Mine is white ash....1-1/4" wide at the center 1/3 of the bow, tapering to 3/4" at the string knocks.....then I sanded the transition of the taper so it looked like a long football shape. 1/2" thick in the center 5" and tapers to 3/8" thick at the tips.....that will leave your tips a little "stiff" but when ya cut out the side patterns it rounds out the bend profile.
Each one of the "steps" is 1-1/2" long.....and the center of the cut pattern is 9-1/2" from the string knock, that puts the first cut step at 7" from the knock.
By the way the ash I used was pretty dense stuff.....between 1/8" and 1/16" growth rings, and of course was vertical ring. My experience with a "d" bow is that you should have no trouble getting 27" of draw from your stick....even 2 inches shorter.
You will probably be real happy if ya leave the center 5-6 inches a little thick and "work the bend" intowards the center, will keep from gettin the bend in the middle thing.
rich