Remove giblets from chicken and discard. Place chicken breast-side down on work surface. Use tip of sharp knife to make four 1" incisions along back of chicken. Using fingers or handle of wooden spoon, carefully separate skin from thighs and breast. Using metal skewer, poke 15-20 holes in fat deposits on top of breast halves and thighs. Tuck wing tips underneath chicken.
Combine salt, baking powder, and pepper in small bowl.
Pat chicken dry with paper towels and sprinkle all over with salt mixture. Rub in mixture with hands, coating entire surface evenly. Set chicken, breast side up, in V-rack set on rimmed baking sheet and refrigerate, uncovered for 12-24 hours.
Adjust oven rack to lowest position and heat oven to 450 degrees. Using paring knife, poke 20 holes about 1 1/2" apart in 16x12" piece of foil. Place foil loosely in large roasting pan. Flip chicken so breast side faces down, and set V-rack in roasting pan on top of foil. Roast chicken for 25 minutes.
Remove roasting pan from oven. Using 2 large wads of paper towels, rotate chicken to breast side up. Continue to roast until instant-read thermometer registers 135 degrees, 15-25 minutes.
Increase oven temperature to 500 degrees. Continue to roast untilskin is golden brown, crisp, and instant read thermometer registers 160 degrees in thickest part of breast and 175 degrees in thickest part of thigh, 10-20 minutes.
Transfer chicken to cutting board and let rest,, uncovered, for 20 minutes. carve and serve immediately.