The Jam Jar Jet
Read this article in MAKE:
05: Science, Weather, and Outdoors, Page 102.
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Don't think you can build a jet engine at home? Here's a simple jet engine--a pulsejet--that you can make out of a jam jar in an afternoon. All it takes is bending some wire and punching a few holes.
Note: If you have difficulty obtaining two copper reducing fittings that fit together securely, you may omit the smaller of the two fittings, and drill the wire attachment holes in the narrow end of the single reducing fitting. The effect of this change on the Jam Jar Jet's performance will be minimal.
Links
- jetZILLA
Larry Cottrill's jetZILLA, an online magazine of amateur jet propulsion. - Pulse Jets
Homemade pulsejets webpage and discussion forum.
Make: Noise — Discuss this article
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Showing messages 1 through 19 of 19.
- Mildly satisfying for your inner Pyromaniac
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Finally got this working last night. I was hoping for 5 foot shooting flames and was a little disappointed...still worth it for the sound you get.
Forget the DWV copper fitting. I followed advice above and used a 1.5 x 1 standard copper reducer from Lowes...worked great.
When the author says "Shake vigorously"...he means it. You'll get no combustion if you don't vaporize enough of that methanol by shaking.Posted by Gearhead on April 14, 2006 at 05:48:59 Pacific Time
- Needs more warning
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Damn these articles for making this appear to be a safe little thing that some have even suggested doing indoors. OMG I almost took my hand off! I'm used to working with alcohol in compressed situations but that damn jam jar lid flew off and I have yet to find where it landed. No jet, just BANG and flying lid. Thank god for no flying glass!Posted by nitr0burn on March 15, 2006 at 09:32:42 Pacific Time
- Possibly easier to find parts
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Searched for two days before finally finding jars at a grocery store (practically the last one in town I hadn't checked!) and went to a friends house to build this since he's got all kinds of fittings around his shop.
He didn't even bother to look for a fitting. Grabbed one of those new aluminum "bottles" some beers and energy drinks are coming in. Found a spot on the next 1" wide and a spot a little lower 1.5" wide then cut it out.
Worked for one run...but the cone looked like it had taken a LOT of heat. And it was too hot to open when I left. He ran it again the next day and cracked the jar.
But a proper sized chunk of an aluminum bottle may be easier to find and seems to work.Posted by jhitesma on March 14, 2006 at 16:38:24 Pacific Time
- DWV vs standard fitting reducers (and an address)
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You can get the 1 1/2" to 1 1/4" DWV fitting reducer here:
http://www.plumbingfittingsdirect.com/dwv/20002.html
I have never seen 1" DWV, so I am really curious how the author got it. You can grab a standard fitting reducer here:
http://www.plumbingfittingsdirect.com/press/11700.html
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The difference between standard and DWV is that DWV is thinner (it does not have to stand pressure) and shorter than standard compression. So if you sub out the standard, you will have to remove material from the top and bottom (so that it is approximately the same height as the DWV.
Hope the link helps.
dpPosted by dirtypants on March 14, 2006 at 00:01:04 Pacific Time
- Fittings
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Hi -
Thanks to everyone for their comments about the fittings. We added a note above that may also help:
If you have difficulty obtaining two copper reducing fittings that fit together securely, you may omit the smaller of the two fittings, and drill the wire attachment holes in the narrow end of the single reducing fitting. The effect of this change on the Jam Jar Jet's performance will be minimal.
Thanks again for the feedback!
-tPosted by terrie on March 03, 2006 at 09:19:22 Pacific Time
- DWV Hack
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give up on trying to find copper DWV!!!! you are not going to find it anywhere (including searches on the internet). as mentioned in other posts, just find something as a suitable substitute. i was able to find a 1.5" to 1" copper reducer at Lowes. it works great!
hope i have saved you time.Posted by ajschiltz on March 01, 2006 at 06:50:24 Pacific Time
- DWV Hack
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Do you have the part number, or the upc code for that copper fitting, I can't seem to find one anywhere, and I have a whole box of jam jars ready to go.Posted by MrCaN on March 08, 2006 at 07:20:47 Pacific Time
- DWV Hack
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you can find them at a plumbing store. Usual the fancy appliance and plumbing places of "back areas" that have all sorts of fittings, thats where i got mine after 2 days and talking to a ton of people. The methonal was the hard stuff to find.Posted by dudemanorig on March 26, 2006 at 19:02:08 Pacific Time
- copper fittings
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I made one of these from the instructions, but couldn't find the DWV fittings at my local hardware store, either. Not to be deterred, and knowing that copper can be (relatively) easily cold worked, I set out to make a couple of fittings fit together. It took a fair amount of hammering, some press fitting with a vice, and I then had to cut a half an inch off the small end of the "cone," but I got it to work. It was a small price to pay to have a controlled explosion in a glass jar (my mommy loved it).
