Momma Bear flue information

Hi my Mamma bear has a wide open flue opening so when you start a fire and it is really burning hot it is burning inside the flue pipe. You can hear it roaring in the pipe so I have to run it with the air doors closed all the way down. Is this normal? Do I need to add a flue baffle inside the fire box? One of my concerns is the cedar shake roof on the house and the old owner told me he had a chimney fire on this stove once. Please ant help will be grateful!! There is no damper on the flue either only fire control is the two air doors on the fire box door.

should be a damper in your pipe first foot or so after the stove, run mine 3/4 or more closed at all times except when loading then it's wide open to keep the smoke from coming back into the house and to get the new wood going..