Mike's Build Log

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Re: Mike's Build Log

Postby Mike Everman » Sun Jul 16, 2017 12:12 am

My thoughts too. Here's another try with rounder, but still tangential exits. I can get a brrrr, but thats all:
https://www.youtube.com/watch?v=WkxUnm0thwA&sns=em
Going to go look for likely candidates with more of a neck down. Perhaps they will be beerish.
Mike
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Re: Mike's Build Log

Postby Mark » Sun Jul 16, 2017 2:25 pm

If I had my druthers I'd opt to have a flat bottom jam jar instead of one that's convex or concave just as if choosing between a cylindrical jam jar vs. one of those rounded corner jars, the more extraneous curves and bends often dampen feedback. But in some cases curves and tapers might be what's best. Seems really hard to say anything definitive because every shape has it's own proclivities. So with that big caveat I wonder about multiple holes, how perhaps one hole randomly gets a head start on the other hole on the inflow phase, it seems like it's difficult to govern the flamefront or keep it coherent. With a simple hole it might not steer the air as well as one that is channeled/focused for a bit before entering the combustion chamber. Maybe just some little snorkelettes would help, albeit more weight and complexity. Snorkels add an appreciable amount of thrust to any jam jar.

Another pesky thing is simple jam jars don't like to be jostled. I remember chucking up a jam jar in my big lathe and setting it to something like 60-80 rpms thinking that the spinning would coat the walls of the glass jar with methanol and keep it from stressing. So I spun it up and then lit it and the jar ran about 5 seconds before flaming out. If you watch flames travel or dart down a jam jar sometimes they vary and go off to one side or the other or a flat advancement and who knows what's what or to what benefit how events are set into motion. I think plain holes are sometimes too tortuous for air flow and funneling evens the flow out. One time I thought about using a Dyna-jet head inverted for a jam jar lid, the inflow phase those ten ports converging into one, something like that crossed my mind. The outflow a single hole branching into many. If you're going to have many holes maybe a taller narrower can would help and also lessen the rainbird effect, although a fire sprinkler might simulate a helicopter dropping chaff or flares to evade missiles. ha
https://www.youtube.com/watch?v=IeDMipBdC-o#t=7s

Again, I really like your project Mike.

Beerish tidbit
https://pbs.twimg.com/media/DDQ-P7CV0AEaGV8.jpg - (Top left)
https://pbs.twimg.com/media/CwXbX_OUAAALCIU.jpg
https://www.haskells.com/media/catalog/ ... _0_1_1.jpg
Last edited by Mark on Sun Jul 16, 2017 8:25 pm, edited 1 time in total.
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Re: Mike's Build Log

Postby Mike Everman » Sun Jul 16, 2017 5:39 pm

Yeah, jostling is bad. I also need to protect my jets from the sideways slipstream, so i expect either some right angle snorkels or just a diverter sweep. The coors light aluminum bottle is pretty good, flattish bottom, short neck, screw cap. The shoulder is about 35deg from vertical. I wonder if i want jets to collide inside or not...
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Re: Mike's Build Log

Postby Mark » Sun Jul 16, 2017 9:51 pm

I had forgotten about the Coors bottle but recall a restrictive breathing snorkelette I put on one with low thrust and erratic combustion. There's a hose clamp and a 6 inch piece of inconel tubing on this one to weight it down. With a ~1/2 inch diameter snorkel that kind of volume can crank out enough sound to be on the verge of hurting your ears, but only 3 or 4 ounces of thrust at best. Such are the snorkelers.
https://www.youtube.com/watch?v=yHRNdqtUIxw

There's several other Coors-like aluminum bottles out there you've probably seen. This Sapporo comment is pasted from an old post.
"has a bold invigorating sound that it feels will resonate with 20- and 30 somethings".
- See more at: https://www.packworld.com/article/packa ... hot-bottle
"The Sapporo's aluminum bottle sounds a little thin like the Coor's light cans I toyed with. But they really fly when first lit if you don't hold onto them or if you don't use any ballast, the initial whoosh can cause them to take to the air. So they dent easily and would need lots of cooling if you ran them full snorkel. "

