Just a quick note on speed, There is a point of diminishing returns when valves get faster than a certain speed, much like there is diminishing returns on really large chambers.
Also keep in mind, as Ragnarok has said many times and Technician1002 never seems to wrap his mind around, valve opening speed has some serious diminishing returns.
This gets brought up because I designed valves to be fully open before the projectile in the barrel has moved more than it's diameter. Much slower valves produce very similar muzzle velocities even if the projectile moves servial times it's diameter in the barrel as the valve opens.
The 4 1 inch valves in comparison to a single 2 inch valve is not related to valve speed but a factor called CV, which is related to the pressure drop on a a valve for a given flow. This is often listed for the flow for a 1 PSI drop over the valve for water and 15 PSI for air. A single 2 inch valve has more flow than the total of 4 1 inch valves in parallel.
The flow rate through a valve is determined by the nature of the design and by the type of flow. The size of valve required for a particular application is generally established by the Cv rating. This figure is evolved for standardized units and conditions, i.e. flowrate in GPM and using water at a temperature of between 40°F and 86°F at a pressure drop of 1 PSI. Cv ratings for each valve are quoted. A standardized system of flowrate values is also used for pneumatics. In this case the air flow in SCFM upstream and a pressure drop of 15 PSI at a temperature of 68°F.
Quote from here;
http://www.omega.com/TechRef/techprinc.html
It is a simple matter of looking up some CV values for some common valves online for gate, globe, ball, butterfly and other valves to compare the CV value for various size valves.
Edit;
Located a table of ball valves here;
http://www.jomarautomation.com/products ... cients.pdf
A 1 inch ball valve has a CV of 87 and the 2 inch 396.
The launcher is fine to build. Enjoy it.
