Vacuum actuated QDV
Posted: Tue Oct 05, 2010 2:43 pm
Here's how it works: First open the 3-way valve so that the pressure pump is open to the chamber behind the piston. Use the pump untill the piston shoots forward and the sear catches onto the middle set of washers. Pressurize the chamber through the inlet at the bottom forward end of the gun (I plan on hooking up an onboard stirrup pump to this area) Switch the 3-way valve to the vacuum pump (some air should hiss out of the check valve and shoot the pump handle out). Start pumping and pull a vacuum on the chamber behind the piston. Load a gold ball using the sliding breech. Pull the trigger!
I plan on building this hand held pneumatic golf ball launcher using 2" sch 40 aluminum pipe and fittings. I thought about what kind of valve I wanted to use and figured that I might as well make a QDV because I have made two before and it is very efficient. I tried to improve the original QDV design by doing away with the rod that serves two important purposes. (1) to actuated the piston by manually pulling it back and (2) resetting the piston by pushing it back forward.
I want to use pneumatics to do the same job that the pull rod does. A benefit is that there is less dead space between the piston and the projectile because there is no pull rod. Another benefit is that the piston may accelerate even faster becuase the pressure on the barrel side of the piston is pushing against nothing but vacuum. The last major benefit I can think of is that it is easier to fire the cannon because all it takes is a pull of a small trigger to disengage the sear.
Does this design seems theoretically and practically sound?
The drawing at the bottom left of the schematic is a top-down view of the valve housing. I couldn't have the pumps in the overall diagram because they are positioned horizontally and would cover up everything
I plan on building this hand held pneumatic golf ball launcher using 2" sch 40 aluminum pipe and fittings. I thought about what kind of valve I wanted to use and figured that I might as well make a QDV because I have made two before and it is very efficient. I tried to improve the original QDV design by doing away with the rod that serves two important purposes. (1) to actuated the piston by manually pulling it back and (2) resetting the piston by pushing it back forward.
I want to use pneumatics to do the same job that the pull rod does. A benefit is that there is less dead space between the piston and the projectile because there is no pull rod. Another benefit is that the piston may accelerate even faster becuase the pressure on the barrel side of the piston is pushing against nothing but vacuum. The last major benefit I can think of is that it is easier to fire the cannon because all it takes is a pull of a small trigger to disengage the sear.
Does this design seems theoretically and practically sound?
The drawing at the bottom left of the schematic is a top-down view of the valve housing. I couldn't have the pumps in the overall diagram because they are positioned horizontally and would cover up everything