Odds and ends

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Mark
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Joined: Sat Oct 11, 2003 10:14 pm

Re: Odds and ends

Post by Mark » Fri Nov 24, 2017 6:18 pm

Some future plans are to string this Nilo filler wire I bought for some Curie point experiments across the length of the yard which gives me about 110 feet if I max out and if really crazy there is the diagonal which would provide even more length. But the aim or hope is to wire guide little beer bottle snorkelers so as to make something entertaining instead of the ordinary static running devices. If I work out an ignition system, the bottles could be lit from the opposite side of the yard and watched as they jet along the wire suspension towards the camera or from other vantage points. But as perky as the bottles are, the most robust snorkel diameters are proving to be impossible to sustain. I don't know if the impressive barks are just a variation on the sudden barking dog tubes they do as a chemistry demonstration that can't sustain breathing even if given fuel or if there's a chance the snorkelers can overcome their brief life proclivities. Also there's the question of how much sag the wire will have or if it really matters in the grand scheme of things.

Another thought on the piglet snorkeler with the 1.25 inch diameter exhaust, it would be fun to mount it on a skateboard and put an augmenter on it too to enhance the thrust and then tether it to a pole and let it go in wide circles on some flat pavement. You could dress it up a bit to enhance the aesthetics instead of just a plain tank on a skateboard, put a cowling or embellishment of some sort to make it more interesting.

The ~13 kilogram roll of wire is 36% nickel and the rest mostly iron with 1.6% niobium, 0.2% carbon, and 0.4% mangane. It's very similar to Invar.

"Invar, also known generically as FeNi36 (64FeNi in the US), is a nickel–iron alloy notable for its uniquely low coefficient of thermal expansion (CTE or α). The name Invar comes from the word invariable, referring to its relative lack of expansion or contraction with temperature changes."

"It was invented in 1896 by Swiss physicist Charles Édouard Guillaume. He received the Nobel Prize in Physics in 1920 for this discovery, which enabled improvements in scientific instruments."
https://en.wikipedia.org/wiki/Invar
http://www.espimetals.com/index.php/84- ... 6-invar-36
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Mark
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Re: Odds and ends

Post by Mark » Wed Nov 29, 2017 2:50 am

Yesterday I tried an experiment with this 3/4 inch diameter exhaust snorkeler download/file.php?id=14741&mode=view because of the tall faint flame I saw with the piglet snorkeler with the larger diameter 1.25 inch diameter snorkel I videod the other day. It's just easier to start and more reliable than the piglet with the high performance snorkel.

So I got a finger pump sprayer filled with methanol and boric acid which normally makes a bright green flash when sprayed while lit with a cigarette lighter flame. But even though there is an obvious faint flame ejecting out of a snorkeler when running, it doesn't seem to want to light on fire the flammable mist no matter how directly the spray is misted into the flickering exhaust flames. Perhaps the flaming exhaust is too depleted of oxygen. But I did notice an ever so slight increase in perkiness as some of the mist must have been ingested by the snorkeler with each spray attempt.

But then it occurred to me it might make for a spectacular increase in snorkeler power if I skirted the perimeter of the snorkeler exhaust/intake in a plume of pure oxygen from an oxygen tank. Instead of the intake taking in ordinary air, some pure oxygen could be sucked in if a tube with little holes surrounded the intake so as to have it ingested with the fresh air on the intake phases. Maybe this would be akin to cars that use a nitrous oxide boost. Just a thought.
https://www.youtube.com/watch?v=08zgiU18p6I#t=1m49s

In other news a quirky thing happened today with a 12 ounce paintball snorkeler with a 1/2 inch diameter plumbing pipe exhaust. Instead of just revving up energetically/barking and flaming out or doing some sort of weak start and then dying, it revved up running a few seconds and then suddenly backfired and flamed out. I've never had one backfire before. This configuration of 1/2 snorkel on a 12 ounce tank has of yet not sustained the full grease ear cracking rev that so impressed me awhile back. But again the point being, never ever has one started up revving for a few seconds stabilizing and then suddenly going off like a gunshot. It was quite odd.
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Mark
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Re: Odds and ends

Post by Mark » Sun Dec 10, 2017 12:38 am

So another jam jar of modest results. Perhaps the fuel/air ratio is more fragile with smaller sizes as the heat builds up evaporating more fuel than it can use. Also the fuel becomes watery as it runs of course, the byproducts of combustion CO2 and H2O. 2CH3OH + 3O2 ===> 2CO2 + 4H2O
Jam Jar Jet Mini Quartz
https://www.youtube.com/watch?v=VgMJac_amhk

In other news we had a light dusting of snow last night in sunny Florida and testing has been kind of dismal. The temperature the other day was 7 degrees F below the flash point of methanol so I took to preheating my paintball tanks and aluminum beer bottle snorkelers with a propane torch just to get them hot enough to light - the flash point of methanol around 52 F or 11 degrees C. I like cold air but the smaller snorkelers seem to be less perky and less likely to rev up and sustain. Conversely if it's too hot outside they refuse to run or perform as badly as being too cold - the Goldilocks zone somewhere between the two. The high today was 48 F/9 C thereabouts. Even my Bic butane lighters are making the smallest of flames as if running out of fuel but in reality it's just the cold.

