i'm not a physics guy, or a mechanical engineer, but i think this should be a really simple formula - i'm assuming some of you folks will know this off the top of your head: okay, so i'm trying to figure out how big of a winch to buy for a very large tow truck i am building. winches are rated based on how much they can pull. eg. a 20,000 lb winch can pull 20,000 lbs at a 0 degree incline (flat surface.) so if i have a vehicle that weighs 40,000 lbs, and a ramp angle of 30 degrees, and a drag coefficient of .5 (if i'm towing a disabled tracked vehicle, i'm guessing a drag coefficient as high as .5 isn't unreasonable) then how big of a winch would i need to pull this up the ramp? i'm looking for a formula, so i can change the values of my variables: weight of vehicle, drag coefficient of vehicle, winch size, angle of ramp. is this a basic formula that you folks know?