Crack of the Snorkelers

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PyroJoe
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Crack of the Snorkelers

Post by PyroJoe » Sun Apr 11, 2010 5:09 pm

Hi all,
Built a snorkeler jar 6" diameter x 12" height. Tapered the top 6" by 20 degrees. Using a standard 1" pipe nipple approx. 4" in length for the snorkel pipe.
Runs great (w/ methanol pool), noticed at times it will start producing a very sharp crack noise a few inches above the snorkel pipe. Almost sounds like a small firecracker, anyone know why/what produces the effect.
Strange stuff.
Joe
Last edited by PyroJoe on Mon Apr 12, 2010 3:40 am, edited 1 time in total.

Mark
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Re: Crack of the Snorklers

Post by Mark » Sun Apr 11, 2010 8:49 pm

I noticed that effect on my pint snorkeler, it just starts to annoy your ears. It's like a very loud wet towel popping effect where the tip breaks the sound barrier when you snap it. And too, when I stand next to my piglet snorkeler a loud popping/cracking noise is also heard. I know the sound you are talking about. I don't know if the sound is emanating from inside the tank or snorkel and just fooling the senses or if it is some sort of delayed perfect fuel/air expansion/collapse effect happening beyond the exhaust. In the daytime you can't see any fire above the exhaust, but at night it is quite evident.
One time I drilled an inch wide hole in a flat top stump not quite three feet tall and put a pipe in the hole and held my piglet snorkeler upright in this way. So the magical popping/cracking effect was right about ear level as I stood next to the piglet. And you would swear that strange cracking of the air was occurring some fair degree above the snorkel in no way "attached" to snorkel itself. It was a very robust cracking sound intermittent and producing an echo effect off the house. It's a mysterious sound, seemingly like a time-delayed charge going off, some more prominent than others.
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Re: Crack of the Snorkelers

Post by PyroJoe » Tue Apr 13, 2010 3:21 pm

Thanks Mark,
Here is a picture of the setup. Although the snorkel has been sliced to add a fuel system. It runs this way, and can be fueled with a spray bottle spraying methanol into the sliced opening. Should be a good candidate for fuel tests.
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Re: Crack of the Snorkelers

Post by metiz » Tue Apr 13, 2010 4:29 pm

Hey guys

Snorklers aren't that loud right, Can they run of off a propane feed or do they need Methanol or something like that?
Never thouht I'd be asking for this again but can any of you share some plans for a small one? I want to run some stuff in the garage without knocking windows out :)
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Re: Crack of the Snorkelers

Post by PyroJoe » Tue Apr 13, 2010 5:09 pm

Hi metiz,
What are the available snorkel pipe sizes? This helps determine the size of the jar somewhat like the rectifier diameter will determine the diameter of the CC in PJs. Most of the smaller jars are methanol fueled. Propane is rather troublesome at small scales.
Thanks, Joe

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Re: Crack of the Snorkelers

Post by metiz » Tue Apr 13, 2010 5:25 pm

Heya Joe

A real small one is not necessary. I just want something that I can run in the garage without everyone bitching their windows are falling out of the walls. I can roll pretty much any pipe size (read: hammer)
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Re: Crack of the Snorkelers

Post by PyroJoe » Tue Apr 13, 2010 6:31 pm

Here is a small one, click to enlarge:
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Re: Crack of the Snorkelers

Post by PyroJoe » Tue Apr 13, 2010 6:32 pm

Medium:
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Re: Crack of the Snorkelers

Post by PyroJoe » Tue Apr 13, 2010 6:33 pm

Large:
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Re: Crack of the Snorkelers

Post by PyroJoe » Tue Apr 13, 2010 6:42 pm

Longer snorkels can be used on the above, but often the cycle will outrun what the fuel pool is capable of producing, leaning out the fuel mixture to non-sustaining. Also short snorkels can often be lit from the snorkel without the need for a sparkplug, or dropping a match down the snorkel. :wink:

It is best to run these in a low humidity environment. Although the large one appears less affected as it ran outside in a light rain shower last night.

If a spark plug is used, I will often use the 66.7% the height of the jar for intake length, this corresponds to the intake lengths I use in VPJs. The 20deg. taper on the top of the jar is also the same as seen on the Kraken (just much longer and offset). This combustor also scales down very close to the valved Atom Jet.

Mark probably has better parameters on the long snorklers, his experience is a very valuable resource in this area.
Hope this is of some use.
Joe

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Re: Crack of the Snorkelers

Post by metiz » Tue Apr 13, 2010 9:08 pm

Yes, those will do nicely. Thanks

Can I run medium and large of off propane? I have some REALY thin fuel pipes laying around. Maybe I can coil it up on the bottom of one of those cans and punch a bunch of holes in it so I'll get an even flame?
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Re: Crack of the Snorkelers

Post by PyroJoe » Tue Apr 13, 2010 10:05 pm

The large one may take propane, it is very tricky fuel for these types. There are a few lip fed jars in the forum, Mark may know of propane fed snorkelers, I can't remember any at the moment.

