MadJock
If the Nose baggage compartment comes open on certain aircraft they can become almost un flyable.
While air and water are different we all know what happens when we stick your example of a plate (air brakes ) into the slip stream.
i am not an aerodynamic expert but know even a small change like Piper made fitting Lopresti air intakes improved cooling and speed to some of their aircraft namely the Seneca and Saratoga.
Aircraft designers spend ages in wind tunnels studying how one curve effects the airflow over another and then onto and over control surfaces.
The loss of a complete screen would in my guess create massive drag as well as disruption of airflow over vital control surfaces making the aircraft almost impossible to fly.
I do not know if there have been instances of complete screen loss or the effects of that screen loss
But I stand to be corrected too