I think that the most important thing is that the diffuser is roughly conical in shape, doesn't extend too far into the jar (like no more than 1/2 to 2/3), and that there's a small gap at the top of it for air movement. Really, you can use any quasi-conical piece of metal for the job... like Grandad's old ear trumpet, a section of the intake or exhaust system of your dad's old Chevy, your kid brother's trombone bell...Posted by tenax8 on February 27, 2006 at 16:38:04 Pacific Time
- Difficult to find parts
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Is it just me, or are the parts for this project rather difficult to find? It turns out nobody sells Mason jars in Feburary, and I've been to a number of home centers and I've never seen anyone that sells copper DWV fitting. All of the DWV fittings I've ever seen in stores are PVC. I wasn't even aware they made copper DWV fittings; I knew they did cast iron, but that is relatively scarce.Posted by kenh2 on February 24, 2006 at 10:30:06 Pacific Time
- Difficult to find parts
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I'm from Baltimore, MD and I found the exact same mason jar "Kerr" used in the article at a chain crafts supply store called Michael's. I could only find the copper/brass 1.25 to 1 DWV fitting at a Lowe's hardware store. No luck on finding the 1.5 to 1.25 DWV fitting anywhere. I put the jam jar jet together with just the 1.25 to 1 DWV fitting alone. It may be possible to make the jam jar jet work without any fittings so don't give up if you can't acquire them. I found the fine copper wire at a Radio Shack. For fuel I first used (mistakenly) Iso-Heet gasline antifreeze and it didn't work at all. I read the ingredients and it turns out Iso-Heet has isopropyl alcohol instead of methanol... lesson learned. I tried Johnsen's gasline antifreeze (from Advance Auto) which clearly said it contained methanol and it worked first time! It was awesome! Afterward the jar was very hot and stayed hot for a long time and so I left it alone until the next morning to show it off to the people at work. But it didn't fire up at all the next day. I think my gasline antifreeze went bad. I noticed the methanol didn't smell as strong and besides there's no good way to reseal the bottle of gasline antifreeze (you're supposed to empty the entire contents into your gas tank so the bottle is not made to seal again). I've been meaning to buy another bottle and try again. Its a shame to buy a whole bottle and use only 2 teaspoons but then again it only costs 89 cents.Posted by stom on February 24, 2006 at 16:24:08 Pacific Time
- Difficult to find parts
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home depot has the large fitting (well they do in ottawa anyway)Posted by !sam! on February 27, 2006 at 13:07:50 Pacific Time
- Difficult to find parts
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Are you sure those are actually DWV fittings, and not regular plumbing fittings? I looked in our local Home Depot, and they definately didn't have any copper DWV fittings. Could you post the SKUs of the fittings you got?Posted by kenh2 on February 27, 2006 at 13:18:01 Pacific Time
- Difficult to find parts
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Hm, I didn't think to try Michael's for Mason jars; I will check them out.
However ... I did look at Lowe's (in Sterling, VA, FWIW), and while they do sell copper fittings in the right size, they were definately NOT DWV fittings. They were standard water supply fittings. I don't believe any home center sells copper DWV fittings. You can see the difference in the photograph in the print article; DWV fittings are stubbier, and they have a recess in the female fitting so there is a smooth transition so waste water can flow. I suppose I could try the regular fittings, but the article was emphatic about using the exact parts specified.
I found people on the web that make copper DWV fittings, and I guess I could take time off work and go to a plumbing supply house to get some, but they're clearly not as available as the author had suggested in the article.Posted by kenh2 on February 25, 2006 at 21:53:28 Pacific Time
- Difficult to find parts
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Could you post the URL for the place you found on the internet that makes the DWV fittings? (Or perhaps the author can give me a source?)
If there is enough interest in getting the exact fittings described in the original article, I might buy enough to get them from the factory and make them available to MAKE subscribers.
Just a thought.Posted by Silverspoon on March 07, 2006 at 16:48:26 Pacific Time
- Difficult to find parts
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I live in Mormon Country (S. ID) and Masson jars are trivial to come by.... As for the copper DWV, absolutly no luck. I've even looked on line and found nothing that looks close.
Perhaps the author could point to his source, or a safe alternative.....Posted by flyerJ on February 24, 2006 at 12:51:34 Pacific Time
- jam jar jet
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Is this safe or sane to make in an apartment complex?Posted by hbpron on February 09, 2006 at 19:01:19 Pacific Time
- jam jar jet
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As far as safe or sane goes, I can't make a recommendation. I can say, though, that I made the jam jar jet in a 3rd floor 1 bedroom apartment, and the first thing that I thought after lighting it up was, "Boy, they really should have mentioned that this is an outdoor project." It is fun, though, and a little surprising the first time you get it going.Posted by delaney.nye on March 11, 2006 at 22:22:57 Pacific Time
- jam jar jet
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well, if ppl still read this plz read...
i tried making it out of like a um, a tin jar thingy, and, the hole on top was 10mm and all the results i got was a BANG!Posted by jet-boy on June 17, 2006 at 20:27:50 Pacific Time
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