SpudFiles

I tried it again, filled the syringe to the Max placed as far in as it can go and quickly repeated. It went off after 15+ ignition attempts. Not enough power to move the projectile even an inch. Retried with spray and pay and it launched 10 feet

battlelava wrote:

jackssmirkingrevenge wrote:video of what you're doing to fuel? are you sure the measurements are correct? are you venting between shots?

I did it exactly like it was done in the syringe pages video. In between injecting fuel (because i have a 10ml syringe) I placed the cap on the end and only removed to inject more fuel. I did 2 10ml injections and 1 3.5ml injection. I then waited for the fuel to mix. In between shots I took out the projectile, sprayed the air duster through it and left it there for roughly 5 minutes to completely air out.

I was so let down, and its probably a stupid problem too.

Wait, I thought it was decided that air dusters don't actually use real air, and therefore would purge the nesescary oxygen from the chamber for combustion to occur?

Lockednloaded wrote:

battlelava wrote:

jackssmirkingrevenge wrote:video of what you're doing to fuel? are you sure the measurements are correct? are you venting between shots?

I did it exactly like it was done in the syringe pages video. In between injecting fuel (because i have a 10ml syringe) I placed the cap on the end and only removed to inject more fuel. I did 2 10ml injections and 1 3.5ml injection. I then waited for the fuel to mix. In between shots I took out the projectile, sprayed the air duster through it and left it there for roughly 5 minutes to completely air out.

I was so let down, and its probably a stupid problem too.

Wait, I thought it was decided that air dusters don't actually use real air, and therefore would purge the nesescary oxygen from the chamber for combustion to occur?

I let it sit for 5 mins afterwards to air out further. Obviously with both ends open

First off, I must say this is a pretty dodgy looking thread.

To solve your problem:
-MEASURE the chamber volume.
-DO NOT "vent" the chamber with inert or flammable gases. Vent it with AIR.
-Inject about 4.5% of the chamber volume in propane in such a way that half of it doesn't leak out before you replace the cap (use a fueling port, don't take the cap off)

Finally, just try it with a potato and see how that works. Develop fancy ammo out of cardboard tubes and tape afterwards...


To everyone eager to correct my fueling percentage: don't bother. I intended nothing different.

Before I screw up something else, for a filling port can I take put another screw in.

I'll use a potato, exactly 24.5ml of propane. I'll let it mix for 10 minutes and then ill give it a go. I'll also try to video tape the whole thing.


I was never good with stoichometry (can't even spell it lmao)
I don't even think i balance the equation correctly

What the man said, I agree with everything DYI stated, except:

DYI wrote:Inject about 4.5% of the chamber volume in propane

You should not try in inject your chamber volume into the propane, this will only dilute your fuel.

You should not try in inject your chamber volume into the propane, this will only dilute your fuel.

"In inject"? Really Jack? If you're being all persnickety about grammar, you should make a special effort to check for things like that

Alright, let's reword this: "Fill a syringe with an amount of propane which will, at current ambient conditions, occupy a volume equal to 0.045 times that of the chamber volume. Then inject this amount into the chamber".

Happy now, Jack?

I was trying a double bluff where you would expect me to say "OI! 4.19%!" but I didn't, so I picked on something else, but clearly I failed miserably.

I figured that's what you were up to, but seeing the above test where he failed to notice the 1:1 correspondence between NaOH and NaCl, I fear he may fail to notice the jest as well

well this is what i have to show for myself, mind my overhairy legs I only have 2 hands



waited a few minutes with some shaking




Edit: So i recorded all of that 20 minutes ago, I just retried it and it went off. Moved the projectile about 20 inches in a 24 inch barrel

You seem to be doing it right.

So the chamber and barrel are same tube?

stupid question, are you loading the projectile before fuelling?

are you sure about the dimensions?

jackssmirkingrevenge wrote:You seem to be doing it right.

So the chamber and barrel are same tube?

stupid question, are you loading the projectile before fuelling?

are you sure about the dimensions?

loading it before fuelling, i forgot to show the photo of a light at the muzzle pointed up to show it was 100% airtight.

I don't have a digital caliper but I used a measuring tape and found it to be 1 7/8 (1.875) (I think i will go double check) which is pritty close to 1.9 and i measured it on a ramrod to set the projectile.

I see you've still failed to implement a fueling port. What type of pipe is this? Checking the standard dimensions will be more useful than trying to measure an internal diameter with a tape measure (that is assuming that you continue to refuse to MEASURE THE VOLUME DIRECTLY).

Another stupid question: You're not pulling up the plunger on the syringe to "fill" it, are you? It appears you're restricting your propane flow with a tiny orifice for no apparent reason, which must cause quite a bit of trouble for filling the syringe.

DYI wrote:I see you've still failed to implement a fueling port. What type of pipe is this? Checking the standard dimensions will be more useful than trying to measure an internal diameter with a tape measure (that is assuming that you continue to refuse to MEASURE THE VOLUME DIRECTLY).

Another stupid question: You're not pulling up the plunger on the syringe to "fill" it, are you? It appears you're restricting your propane flow with a tiny orifice for no apparent reason, which must cause quite a bit of trouble for filling the syringe.

Standard dimensions are 1.9" . By measuring the volume directly, do you want me to fill it up with water and measure it in a beaker, because i don't have anything precise enough to measure it. I am not touching the plunger at all, its just hard to seal the tip on the propane torch with the syringe tip without gas leaking because it won't fill it then. the propane tip is just a standard benzo fuel without the air mixer top on.

...because i don't have anything precise enough to measure it.

You have a syringe

Standard dimensions are 1.9"

You still haven't said what type of pipe it is.

Also, I suspect you're losing a lot of propane by having to open the breech several times. Tap pipe threads into the thicker section at the breech and stick a small ball valve on there - that'll free you from having to open the breech to fuel. Alternatively, just get a larger syringe.

Finally: I recognize the propane fitting, I'm just curious as to why you didn't unscrew the orifice from the rest of the valve to get the full flow it's capable of.