My first Advanced Combustion (Updated, My first shot)

[SpudUke5]

Well this is my first, as you can see from the title and it wasnt hard really to make but i just have 1 thing that concerns me. the meter isnt very held in there as in that is twists easily at the joint where the brass pipe nipple and the pvc meet, so what do you guys do to make it firm and tight?

And i also but a makeshift stand under the meter so that it supports it a little. I am going to soon double layer the area where the brass nipple meets the pvc chamber wil flatten 3/4 inch pvc (sheet pvc).

Barrel Is detachable.

Most of my attachments are held in by hose clamps.

Anyway, here are some specs:

Chamber: 2 foot sch40, 4 inch pvc
Barrel: 91 inches sch40, 2 inch pvc
Meter: 63 psi, made from black steel and some brass parts
Combustion source: Propane
Igniton: Stun gun
Meter Length: about 11-12 inches
C:B ratio: 1:1

Here are some pics. ( As soon as i learn to use the uploader i will use it PCGuy)


The cannon, with my feet, which is a must


The ignition and the circuitry for the chamber fan


The Propane meter. As you can see the 3/4 inch pvc that holds the meter up a bit. But if it was taken out ther would be no difference in the height of the meter.


Chamber Fan (sorry about the flash, looks kindof wierd)


Propane holder.

More pictures are to come.

Also is friction a good way to keep my chamber fan in place?

EDIT: No video for now but i wanted to try it out today and i went outside, although its cold, and tried it.

So first, i put too much propane bec i completely opened the ball valve and i now found out that some parts leaked. Well that didnt stop me so then i tried again, slowly opening the ball valve. Got the pressure this time. Then i try to ignite, but still doesnt work. So then i end up finding out my ignition was creating a spark with a hose clamp. Then i fixed that and tried again. When i tried it this time, i noticed that some of the propane maybe leaking through the pipe nipple where i have my meter connected to my chamber. So i then tried to fire it at 80 psi but it didnt work, so then i vented it and tried again but still didnt work. Then i tried it again but added a little more because of the leak i thought. then it obviously didnt work. Then i vented it and tried to fire and......bang!! , man did that shock me a little, but it was cool.

I was dissapointed with some of my results. So tommorow or today (depends on if i finish my homework), i am going to re-teflon my leaking area. I think my propane meter ratio for the pressure maybe off, but i did put in the correct calculations in for my meter volume. I used http://www.advancedspuds.com/SpudToolonline.htm.

One thing that i think maybe wrong is that the ID of my pipe isnt exactly .5 inches, but less, so i will have to measure that. Also i think the leaking in the pipe nipple to the chamber, i may have lost some propane there. So there are multiple reasons that my cannon is not working on my first shot, or maybe if i fix all the leaks and try it at 80 psi, it may work but i dont know yet and i would like to have input from everyone, especially people who have experience with this.

I also forgot to mention its a little cold here, like 50 degrees fahrenheit, or 10 degrees Celsius, for you non Americans
Thank you for reading (plz dont skip my update )

[c19o]

Looks nice, all it needs now is a paint job!
O you didn't tap the meter hole in a place where the pvc is double layered, that might be a hazard. If I were you I would make curved piece of wood or something, pvc, thats as long as the meter. Just stick in between and hose clamp at the other end.

[The Kid]

looks nice all i think it needs is a paint job. you really should have taped it through a double layer of pvc for a little extra safety but than again gort ever tapped a double layer on his blue flame 3, long story short nice work.

[SpudUke5]

Yea i said in the post i plan on doing it double layering that area tomorrow, its late here. But thank you for the positive comments.

[SpudBlaster15]

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[TwitchTheAussie]

And epoxy in ya fan. Ive made my mistake by trusting friction.

[SpudUke5]

ok thx, ill epoxy it right now and ill take out that spacer.

EDIT: Epoxied, and spacer out

[ralphd]

Nice job. Radio Shack has rocker switches that mount flush and are black which will look nice on the plastic box. By the way, how good is the stun gun? I've been trying to find a better ignition system.

[mark.f]

Looks good so far, but I have a few comments:

1.) Remove that brass bushing and nipple from the elbow of the meter and replace with a face bushing and close nipple. This will bring the meter pipe closer to the chamber. Also, if at all possible, maybe plug the hole and re-tap some threads into where the coupling overlaps the pipe. With all the stress on the meter in it's current state, it wouldn't hurt to replace that hole with a plug, which won't have any stress on it unless you bump it into things.

