Work in Progress 2013

[Roark]

FWIW, some of the old-school boilers used vermiculite (expanded mica) as insulation. It handles the high temps very well, and it's light and will conform to odd shapes and corners easily. Best of all, it's cheap and environmentally safe. If you decide to experiment, you might try it.

[Elorrum]

I think you'll need an oven periscope, or viewing ladder. remote cake tester straws.

[ygmir]

yeah, and really, there's no way to lower it easily, more than maybe 3 " or so.
when I take it back apart to move, I'll see. But thinking I could just make a bench, very stable, for sitting, or baking.

[Elliot]

An other idea for insulation: Rockwool. Several types, used in furnaces and whatnot. Available at an insulation specialist in Sacramento.

[ygmir]

yeah, good idea. It seems the multiple layers of foil, inside the 2" space are working pretty darn well. It was cool enough, to touch easily, while the smoke channel was sizzling.
I don't know that insulating the smoke channel will do much, with the smoke moving fairly fast around the passages, I'd not think that much is lost, or could be gained. I think now, more than anything, will just be experimenting with flow and settings and fires. the basic oven assemble is 5/16 steel, with 1/2" doors, so, takes quite a while, to heat up. Considering 400 to 600 deg. exhaust, I bet it'll just take a while.

Getting exhaust temps higher will be workable, too, depending on heat in the Hof requirements.
IMO.

[theCryptofishist]

Dust Devil has the jet engine.

[ygmir]

Dust Devil has the jet engine.

I want to make a simple one one day, just to see what happens.

[theCryptofishist]

I don't think there is such a thing as a simple jet engine.

[ygmir]

IIRC, the concept had hardly any moving parts, but, they had to be pushed to get the airflow going the right way.
now you're going to make me google, aren't you!!

post google edit;
seems early engines had compressors, though I saw a reference to one without. Ramjet seems it might be the design I had in my head. Maybe pulse jet.

just thinking how cool a jet powered Frankencamper would be........

[burner von braun]

I believe you're thinking of a pulse jet engine. Astonishingly simple design, probably not very efficient, and loud as all get out. Too good to be true!

I like your lag bolt and chain link stakes there FGJ, they virtually eliminate the potential for rebar type injuries! Do you think they bite into the playa enough to be hand racheted into the ground, once started with a hammer, or are they more of a 'strictly power tool' kind of thing? I think I'll bring a few this year and test them out. Thanks!

[trilobyte]

There have been a few great pulse jet installations over the years. This one from Christopher Schardt in 2011 springs to mind…

phpBB [video]

Unfortunately I don't think Garden Of Rockets was up and running for most of the event. To paraphrase the old Daniel Boone saying, sometimes you eat the playa, and sometimes… well, it eats you!

I love how things are coming along on that project, Yggy, amazing work! I imagine that with those fins being located right at the bend they're able to absorb and then radiate out an awful lot of the heat energy coming out outta that thing.

Nice one with those chain links, figjam! We use caribiners in our hurricane stakes, and then tie off (or bungee off) of those.

[FIGJAM]

I believe you're thinking of a pulse jet engine. Astonishingly simple design, probably not very efficient, and loud as all get out. Too good to be true!

I like your lag bolt and chain link stakes there FGJ, they virtually eliminate the potential for rebar type injuries! Do you think they bite into the playa enough to be hand racheted into the ground, once started with a hammer, or are they more of a 'strictly power tool' kind of thing? I think I'll bring a few this year and test them out. Thanks!

You could pound them in past the soft playa on top (5 or 6"s), then ratchet them in, but thats a lot of cranking.

Don't expect a cordless drill to be able to handle this.

My big drill I think is 1/2 horse and you can really feel the torque the last 6"s.

When thier in, you would think you had ancored into a phone pole.

12" nails would work depending on the size of the structure.

[Roark]

I built a pulsejet years ago. LOUD. And with a rich mixture shoot gouts of flame. Sounds like a perfect mix for Burning Man.

The only moving part was the reed valve. Had to be replaced about every 30 minutes. Fussy. But what a wonderful noise!

[ygmir]

I guess I forgot to post the bypass I made, to direct more heat and smoke directly at the smoker/oven. Temps still seem stuck around 300 deg. max. I'm guessing all the "heat sink" of the oven assembly, is just overcoming the output. It also may take some time and fiddling with valves and flow, to get it better.

4" bypass to directly under oven/smoker floor:


and here's my attempt to shrink the top, so it quits bulging when really hot.
I cut 1/8" grooves, and "v" ground them out to 3/16" or so, and then laid about 1/4+" bead, (1/8" 7018 rod @ 110 amps DC+) hoping for enough draw and shrinkage, to put tension on the plate when cold, and allow closer to equilibrium when heated.


pattern, centered on center of bulge, I'm thinking it was asymetrical with the top, due to the smoke shelf position and hot spot where flames transition:


center spiral, for final pull to middle, and fill for grinding flat. (the very center ended up sagging right there):


weld detail, seems penetration was complete, or very nearly so:

[Triken]

Yggy~

yer a foogin' Genius!

