Is a vertical stabiliser needed for straight line flight in a glider? My team is designing a glider and I am unsure about whether or not to include a vertical stabiliser. The task the glider must complete is to achieve the largest possible displacement in a straight line. 

Our glider will not be able to automatically adjust the vertical stabiliser's position so it would stay upright and inline with the glider's fuselage for the duration of the flight. Since our glider does not require any changes in it's yaw angle (because it is flying in a straight line), I don't think there is a need for it.

Should we include a vertical stabiliser or not?
The stabilizer is meant to keep the nose pointing into the wind. 

Any asymmetry in he wings/fuselage will create a tendency to yaw, you will need to compensate for that. The easiest is a fixed vertical stabilizer at the rear.