2.) The spacer thing is good for the meter, and you can combine two larger hose clamps to hold both the meter and the propane holder in place.

3.) You can't actually do this now, but next time, since you already have DWV fittings on the launcher, you could use a spigot x FNPT 2" "cleanout" adapter in the reducing coupling to compact the threaded parts a little towards the barrel end.

4.) Finally, drill a 1/2" hole in the project box and mount that toggle switch like it's supposed to be. It also wouldn't hurt to remove the stungun circuitry from the stungun casing and mount inside another, (possibly larger), project box, with the fan circuitry. You would simply replace the switch that triggers the stungun with another toggle or momentary switch. Also, some flextube from the automotive department in Wally World wouldn't hurt either.


Sorry if that sounds picky, but you obviously don't have to do any of it. Just some stuff I think makes a nicer looking cannon. A tip: for larger project boxes, don't look in circuit city. Go to home-depot, and get a junction box and a "blind" cover for it. Much cheaper as the size gets larger, and doesn't look half-bad. You even have holes to run your flex-tube out of.

[SpudUke5]

Those are very good suggestions and im not sure if im gonna do all of them, but i will do some. I dont like to judge a book by its cover, but by its performance

So i will fix some of the meter stuff its just gonna be harder to tighten because close nipples have no where for me to tighten.

But also i dont get what you mean "blind" cover for it. Is that its real name.

Im going to keep the stun gun circuit in its case just because i dont want to mess with ne thing, but for my second advanced combustionm i will take all of these into consideration.

I will drill a hole for that switch because it does bother me also.

Is flex tube the black tube that houses the wires?

And there will always be stress where ever the meter is. But that is going to be double tapped and with the stand between the meter and the chamber, it will decrease it alot. I have a extra hose clamp so that will be used.

I think i got it all, but thanks for the critique. But i think for now i wont go to homedepot because my parents are tired of going. And i go alot to homedepot So ill fix what i can with what i have.

[ralphd]

In my opinion I wouldn't epoxy in the fan. After shooting a few potatos you will notice an odor emanating from your chamber and want to clean it out. Carefully align your fan in the chamber then mark, on the outside of the combustion chamber, where the edges hit. Drill these marks with a small drill and into the edges of your fan. Remove the fan and make those holes a little larger. Replace it and use sheetmetal screws to secure it in. I can't remember the size I used, maybe 1/8 inch but it will thread itself into the chamber but slip into the fan.

[mark.f]

@LikimysCrotchus5: a "blind" cover is what they're really called. That just means they're a solid plate with no holes or anything in them. Also, flex-tube is the black corrugated tube they use to house wires in car engines.

Good luck with the build. I agree that performance is paramount, but a few good looks never hurt now and then if they didn't harm it.

[SpudUke5]

Ok thanks for informing me, and i do agree thought appearance is definalty important, but for me, not yet.

I have also updated my post with my first shot, so plz read it all so i can have your opinion with you knowing what i am talking about.

@ralphd: the stun gun works great , but if you read my update there are things that made me sad. Since you have good experience on this, give me some advice on my situation that i have not mentioned in my update. Thx ahead of time

EDIT: This is also my first combustion, i have never built a spray n' pray.

[SpudUke5]

READ THE EDITED ORIGINAL POST BEFORE READING THIS

Well i am doubling posting only for the reason that my cannon doesnt shoot the first time and its agitating me.

I did what i mentioned in the edited post (taking about and rebuilding the meter so it is tighter so it doesnt leak. This was done and i began to shoot it. Also before that i measured the ID of my pipe, which is 9/16 of an inch or .5625 inches. So then i used the spudtoolonline calculator to find out the psi i am to use which is now 62-63 psi. I also measured the length and volume of the tee.

So i tried it again and there were no leaks. I metered the propane and injected it, used the fan to mix and the got ready to fire. Well it didnt fire on the first time and that is bothering me because i have to add oxygen and do all this troublsome stuff so that it finally shoots after 3-5 minutes of fooling with it.

The only problem i suspect is the cold because it has screwed up other people's cannons and i think my cannon has succomed to it while others dont.

Any suggestions?

[Novacastrian]

It seems that you are simply using to much fuel grasshopper. I would try and go up in intervals of about 5psi from say 30psi. Are you sure that you fixed the problem of the short in your ignition system properly?