Still life Jam Jar Jet
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Mark
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Re: Odds and ends

Post by Mark » Mon Dec 11, 2017 2:39 pm

Another thing tried was a spark plug on a beer bottle starting the propagation internally instead of at the exhaust end using a Bic lighter. And it seems to be more reliable for getting the bottle to rev up. On time, all 5 tries produced a good starting impulse with revving whereas if lit from the tip of the exhaust it's much less likely to build a starting feedback. Ordinarily you get a lot of weak starting impulses or the flame flames out halfway down the snorkel making a whoop sound or even if the subdued flame makes it all the way down the bottle (as evidenced by the heat you can feel when holding it) it often gurgles or just fights you if the mixture isn't just right. On top of that, the bottles have yet to actually run more than a few seconds at best. So some other fueling methods will be tried. Also the angle the bottle is held helps or hinders the probability of a good start. The spark plug was put in the neck so that I could swirl the methanol inside the bottle coating it a bit before a starting attempt without wetting the spark plug which makes the plug less reliable - it has such a tiny gap to begin with. Also that's about as far as my pinky finger could reach and precariously hold the nut while tightening the plug to it. Even with the spark starting method, the jet doesn't rev instantly but rather there's a very brief sudden expanding whoosh before the rev kicks in. I'm only hoping to get a ~5 second run, something long enough for a short flight or whatever.

Another attempt was to put a rubber stopper in the exhaust tip and bang start the bottle with the 1/4 32 spark plug. But all that came about was a gunshot effect, as if the flame front was too fast to get the pool of alcohol to light or stay lit.

I bought this jacketed beaker thinking it would be something to toy with if some kind of lid were made for it. Maybe some rubber bands could be strung over the hose barbs to hold a lid down. The jacket could be filled with water or perhaps methanol which when heated could conceivably be used/directed to take over feeding the jam jar after an initial star with just enough fuel to get it up to temperature - just a vague thought at this point. It was just something to motivate me, an interesting shape that may or may not come to fruition. Being borosilicate there's a chance it will hold up for a couple of minutes at best but that's all I'd bank on but who knows, if the cooling jacket kept the jar from forming high/low temperature gradients next to each other, with an even rise in heat the glass might hold up.

In other news, I decided to burn up some old methanol that had been used for some previous runs and testing and what was left saved in a steel water bottle. It was pretty watery so I did what I usually do, run it a larger engine that isn't so fussy. The usual thing that happens is that the engine runs for a few minutes and then when it stops you can light the top of the snorkel as there's always some fuel that doesn't burn up and as such evaporates fast enough in the hot tank to produce a gas that can be lit making a nice-sized flame like a jumbo candle burning, that burns for some time. But yesterday's event was a first, this fire extinguisher tank after the run didn't want to make a gas that was flammable after the run. In fact when I put some thick leather gloves on and tilted the tank sideways, there was this sudden whoosh as the methanol/watery solution flashed in the hot snorkel. But the flash this time was so uncharacteristic, it was a different kind of distinctive hiss I attributed to the liquid being a very large percent water. The large tank on the right was what ran for ~2 minutes before stopping and leaving the highly watery liquid.
download/file.php?id=15052&mode=view
It's just never happened to me before, not being able to light the snorkeler fumes after a run. Maybe the cold weather allowed for more "distillation" before dying out coupled with the highly reused watery methanol.
As an aside, a fun thing to do with a paintball tank snorkeler is to after a long hot run, tilt it sideways to flash the remaining methanol in the tank with gloved hand whilst lighting the ejected gases with a lighter held in the other hand. Not only do you get a ten foot flame/fireball but the force actually produces somewhat of a kick or recoil force felt in the hand that's holding the tank.
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Mark
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Re: Odds and ends

Post by Mark » Wed Dec 13, 2017 3:06 pm

Well it may not seem like much, but I finally got the perky 1/2 inch diameter snorkel on the 12 ounce paintball tank to sustain for a full grease 5 second run. Instead of the typical 30 ml of methanol in the tank and endless attempts, something around 50 ml was used and the tank maybe held at a slightly higher angle. And even then trying more or less fuel in the past, I was never able to verify that an echo producing/ear piercing rev would ever sustain with that shape. And it's not something that will be easily repeated even after this first success because if it does rev up full grease it will most likely flame out without sustaining, the slosh or whatever chaos that goes on inside the tank makes it mightily fussy.

I kind of liken it to starting a Dyna-jet by priming/spraying some methanol inside the chamber and intake with a finger pump sprayer and then lighting the tail end with a match instead of typically using starting air from a tire pump or air compressor. It's very hard to achieve enough oomph where the feedback kicks in and sustains enough to bring it to life. I've only done that one time with a Dyna-jet. You can spark it from the inside or cork the tail and bang start it without compressed air but try to start one by just lighting the tail with no starting air and you'll acquire a new aspect of the word patience. If it's hot and humid out it's never going to happen and the same if too cold.

The troublemaker on the left.
download/file.php?id=15231&mode=view
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