HEAR valve flipbook
This is one of several recordings made of the HEAR valve on my GB Semi firing. It is recorded at 2000 frames per second. Focus and lighting aren't too great because the box that I have rigged up as a backstop was soaking wet from a water leak, so I was aiming up over my house and not able to focus directly on the gun. It was a huge pain just to get the gun in the frame while shooting at the angle I needed because there was nobody around to help me with the camera.
I was pleasantly surprised to find that the valve's timing was very close to what I had planned when I built the gun. Although I had expected it to open faster than it would close which doesn't appear to be the case. This video also got me thinking about the importance of the size of the rear disk relative to the front disk. It seems to take a relatively long time just to get the piston initially moving to the valve opening point. This could be improved by increasing the size of the rear disk, but also by lightening the piston. I have actually added weight to the piston to purposely slow down its cycling rate. It maybe interesting to record the valve firing without the weight on the piston to explore exactly what it does to the cycle.
As the valve closes you can see the air moving from the air storage chamber into the firing chamber through that clear tube. The air can be seen because the rapid decrease in pressure caused the water vapor to condense and form a white cloud.
There is a plastic strip with marks every inch sticking out right next to the piston.
related linksflipbook measurement tool
my high speed camera
another HEAR valve flipbook
yet another HEAR valve flipbook