Tin Can jets

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Mark
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Re: Tin Can jets

Post by Mark » Fri Dec 12, 2008 11:22 pm

As having made 3 different sized Logan pulsejets shooting from the hip/blind watchmaker style, I wanted to say that they are very forgiving if you starve them for air or overfeed them with a less than ideal side port size. The Logan will still be happy to run with an inadequate diet, accept your faults, and forgive you like a trusting pet dog, and by simple trial and error you can find the ideal width and length for a side port fairly fast, for by the sound, it tells you. That's why I like them, they are idiot proof. The goldfish of Pulsejet Land. ha
It's very temping to think about assembling a quick/short lived plastic one just to hear that sweet reving sound. Instant full grease. Or even a five minute project/crude aluminum one would be fun, instead of a plastic 2 liter whistling bottle with methanol, how they rocket off in a flash and are down range in a blink, the Logan will rev up "almost" before you light it, instant on with methanol. With a prime, you don't even need a spark plug, they will greyhound as soon as the gate is open -- ala a simple flick of your Bic at the exhaust end.
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Pete Doyle
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Re: Tin Can jets

Post by Pete Doyle » Tue Jan 13, 2009 4:37 am

It was suggested back in December, when I posted a video of a tin can pulse jet that worked, that I try for a more robust design.
Here's one. The video is dark. When I can get to the video editor, I'll brighten it up
It's a SS water bottle. A 1 1/4" pipe nipple screws directly into the neck of the bottle. A reducing bell brings the tailpipe to one inch. Drill a hole for a sparkplug in what was the bottom of the bottle. A 3/4" hole in the side (yes. it's another Logan) and a 4 inch X 3/4" nipple. Add a propane jet. Starts with a little air.
http://www.youtube.com/watch?v=KkS8vFxbeec
pete

GRIM
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Re: Tin Can jets

Post by GRIM » Wed Jan 14, 2009 1:04 am

Hi Pete
Well done, That looks great ,
I have never built a Logan , but the tail looks a little long to me, just the same IT RUNS ,and pretty much weldless,
very good,

Keep the vids coming, Love it,

G

Pete Doyle
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Re: Tin Can jets

Post by Pete Doyle » Wed Jan 14, 2009 3:24 pm

Grim: Thanks. The tail is a piece that I had lying around. I will try to optimize it shortly.
pretty much weldless,
It's completely weldless. It literally screws together like its pipewood cousins. I do have a piece of lighter SS tubing that is just a tad too small. If (when) I can find away to bush it and press it into the reducing bell, I'll give that a go. It also ran nicely with a 1 1/4" tail, though more mellow.
Pete

Mike Everman
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Re: Tin Can jets

Post by Mike Everman » Wed Jan 14, 2009 5:41 pm

Niiiiice.
Mike
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Moehawkkid
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Re: Tin Can jets

Post by Moehawkkid » Tue Feb 03, 2009 8:58 pm

I have been trying to make a tin can pulse jet and all that I can get it to do is just have a flame shoot out the top. What should the size of the whole be and what size can? I have made no other jets this will be my first. Please tell me what I need to do thanks.

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Re: Tin Can jets

Post by Pete Doyle » Fri Feb 13, 2009 5:11 pm

MoeHawk: Can you post a picture of what you have? I'm unsure about what you mean when you mention "shoot out the top".
There are two or three holes in the can, of course, but they should all have either a pipe in them (two of the holes, intake and exhaust) or a spark plug (if you are using one).
The construction is simple. Starting may not be.
How do you start it (or try to)? Are you using propane as the jet fuel? Size of cylinder? Temperature of the cylinder (should be warm)? Size of can? Diameter and length of the intake tube and the exhaust pipe?
Hole sizes and pipe sizes are covered in my earlier posts. I make the holes a tad smaller than the pipe so that I have to press the pipe pretty hard to get the threads to catch onto the edge of the hole.
Pete

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Re: Tin Can jets

Post by jamjarjim » Tue Aug 26, 2014 3:29 pm

larry cottrill wrote:j.m. -

Welcome!

Keep in mind that even a "perfect" augmentor (whatever that might be) is only going to improve thrust by some reasonable fraction. A straight tube is not going to do as well as something with an inlet flare. Please look for the augmentor paper by Bruno Ogorelec, in the FAQ section at the top of the fora directory.

What you could try next that might be a real improvement, and is only slightly more complex than the original "plain" jam jar would be this design by Hank Whittle, from an article I published a few years ago in jetZILLA:

http://www.jetzilla.com/Vol01Num06/jetZ ... #Article_2

This one almost crosses over the line from jam jar to pulsejet (but not quite, because is still relies on a liquid pool for fueling).
L Cottrill
Hey folks,
Has anyone tried to make the Jam jar in the above Jetzilla post???????

I suspect that 6 fluid ounces may be a bit of a small jar, I measured 6 fluid ounces of water and put it in a small jar and it was barely a 2" x 1.5" cylinder. I experimented with a larger, known good jar and adapted it to have the same number of holes and pipe fitted to the lid as in the above article. I adjusted the size of the holes and the pipe to scale as best i could. It does not run. Mainly there is slowly travelling flame within the jar, occasionally some weak oscillations. The design and operation is ver different to Ghrey's "Thermo Jam" (which works a treat).

Have i missed something here????

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Re: Tin Can jets

Post by Mike Everman » Wed Aug 27, 2014 3:54 pm

I think 6oz is a typo and should be 16? The dimensions of a 6 oz has the lid less than 2.5" dia (which is a fine diameter for a jamjar otherwise), but with the diameters of holes and tube, that leaves less than .25" between holes, wall and tube. I do not think Larry would ever blow his pictorial scaling like that. A 16oz is more like 3.5" dia. That gives you 1/2" webs between things. Just guessing. Maybe the number of oz. does not include a 6, ha.
Mike
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jamjarjim
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Re: Tin Can jets

Post by jamjarjim » Thu Aug 28, 2014 10:10 am

Thanks Mike.

I had wondered if it was a typo. The jar i used to test the design was 14oz.

I've attached a photo of two of my usual Jam jars, the one on the left is 16oz, the one on the right is 14oz. The other photo shows how i adapted the 14oz jar to be like the jetzilla article design.

Regards, Jim.
Attachments
2014-08-28 09.33.24.jpg
The 'Hank Whittle' ?????
2014-08-28 09.32.36.jpg
My usual jars (they work well!!!)

Mike Everman
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Re: Tin Can jets

Post by Mike Everman » Thu Aug 28, 2014 2:58 pm

So how did they go?
Mike
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jamjarjim
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Re: Tin Can jets

Post by jamjarjim » Wed Sep 03, 2014 4:29 pm

The two jars in the lower photo run like grease. They are standard 7/16th or 11mm holes in the lids, they have good compression. The top photo of the Jetzilla type jar didn't do anything notable except burnsome fuel. It clearly has little chance of containing much pressure given all those holes!!!!

Been trying to get some video editiong software together so that i can cut down clips to a manageable size for sharing. Will share what i have ASAP.

Regards, Jim

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