My take on those results is I do not have to carry such a tall windshield. one inch above the bottom of the pot may be enough, even in windy conditions. Extrapolating to flux ring pots, the air temperatures up the sides of the pot, after the heat exchanger can only be lower than for none flux ring pots. A Windshield's job is apparently to buffer the inlet air and the flame rather than the sides of the pot

Hi Derek,

>My take on those results is I do not have to carry such a tall windshield. one inch above the bottom of the pot may be enough, even in windy conditions.

My test on the STD windshield design show that in strong wind they may not be that efficient, I suspect that the wind travelling over the top of the windscreen causes a sucking effect, the hot gasses are then sucked up faster than normal causing loss of efficiency. But at the moment this is only a theory, I have to do some more tests to prove this.

Tony

Hi Tony,
I am interested because We persuaded myself to buy a eta packlite and I intend to lighten it. One of the first candidates is the windshield. It would help a lot to understand windshields. The existing windshield is only 60mm tall yet 91 grams heavy and is mounted about 25 mm off the floor. A standard windshield that fitted in the pot when packed, would be limited to 80mm. The top of the flux ring when on the stove is about 70mm off the floor.

On another issue: help from anyone who has a packlite. Does the brass mixture tube from the jet to the burner unscrew at the elbow? Is the brass round base below the elbow solid? Can it just be cut off without exposing the internal cavity. The purpose of the round base appears to be to support the burner, but the burner is supported by a split pin and has very little weight on it.

Isn't the ETA Power fuel consumption of 7.9 / liter MORE than 6+ for the average remote or upright??!!

Looks like you put the minutes to boil in for the fuel per liter in that one chart, I can't see that chart while posting but the 6+ numbers should be 11.6 and 13.3 from the earlier chart. I get a bit different # of liters for the ETA power, the only one I checked, 24 liters and 92 liters, about the same.

The weight difference of the stoves/pot is constant for the trip, while the fuel difference only reaches its maximum near the end of the trip, assuming you take the same amount of fuel for either system. (This favors Ti pots)


Another way to look at this is how many canisters you are going to take. Using your figures the ETA Power ,229 g fuel , / 7.92 is 28 liters, while the average upright and remote would get between 17 to 19 liters. So if you need to take an extra canister (12 oz) it becomes closer weight wise , but you also save some cost on fuel and waste of canisters? Partial canisters? Margin for error?

EDIT: In this case as the stove with the Ti pot burns more fuel the difference of the extra fuel weight should go down, except for the extra canister weight itself remains the same.

Winter time more fuel used to melt snow for drinking water. Snow is hard to melt?

Edited by dayhiker on 10/21/2009 07:31:28 MDT.

Hi Larry

I am not sure what you are asking. Please help me.

The Eta Power has a fuel consumption of 7.9 g per litre water, while the average for the Uprights (ie no heat exchanger pot) was listed as 11.6 g of fuel. I am not sure where you got the 6+ figure from?

Cheers

Larry has noticed what I pointed out earlier:

Sorry to persist Roger, perhaps you should look at the table in your report! Performance or efficiency surely means that higher numbers are better. Fuel per litre would be lower numbers are better. In the column the more efficient heat exchanger stoves have higher numbers but it is headed fuel per litre that is surely wrong, a typo, not just a slightly wrong word.

Under "efficiency in real life" Larry points out that his example the eta power uses 7.9 grams per liter whereas the average upright uses 6.5 grams per litre. As we know that heat exchanger stoves use less fuel to boil a litre something is wrong.

Hi Larry and Derek

OK, now I get it. I think something happened along the way such that the last two lines in the published table under the heading 'Efficiency in Real Life' has the wrong figures. The values for the Uprights and Remotes are actually the time to boil from a previous table I think! Oops!
I will have this corrected ASAP - my thanks to you for seeing this.
(Edit: Addie tells me this has now been corrected.)

Now to the issue of the word 'efficiency' Derek suggests that 'Performance or efficiency surely means that higher numbers are better. Fuel per litre would be lower numbers are better.'

Well, not always. That is one definition of fuel efficiency, bolstered by the American practice of talking about 'miles per gallon' when discussing cars. But the rest of the world (which is all metric) measures a car's fuel efficiency in terms of 'litres per 100 km'. That's the same as grams per litre boiled.

You see, there is NO formal definition of the term, so it can mean anything you want it to - as the Duchess said to Alice. I take efficiency to mean using as little fuel as possible.

I suspect this argument may not have a satisfactory resolution, as we are proceeding from different origins. But can you suggest a better term which could be added to the article?

Cheers
Roger

Edited by rcaffin on 10/21/2009 15:40:12 MDT.

Hi Roger,
If you amend those 2 incorrect figures I have no argument with your meaning. I was just trying to explain why I knew they were wrong.

Derek:

"The is a typo in Roger's report. Under "Efficiency in real life" the column fuel/litre shows instead efficiency which is a sort of reciprocal."

I think Derek was thinking if the numbers are right the label is wrong?

Efficiency =C.L / g (oz) was about the same as the boil times for the average upright and average remote, 6+

I assumed the words were right but did not understand the numbers.

Edited by dayhiker on 10/21/2009 07:55:31 MDT.

Larry,
You are right

Where is Part 4 ?

> Where is Part 4 ?

Still coming. My flow got interrupted when we headed off to Switzerland for 6 weeks in July. :-) :-) :-)

I have some higher-priority stuff to complete, then I will fire up the pots (so to speak). Anyone else noticed how the week flies past so fast?

Cheers

What everyone really wants to see is something blown up. Safely, of course.

Hi Joe

> What everyone really wants to see is something blown up. Safely, of course.

Sigh - you should read the articles at BPL, especially the one on
Exploding canisters! Your wishes would be answered. However ...
.

.
This burst at 100 C with one hell of a bang.

Cheers

Edited by rcaffin on 10/21/2009 17:51:00 MDT.

I viewed the below linked video with the sound off, so I will not vouch for the narration, but the video is pretty interesting:
How not to use a stove.

P.S. The video is unnecessarily long. The action is at 7:47, so move the progress indicator to about 6 minutes when the stove goes out and he tries to re-light it.

Edited by hikin_jim on 10/22/2009 17:15:16 MDT.

Hilarious. The guy is utterly ignorant and incompetent!

Cheers

Hey Roger,

What happened to Part 4 of this series - efficiency, pot diameter etc.

I was also wondering if part 4 and 5 are up yet? It has been nearly a year and half since the last post.

thanks

Mike