SpudFiles

Read about it, but I have access to a lot more stainless material than I do lantern batteries though...

I did read the thread, just somehow I missed that you specified the power source.

You might be able to use stainless steel electrodes if you can get the voltage down really low (like 2V). IMHO, graphite is the material of choice for inert electrodes, unless you're going to coat the stainless steel with something, and unfortunately all the coatings I can think of are very insulating.

I've just used pencils in the past...

saefroch wrote:Who ever said anything about "cells"?

I was talking about electrolysis cells, not electrical cells (or batteries, as they are generally - although technically incorrectly - known).

Electrolysis setup v.2 to be tested soon, 2 litre bottle this time and 2 large stainless steel bolts as electrodes, appendages crossed

jackssmirkingrevenge wrote:Thanks for the tips is there a cheap plentiful source of graphite that doesn't involve me dismembering pencils though? Or another suitable electrode material? Can I go with stainless steel then ethically dispose of the electrolyte in an environmentally friendly manner?

a easy way to get your hands on some graphite rods is to buy some woodless graphite pencils from a art supply (I have no idea what they cost though)

is there a cheap plentiful source of graphite that doesn't involve me dismembering pencils though?

No.
Buy a bunch of cheap pencils from the dollar store and burn them.
You have to take a material's properties into consideration before you begin an otherwise laborous task

Though you may want to clean them afterwards; you know... scrub the carbon off the carbon.

I put some nice electrodes together in 30 minutes like this.

Edit... Though you might try carbon fiber. It's expensive, but you may be able to get it for free if you can find some broken fishing poles or arrow shafts. Have any sporting-goods stores nearby?

I once opened up about 20 zinc-carbon AA batteries for the carbon rods.

Besides being a PITA to get them out and to clean them, they break up due to bubbles forming inside the surface.
Go with stainless steel instead.

Use stainless steel. Make sure you have plenty of area as well. Use sheets (buy them, or make them-cut up a cheap bit of stainless cookware) and NaOH or sodium/potassium carbonate as an electrolyte. Graphite will just fall to crud and doesn't work real well. Also, make your electrolyte fluid have as much volume as you can, to keep the system cool (and more efficient). By the way, anyone who starts banging on about hexavalent chromium coming off into the solution from the stainless electrodes is an idiot


I wonder why you don't use the H2/O2 mix as it is? It's stoichometric, will ignite in a large range (so if you have anything that affects the mix, it shouldn't be a problem) and will be a more effective fuel, particularly for light projectiles. (especially for light projectiles, water is a much lighter propellant gas than CO2, and hydrogen/oxygen mixtures have a FAST flame front.

If you don't try it...I will...I think I can get SOS with an atmospheric pressure mix and a suitable projectile (and launcher).

inonickname wrote:I wonder why you don't use the H2/O2 mix as it is?

Using GasEq and a rich product set:

Peak pressure of atmospheric H2/O2 mix: 9.8 atm (absolute pressure)
Peak Pressure of atmospheric butane/O2 mix: 18.7 atm (absolute pressure)

Does that answer your question?

Fnord wrote:Though you might try carbon fiber. It's expensive, but you may be able to get it for free if you can find some broken fishing poles or arrow shafts. Have any sporting-goods stores nearby?

you'd need the raw carbon fibre though, wouldn't an arrow shaft or fishing pole be encased in resin and therefore insulated?

In any case, the electrolysis project is on hold while I concentrate on other projects.

Ragnarok wrote:

inonickname wrote:I wonder why you don't use the H2/O2 mix as it is?

Using GasEq and a rich product set:

Peak pressure of atmospheric H2/O2 mix: 9.8 atm (absolute pressure)
Peak Pressure of atmospheric butane/O2 mix: 18.7 atm (absolute pressure)

Does that answer your question?

We both know pressure isn't everything..With lighter projectiles, the higher flame front speed, higher temperature and lower density propellant gas are going to pay dividends.

Pencils and the like arn't as good as the carbon rods from electrical cells, as they tend to have additives to adjust the hardness which makes them less suitable. Though even the ones from lantern batteries fall apart pretty quickly due to the bubbles wearing them away.

inonickname wrote:We both know pressure isn't everything.

It isn't everything, but the higher temperature and lower density gas just aren't going to be relevant at these relatively low mach numbers (in the propellant, that is), and will more likely result in greater heat loss - hence, the pressure is more use.

H2/O2 mixes will have their advantages - when the pre-ignition pressure is increased to make up for their relatively low post-ignition pressure.
I would imagine the first mile a second hybrid might well be H2/O2 based, but I can't see it being a big hit in atmospheric systems.