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Posted: Thu Feb 10, 2011 2:53 pm
by Labtecpower
I has O-rings !
I found them in some PVC connections when I was looking for a way to attach my barrel.
They fit pretty good. (slightly too large, doesn't matter that much)
The two together cost me 6 euro's. Much better than the 16 euro's the other ones cost. (still not very cheap)
The connector I bought;
Gas tank;
I found out that they use EXACTLY the same ones for propane. It should have a fairly high pressure rating.
Another connector pic;
I found the smaller O rings in a smaller connection.
The pvc has a PN16 rating on it. Should be strong enough I think?
I have to make another hole in the bottom of the tank before I start to weld.
At the supplier of the PVC fittings, I found a large collection of pressure rated PVC piping. 32 mm, 40 mm, 50 mm, up to 100 mm.
Nice barrel source
And something for JSR:

Posted: Wed Feb 16, 2011 9:49 am
by Labtecpower
The project is really starting to take shape.
I finished all the parts of the valve, and the gas bottle will be welded on tomorrow.
I found a certified MIG/MAG welder, who will do the welding for free

Posted: Wed Feb 16, 2011 10:23 am
by Crna Legija
have you checked ebay for the orings? also what pressure you planing to run this at?
Posted: Wed Feb 16, 2011 10:42 am
by Labtecpower
I didn't check ebay.
I'm going to run this thing up to about 8 bars. The tank is tested up to 30 bars.
I think the performance is impressive at that pressure, because of what I have seen from tech's movies.
Posted: Wed Feb 16, 2011 10:44 am
by Crna Legija
come on you could be the first to have a QDV at 300psi wouldn't that make you sleep better at night.

Posted: Wed Feb 16, 2011 12:45 pm
by Labtecpower
DONT BRING ME ON IDEAS!!!
if I get a compressor with a long tube, I might try it.
I'm not wanting to lose an eye or so.
and, another con:
The tank is 6 litres. If I pressurize it to 20 bars, it uses 120 litres of air!
That's a bit much to pump

Posted: Wed Feb 16, 2011 1:17 pm
by Technician1002
-_- wrote:come on you could be the first to have a QDV at 300psi wouldn't that make you sleep better at night.

The only reasons I have not gone to 300 PSI is lack of a source and they get just a little scary above 100 PSI.
Posted: Wed Feb 16, 2011 1:25 pm
by Gaderelguitarist
Looking sharp. I know I definitely wouldn't trust myself with the welds yet.
What are your thoughts on removing the lip towards the backside of the tank? Personally, I would remove it, grind it smooth, sand the whole thing, and paint or powder coat it.
I doubt you'll need to go that high with the pressure, as the idea is high volume low pressure versus low volume high pressure. However the second would be interesting for a smaller QDV launcher with a more linear tank.
Posted: Wed Feb 16, 2011 1:25 pm
by Labtecpower
scary as in: launching the projectile AND you, or scary as in: might blow up
I want to take it to at least 8-10 bars.
Just curious, how long are your 2 inch barrels?
I found some 3m long PN10 pipe, two inch.
Posted: Wed Feb 16, 2011 1:43 pm
by Technician1002
In the larger diameter barrels, launching the operator is already a problem when launching any thing heavier than a 12 oz soda. A 20 oz or 500 ml water bottle in the 3 inch barrel has some serious recoil. Those items at over 100 PSI would a problem for anyone weighing less than 150 LBS.
This shot with a Gatoraid in the 3 inch barrel gave me a bruise. Turn up the sound! Look for the football field lights in the distance. It landed between them.
http://inteltrailblazerschallenge.wikis ... d+shot.avi
How long are my 2 inch barrels? Here is a photo. My only removable 2 inch barrel is just over 7 feet. It is the long black one. The two red and white 2.5 inch barrels are 7 foot and 3 foot for size comparison.

Posted: Wed Feb 16, 2011 2:04 pm
by Labtecpower
Thanks for the photo
I may be having some problems when shooting, because I weigh only 60 kgs, 132 pounds.
maybe i'm going to make a recoil absorber, with hooks in the ground to absorb the shock.
First i'm going to test if i'm getting launched by the cannon

Posted: Wed Feb 16, 2011 2:13 pm
by Technician1002
Use light projectiles with high pressure and smaller diameter barrels and you will be fine. Heavy projectiles in large diameter barrels at high pressure is when the real recoil starts. That was a full gatoraid launched from the 3 inch barrel. Gradually work up the pressure till it gets to be plenty of kick.
You are about 1/2 my weight.
This is where it landed.. next to the 50 yard line on the track around the football field.

Posted: Wed Feb 16, 2011 2:23 pm
by Labtecpower
I will start using light projectiles, and not immediately at 8 bars.
If the recoil isn't too bad, I will start using heavier projectiles
Do apples and potatos have much recoil?
If shooting very heavy projectiles, I will let a friend of mine try first. He's pretty fat

Posted: Wed Feb 16, 2011 2:40 pm
by Technician1002
Spuds and apples are fine with little recoil.
Posted: Wed Feb 16, 2011 8:57 pm
by Crna Legija
Labtecpower wrote:Thanks for the photo
I may be having some problems when shooting, because I weigh only 60 kgs, 132 pounds.

now your avatar make sense
