My (previously-mentioned) fire piston does not, usually, produce an actual flame.
You whack the plunger down to compress the air around the little tuft of cotton you've put in the bottom of the cylinder, and you get some smoke in the cylinder when the plunger recoils. More whacks make more smoke. That's it.
When it does manage to produce a flame, though, the flame always occurs on the second quick-succession whack of the plunger.
It took me a moment to figure out why this was, given that the first whack obviously uses up some of the oxygen in the cylinder and thus makes it harder for any combustion to happen the second time.
The reason must be that the first whack starts the cotton smouldering, and the second whack actually achieves visible ignition. Mainly, presumably, of the flammable partly burned smoke from the first whack.
If you had a smouldering coal in the cotton in the first place, you'd probably get more of a spark on the first whack.
Ideas, involving glow plugs, electric matches and dropping burning stuff into the cylinder, suggest themselves. Or you could just use a more robust cylinder that supports a higher compression ratio. Tim smacked his with a sledgehammer.
(More discussion regarding gas-compression-related fire-making widgets can be found on the site that used to be trackertrail.com. I've very little interest in actually roughing it, but a lot of the techniques and technologies involved are very interesting nonetheless. And it certainly doesn't hurt to know.)
[The fire-piston also has amusing instructions!]
30 October 2006 at 7:15 pm
Good link to Survivorman :). It's actually a pretty decent series - fun to watch in a voyeuristic "better him than me" sort of way.
But there is good information to be had by watching, and although I have no plans on being lost/trapped in the wilderness somewhere, I'd feel pretty stupid about perishing in such circumstances if it could be avoided by watching some TV.