The best ignition for a fire bottle

[Ropik]

Some time ago, I started "The best fire bottle" project in my workshop. Please don't say something like "Fire bottles are kEwL, uneffective and primitive and...". Yes, they have drawbacks, but everything has them. Fire bottles are cheap, simply made from normal chemicals and reasonably effective on many targets.
OK, let this argumentation aside, there is the problem:

The ignition method should has these qualities:
- simple to construct and operate
- reliable
- made from readily available materials
- it shouldn't give the thrower's position away by big flame or something like that

I tried many manners of ignition, but none of them fits all requirements.
1) Normal "rag ignition" - wasn't tried, too dangerous due the backflash possibility, fire bottles with this ignition method can not be stored because the fuel evaporate from them constantly.
2) Road flare - extremely reliable, but also extremely visible and I have troubles obtaining the flares here.
3) Sparklers - two sparklers taped on opposite sides of the bottle, so far best method, but the burning point of the sparkler must fall in the napalm filler, the sparks don't ignite it in most cases and this decreases reliability.
4) Comonnly available rocket fuse - tried, but results was worse than with sparklers.
5) Blackmatch - too brittle and weather unreliable.
6) Acid ignition - good, but the "readily available materials" rule is broken due to chlorate required and the acid either displaces part of the fuel, or (when it is in test tubes outside the bottle) makes handling dangerous.
7) HTH/glycerin(see Anarchist arsenal) - usable, but due to long ignition delay it is unsuitable for attacks on moving targets.
8) Mechanical ignition by matches and spring(see the IMH) - wasn't tried because it complexify the fire bottle construction too much.

Any ideas are appreciated.

[Bert]

1) Normal "rag ignition" - wasn't tried, too dangerous due the backflash possibility, fire bottles with this ignition method can not be stored because the fuel evaporate from them constantly..

You cork or screw cap the liquid filled bottle and tie the rag around the neck. You damp the rag with flammable liquid immediately before use. Unless you don't have time, in which case you've got worse problems than evaporation to woryy about.

[The_Duke]

A small explosive charge fixed to the bottle would work. Even a M-80 or a blasting cap will probably work fine.

[Ropik]

I tried even this method, but it has three drawbacks: you must fiddle around with another bottle of flammable liquid, I throw the bottles like stick hand grenades, thus I must tie the rag around the body of the bottle, and this burning rag is extremely visible

[The_Duke]

Well then, why not just tape a piece of visco fuse to the bottle. There will still be some flame visible but it will be considerably less than that of a burning rag, and less likely to give away your position to the enemy.

[Ropik]

Uh... The first reply was for Bert.
According to Expedient hand grenades: "explosive fuse like "cherry bomb" is not fully reliable and may disperse the filler instead of igniting it."
Blasting cap is even less likely to work, it was used in japanese impact ignition fire bottle, some were tested by Allies and proved to be unreliable.
Visco was tried("rocket fuse") and it isn't good. The main problem with every normal fuse or sparkler is that the burning point must land directly on the napalm to ignite it. Sometimes the glass shard with the fuse fall to some other place and the bottle fails to ignite.
Thing to try would be the "bengal match" used on Finnish molotovs. Anyone knows the composition used?

[Jacks Complete]

Nice thread!

I agree that a simple but effective fire bottle would be a real asset to our arsenal of knowledge.

I don't know what HTH/Glycerine is? I assume it is a strong oxidiser, in the manner of the KMnO4/Glycerine ones?

A small mechanical lighter might be a good answer, as it could be based on the breakage of the entire bottle. Strap it tightly around the glass bottle, and it lights (somehow) when the bottle breaks, and the tension is released.

Impact explosives are generally out, due to risk.

I'll have a think. Something with a fuse to the inside and a lighting system on the outside might be the best way.

