Putting a lot of spin (angular momentum) on a disc is crucial for it to fly straight (with forward momentum) and curve uniformly.  Without spin the disc will just fall flat or flip over.  The spin of a disc provides balance and minimizes any fluttering action through the air.   The reason for this can be explained through Total Kinetic Energy.  There are two types of energies in a spinning disc: Linear Kinetic Energy and Rotational Kinetic Energy.  The Equation for the Total Kinetic Energy it can be seen that if mass is increased, it will take a higher linear and angular velocity to keep that same Total Kinetic Energy.  The Equation also shows that with a greater moment of inertia, the less angular acceleration is needed to keep that same rotational energy.
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