Recent content by mikemo

jrmichler, Thanks for that excellent information. I had to read it through a few times but I believe I understand what you are saying. The construction is close to what you assumed. Parts are assembled in a straight line (no bends). The rear is the tank, the center is the valve, and the end is...

Will do :) I measured 5 shots last night and averaged 33 m/s. Now I can sleep at night. Thanks again. Any hints on the math needed to compensate for the drop in pressure as the air from the tank expands? My calculations assumed a constant pressure as the projectile traveled down the barrel.

Well, you nailed it. There is a major issue with my sensor. The capacitance in the phototransistor was high enough to cause a slow recovery of the signal when the sensor went dark. I lowered the gain by about a factor of 6 and the signal looks quite a bit better. Still, it seems that if I want...

Thank you for verifying my calculations. Yes, now it's time to have a closer look at my measurement setup. I have the gain of the phototransistor quite high, and that can cause slower responses (Miller capacitance multiplication). I'll measure pulse response on the bench and respond with my...

Yes, that is correct. 35 PSI and a 14" barrel.

Thanks for the reply. I think "slug" may be a poor choice of words. Projectile might be more appropriate. It is made from 3/4" schedule 80 PVC pipe and two pipe caps. Weight was added by inserting a 2 ounce lead fishing weight before gluing on the caps. The total weight is 75 grams and the...

Hello, and thanks for reading. Any help with this will be greatly appreciated. One of my hobbies is amateur radio. We often use wire for antennas, and getting those wires up in high places can be a challenge. I built a pneumatic "launcher" for this purpose, using ideas from others who have...

I'm a new member and am following the directions to post an introduction. I am a computer data center guy that deals mostly with computer hardware, power and cooling, along with some networking and very light programming. My undergrad physics classes were a long time ago, and I've come for help...