Mark Thomasson wrote:

Good work Arne,  have you tried it with the pan in place?  It may help... or not. 

That is a very good point, Mark!

I may well have over-focused on the yellow torch flame with no pot or pan on the burner.  Today I made several boil-tests on ½-litres of water. I have to say that whatever version of the booster and set-up I used, my best time with the booster on was 20-30seconds worse than with no booster on (and copper tube removed).

The time to boil 0.5 litre was 4:30 minutes at the first test with only the original burner. On later tests without booster, the time to boil went up to 5:20 min. The difference between the tests was that I had to fill water from a new can, which had been sitting under the cabin sole, so may have been a bit colder. The other was that the kettle now was wet on the outside, after cooling it down before next test. I noticed it took quite some time for the wet kettle to dry up on the outside.

Still, the best I could get with the booster on and wet kettle was about 5:45 minutes  -  25seconds slower than without the booster on.

Sooo, I am now listing several degrees to this conclusion:
Those cunning Swedes who designed the Origo 3000 alcohol stove has done a quite good job. Look at the photo to the right, below. The primary flame is coming up that central tube. With no pot on, the flame rushes right up without getting mixed in more air. However, there is a gap outside that tube where air can rise easily. With a kettle or pan on, this air will partly mix with the central flame, and the result is a better combustion than with no kettle on. It isn’t perfect, but not bad either. There is some blue, red and white in the flame at full power. As the burner is turned down, there is more and more blue in the flame, and it is fully blue on minimum setting.

It seems that my booster was a failure, but at least it was interesting  -  and

 ..a negative result is also a result...

Arne.

PS: How is time to boil of 0.5 litre of water on your stoves? I guess the 4:30min I achieved, was with 15°C water and, as said, with a dry kettle.

PPS: I have a couple of ideas left to try, but...

20170920 The stove in use. Note the central yellow flame which spreads into blue up along the side. Not much difference with or without the booster on.

(Photo album, section 5 - 47)

Good work Arne,  have you tried it with the pan in place?  It may help... or not. 

Secretly I'm hoping that only the bike pump works and there will be a youtube video of Arne pumping up his supper  :-)  Or, perhaps a black-smith's bellows instead.... nice and low tech, just like the Junk Rig.   Seriously though, I wonder if the combustion might also be effected by the heat sink of the larger ring of copper?  Thanks for sharing the results.

Arne Kverneland wrote: Fans don't seem to do the job. They just make a disturbing wind. 

I'm replacing "Fans" with "_______", and making this my new mantra for anything I see on the political news channels.

You can, of course, get little fans that run from dry cell batteries, but I doubt that they would suit.  I'm watching with interest.