Odds and ends

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Re: Odds and ends

Post by Mike Everman » Wed Dec 04, 2019 1:35 pm

Following with interest, Mark!
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Re: Odds and ends

Post by Mark » Wed Dec 04, 2019 4:57 pm

One thing that came to mind is that the ability to sleeve the snorkel to any depth in the neck is very useful, instead of just toying with length and diameter from a fixed point at the top of the bottle. Perhaps by lowering the snorkel deep into the bottle neck, the flame entering into bottle doesn't flare out or diffuse before reaching the bottom where the fuel is. The transition from snorkel-to-bottle-flow might remain more coherent as well.
One thing that defeats a lot of bottles is the little ridge or narrowing at the very top of many bottles. You can feel it with your finger, which I suspect causes turbulence or flow separation. In the same way at the bottom of the neck, flow transition there is something to consider.

So many times a wonderfully shaped bottle might have had a chance if not for that non-uniformity. Bottles with screw caps seemingly always have that flaw. And even a 2 liter chianti bottle with a fancy cork I'm about to try has a minor burr you can feel with your fingernail. Also the neck has a mild wide, narrow, wide flaring shape instead of a straight shot into the bottle. A stubby piece of tubing/insert might be needed to even out the flow. But somewhere out there there is hope for the perfect bottle.
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Re: Odds and ends

Post by Mark » Thu Dec 05, 2019 2:51 pm

I ordered a decibel meter just to see what kind of sound is being produced with jam jars and such. Inquiring about them, a few comments came in.

"If you've a half decent smartphone, look for any number of free apps which use your phone's hardware to act as a decibel meter. Some of them seem to work pretty well."

"Commercial decibel meters have (or did have in my time) selectable weighting curves and most importantly, they were calibrated. Calibrated equipment allows 'legal' measurements (in my case noise levels in train cabins), a cheap or diy sound level meter could be technically as good or even superior,
but it would not be acceptable for commercial monitoring purposes. A sound level meter is a fairly simple device, it is the calibration that is important."

So it's yet another device one could use when experimenting. Imagine a hygrometer to measure humidity, thermometer for temperature, barometer and altimeter for air pressure and altitude, sound level meter, and if by some means an anemometer to measure exhaust speed, slow motion camera, a scale for thrust, and a clock you could really get to know your subject or keep track of what mysterious conditions favor a better running jam jar jet or snorkeler.

I believe you were working on a crude floating anemometer Mike. ha

"A common anemometer for basic use is constructed from a ping-pong ball attached to a string. When the wind blows horizontally, it presses on and moves the ball; because ping-pong balls are very lightweight, they move easily in light winds. Measuring the angle between the string-ball apparatus and the vertical gives an estimate of the wind speed."

"This type of anemometer is mostly used for middle-school level instruction, which most students make on their own, but a similar device was also flown on Phoenix Mars Lander." (Wiki)
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Re: Odds and ends

Post by Mark » Fri Dec 06, 2019 9:06 pm

Seltzer Jet Ramblings ...
Although seemingly rather subdued as it flags and dies, the effect belies or gives a false impression because this Seltzer jet is actually pretty loud. I ran it in my garage with the garage door cracked about about a foot hoping to minimize noise to my neighbors. I will get my decibel meter soon to measure it. It had been getting a bunch of weak starts until I noticed the old fuel was cloudy and had too much water in it. Sometimes you can get away with it and sometimes you can't. So with new fuel, not some leftovers from previous experiments, it got up on a plane so to speak and ran. About 20 ml of methanol was used for this experiment. I had earmuffs on but lifted them momentarily to take in the sound. I think maybe the ability to walk down in thrust until it dies is what partially fools a viewer's perception/insight when seen as a video presentation.

And I should have done a thrust measurement. Recall a 2 1/4 pound thrust Japanese Tigerjet has roughly the same diameter exhaust as this 1 liter Seltzer jet...The Tiger having an inside tailpipe diameter of 22 mm to the 19 mm quartz snorkel. I'd be lucky if the Seltzer jet was getting a 4th of the Tigerjet thrust but who knows? The 750 ml Jagermeister jet used a 13 mm diameter snorkel and made about 3.9 ounces of thrust. At any rate I got the noise level down pat. ha
Wonder what the frequency and breaths per second are?