[Isotoxin]

I suggest a mechanical fuse as per NBK's idea(although I have seen it in other places as well)

-Easy to make
-Cheap
-Uses common materials

By using match heads inside a thin paper tube with a small match strip with a pull cord you will be able to keep the bottle somewhat airtight and safe.


http://img171.exs.cx/my.php?loc=img171&image=fbignitor8qi.jpg


Note to NBK: Yes I know its not a gif and I know what you say about gifs. However I can't save gifs on Linux and I adjusted the jpeg to only 10KB so I think its ok as far as slowing people down goes. Edit it out if you find it lacking


Overall Ignitor Assembly
Pull String
Match Head(s)
Friction Ignitor Strip
Cork(or cap) with small hole
Standoff tube(not needed)


An explanation(with theory):

As per the original posters ideas this is easily homemade and should be very reliable and easy to construct. Testing, of course, is a must before use in combat or in the live firebomb.

From the common small matchbox the strips are removed using a knife and 2 are glued back to back. Before being glued fishing line is folded over itself a few times(to get a better grip on the glue) and layed inbetween the 2 strips with the free end(a foot or so) coming out the shorter side(ie the top or bottom) of the 2 strips. The strips are placed between 2 pieces of wood and a vice is applied untill the glue is dry. Of course other methods could be used.

A paper tube is rolled like when making salute bodies but not so thick so that 2 match heads can fit tight(but not to tight) with the 2 strips and string(from now on called the friction ignitor strip). The tube should be make with the friction ignitor strip at hand so that you only need to do this part once. Have 2 rows of match heads on each side of the friction strip all the way down the tube. Glue may be used, expecially on the bottom pair to prevent them from falling out. It must be remembered that the bottom pair of match heads is what will ignight the pyrotechnic mixture so take care that all the match heads will transfer their flame to these 2. Tape should be used to make sure the match heads are kept in firm contact with the friction strip but not so tight as to make pulling it out impossible. When you pull it out quickly the match heads should ignight.

Now let us discuss the 'firebottle'. The gelled fuel is filled about up to the part of the bottle where it(the bottle) starts to converge to the mouth. A standoff of a somewhat smaller tube is used to keep the ignightor in place. Imagine a tampon with one slightly bigger tube and one slightly smaller tube and how the smaller tube rests on the asorbent material. The secondary tube should rest on the match heads and the string goes through it out the top. A very small hole is made in the cork(or top) of the bottle and first the ignitor is placed into the fuel so that about 2/3 is submerged and then the string is threaded through the standoff and then through the cork and the stand off is pulled tight against the cork and ignitor and the bottle is capped insuring that nothing will come lose in storage and transit. A small amount of slack can be placed in the fishing line within the standoff tube to add a sort of safety to the device.

Now the question is can the string be pulled, the bottle lit and then be thrown? Or must the thrower use some sort of method to get it to ignite in the air or once it lands?

Possible ideas:

Holding onto the string and throwing the bottle
Using rubber bands or springs to jerk the string once it lands(or use a spoon for in the air ignition)


Other members may have better ideas

Update + More Notes:

After writing that I have come to think that firstly the stand off could be done away with if you were to simply fill the bottle up more and use the bottom of the cork as the thing that puts pressure on the ignitor. This is better because it lets you pack more fuel inside and means less parts. HOWEVER:

I think that PERHAPS trying to ignite the fuel with the bottle sealed up might be difficult without having some air space in the bottle to add a small bit of oxygen. I don't know if thats true or not - testing must be done.

To insure compleat air tightness a drop of waterbased glue may be placed on the outside of the cork ontop of the hole the string comes out of. This will form an air tight bond with the string but let the string slide out as well.

Please give me feedback/comments

[Skean Dhu]

What about a M-80 type device that has pyrotechnic stars , mixed in with the main charge?
There are plenty of mixes that are just KNO3, charcoal and Sulfur, or you could canibalize some consumer fireworks assuming you can buy them, many fountains have stars in them so you wouldn't have to buy shells necessarily(sp?).

