This has to do with projectile position in the barrel as the valve is opening. Look at GGDT for the graph of projectile travel. Note in the first 5ms or so, the projectile is still within a few inches of the breech, so faster valves don't change much for the remainder of the launch. A slower valve w...

The performance suffers because much of the projectile launch happens when the valve is still mostly closed, so full valve open and full power does not show up until the projectile is most of the way launched. It's like pulling away from a stop sign by taking your foot off the brake.. moving slowly,...

Most small QEV valve have a small relatively lightweight piston that remains closed until there is a substantual drop in pressure on the pilot, so the time is in 2 parts. First is time delay before the valve does anything. This is related to the input plumbing to the pilot. The bigger this is the lo...

As I said, it's a 2 inch union burst disk valve. So the math should look like this right? CoF= 3*25.8 The other think is that I'll need to find a way to "trigger" the burst disk. I would use a small secondary chamber filled with more pressure than the main 4" chamber. Using boyle's law, I can solve...

In high flow situations, a small valve will have a pressure drop on it. This effectively lowers the pressure to the barrel. A larger valve will have a lower pressure drop resulting in higher pressure to the barrel. How much change between the valves, I don't know. In a larger valve with a small barr...

Your flow coefficient will depend heavily on your valve. How does the flow go through? The rate of flow will not exceed the capacity of your valve.

Have you looked for the GGDT and HGDT tools? They work great for modeling performance.

Gas Gun Design Tool and Hybrid Gun Design Tool Search for posts by D_HALL for lots of info on the subject.

A 24VAC sprinkler valve is easly operated on 18VDC using 2 9 volt batteries in series. The reason it works is due to the impedance of the solonoid vs DC resistance. The current is actually higher on 18VDC than it is on 24VAC, so it has no problem operating. Use this for intermittant use only. Contin...

For safety, Please do not premix your fuel and Oxygen. A static discharge or other accident is very dangerous. Especially do not transport mixes in a vehicle. Danger goes way up when confined or larger amounts are stored together. Please use fuel and air only. Example of an accident with a premix of...

He may be better off trying to find burst disks that will burst at the pressure needed to get those distances Getting a burst disk calibrated for a repeatable distance is a problem. Question, is launcher modifications permitted between shots for different distances? If yes, instead of a burst disk,...

Set it back to keep the voltage constant. Many supplies like the one you are feeding will draw higher current at low voltage in an attempt to keep the output power up. The reason the current dropped (and was not adjustable) is because the LED driver was supplying all the current needed at the full r...

Set the voltage to to below the absolute maximum your device will accept without damage. This is for protection. Too much voltage lets the magic smoke out. Set the current to just above the maximum start up current of your device so if your device is overloaded or shorts out, the current is limited ...

In a nutshell, an LED driver is often designed to drive a series string of LED's. High power white LED's often run at about 3.6 volts so 3 in series is 10.8 Volts. If you drive only one at 3.6 volts, you can use the lower end of the supply voltage. If you try to drive 4 or 5 you need the higher supp...

You may wish to do some in barrel launch testing to find the optimum length for your barrel. I found that a 2 inch barrel has some serious flow limitations that reduce the flow considerably if it is very long. For some ideas, here is a link to some 3 & 4 inch barrel length testing. This is a page I ...

Quick reply on the LED driver and Constant Current regulation. LED's draw more current as they get hot and operate at a lower voltage. Setting an LED driver with no current regulation will place an LED in thermal runaway. It gets warm, lowers voltage, draws more current, gets hotter, draws more curr...