Mike's Jam Jar experiments

[Mike Everman]

I was just thinking I'd make a flying jam jar, like a Hero heliocopter like thingy. Starting out, though, I need to get a reliable beer can jar going. Tried several holes today (in the base, and no luck, but it is imminently going to rain, so better stop. Pyro, didn't you get one going?

[PyroJoe]

Yes, all aluminum, two bases from two seperate cans. Approx 3" in diameter. 6" tall on the final assembled can. 7/16" hole. the bases need to be hammered reasonably flat. Some days they run better than others.

Probably run much better with a set of valves. Say, how far apart are those 1/4" holes drilled center to center?

Joe

[Jutte]

Worked in a crappy rainy Monday - got home soaked.Blahh !
That hovering ping pong ball just made my day !!! LOL !!!
Thanks Mike!

[Mike Everman]

Thanks, Jutte. I did one for the kids that must have bounced 20 times!

[Mike Everman]

ωd/ωn = (2π × 58Hz)/(2π × 153Hz) gives a dfr (or φ) of 0.379, which is close to the V-1, but way under 0.431 for Valve Glide™ and the upper limit of 0.59 for the valve to close in time before +tive pressure ensues.

OK, so I'll do one with the valves as close to 134 Hz as I can get. and of course do the quad in/out valve test.

[Mark]

I was just thinking I'd make a flying jam jar, like a Hero heliocopter like thingy. Starting out, though, I need to get a reliable beer can jar going. Tried several holes today (in the base, and no luck, but it is imminently going to rain, so better stop. Pyro, didn't you get one going?

If you could get the beer can jam jar spinning, the alcohol might climb the walls and help cool the sides of the can as it twirls. Were you thinking of blades like this balloon?

(Your beer can here) ha
http://www.sunriseimports.com.au/shop/i ... y-p243.jpg

[Mike Everman]

Yeah, exactly, only made of beer can aluminum. I'd like to to be a project that can be done as you drink a six pack, and uses only four of them. ha

[Mike Everman]

Same bounce video, but at eighth speed. Moviemaker isn't so bad, I can't wait to do a 1200 fps of a jar and slow it down even more.

[Mike Everman]

When I watch it run, the valves are moving very little for sure. By "these holes", do you mean the currently unimpeded?

Yes.

You are going to have a valve strip on the top of the lid, and one on the bottom. The one on the bottom is supposed to open on the -tive portion of the cycle (top shuts), thereby admitting air and the one on the top opens during +tive pressure (bottom shuts), thus exhausting.

I warned you to be careful, because the spraying may cause alcohol to go in places where you may not want it to go. Once you ignite it ... you'll find out where it went.

And yes, this may turn out to be quite more powerful when you get it all worked out.

I was just girding myself up for this, but can't do it when it might wake the family. ha Really, I'm a bit concerned about touching this one off. Need to put it in a box or something.

[Mark]

I recall some thoughts about rotary vavles, how a pulsejet prefers to sense feedback, to fluctuate as the permutations of erratic flow occur, that a perfectly predictable valve gating/timing isn't the best bait for feeding in a constanly changing/yanking eddy current environment. Without some sort of coherent flow, I think the in and out ports are going to be trying to read the environment and each terminal is going to be sensing and compensating without knowing what the other port is doing fast enough to sync up. To me, I just see an entropy developing, the bait falling off the hook when you go for a cast or expose it to the currents. Squid will stay on the hook however. ha
If you set up a hammer wave, with a sudden increase in pressure inside the jar, the ports are so restrictive that a large leap in thrust seems doubtful, it's a tortuous pathway to get out of the jar, unlike a funneled or channeled air flow. If I may stray a bit, I think about those magnificent water fountains outside the luxury hotels. In order to get coherent flow they use a bundle of smaller tubing within the line to "beam" the water out, to help sustain the free water from breaking up.
Again, if each valve is reading a different condition, it may not be doing what's in the best interest of the other, in such a two-headed turtle chaotic environment to boot. You may get very good mixing, but I can't even begin imagine how the valves will snyc up with any predictability. Recall the grid of the V-1, even those reeds are playing to a different drummer than the ones next to them by some degree. The Schmidt tube suffered this effect to a greater degree.
Another headache is the outflow valve will likely overheat with a "steady" stream of fire hitting it. Then you are also redirecting thrust with the valve, exhaust flow is not going to be straight up unless you use a pyramid design or some kind of reflector. I shouldn't say such a jar is an impossibility, it's just that the "two computers" are not linked by an omniscient rocker arm of sorts. Nature has a way of self-synchronizing, wanting to develop feedback, but you have to do it her way.
If you think about some pulse-detonation tube designs, some have a valve at either end, but it's a straight pipe where there is forced time/distance to play with. Now a jam jar is shallow and that is helpful, I don't think anyone would consider a long duct, capped at one end and at the other a reed bank admitting air flow and an adjacent valve obverse.
In the glass-walled Dyna-jet experiments conducted by Project Squid, they found the outside air would choke the outflow when it started to rarify, such that inflow occurred while there was still outflow going on, the inflow choosing the perimeter to advance inward. You can imagine this happening in a simple jam jar too.