1 3/4 pounds static thrust for the Tigerjet according to Don Laird drawing. 2 1/4 pounds moving I guess.
http://user.it.uu.se/~rist5661/rocketer ... iger_1.gif
http://user.it.uu.se/~rist5661/rocketer ... iger_2.gif
Tigerjet running
https://www.youtube.com/watch?v=H2xTYTzutig

Seltzer and Quartz Jam Jar Jet
https://www.youtube.com/watch?v=30u_qEhm_uk
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Re: Odds and ends

Post by Mark » Sat Dec 07, 2019 3:15 pm

Although a wind chime calculator video and stuff, this was kind of interesting. If you skip to the 25 minute mark he talks about the missing fundamental of a tube that should be making C2 or 60 Hz, something obvious but I hadn't thought of, the "naked chime" effect. I noticed the same effect I think holding a meter length my quartz tubing and striking it with one of those rubber hammer tools a doctor uses to elicit a knee jerk response. Up close is a very pronounced long sustaining hum.
http://leehite.org/Chimes.htm
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Re: Odds and ends

Post by Mark » Sat Dec 07, 2019 6:08 pm

I did a couple of trials on the Seltzer Jet and it produced a thrust of a little over 360 grams or about 12.7 ounces of sound! On an ideal weather day and/or tuned snorkel to seltzer tank it seems conceivable to achieve a pound of thrust. A pound of thrust would be a little over a half the static thrust of a Tigerjet at 1.75 pounds static thrust. The noise my Tigerjet makes is pretty loud too but it pulses at perhaps 240 cps as opposed to the Seltzer Jet at who knows what and the volumes are much different. It took about 20 trials just to get two good runs. So many times when you go to light it the mixture isn't right and the sound is just a bloop or weak whoosh or false start and stop. So it's a pain and a lot of work. I can see a novice giving up very quickly. These things take a lot of trial and error to be sure. Even something as seemingly insignificant like 10 extra ml of fuel can throw off the slosh/good starting ignition sequence.
Eventually I'll be pushed out of the nest and have to work on a new fueling method. The secret is to make it fun.

In this clip it's interesting that the bottle didn't show any collapse of inward flex on the negative pressure phase. I used to fire 3 liter bottles so fast you couldn't follow them with your eye and they would crush some like the walls of a thinner Lockwood sometimes do. Maybe the PVC tube reflects some stored pressure back into the bottle or it refills too fast with the larger exit/exhaust than a whoosh bottle? But not even a little collapse.
XL Soda Bottle Rocket Engines (Static Testing)
https://www.youtube.com/watch?v=jbuDYitVRuo
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Re: Odds and ends

Post by Mark » Sat Dec 07, 2019 6:09 pm

Tidbits aside from moisture taking up space that would otherwise contain more O2 and N2.

"The atmospheric pressure, temperature and humidity all affect the density of the air. On a hot day, or at high altitude, or on a moist day, the air is less dense. A reduction in air density reduces the amount of oxygen available for combustion and therefore reduces the engine horsepower and torque. For tweaking the fuel/air mixture, or predicting engine power, the air density is the most important consideration."

"Dew Point temperature is used in this calculator, rather than relative humidity, because the dew point is essentially constant for a given air mass. That is, the dew point changes rather slowly and is not significantly affected by temperature. On the other hand, the relative humidity changes greatly during the day as the air temperature changes."
https://wahiduddin.net/calc/calc_hp_dp.htm
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Re: Odds and ends

Post by Mark » Sun Dec 08, 2019 4:38 pm

There are not many thrust tests on jam jars but I did find this one.
https://www.youtube.com/watch?v=p23NGY7Lgek
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Re: Odds and ends

Post by Mark » Tue Dec 10, 2019 1:47 am

Well I finally got around to using the Radnoti glass you sent me Mike. It's had some strong revs with larger diameter tubing too. Very fast combustion requires very precise fueling and seemingly exacting selection of tubing size. It can cause quite a bit of dismay all the lengths and diameters that don't work the way you want or expect them to. And I have enough tubing pieces including bamboo to make Zamfir jealous.
I will say it was refreshing to see the Radnoti glass start right up today and the very next try is what you see here. And the silicone rubber bands and silicone jars make it as fast as can be for assembly of part A to part B work.
It's interesting to watch all the percolation at the bottom of the Radnoti.

Radnoti Jam Jar Jet with Quartz Snorkel
https://www.youtube.com/watch?v=1MqM0FB5BhM
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Re: Odds and ends

Post by Mark » Tue Dec 10, 2019 6:06 pm

It may be that the smallish volume of the 11 ounce Guinness beer bottle isn't quite large enough to match the flow of the snorkel here. Recall this snorkel was used on the previous Radnoti glass experiment. On the other hand a larger snorkel on the Radnoti would make more thrust and sound. Restrictive snorkels are usually an easier target, more forgiving than one optimized for thrust.
Of course an ideal fueling method would allow for shapes that would otherwise not sustain.

