Why is the component of gravity radial

Question

Task: Show the force vector components of a glider plane in a loop the loop motion (uniform vertical circle) at 45 degrees to the horizontal.

Problem: I had assumed that the weight force would be pointing vertically downwards and tangential to the circle and not contribute to the net centripetal acceleration or force (Newton's 2nd). But my teacher says that gravity will have an affect at the 45 degrees, and the component of it will be radial.

What have I done wrong if you could include some diagrams to help explain would be good thanks.