[xyz]

I'd use cannon fuse running down inside the bottle (through a hole in the lid, which is then epoxied to hold the fuse in place) to a about 20 or 30 grams of KNO3/Sugar or similar incendiary inside a sealed container (so the napalm won't get to it). Use a container that won't be attacked by the napalm, but will be melted by the incendiary and not blown to pieces. A film cannister comes to mind, but is too big to fit in bottles. I suppose you could make a molotov cocktail using a large glass jar though.

Light it and throw it, it doesn't matter that the fuse won't light the napalm, because the incendiary on the other end of the fuse sure as hell will.

Use 2 parts KNO3 to 1 part sugar (by weight) as this mixture will easily burn without atmospheric oxygen, allowing it to ignite the napalm even if it's still completely submerged in it after the bottle has broken.

Please note: The KNO3/Sugar is NOT there to explode and break the bottle, it is there to burn fiercely and ignite the napalm AFTER the bottle has hit the target and broken. It may be able to break the bottle on it's own, but I certainly wouldn't rely on it.

[Ropik]

Jack's Complete: HTH is calcium hypochlorite. It works very similarly to KMnO4 delay.
Mechanical ignition was tried(see the first post) but it kills the main merit of a fire bottle - fast and easy manufacturing.
Isotoxin: There must be some way to ignite it after landing for effective, safe function. When you ignite it before throw, you risk the explosion of gas vapors/air mix in the bottle.
xyz: This is good, but it has the same problem like any delay - when you attack something moving, the napalm mostly stick to it, but the delay igniter might fall to the ground and then you are in trouble. It may be useful if you can make really trusty, short delay to ignite it more or less directly in the moment of landing. Or use it only for "demolition" bottles, which are to be thrown on building, standing cars etc. And about glass jars: they have very good size/capacity ratio, but half-liter liquor bottles are most easily and accurately thrown - at least for me. Things like quart jar with napalm are too large to grip and too heavy to throw far.
Skean Dhu:I used something like overgrown M-80(7 grams of flash powder) with coarse aluminium(partly) and it was very reliable, but you must either obtain aluminium and similar things, or buy some normal banger, but in time of need for fire bottle, consumer fireworks would be probably banned already. And the delay is unacceptable, because you must make it long to make really sure that it doesn't go off in your hand. Maybe if you ignite it by a sparkler, which would ignite napalm already and the firecracker would take care of unbroken bottles...

[Anthony]

IMO to be of use, a firebomb must ignite immediately on impact, so fused ignitors wouldn't be very good.

I'm sure the burning rag method is used for a reason - easy and reliable. How about a slight adaption? Attach the end of the rag to the bottom of the cork, or inside the screw cap. Then simply unscrew of uncork and draw out the ready soaked rag, ignite and throw.

The flame is visible, yes, but so is a liquor bottle flying through the air! Or is the concern that it is visible whilst you are still holding it, and waiting for your target to present itself?

In which case, can you not simply ignite the rag immediately before throwing? Perhaps a pull-string matchbook ignitor would be useful here.

Actually, have you tried simply taping a matchbook ignitor to the bottle?

[Ropik]

Yes, I tried this igniter, but it will go out in midflight. The most inconvenient thing with the rag ignition is that if the rag doesn't fully plug the mouth of the bottle, the flame can flash in the bottle and it will probably explode due to gas/air mix inside. I wouldn't rely on something like this.
The "rag under a cork" is suggested in the Black book of arson. IMO, the Harber's "Jar molly" is the only pretty safe example of this method, because the rope has constant diameter everywhere.
The flame isn't too noticeable at daylight. If you use this ignition at night, THEN it is a problem, because the arc of the bottle reveals the thrower's position with pinpoint accuracy.
I think that the rag ignition wasn't used because it has many merits. It was used because nothing else was available at the moment. It's worth noting that none of the armies that mass-produced fire bottles used this method. The most common was either some form of a "Bengal match" or a strip of film - in times when films were made from celluloid.

