An earlier thread on UKW discussed various aspects of windshields and
materials etc. Having taken some of the information to heartIK have been
experimenting with a foil windshield for my Mini Trangia.
I know it has been said many times that boiling speed doesn't matter but I
have come to a conclusion, certainly with Meths, that it does. My
reasoning? The faster the boil WITHOUT increasing fuel consumption then
obviously the less fuel used (carried).
Now to my point.
Using my foil windshield I have increased boiling speed and NOT increased
fuel consumption.
I constructed a shield which was 10cm high (this almost came to the top of
the pan but still allowed enough space to attach the pot grab) and
completely surrounded the stove with an 5cm overlap. To start with I
punched 5mm diameter holes around 1/8th of the circumference at ground
level.
This worked OK in still air but far better in some wind (with the punched
out holes towards the wind). Taking this one stage further I punched a
single 25mm hole (at ground level) in the same 1/8th circunference area and
tried the system again. This time, in a slight breeze the stove's
performance was better but in a wind the damn thing went like a rocket.
The above was a prototype. I have now made another version with only the
single 25mm hole in the circumference but this time almost at one end of
the foil. By increasing or decreasing the overlap I can open or close the
'damper' (for those of us old enough to remember 'dampers'😉 and thus control
the stove. It now roars like a mini-furnace.
I have also discovered that to get the unit 'fired-up' in still air a puff
or two from the old lungs seems to start a self perpetuating process of
increased heat output. (It is possible to hear the meths boil and really
perform by blowing into the vent)
All this and still 2 fluid ounces of meths burns for 19 minutes - exactly
the same time as without a windshield, but in that time I can now boil 2
full litres of water instead of barely 1 litre.
I hope I haven't bored members with the above or been preaching to the
converted. Perhaps what I've laboriously discovered has been long known ---
but not by me.
Cheers all,
John S-Mallory