock!

I've been learning how to stay warm for over fifty years, and I'm still learning new things all the time. How we manipulate heat is one of the things that make the difference between being miserable in the bush, or being warm and happy.
 
dawsonbob said:
It's actually a perfectly valid question, and one that's easily answered.

Heat, from any source (fire, etc.) is actually energy, the same as light is energy, and exhibits much of the same behavior. Heat radiates directionally the same as light would, and reflects (bounces off) from a reflector — in this case the log wall you have set up — exactly the same way light would. In other words, if your reflector wall is vertical, the heat will bounce directly back at the energy source (the fire). If, however, your reflector wall is angled back at 45 degrees, then the energy (heat) is going to be reflected straight up ... not back at you.

You can easily test this with a flashlight and a white card as a reflector. The angle of reflection is equal to the angle of incidence, or something like that.
Click to expand...

Thanks. That's exactly as I was thinking about it, but was wondering if I was overthinking it. I would imagine "aiming" the heat back at me would be best. A lean-to acting as a reflector behind me makes perfect sense, as it would seem to "bounce" the heat down toward me (before of course rising as heat would tend to do). Something just bothered me about a reflector on the far side of the fire, angled up. It seems that it would not retain as much heat back toward the fire, and me sitting on the opposite side of the fire. I guess most any reflector/wind screen would help, proper angle would likely improve it, and dense material would improve it still further. I need to get outside and play more. It would make this theoretical stuff more fun. Thanks to all!! William
 
william O said:
Thanks. That's exactly as I was thinking about it, but was wondering if I was overthinking it. I would imagine "aiming" the heat back at me would be best. A lean-to acting as a reflector behind me makes perfect sense, as it would seem to "bounce" the heat down toward me (before of course rising as heat would tend to do). Something just bothered me about a reflector on the far side of the fire, angled up. It seems that it would not retain as much heat back toward the fire, and me sitting on the opposite side of the fire. I guess most any reflector/wind screen would help, proper angle would likely improve it, and dense material would improve it still further. I need to get outside and play more. It would make this theoretical stuff more fun. Thanks to all!! William
Click to expand...

That's exactly what you're doing with reflectors, is aiming the heat. I think you've got it — now go outside and play. As you said, theory's fun ... but bush-time teaches you what works in the real world.
 
One of my friends built a reflector out of about six aluminum panels that are joined together and have some stake loops on the back side. Positioning them vertically in a curved pattern behind the fire seems to yield the most reflected heat. As others have suggested, I expect the same would be true for logs or rocks.

DancesWithKnives
 
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