The Sapporo beer can is made of steel. I've one in a box somewhere. "The steel itself is unique in that it is much stronger than aluminum, but is flexible enough to be molded into the distinctive and identifiable shape." https://beeralien.com/unconventional-ca ... ation-day/
And if you want you can mix and match. Oh!
https://dpcr19kltm61a.cloudfront.net/ba ... _64536.jpg

As close as I got to a whirligig craft. https://www.youtube.com/watch?v=ECH7-u5ASs0

I was looking at some 12 inch diameter rubber band props on eBay. (12.2g (0.43oz) per propeller) Don't know if they would be the best choice or not but they have a lot of sizes should one want to go smaller. And what would be a easy way to attach them to a can? I was toying with those tiny 5.5 ounce V-8 tomato juice cans this morning.
http://www.ebay.com/itm/4pcs-4x12-1-4mm ... SwiYFXFAKs
https://richmedia.channeladvisor.com/Im ... peName=352
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Re: Mike's Build Log

Postby Mark » Tue Jul 18, 2017 11:20 pm

TIdbits
If I recall PyroJoe used a half and half mix and match can philosophy for one of his jam jar cars, like the Coors LIight/Sapporo aluminum to steel photo in the previous post. Anyway the 16 ounce Coors Light aluminum bottle with the screw cap is the same diameter as a typical 12 ounce Coke can and if you have a regular 11 1/2 ounce can of Campbells soup with the seamless bottom and pull-top top, it's about the best fit for sleeving an aluminum can over a steel can. In this photo I put a pinhole in the aluminum can bottom to let the air pressure out as I sleeved it on. It fits so tight you can see the ribs of the steel can imprinting on the aluminum. And you'd be hard-pressed to pull them apart once you push them together - an insanely tight fit.
In other news I ordered a set of 4 of those cheapy orange colored 12 inch diameter rubber band propellers on eBay. I have no idea if I can come up with any good ideas to get something off the ground, maybe put a propeller on a plastic lemon and admit defeat.
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Re: Mike's Build Log

Postby Mark » Wed Jul 19, 2017 6:43 pm

Maybe one thing to try would be to spin-up a jam jar with prop to a pre-takeoff speed and then light it with a propane torch.
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Re: Mike's Build Log

Postby Mike Everman » Wed Jul 19, 2017 8:06 pm

Yep,
Well, two .36" holes runs for a few seconds but not super strong. wonder if I want a wall in there to keep the streams from hitting each other on the inside. I'm hit and miss on my benchmark 12 oz salsa bottle with .52" single hole running. humidity is all over the place, runs in the morning but not at night.
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Re: Mike's Build Log

Postby Ghrey » Thu Jul 20, 2017 2:37 am

That looks like a fun project. Have you thought about asymmetrical tube lengths? Intake and exhaust?
In the process of moving, from the glorified phone booth we had to the house we have.

No real time to work on jets, more space, no time.

Life still complicated.
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Re: Mike's Build Log

