My Hybrid Build (buidlog)

[airpress]

Hello.

I decided to start a new hybrid project.
I will start from the beginning with a new cannon, i keep the pmhl not in mind. Extually it works great but i wan't something new. :p

I had some part laying around here.
I will start with this first.



2" 30cm as chamber
2" endcap, later on, the metering system and air inlet will be mounted on the endcap, maybe as quick disconnect metering, i don't know yet, time will see :p
2" to 1" reducer
1" to 3/4" reducer nipple

As you can see I will use a 3/4" union for the burst disks.
The ignition cables will sit(epoxied) inside a 1/4" elbow, screwed in the middle of the chamber.

I will take the time for this one and will try to make it as nice as my other pneumatic launchers!

Greetz, airpress.

[MrCrowley]

I would first suggest that you go with at least a 1" union. It will make quite a bit of difference in terms of power and I think that a 2" x 1' chamber is a bit big for just a 3/4" union. Even better, go with a 1.25", 1.5" or even 2" union. The costs and benefits both increase you increase the union size so decide whether a 2" union is worth it knowing that you'll have to cut larger, and more, burst disks than if you were using a 1.5" union.

I would also suggest an alternate method for installing the electrodes. Although the chamber pipe should be fine with a fitting tapped in to the middle of it, it weakens the pipe unnecessarily and the last thing you want to think about when firing the cannon is whether the 1/4" elbow is going to fail under pressure. You could instead put a 2"-1" bushing where the end cap is and install a 1" tee fitting with the perpendicular port of the tee used for fuel metering and the other end of the tee you could attach some homemade electrodes that extend from the back of the chamber all the way in to the middle. I think Hubb used an electrode design similar to that.

[airpress]

Thanks for the tips, I appreciate it!

I've got some 2" to 5/4" reducers here laying around.
I understand your thing for larger unions.
I will go for a 5/4" union.