22 Responses to Bman’s Bits: Rocket Stove Demo

1. Bman says:

   November 9, 2012 at 1:26 pm

   By the way, you can use just about anything as fuel. You dont have to use charcoal briquets.

   Reply
2. sortahwitte says:

   November 9, 2012 at 1:37 pm

   As soon as I saw the pbr, I knew this was an authentic Bman post. You just can’t be too careful.

   Reply
3. R.D. Walker says:

   November 9, 2012 at 1:45 pm

   I finally got a chance to watch. Great vid my man.

   Reply
4. Jim22 says:

   November 9, 2012 at 1:53 pm

   “A night of Pabst…” I’ll use that.

   The burger will be good. I can predict it.

   Only thing I’d say would improve it is to use steel duct pipe. That looks like aluminum. It won’t last as long.

   Good job.

   Reply
5. Bman says:

   November 9, 2012 at 2:05 pm

   Good point Jim. I should’ve mentioned that. The part that I showed was aluminum, however the part in the stove is steel. I use the other piece for the top, like a smoke stack for heating purposes on the Pontang. It works great for that too.

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6. notamobster says:

   November 9, 2012 at 2:35 pm

   You are the fucking man, Bman! I love it. I made a rocket stove from a green bean can and some tomato paste cans with steel tape.

   It couldn’t get enough air to stay lit, but the kids and I had a blast with it!

   You rock!

   Reply
7. Jim22 says:

   November 9, 2012 at 2:55 pm

   I’m thinking five gallon bucket with a six-inch diameter fire chamber instead of four. I think it would make more heat from bigger fire. Probably wouldn’t need a metal bucket.

   What about a draft control on the end you put the fuel in?

   Reply
8. Bman says:

   November 9, 2012 at 3:00 pm

   Thats a great idea, Jim! One issue I have is the buildup of ashes over time. I need to figure out a way to remove the ashes without distubing the flame. If the ashes build up too much, it blocks the air intake.

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   • R.D. Walker says:

     November 9, 2012 at 3:03 pm

     I bet the appropriate application of one of these would really make that rocket blast off.

     

     Reply
9. Jim22 says:

   November 9, 2012 at 3:03 pm

   I would do what they do in wood/coal stoves: Make a grate for the fuel to lie in. If it’s full of holes or made from several bars the ash will fall through and can be removed without disturbing the fuel.

   Reply
10. BaconNeggs says:

    November 9, 2012 at 3:35 pm

    Thanks for the video Bman, very inspiring from the Pabst blue ribbon man. Hahaha.

    I think I shall have to get my two boys to make a cookout with me, using some of the cans we currently recycle, they will be amazed.

    Its a great fun way to teach an important survival lesson and grill some burgers or dawgs.

    Reply
11. notamobster says:

    November 9, 2012 at 3:43 pm

    Bman – use your metalworking skills to combine two elbows – juxtaposed 180 degrees from each other. Cover one side as a clean out. Or you could make your next stove out of bricks like my other video shows and be able to reach in and clean that sucker out.

    Don’t forget the swedish fire torch! Awesome. Put your little metal grill on there and you got a portable grill. The rocket stove is useful if you just have twigs to burn. Just some thoughts.

    http://therealrevo.com/blog/?p=78602#more-78602

    Reply
12. Locke n Load says:

    November 10, 2012 at 2:17 am

    Loved the video dude, well done. Like the burger.
    Dumbass question, but couldn’t you amplify the intensity of the flame by stacking smaller vented cans for the burner and creating a venturi effect? I mean, I know its combustible gas thats providing the heat, but doesn’t flamable gas act like a liquid? Wouldn’t that work like a torch?

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13. Slaphappypap says:

    November 10, 2012 at 7:46 am

    Solid Bman! Looks like you’ll be eating burgers/dogs for awhile. Just for the fun of it.

    Reply
14. notamobster says:

    November 10, 2012 at 8:33 am

    Locke – the venturi nozzle requires pressure on the input side (see rocket exhaust venturi). Otherwise, it’s just a restriction.

    Bernoulli’s principle applies in fluid dynamics, whereas the same idea is expressed in the form of turbulence through a gaseous venturi.

    The convergent inlet of the venturi forces the slow of liquid in fluid dynamics and air in aerodynamics.

    An increase in pressure results in a slowing of flow – in either case – it is through the rapid expansion of the divergent outlet that flow increases and pressure drops. You can’t produce this without some means of back-pressure which is anathema to the idea of the rocket stove.

    The rocket stove relies on the smooth, unfettered influx of laminar airflow. It’s basically just a more efficient fire because the increased oxygen allows for the burning of the hydrogen & methane off-gases which are the natural biproduct of the oxidation and decomposition of wood.

    If you put a chokepoint (venturi) prior to combustion, you lose airflow, defeating the gasification. If you put a venturi aft of combustion, you will force the pressure differential out the inlet (which must remain open), thus defeating the purpose – gasification.

    You could increase oxygen further by increasing turbulence prior to combustion – but that’s a tough line to toe. Also, you don’t want to invest a lot of time or money in the process, as this is a cheap, simple cook stove. Once, you’ve invested too much time or money it is no longer cheap or simple.

    See, RD, I like science, just the technical (mechanical) sciences. My nerd creds remain intact.

    Reply
15. notamobster says:

    November 10, 2012 at 8:38 am

    You could achieve the desired effect by using something I’m sure your asiaphile ass is familiar with – a collar that is slightly larger than you pans cooking surface.

    It creates a venturi by using your entire combustion can area as the throat of venturi (but with no convergent inlet) and the collar becomes the (non) divergent outlet, increasing the speed of the exhaust gas outlet through rapid expansion, but directing it up the side of your pan.

    Reply
16. R.D. Walker says:

    November 10, 2012 at 8:38 am

    Never doubted you for a second.

    I can’t believe nobody even acknowledged the benefit of my foot bellows turbo booster.

    I didn’t mean that it would be for constant use. Just that it would sure help getting things going and adding oomph when things slow a bit.

    Reply
17. notamobster says:

    November 10, 2012 at 8:41 am

    A rocket stove uses a ton of fuel on it’s own. It burns hot and fast. Increasing input airflow will make it burn faster, using even more fuel.

    I didn’t want to point that out.

    Bellows are used in fireplaces and cook stoves because they are extremely inefficient. gasifiers tend to be 90% efficient.

    Reply
18. R.D. Walker says:

    November 10, 2012 at 8:42 am

    You inspired me, dude.

    It couldn’t get enough air to stay lit, but the kids and I had a blast with it!

    Reply
19. notamobster says:

    November 10, 2012 at 8:47 am

    It might have actually helped with my mini-stove version.

    Reply
20. Locke n Load says:

    November 10, 2012 at 9:39 am

    Outstanding explanation Nota, thanks. Forgot about the pressure, doy. Been a LONG damn time since I took physics

    Reply
21. Jim22 says:

    November 10, 2012 at 1:35 pm

    I wonder if the flow would be increased with a longer chimney. It certainly makes stoves ‘Draw’ better if you make the chimney taller. Sorta like a syphon in reverse.

    Reply