[TreverSlyFox]

The best description I've found of the Finnish Molotov is at http://www.ankkurinvarsi.com/jaeger/OTHER_AT_WEAPONS1.htm

It would seem that the "best" expediant replacement for the "Bengal Match" would be "Survival Matches" or "NATO Waterproof Matches" as sold at www.sportsmansguide.com Item #AX5A-21053 $6.95 for 50 matches. Though shorter than the Bengal Match they could be "Chained" togeather so one would light the other in sucsession. They burn for 12 seconds so you'ed need to chain 3 togeather for a 30 second burn time. And the Finns used 2 Bengal Matches, one on each side of the bottle, that burned for 60 seconds, too insure reliable ignition when the bottle smashed. The "Matches" would leave less of a "Signature Trail" to your position than a burning rag would.

It's also mentioned that later on in the war they used a "Capsule" of Sulfuric Acid within the bottle to ignite the fuel rather than having to "Lite" the matches. I'm not a Chemistry Major so I have no idea how the Sulfuric Acid ignited the fuel or how they insured the capsule of Acid would break when the bottle did. I'm sure others here can explain how the Acid ignites the fuel.

Just food for thought.

[nbk2000]

How's about putting a metal tube that runs almost the length of the bottle through a cork, with the open end being surrounded by a pull fuse match-book igniter, and the central tube containing a sparkler?

The pull igniter gets the sparkler lit, and the tube protects the bottle contents from the sparkler until it's broken.

Assuming you use a length of copper tubing, one end sealed with a bolt, you should have a bit of time to throw the bottle.

Guarantee it'll ignite once that (hot enough to ignite thermite) sparkler gets exposed. :)

[Ropik]

NBK: If I got this idea right, it is supposed to works like: The sparkler burns in the pipe, thus more or less invisible, and when the bottle breaks, the napalm gets into the pipe and ignite. It's rather good idea, but it will probably work only with thin napalms, otherwise the filler will not run into the pipe, or it will be too slow. But I will try this definitely.
TreverSlyFox: I think they used sulfuric acid/chlorate ignition. I read somewhere that their Molotov fuel has potassium chlorate in it.

[TreverSlyFox]

Ropik,

Your right, after much testing the "standard" mix in their factory produced Molotovs became 60% Potassium Chlorate, 32% Coal Tar, and 8% Noulee. Not sure what "Noulee" is, as a Goggle search doesn't turn up anything on what it is.

[Bert]

Ropik,

Your right, after much testing the "standard" mix in their factory produced Molotovs became 60% Potassium Chlorate, 32% Coal Tar, and 8% Noulee. Not sure what "Noulee" is, as a Goggle search doesn't turn up anything on what it is.

I suspect that this mix is the "bengal match", not the molotov cocktail itself. What the HELL is nouleee?! Sounds French...

[Ropik]

I think that it is some oil fraction to get it all going... May someone with access to tar test the mix without the mysterious noulee to see how keen it's to ignition?
I doubt that it's the bengal match - it's probably sticky as hell and the match is in stick form(surprise, isn't it?), unless the noulee is some polymerizer for the tar, of course...

[c0deblue]

Expanding on xyz's and NBK's ideas, how about using a glass test tube filled halfway with an incendiary material like KNO3-sucrose and the rest of the way with wax? After filling the lower half of the tube with the incendiary, a piece of visco fuse is inserted and a plastic drinking straw is slipped over the fuse before pouring the hot wax in place. The lip of the test tube can be inserted through a plastic "washer" sized so it is held securely between the mouth of the bottle and the screw cap, or a tube can be chosen that just fits the mouth of the bottle without falling in. In this case, two O-rings provide a positive seal and prevent the test tube lip from damage when the cap is screwed down. A pull-type fuse lighter of the type previously discussed is mounted within the straw and the pull cord is fed through a small hole in the cap leaving an inch or two of slack. A safety against accidental activation is provided by tying a knot in the cord which must first be yanked through the hole in the plastic cap before tension can be applied to the pull lighter itself. When the incendiary mixture is ignited, the wax confines the pressure to the lower half of the tube, breaking it and igniting the gelled gas. With a plastic jug and un-gelled gas, this test tube arrangement might also make a fair FAE if a suitable bursting charge is layered or combined with the incendiary mixture.

