[calluna28 (OP)]

I have written a fiction on real life dragons and i am trying to explain the science of how they breathe fire, i need it to be something that would work in real life as we would like to be able to make a working model.

So far I have got that they produce a highly flammable gas that is a mixture of acetone and air. They do this by extract acetone from fat and mixing it to the required concentration in the insulated fire breathing gland. Next they exhale the gas, and spark it by channelling eletricity. Some dragons breathe a lot of fire so it needs to be easy enough for them to get what they need to make it.

I want to say the dragons deposit aluminum on the bones, both for strength and for conductivity. Static electric is generated by the dragon grinding its teeth. The top teeth contain aluminum and thus are able to connect with the rest of the aluminum in the body, and the friction between the positively charged aluminum of the top teeth and the negatively charged bone of the lower teeth creates static electric which produces a small spark.

How much of this is possible?
I know it is possible to deposit the aluminum on the bones and teeth but would that help the dragon conduct electric?
Would bone and aluminum actually create static electric?

Close up the teeth are not smooth, they are all covering in tiny bumps to help create more static.

Also, i have a single dragon which produces loads of tiny sparks from it's body. I was looking at the eletric eel and other things, would i be able to say the dragon is able to posivitly charge the ions on it's skin so is constantly losing eletrons in a shower of sparks?



^^ thank you lovely people


 

[CliffordK]

The electric eel essentially uses the nervous system (axons) to generate pulses of electricity.  The advantage of that is that it could be easily controlled by the brain. 

You may also look at spontaneous combustion, often discussed in relation to the decomposition of hay, or other substrates which can generate a lot of heat, to the point where the hay will begin to smoke, or burn.

I'm not quite sure about static electricity.  You may need an insulator that can support different electric charges on the surface of each side of the insulator.  For example, a balloon is made of rubber, generally a good insulator. 

You would also have to have a level of isolation.  So, for example, if you wanted to spark between the top and bottom of the mouth, the two jaws would have to be electrically isolated.

A capacitor is an interesting device that has multiple layers of conductors and insulators, and can capture a charge between them.

[evan_au]

The electric eel is capable of generating voltages up to 600V for 2ms, which would be enough to generate a spark and set alight a plume of acetone and air.

They do this via thousands of stacked nerve cells (each of which can generate around 0.1V). They don't need a highly conductive element like aluminium - they use the normal salty solution that makes up our bodies.

Aluminium is hard to extract from food, because aluminium is extremely reactive, and strongly bound to the oxygen atoms with which it forms an ore. Implanted in the body, metallic Aluminium would quickly react with many chemicals in our bodies... (but maybe mythical fire-breathing dragons have different biochemistry?)

Perhaps an easier way of generating sparks with static electricity would be to rub together two different insulating substances - one would become negatively charged, and the other positively charged. Perhaps two different types of hair or scales?

As birds, planes (and dragons?) fly through the air, the insulating air running over their surface can separate charges, building up a static electric charge. Aeroplanes have little spikes on the end of their wings which discharge these built-up charges. They are intentionally high resistance in an aeroplane, so they don't interfere with electronics. If they were low resistance, they would, in effect, leave a small shower of sparks behind them.

There is still the issue that as well as making a BBQ of the dragon's dinner, the flame would slightly scorch the dragon's nose, especially if it were flying into the flame...

[alancalverd]

You won't generate a static charge by rubbing a metal (e.g. aluminium) against anything.

No problem generating a flammable gas - I'm sure dragon farts contain as much methane as human ones, and a bit of helicobacter pylori in the gut will add a hint of hydrogen, so the mixture will behave pretty much like the gas in your cooker.

Now if you exhale the gas through a fine conductive mesh, something like wet whalebone, the flame won't strike back and burn the dragon: the principle of the Davy lamp.

Whilst it is easy to control biogas under pressure, the specific energy content is low. Fortunately you don't need a lot of primary fart gas to do a lot of damage to your enemies. The trick is to use an afterburner: sneeze some fine dry powder or combustible liquid into the flame, and add a high velocity bypass of ordinary exhaled air. Aluminium or iron is ideal (the principle of the thermic lance) but not easy to obtain from a biological source. Dry maize flour is cheap and works brilliantly, as long as you have a friendly miller (IIRC there are always jolly millers in dragon stories) or you can use olive oil (if your dragon lives in the Mediterranean), mashed locusts (ditto), fish or seal oil (plenty of Nordic dragon sagas), or mutton fat (Welsh dragons live on the stuff, lookyou).   

I'm always surprised that Stridulae don't burst into flames, and stroking a cat with amber will produce nice sparks, but I think electrostatic ignition is too unreliable, especially in a wet Welsh winter or on a North Sea beach. My preference would be to use electric marine fish (genus Torpedo) cells to produce a low-voltage, high current flow between your jaws. Your front teeth having been roasted into carbon rods, as you slowly open your mouth you will generate a plasma hot enough to start a jet engine.   

Flying into the flame will indeed cause problems but Chinese dragons don't fly, Godzilla apparently flies backwards, and the AGIP heraldic beast is only depicted flaming en passant. Having been beheaded at least twice, by Sigurd and Siegfried in different centuries, the details of Fafnir's armament have been lost, but combat records (according to Wagner) suggest he only breathed fire when on the ground. Welsh dragons are also extinct but the Civil Aviation Authority remains vague on the date or cause of their demise - "prehistoric pilot error" is inexplicit, IMHO. 

[allgoaway]

reading this over got me thinking. I know that moving a wire threw a magnetic field will make a charge, so if an iron rich blood moves threw a polarized skeletal stretcher could it build to a point of a plasma discharge? i.e. a visible ark.     

[RD]

The spark which ignites the gas in cigarette lighters is generated by piezoelectric material.
Bone has piezoelectric properties ... https://en.wikipedia.org/wiki/Bone#Repair

[CliffordK]

Many cigarette lighters (as well as flint rifles) use flint & steel to generate the spark.   
But, there are some such as the long handled lighters that do use the  piezoelectric sparks.

[allgoaway]

but could either of them make an iron rich blood spark, or would they need another catalyst?

[dlorde]

but could either of them make an iron rich blood spark, or would they need another catalyst?

The iron in blood is not metallic iron, it's ionic; single ions, each bound in the porphyrin of a haemoglobin molecule.

[CliffordK]

What if you had a gizzard like chickens and birds?  Then one could swallow flint and iron.  However, one would still have to have access to elemental iron (was it easily found before the iron age?)