[aserendipity]

Yes indeed
and Hurray for all the Genius few among us
I am grateful for you.

[ygmir]

first test, a success. 90% anyway.
got the top well over 600 degs (melted wheel weights).
very small amount of movement, and I'm not sure it wasn't the heat distorting the air and me looking through it.
Stayed flat as far as I could tell.
I suppose until I cycle it a couple of times, nothing is for sure, though.

[Roark]

Admit it Ygmir... you cut that top for no reason other than you like looking at the pretty starburst pattern. Maybe cut the sides with a pattern like the Burning Man? )*( Or a cow from an ancient cave painting maybe?

On a serious note, there was a heat-spreader in the early Apollo program that was eventually cut in a spiral from the middle outwards. The reason was exactly what you encountered: thermal distortion. One side of that heat-spreader could be at +200F, and the other end -140, and the thermal stresses would constantly shift as the spacecraft did it's thermal roll. So you're in good company, Hermano. Sometimes even the uber-techie aerospace weenies decide a little pattern-based stress-relief is a good thing!

[gyre]

The U.S. EPA advises that vermiculite from the Libby Mine should be considered to be contaminated with asbestos.

Many of the "safe" materials are also dangerous if airborne.

[aserendipity]

hmm, so the criterion of success becomes..?

[ygmir]

second test in progress.........

[LeChatNoir]

Hey Ygmir,

I glanced through the thread at the stove photos (This is a really fun thread by the way). And I"m going to go back and read in depth. I'm curious to see how the second test turns out, but so far your approach looks to be what I'd suggest at this point. I may change my mind after more detailed reading of the construction, though.

[gyre]

Hello, LeChat!

So good to see you on eplaya!

How is everything?
How's Karine?

[ygmir]

hey LCN.
I'll look forward to your feedback.

I"ve had 3 tests now, and getting the top well above 600 deg. and still no "hump" or much if any movement at all. I feel the cutting and welding to put the top under tension, when cold, has helped. So when it's hot, it's under little to no pressure from expansion.
It also seems with the smoke shelf/after burner area, I get pretty even heating of the entire top, in that all lead pieces melt at close to the same time. also it seems even burning as hot as I can get it (so far anyway), I get no red hot "spots".

I've moved the heat diverter to right at the top, but on the vertical side, and increased diameter to 6". It seems to have increased the heat to the oven, and smoke to the smoker, so, test 3 is mostly a success.

[Box Burner]

Dust Devil has the jet engine.

I want to make a simple one one day, just to see what happens.

I don't think there is such a thing as a simple jet engine.

RamJets are actually simple




but work best when they are moving.

A ramjet, sometimes referred to as a stovepipe jet, or an athodyd, is a form of airbreathing jet engine using the engine's forward motion to compress incoming air, without a rotary compressor. Ramjets cannot produce thrust at zero airspeed, thus cannot move an aircraft from a standstill. Ramjets therefore require some other propulsion system to accelerate the vehicle to a speed where the ramjet begins to produce thrust. (From Wikipedia, the free encyclopedia)

[Ugly Dougly]

What, is someone telling Ygmir that something is impossible???

Some people never learn....

There was a documentary on TV where these guys had a ramjet on some sort of rotating rig, and used a leafblower or somesuch to light it off. Massive fun.

[ygmir]

yeah I think ramjet is what I was thinking,,,,,,,my time frame was probably wrong. but I do remember talk of getting a plane/rocket moving so the airflow was right, and it'd go on it's own.

I'm seeing one, on wheels, inside one of those steel balls people ride motorcycles inside of..........I wonder how fast it'd go?


*runs out giggling*

[Elorrum]

Good weld detail. Like a laid out roll of coins. Do you know if cast iron as a material is less subjectable to bowing as it heats and cools?

[ygmir]

Good weld detail. Like a laid out roll of coins. Do you know if cast iron as a material is less subjectable to bowing as it heats and cools?

yes, cast iron is more stable that way. But, I've not had luck welding cast iron to steel, and it'd be expensive to get a plate that size. So, I opted to try it, and modify if it was unworkable. Seems the modifications have worked, and a great data point, too. I only found vague references to trying it that way in my searches.

[knowmad]

I found a picture of something I have been planning and am now beginning to make.

I have the Trampoline frame, (cloth is rotted out) and the large post's. I'm going to use an old tent fot the fly, but am also looking into finding some old drapes.
I'll keep ya posted.