On snorkelers, the intermediates.
Something like a tube within a tube or like the convection experiment where a strip of paper divides the tube into two halves and the candle below can still breathe might be fun to try. But it all goes back to the fact that you are evolving into a pulsejet the more you try to get more power out of a trilobite jam jar or a just starting to walk on land piglet snorkeler.

[Mike Everman]

Merry Xmas, guys!
Here's a 600 and 1200 fps vid of a jam jar. The 1200 needs more brightness from the fuel!

[PyroJoe]

A small quantity of nitromethane into the methanol fuel tends to add some white and brightness to the flame.
Joe

[Mike Everman]

Yeah, I'll try that. I saw a guy on youtube adding magnesium powder or somesuch as well.

[Mark]

I once tried some 1000 mesh magnesium powder in my fire ring thrower at night. After lighting my ceiling on fire, I took it outdoors and with some boric acid and made some beautiful green vortex rings that grew to 8 or 10 feet across as they shot upwards out of my internal snorkeler device. So then I tried the magnesium powder but I only got glints of white light, the methanol apparently wetting the talc-like powder too much. You could tell the magnesium was there, but not by much.
Another thing is that my magnesium powder has a natural oxide on it like alumunum does that prevents further rusting. But one time I took a cleaned surface magnesium fire starter with sparking insert removed and immersed it in methanol. It fizzed like an Alka Seltzer in water releasing hydrogen gas. Because of this, I thought it might be fun to imagine a light-weight sintered disk of magnesium or even some "bright" magnesium powder to go with a verticle lifting jam jar prototype, perhaps using magnesium powder coated with stearic acid which would hopefully dissolve in methanol. But there is a catch. Even small amounts of water will retard the reaction. When methanol burns, it forms water and CO2. Still, a little extra hydrogen in a jam jar might be fun stuff, provide extra lift if you wanted to try for a verticle takeoff jam jar.
"Anhydrous methanol attacks magnesium alloys catastrophically at room temperature; however, the rate of attack is reduced by the presence of water."
http://www.magnesium.com/w3/data-bank/index.php?mgw=166
If you should find some bright magnesium powder, when you go to light your jam jar it should make an impressive "whoosh." Whoosh being slang for bang. If you build up too much H2 in the jar, it's just as if you had some water in a jar and added some sodium, same reaction, hydrogen and air go bang. One difference is that the heat from the sodium reaction will light the hydrogen for you.

http://www.survival-gear.com/survival-g ... tarter.jpg
http://www.chem.uiuc.edu/clcwebsite/meth.html
http://www.youtube.com/watch?v=LmvUavGCAD0
http://www.groupsrv.com/hobby/about406397.html
http://www.firefox-fx.com/ChemM.htm

[Jutte]

Burnt my old cat kennel up today.
1m x 800mm rectangular box kennel, carpeted inside with a typical little
doorway.
So...I sloshed some petrol in it...and thought hmm...big jam jar.
You know how little jam jars go whoosh and burn off your eyebrows?
Damn this thing went whoosh alright...luckily I remembered the little
jam jars and was on my way back...wahoo that thing had some thrust alright !
It started to cycle really slow, die away and start again...that is until the
fire really caught hold and burnt the thing down.
LOL...kids thought it was great ...flames going 2-3 m into the air !
Pity ...I didn't even think to video it..oh well !