Postby Mark » Thu Jul 20, 2017 3:10 pm

I was looking at a 4 inch clear glass sphere/Christmas ornament I had weighing in at 32 grams but maybe an ounce more volume than the pint-sized Coors Silver Bulllet bottle and if my food scale is accurate about 1/3 ounce more in weight than the bottle. It overflowed the bottle when pouring water into it from the sphere. Anyway it'd be nice to have a sphere made of fused quartz; it always strikes me how relatively light some of my thin-walled 4 foot quartz tubing is. Steel is 7.9 grams per cc and quartz 2.65 grams per cc. Aluminum is 2.69 grams per cc. Granted you'd needed to increase the thickness over steel but perhaps not so much as to equal steel in weight for some shapes. Maybe a quartz jam jar jet snorkeler/QJ3S airplane engine would be easier. I could have one made easy enough I suppose, just a cylinder and snorkel really. But back to the sphere, it's quite reminiscent of a Hero's Steam engine with twin snorkelettes, you'd just want the jam jar effect to go with it. There's a sketch in Reynst's Pulsating Combustion of a sphere with twin exhausts at opposite sides. But all this is just dreamland because I don't have the wherewithal or drive to bring it about just yet thinking there must be an easier way or there's something more gratifying I can make right now. The glass sphere seemed so light I had to heat a finishing nail red hot to make sure it wasn't plastic by poking it. Just tapping glass sometimes it's oddly hard to tell or maybe have been plastic-coated.
You could put some wings on this and spin it up an release it, an Eolipila toy but instead of steam maybe just a burst of hot gases from a methanol whoosh if light enough, just to get one motivated or get a feel for what's needed.
https://www.youtube.com/watch?v=RDABtbUXzYs

I thought about using a very light very long propeller, it crossed my mind that a slow spinning jam jar might be less fussy and easier to balance.
https://www.youtube.com/watch?v=syJq10EQkog#t=1m19s

So I ordered some of these 15 inch props not even having any sort of plan for the jam jar engine yet, the heart of the matter. I do that often, do things out of order, but I don't know how else to motivate myself other than to put the parts out on a table and see what the bone fragments say. Maybe throw in some hawk or eagle feathers and peacock eyes for decoration, I'm not sure.
Description :
- Length : 15 inch
- Pitch : 7.5 inch
- Hole for Motor Shaft : Ø3mm(GWS)
- Weight : 28 grams
- Colour : Yellow
http://www.ebay.com/itm/259-4x-EP1575-1 ... XQUmFSjzyG
An ancient laughable art ... the analogy is all I'm trying to get across. In a bowl full of things, each little object "wants" or has the potential to suggest something.
https://www.youtube.com/watch?v=vz_BoX2lYBg#t=1m58s
What Technology Wants - Story begins after the robotic introduction
https://www.youtube.com/watch?v=nF-5CMozGWY

PS Don't even begin to tell me about humidity - it's like night and day/untold hardship for performance. Around October it starts to be prime time for jam jars.
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Re: Mike's Build Log

Postby Mark » Fri Jul 21, 2017 11:41 am

I was thinking about this thrust reverser design that would allow the jam jar to keep its basic format hopefully without any difficult modifications as a way to get something off the ground. Maybe split the reverse thruster into two 180 degree angled aluminum bifurcated augmenter tubes to add some spin along with downward thrust. A snorkel on the jam jar would add thrust. Trying to keep it simple is the hard part.
https://www.youtube.com/watch?v=BR6n31OphuY
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Re: Mike's Build Log

Postby Mark » Fri Jul 21, 2017 6:13 pm

If you had a variable speed turntable that would be a good thing to do some testing on. In that way you could spin up a jam jar with fueling now on the sides to see how it feeds or what makes for a more stable run, the fuel climbing up the walls having much more surface area exposed, the methanol no longer residing on the bottom of the jar. The flame wouldn't impinge or dance/blowtorch the pool of fuel on the bottom like a typical jam jar motif. Perhaps there'd be some benefit we aren't aware of or another shape that would fit the bill/a more conducive shape for spinning pulsating combustion. Maybe a different aspect ratio, maybe a narrower cylindrical jar or wider? Wider at the top or bottom? Or hourglass salsa shaped. ha And you could have a flow rectifier internally just like some jam jars or like Reynst's big water-cooled variable-volume-for-starting wonder.
The thought crossed my mind to put my mini-lathe up on end because it has a variable speed dial but with no specific indicator to tell you how fast it's spinning. But there's no room for a spinning prop. A record player on 78 rpms only spins about once a second of course. But with a very long ultralight blade by some miracle of enough thrust you could have liftoff.
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Re: Mike's Build Log

Postby Mike Everman » Fri Jul 21, 2017 7:24 pm

Ha, I'm 3d printing an hourglass shape right now for another project. I think a reynst pot might not need the venturi ring inside if it were wasp-waisted. I'm starting to lean toward not spinning the pot, but too early to tell...
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Re: Mike's Build Log

