Here's a photo of one of my drum smokers, as you can see it is a little different. I used a section of 2 inch steel/aluminum exhaust tubing to make a fresh air intake tube. I welded it in the drum about 2 inches from the bottom. On top of the air intake tube I have an adjustable slide to regulate the amount of air entering the drum and to also act as a rain guard. I used a piece of 3 inch steel/aluminum exhaust tubing to make an exhaust stack, it also has an adjustable slide to act as a rain guard. There is no bending over to adjust the air intake ballvalves. (This makes it alot easier on the 'ol back, not alot of bending and easy to see if cooking at night in areas that don't have good light) Construction is open to the imagination.
I placed 5th in both pork shoulder and chicken using this smoker design at the 1st comp I carried it too.