Problems with shoulder fired canon.

[Tom]

Just like spuddin, I'm building shoulder fired rocket launcher. I don't have a chamber, the barrel(and chamber) is 75MM or 5.5 inch. I am going for the design and not really for the performance. So i purchased the PVC pipe yesterday and done some little testing, i tried to shoot a soda can. My fuel was lighter refill gas and i didn't measured it out. I tried to shoot but every time the projectile(soda can) gets sucked back into the barrel . What could this be, maybe too much fuel?
Tom

[BigGrib]

umm maybe too little fuel and the fuel burns out before the soda can exits the barrel and the vacuum draws it back into the barrel

[Tom]

Thanks, i think it the second problem. I'm going to test it by measuring my amounts of fuel that I'm putting in.
But if it is that the fuel burns out too fast can i help it with drilling some holes in the pipe at a distance were it doesn't loose power? For the fuel-problem, i think I'm going to use a modified lighter.
Tom

[DYI]

So how big is the chamber? Do you mean it is 75mm (3") of 140mm (5.5") pipe?

Here's your problem: The barrel is so large that, by the time the projectile reaches the end, the system's pressure is actually below atmospheric, and the ambient pressure pushes it back into the barrel.

[Tom]

So how big is the chamber? Do you mean it is 75mm (3") of 140mm (5.5") pipe?

No it's t 5 inch (1 meter) long by 75mm (3 inch) in OD .
I have tested the gun again but he doesn't shoot reliable, because of less or too many fuel. I think I should make a fuel meter tomorrow, just from a syringe or a pump. Then I can concentrate on the vacuum problem.
Thanks for the help!
Tom

[DYI]

Something tells me that Tom is using a translator program

Your post still makes no sense. One metre is 39 inches, not 5 inches. So is it 75mm diameter and 1000mm long, or is it 75mm diameter and 127mm long?

[Tom]

ARGH.....
ahem.
It's just like you said "75mm diameter and 1000mm long". My propane meter is finished, nut I need to go too school .

[BigGrib]

I dont think it's a translator problem i think it's a fat finger problem. I can recognize the symptoms a mile away

[Brian the brain]

Something tells me that Tom is using a translator program


Tom is Dutch.I recognise the typical Dutch grammar.
He says "he"where in English one would say "it"
75mm diamiter by 1 meter( 1000mm) is a normal size.

You did get pressure rated pipe I hope, Tom??

Gewone PVC buis klapt uit elkaar.Meerdere video's van gezien.
Niet de eerste keer, maar er komt een dag...

[psycix]

Tom how far back is the projectile?
When the projectile is sucked back it means your barrel is WAY too long for your chamber.
Put the projectile more to the front.
This will make your chamber bigger.

Zet t projectiel ongeveer op de helft van de buis. Dan heb je een 1:1 ratio.
Ik hoop dat t werkt.

[Brian the brain]

The Dutch are taking over this forum hahaha
We need to form a clan!

Probeer was psysix zegt.Lijkt mij de oplossing.
En kijk uit want combustion valt onder de wapenwet

[Jared Haehnel]

Don't worry I've got my trusty spud gun right here.....

[Brian the brain]

It's on now!! muhahaha

The Dutch are back to reclaim New York!

And from there we might as well take the world

I tried to shoot but every time the projectile(soda can) gets sucked back into the barrel

Okay...maybe some other day...
A man can dream can't he?

[psycix]

Een combustion valt onder de wapenwet?
Dus pneumatics tellen zeker als luchtbuksen oid?

Nee hoor meneer de agent, dit is een 3 meter lange 50mm luchtbuks


Dutch world domination!

[Tom]

Thanks for the comments, I know my english is bad. But rather a good grammar then those stupid posts with alot of bad grammar. BTB I'm using pressure rated PVC pipe. I will dril a now hole for the projectile block to make the chamber bigger.
Tom