Fuel Pods

Just build a cannon and want to show it off? Post it in here.

Postby BigBang » Wed Apr 26, 2006 10:55 am

Good Morning Gentlemen,

I'm not sure if this post is most appropriate for the Finished Cannons forum, but I thought more people would see it here. If the mods think it is better somewhere else, please feel free to move it.

Anyhow, over the winter I got bored and needed something to do. It was too cold in OH to shoot spuds, so I worked on my idea for a universal fueling system. I have gotten tired of making a new fuel meter for each cannon and so I wanted something I could use for any canon I might build in the future. I know there are many ways to skin this cat, but the following is what I came up with. I call my latest creations Fuel Pods.

<a href="http://www.spudfiles.com/uploader/uploadFiles/FuelPodsA.jpg">HERE</a> is a picture of the Fuel Pods and the regulator setup.

I bought the regulator at Home Depot. It was the smallest I could find. It came with a 200psi gauge, which I swapped out for a 60 psi gauge I got from McMaster Carr.

I made the fuelpods from two endcaps turned face to face. I made one each out of 0.5", 0.75", 1.0", 1.25" and 1.5" SCH 40 endcaps. A closeup picture of the 0.5" fuelpod is shown <a href="http://www.spudfiles.com/uploader/uploadFiles/FuelPodsB.jpg">HERE</a>.

A picture of the largest fuel pod in use is provided <a href="http://www.spudfiles.com/uploader/uploadFiles/FuelPodsC.jpg">HERE</a>.

There will, of course, be a corresponding female quick disconnect installed on the spudgun.

On top of each fuel pod you will notice a pressure release valve. On my previous detachable meters, I've had to "burp" the meters several times before getting the correct fuel mix. Without burping the meters, the first few fuelings might yield lean mixtures. For the fuel pods, I'll just open the pressure release valve a bit and let the propane displace the residual air. I suspect I'll get good ignition the first time.

Also, I measured the Fuel Pod volumes to be the following:

0.50" pod volume = 8.44 ml
0.75" pod volume = 17.85 ml
1.00" pod volume = 43.91 ml
1.25" pod volume = 81.23 ml
1.50" pod volume = 109.37 ml

It has been my experience that my regulators are reliable in adjusting pressures from 20-60psi. Based on this observation, and the fuel pod volumes, I can fuel (1X) any spudgun from 265ml to 10.52L without any gaps. This will surely cover any gun I plan to make in the future.

A figure demonstrating 1X fueling solutions can be found <a href="http://www.spudfiles.com/uploader/uploadFiles/1XFuelPodSolutions.jpg">HERE</a>.

BTW, considering all five fuel pods and the regulator I have about $75 into this project. The first detachable fuel meter I made out of copper cost me nearly $50, if I recall correctly. The fuel pods will save me money in the long run.

Off to lunch! Have a great day.


Edit: I think the links are correct now.
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Postby Mr.Plow » Wed Apr 26, 2006 11:08 am

Interesting! They look like a really pretty version of the "Aturner style" setup I borrowed to use on my BanjoCannon (<a href="http://www.neospud.com/images/sidechamber.jpg">picture!</a>). As always, I'm mega-impressed by how great everything you build looks...

The topside valve is a great idea. I never really thought of that kind of problem when I made mine. I wonder to what degree performance is augmented by having the mix be that precise.
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Postby BigBang » Wed Apr 26, 2006 1:04 pm

Mr. Plow,

Thanks for your kind comments. Yes, I remember seeing your detachable fueling system sometime back. My first idea for a detachable fueling system came from a meter designed by Boogieman. I believe SpudMonster also designed a detachable meter. Again, there are many ways to skin the cat - this is just the idea that occured to me. I didn't know it when I started the project, but I was especially happy to learn that the set of Fuel Pods covers such a large continuous range of combustion chambers.

As for performance increases, the only time I had misfires with my other detachable meters was on the first shot or two if I forgot to burp the system. All my calculations assume only propane in the meter at the time of fueling. Without burping the system I suspect the mixtures were a bit lean. The bleed valves were easy enough to add and should solve this minor, but sometimes annoying, problem.