Guinness Jam Jar Jet with Exhaust Tube
https://www.youtube.com/watch?v=EyTsUscv-5Y
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Re: Odds and ends

Post by Mark » Sat Dec 14, 2019 12:30 am

Yet another "will it jam?" shape comes to life. In other news my new sound meter which measures my TV sounds not turned up high but quiet normal in the 40's decibel range but my aluminum Budweiser beer bottle snorkeler sampled a 123 dB peak 18 inches away from the exhaust. I don't know how useful it is or what kind of bias it has for high or low pitches, etc. It supposedly has a 2 or 3 dB accuracy. And my scale at a straight on angle at the camera, the digital readout mysteriously doesn't get picked up on video but at an angle with the camera off to the side and up close it does. But to get video of an event and a thrust measurement together is proving difficult.

In the background is a 750 ml wine bottle thermos that I cut the outside jacket off with a band saw which was a pain, the blade would bind on the wobbly outside shell as the thermos bottle was being cut and then get kicked off the pulley. And there's a kitschy perfume bottle that doesn't run as of yet but worked as a hummingbird feeder with red silicone band for attracting the birds.

A somewhat better photo of the roughly 3 inch diameter nicely shaped and etched candle oil lamp ... I'm liking these no build jam jar jets. ha
https://picclick.com/Princess-House-Her ... id=1&pid=1
https://www.ebay.com/itm/NEW-Princess-H ... SwO~ZcxNIt

Oil Lamp Jam Jar Jet
https://www.youtube.com/watch?v=KLgjG5b79yQ
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Re: Odds and ends

Post by Mark » Sat Dec 14, 2019 9:42 pm

The Princess House jam jar jet is exactly the same diameter and so close to the same height as a Smucker"s jam jar jet. The hole in the top of the oil lamp is a mere 5/16 but happily it works well enough/energetically for that volume- about 1/9 the width of the jar. I'm thinking it might be borosilicate because the glass is somewhat thin like some borosilcate food storage jars I have. The little red object in front of the Princess Jar is a 5/16 diameter silicone metal drinking straw tip. When I rinsed out the oil lamp, it took some time to pour and shake the water out of that small hole.
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Re: Odds and ends

Post by Mark » Sat Dec 14, 2019 10:01 pm

Some morning mediocrity ...
Quartz Test Tube Jam Jar Jet Being Fussy
https://www.youtube.com/watch?v=GfUf8ruHmYM

Quartz Test Tube Jam Jar Jet with Quartz Exhaust Tube
https://www.youtube.com/watch?v=310eYsDJolo

The vertical try just didn't want to sustain. I used some soft monel gauze underneath the metal hose clamp to protect the glass from scratches and to offer some padding.
The car proved too wobbly or for some other reason just flame-outs occurred. Sudden starting jiggles can often upset the feedback. The wine bottle frame is just sort of springy and doesn't sit tightly on the car chassy.
The sound came in at 121.1 decibels about 18 inches from the exhaust end.
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Re: Odds and ends

Post by Mark » Mon Dec 16, 2019 4:22 pm

On the Princess oil lamp I found some warnings on an eBay offering.

"Use only lamp oil. Do not use gasoline, alcohol, or solvents as fuel in this or any other oil lamp. Failure to follow these instructions may cause fire or explosion which could result in property damage or serious personal injury from cuts or burns."

Certainly the restrictive 5/16 hole diameter is risky in ideal conditions but you can see how a wick or the long glass rod that sleeves over the wick, partially occluding the hole, could further increase compressive forces if the flame were to sneak inside the lamp.

https://www.pinterest.com/pin/569283209127076439/

I'm beggining to think the lamp may be made of borosilicate, and if so will be the first borosilicate no-build store-bought jam jar jet I've come across. I burned it nearly dry and it ran for over a minute getting hot enough to burn a small spot on the purple silicone mat it was resting on, right in the center of where the oil lamp was resting oddly. When it runs, the flame keeps the fuel from staying in the bottom center of the lamp, pushing the puddle to the sides. If you give it a whole lot of fuel it dies after 15 or 20 seconds, perhaps becoming too rich.

You can do this easy test though using the index of refraction.
Index of Refraction - disappearing glassware demonstration // Homemade Science with Bruce Yeany
https://www.youtube.com/watch?v=9Tj2KMZhfoc
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Re: Odds and ends

Post by Mark » Fri Dec 20, 2019 10:54 pm

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