My youngest son Wesley, who is an aspiring mechanical engineer interested in defense weaponry came home last week with an assignment to build an apparatus that will launch a tennis ball. The project "rules" disallowed chemical reactions (damn, no acetelyn, hairspray or WD-40).
The designing team (Wesley, Frankie, my oldest son who is about to graduate from the UC system as a mechanical engineer, and myself) had a long conversation about what to build and how to build it. I showed them a photo of an 88 flak gun and proposed compressed air and we went from there.
What you see here is the gun on the second test firing. The first firing resulted in the trigger valve, a 3" knife gate, leaking at the seams 55 psi, so we fired multiple shots at that pressure from my next door neighbor's driveway, which lines up well with the schoolyard across the street.
We fired off about 10 rounds and the muzzle noise when the tennis ball leaves the barrel is unbelievable. A very loud crack. And you can not see the ball until it is about 75 yards out and about 100+ feet in the air.
Total distance was about 225 yards at 55 psi.
These photos were taken today, the 2nd test firing. The gun held 70 psi for an hour. We rebuilt the valve last night. We got one shot out of it but the valve totally failed. I'm going to look at a ball valve next, but one that size is really hard to turn and the pressure release might not be as sudden and as explosive as we want. Or we settle for 55 psi and 225 yards.....which is more than we expected anyway.
The designing team (Wesley, Frankie, my oldest son who is about to graduate from the UC system as a mechanical engineer, and myself) had a long conversation about what to build and how to build it. I showed them a photo of an 88 flak gun and proposed compressed air and we went from there.
What you see here is the gun on the second test firing. The first firing resulted in the trigger valve, a 3" knife gate, leaking at the seams 55 psi, so we fired multiple shots at that pressure from my next door neighbor's driveway, which lines up well with the schoolyard across the street.
We fired off about 10 rounds and the muzzle noise when the tennis ball leaves the barrel is unbelievable. A very loud crack. And you can not see the ball until it is about 75 yards out and about 100+ feet in the air.
Total distance was about 225 yards at 55 psi.
These photos were taken today, the 2nd test firing. The gun held 70 psi for an hour. We rebuilt the valve last night. We got one shot out of it but the valve totally failed. I'm going to look at a ball valve next, but one that size is really hard to turn and the pressure release might not be as sudden and as explosive as we want. Or we settle for 55 psi and 225 yards.....which is more than we expected anyway.
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