$f(\theta)=-0.28(\theta-27)^{2}+880$

An engineer wanted to identify the best angle for a cooling fan in an engine in order to get the greatest airflow. The engineer discovered that the function above models the airflow $\bm{f}(\bm{\theta})$, in cubic feet per minute, as a function of the angle of the fan $\bm{\theta}$, in degrees. According to the model, what angle, in degrees, gives the greatest airflow?