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Postby aturner » Wed Apr 26, 2006 2:10 pm

I've seen detachable meters before, but yours have to be the best looking! Looks like the little ones would fit right into the palm of one's hand.

I like how your largest meter can supply a 1x mix for a chamber over 10L! Hehehe! But I'm also guessing you may be planning to use that meter for a hybrid?

That is a good point you raise, about burping the meter. I have noticed in chrony tests that the first few shots seem to be a bit slower. For example, here are some data I gathered from a combustion launcher a while back:

1. 320.1
2. 331.7
3. 383.2
4. 387.7
5. 361.6
6. 387.6
(velocities in fps)

I've been attributing (perhaps wrongly) the first couple of slow shots to the need to clean/foul the barrel. But now I can also add that lean propane mixes are likely a factor in this. I suppose I can burp my meter, and see if these slow fouling shots improve a bit.
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Postby BigBang » Wed Apr 26, 2006 2:33 pm

Thanks Aturner. Yes the small one is pretty tiny, and the big one is a monster. You are right - this all got started as I tried to figure out a way to do single step 3.25X fueling in the never ending golfball hybrid project in my garage. The reason I never finished it is because I had no place to shoot it - until recently. This past year I have made friends with a guy who lives on a several hundred acre farm. He does professional fireworks for a living (I am now licenced to help him too - fun, fun, fun!) and so he is really interested in helping me do a day of range testing. I bought myself a Beta Master Chrony this past Christmas in anticipation of the big day. I'll get back to work on it soon.

As for the little guys, I think they will be a great help for minis. Fueling small spudguns is always a challenge to get right - IMHO. I also have sketched out a mini hybrid "noise maker." The littlest fuel pod can provide a 3X mix or so for a chamber under 100ml. That is about the volume of a 1.5" SCH80 end cap and union arranged right against one another. The idea for this project came from one of the fireworks shows I worked last year. We "hid" a few very small mortars on the ground a close, but safe, distance from the audience at one show. They were loud as heck and real attention getters. I got to wondering if I could do something similar with PVC and a little propane. Regrettably, I have more project ideas than time. We'll see what I get finished.

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Postby SpudMonster » Wed Apr 26, 2006 5:49 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by BigBang
I believe SpudMonster also designed a detachable meter.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Actually, mine was origionally a detachable meter, but I changed it to an onboard setup for convenience reasons. I didn't use a threaded elbow though. I used a quick disconnect tapped into the chamber, so I can remove the meter pipe if necessary. I also have a QD on the regulator so I can do something similar to this.

That is a very clever and clean setup you have there BB. I like it a lot!
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Postby BewareOfDog » Wed Apr 26, 2006 9:13 pm

It's always a pleasure to see you post, and well done on your fuel pods!
I'm assuming that you "burp" the pods to remove any "air" that was previously trapped in the pod?

I've been using a 1/2" diameter x 12" length galvanized steel pipe nipple for my meter-pipe for over two years now. I've used it on everything from a small potato-gun to my current miniature basketball launcher.

It's nice though, to see that you could easily grab a "pod" to fit any application, and that you would only need to inject once! - What kind of paint did you use, and how many coats? 8)<--- <i>"He blinded me, with SCIENCE!"</i>
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Postby BigBang » Thu Apr 27, 2006 10:30 am

DR... Yup, I burp my detachable meters to get rid of the air. I've never really had a misfire without first burping the meters. But sometimes the first shot or two (if I don't burp the meter) is weak. I get more of a "whump" sound than a sharp "BANG." Aturner's chrony data is consistent with my less scientific auditory observations.

Paint? Krylon Fusion, baby! Nothing but the best. Probably 4-5 light coats to avoid runs. If I could ever find clear primer and cement, I might skip the paint job. But as it is, my stuff usually ends up looking like purple swirled hell prior to paint.

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Postby BigBang » Wed Jul 26, 2006 4:13 pm

Doh! I'm sorry everyone. I didn't mean to kick this long dead topic. I was just attempting to clean up the figures since I referenced this thread in the BigBang Express topic.

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