I’m a member of a club that, for fun (and charity!) is planning an event on the moon. Don’t worry - it isn’t for another 15 years, and people are responsible for their own transportation.
Someone posted an interesting question though - how are we going to set up our fire pit?
I figured the smart people here might have some ideas. A quick search of google suggests that just providing an oxygen tank might not be enough, because it would be consumed very quickly. Is this true? I don’t care what the mechanism is - I’m looking for something that serves some, or all, of the purposes of a fire pit. So, Dopers, what say you? What are our options?
(Posting in GQ because there are probably technically correct answers…but this could easily end up in another forum, I suppose.)
Gas/butane tank in the base of a steel frame. Perma-charcoal in a stainless steel bowl in the top. Burners are under the coal so flames rise out of the coal.*
*Can only be burned inside a pressurized room with an O2 nitrogen mix.
Buoyancy would be absent without an atmosphere … we’ll need something to draw the hot exhaust gases away from the combustion point … they won’t rise away from the flames but remain and choke it out.
I was thinking catalyst to get it going, but actually some iron filings in contact with pure oxygen should get hot enough to ignite any fuel. Or you could use fluorine gas, that should auto-ignite with a lot of fuels.
Sure you can make gas burn, but I don’t think it would look like “fire.” It’d probably look like the faint blue flame you get on a properly adjusted gas burner. You only get the billowing yellow flame when unburnt fuel interacts with surrounding air. For reference, firing a rocket engine on the moon looks like this.
I suggest you make the fire pit inside a pressurized room. Even if you can build a fire in vacuum, you can’t really enjoy it from inside a spacesuit anyway.
I was hoping to slip the fix in before people noticed…oops <thanks for fixing it, Colibri!>
We’re outdoors types, and likely be drunk by then…
So if we want to provide oxygen or other gasses for this, assuming we are not inside our climate controlled tent…can we get a decent amount of ‘flame’ from something the size of a scuba cylinder? If we don’t fight the hypothetical of being there, how practical is it to actually do something like this?
We are in the realms of fantasy anyway so is there anything wrong with just a pile of wood sitting in a steel bowl drilled with multiple injectors in the bottom and sides fed by a very big air tank? You could even deliberately aim air jets around and above to avoid the problem scr4 raises. In other words if you are determined to do this outdoors can’t you resolve the problem by simply adopting the extremely inefficient and wasteful course of throwing enough air at the problem?
If you want to make things go even faster, soak the charcoal in liquid O[sub]2[/sub] first.
Note, you may want to light this from about 25 metres away and I wouldn’t bank on being able to reuse the metal grate.
For a completely different approach, take along a sack of iodine powder and a sack of aluminium powder. Mix well, add a few drops of water, and stand back. Al + I = AlI[sub]3[/sub] and it’s plenty exothermic - you will get a flame. All the water is doing is encouraging the powders to cohere, just to get the reaction up and running - after that the heat will liquefy enough iodine to keep it running.
I suspect not. In order to support combustion you’d need air density that was close to that at the earth’s surface, and that would result in airflow that would escape into the vacuum as a hurricane blast. You could mitigate that with oxygen enrichment and reduced flow but I suspect it would still be problematic.
Furthermore, the smoke and ash would both be driven up and then come straight back down around the [un]happy campers.
There might be potential with a gas like propane mixed in the combustor with air or oxygen and impurities to make pretty blue and yellow flames. You’d need mechanical devices to vary the angle and flow of a few dozen different nozzles to create natural-looking flames. Put some artificial wood on top that glows when heated and it might not be too bad.
Or you might consider shunning fossil fuels in favor of a nice freestanding electric fireplace which produces nice artificial flames and radiant heat. They typically consume 1500 watts so don’t forget to pick up your Russian BES-5 RTG which can produce 3 kW of electricity for 250 years, keeping you and your descendants toasty warm on those cold lunar nights.
<thanks for fixing it, Colibri!>