Postby Mark » Fri Jul 21, 2017 8:05 pm

Maybe one thing an internal ring would do is keep the incoming flame more coherent before breaking up, such that you could have a taller jar and still get the flame to reach down far enough to evaporate the fuel at the bottom. Some very tall jars it seems the flame can't get down to the bottom to evaporate enough fuel to sustain. My narrow 12 ounce paintball tank with 6 inch snorkel is sort of like that, it won't run in the vertical but happily does at a 30-45 degree angle, the pool of fuel more at a slant. Of course hot air wants to rise and if you've ever toyed with inverted jam jars, like turtles, they really don't do very well upside down. I've always wanted to make one that runs upside down though. Even with just enough of a coating of fuel to rev up an upside down jar seems to sense something's amiss. I've gotten revs, it's just trickier. It brings to mind how would you alter/optimize a jam jar to run upside down, make the jars shorter or what ...
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Re: Mike's Build Log

Postby Mike Everman » Sat Jul 22, 2017 12:02 am

The more I think on it, I think spinning the pot is bad. The incoming jet(we think) should be making a nice, doughnutty vortex in there. As soon as you try to spin the pot, I can imagine this inside out circular flow will precess and go chaotic and turbulent. Surely it's turbulent when it combusts, or?
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Re: Mike's Build Log

Postby Mark » Sat Jul 22, 2017 2:33 am

Yea, the spinning jam jar is going to be a risky operation if it's to succeed, risky as in a lot of trial and error or rights of passage but without the cyclops or Isle of the Lotus-eaters. ha

One way I think of having a pretty good chance of working is to get one of those very light aluminum water bottles and just elbow a short 180 aluminum snorkel over the side, or have two snorkels in the top of the bottle if you've had good luck with twin hole jam jars.

Or invert the bottle and use the bottom for the top of the jar. The bottom of those light aluminum water bottles are fairly stiff and it'd be easier to mount a short elbow into that and just leave the bottom with the plastic screw-on cap in place but saw off the finger hole loop to lighten it or come up with a better, lighter plug of some sort. A small amount of methanol will protect the plastic threaded cap from melting, I've used that technique before on some water boats that are angled so that the methanol sloshes and prevents overheating there. Maybe a light plug that protruded into the neck would be of use so that less alcohol and weight would have to be used for a 5 second flight while still getting enough surface area of methanol for the jar to run. Or modify the "bottom" of the bottle by other means.

When igniting the bottle, maybe try a stiff wire guide, sleeved over a little length of aluminum tubing mounted to the side of the jar, like model rocket launch pads have, and hold onto the bottle until the jarring initial whoosh dies and then hopefully let it gently snorkel away into the wild blue yonder. If you've ever picked up one of those aluminum water bottles, they're quite light and yet stiff. You probably couldn't put a beefy/throaty snorkel on a Coke can for example, the negative air pressure phase would most likely implode it or the can walls flex so much as to dampen feedback. I've heard if you put one Coke can in the freezer and heat the other and with a drop or two of oil (?) sleeve one can over the other. That'd be a way to stiffen a Coke can to some degree. Or you could make an expander of some sort if you thought about it or really thought double walls would work or be of use somehow.

I could send you a couple of pint-sized snorkelers to toy with if you'd want. They're too heavy to fly but they won't wear out and are strangely inspiring. If you cup a hand around the exhaust they get louder and you can modulate the sound by varying the constriction but with a little 2.5 inch long necked region from a Reddi Wip cream can held in the exhaust flow, the very narrow 12 ounce paintball tank snorkeler will actually shatter your ears, some sort of vortex street shedding or something. I like how inconspicuous they are, so meager looking until you start one with the flick of a Bic.

Lastly a Coke can still sounds appealing for cost and simplicity, if it's possible to get enough life out of one for a genuine ~5 second jam jar run, taking to the air.
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