[Guerilla]

I think that it is some oil fraction to get it all going... May someone with access to tar test the mix without the mysterious noulee to see how keen it's to ignition?
I doubt that it's the bengal match.

Yeah it was certainly used as the fuel, a sulfuric capsule was put inside the bottle prior to use. This kind of fire bottle would burn furiously with a cloud of black smoke, therefore even if it didnt set the engine on fire it would temporarily blind the tanks prisms allowing the use of satchel charges or other AT-devices. As for the noulee, for all I know its some kind of fuel additive/thickener, one would think it could be substituted with something as simple as sugar. Noulee is a completely unknown word to me too, nevertheless. Theres one book in the local library that deals with the munitions and their compositions of the era, gotta check if it tells anything.

I dont think many of us, as amateur with limited chemical supply, would waste that much chlorate in one bottle though, unless it would predominantly be used as an incendiary device with maximum heat output.

If I was to prepare lots of molotovs in short time with fairly limited resources, I would propably go for simple gas/tar mix and H2SO4 on the bottoms and the bottles wrapped in paper bags having some chlorate composition in them.

[Ropik]

The gasoline/tar mix is very good, but you must have the tar, which is the main problem for me. I would go for napalm B, as I have nearly unlimited supply of polystyrene, maybe with some ammonium nitrate and naphthalene added. This mixture gave me the best results so far.
Do you think that the noulee is thickener?? Even without this, the mix of chlorate and tar would be extremely thick, some additional thickener would probably result in rubbery matter, which wouldn't stick very well IMO.
BUT - fanfares - I discovered nearly perfect ignition method! It is much more suitable for jars than for bottles, however. There it is: String coated with melted sorbitol/KNO3 mix is wrapped around the lid/jar joint while still pliable and then secured with wire. Take care that the ends of the string aren't touching, otherwise the burning time will be cut in half. Cover the string with heavy duty aluminum foil and scotch tape - except one end. You may also embed few matchheads into this end to ease ignition. You are done! The fuse is almost impossible to extinguish by normal means, the foil and tape shield it further, so the flame isn't visible too much, only smoke. When the jar breaks, the glass threads break also and the fuse fall into napalm, igniting it instantly. You may adapt this manner of ignition for bottles without much hassle, it only looks less neat. Enjoy!

[Ropik]

Uh... The optimal fuse was the whole time on this forum... It's the Microtek's fuse from silicone, permanganate and sulphur. Wrapped in aluminum foil and tape, it's impossible to extinguish by throw or weather, it gives off only very little smoke and a small flame, which is more than enough to ignite the content of the bottle, however. You can tape this fuse across the lid(if you are using jars), or along the wall of the bottle and all is set. Because of the slow burn rate, reasonably long piece will give you minute or more to throw the bottle. Sorry about starting this thread. But, I will publish my future discoveries about the fire bottles here. The comparation of napalm additives and their benefits will come in short time.

[Tinton]

I recently read an article explaining how AP is an entropic explosion. (http://www.technion.ac.il/~keinanj/pub/122.pdf) Since it produces so little heat, you could use it as a bursting charge for liquids, without igniting it (haven't tested it though).
Place an airtight rod of AP in the bottle, and attach a fuse at the top somehow. Then tape a sparkler, road flare, or something to the side. Light the fuse and throw it. When the AP detonates, it should spray the liquid all over, and the sparkler should ignite it. Creating a classic firebomb, or even a FAE.