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Re: Crack of the Snorkelers

Post by Mark » Wed Apr 14, 2010 2:21 am

I can't really offer any sage advice, just a few humble thoughts on snorkelers. I don't like to run them in the summer months because the humidity is too high and it really affects them, just like jam jars. All of mine I was able to start by inverting the snorkeler with a rubber stopper or hand held over the exhaust port to prime the tank. Then I light the exhaust tip with a flame usually. On my 7.5 gallon beer keg jam jar, I used a long wire with an ignition system just in case the tank were to rupture or backfire up to the rupture pressure of 60 psi or something around there. On my little pint snorkeler I used a spark plug sometimes but it wasn't really needed. The same with my green fire ring thrower, which was just a snorkel inverted inside the pint canister in order to aspirate a tincture of boric acid and methanol mix into the air.
For many different sizes of snorkelers I found that tanks and canisters are usually very forgiving when trying short snorkelettes. Many different widths and heights will usually allow for sustained combustion. But for me, when you start to make the snorkel as tall as the tank, you have to be more sensitive.
Yet if you look at these two snorkels on the two piglets, both work but the smaller diameter snorkel is more reliable for sustained starts. The larger is more fussy but also more robust if you can get it not to flameout after a few cycles. I first ran it with the larger snorkel and then found the narrower one inch diameter easier going. I used both snorkels though on the same tank, keeping the one tank pristine just to have a spare piglet tank in perfect condition.
Another factor is an internal splash effect, which can cause flameouts when starting. Often the initial whoosh is ear piercing and as a neighbor two house down remarked, it sounded as if I was launching rockets. The initial pressure fluctuation really jostles the pool of methanol in the bottom of the tank. If you have a problem starting a snorkeler, you might try using less fuel at first. My piglets have started with 2 liters in them but it is easier to get them running with less. And when the gods are favorable, the tank will run for 4 minutes or so, glowing red and even yellow hot and yet you know there is that pool of methanol just boiling like mad in the bottom of the tank keeping the lower region "cool".
The beer keg has but a nub of snorkelette and I have been wanting to try a longer snorkel but as with many ideas, the motivation is hard to find sometimes. As is, it makes a noticeable starting whoosh, with my remote ignition, and then chuffs rather slowly for a bit then dies. I need to play with the proportions perhaps adding some sand to make the bottom higher or just add a proper snorkel and maybe wake the neighbors. ha
I know the tank looks a little tall but the diameter is 11 inches and the actual height of the tank without the snorkelette and handle top is about 21 inches or about a 2 to 1 aspect ratio. Even the bottom has a bit of a skirt before the actual tank starts.
I never had any luck with propane, but I didn't do enough testing with propane to offer any advice.
I think it would be fun to try a straight duct as a snorkeler. Straight ducts closed at one end can really bark with methanol, but in order to sustain that effect it would be really tricky. I've barked some straight ducts where it will hurt your ears and the duct only a few inches in diameter. Once you coat the inside of a pipe with methanol, just light the open end with a flame. You will find it most rewarding and quite motivating. Fueling and fresh air, that is the stuff to work out. ha
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Re: Crack of the Snorkelers

Post by PyroJoe » Wed Apr 14, 2010 3:24 am

The large 6"dia. one I posted was constructed of 14 gauge mild steel, I failed to mention that the larger sizes should be constructed with a heavy material. Even the small 3" diam. ones should be reasonably robust, as one of my 3" aluminum cans recently imploded at the bottom, a very rare event. ha

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Re: Crack of the Snorkelers

Post by Mark » Wed Apr 14, 2010 3:44 am

PyroJoe wrote:Thanks Mark,
Here is a picture of the setup. Although the snorkel has been sliced to add a fuel system. It runs this way, and can be fueled with a spray bottle spraying methanol into the sliced opening. Should be a good candidate for fuel tests.
I like that sliced snorkel. It's neat to try new things, like that little fueling tube you mentioned with the higher edge on one side with the hole in it to bias fuel flow.
One thing that might be worth trying is a divided snorkel, like this simple candle convection demonstration. Maybe by some means you could get a snorkeler to breathe more deeply and by doing so increase the thrust of a device, perhaps enough to make a fun toy that would liftoff under its own power. Perhaps a slight angle at the bottom of the divider would be more effective. Seems like it would be fun to try, just to see if you could get the slightest gain.
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