Spinners just look cool. They give airplanes that sleek and aerodynamic “ready to take flight” look. And they are so pervasive in propeller-driven aircraft that we can scarcely imagine attaching a prop without that slick cone ahead of the nose. But spinners do more than look cool. They do cool.
The purpose of the spinner is to direct cooling air to the engine inlets. They work together with the cowling to maintain a stable and safe engine temperature.
Think of the spinner as an air-scoop. It makes contact with the relative wind and smoothly directs it into the cowling. The spinner is just the first step in the whole air-cooling process and as such, is a critical part of the airplane’s powerplant.
Of course, there are other benefits of having a spinner. Much like engine cowling, the spinner has a few aerodynamic benefits. In most cases, the spinner blends with the upper surface of the cowling and keeps the airflow smooth over the nose. This decreases drag and boosts fuel efficiency as well as speed.
Spinners should be checked thoroughly on the preflight inspection. Look for cracks, missing screws or other signs of stress which usually appear near the attachment points. Foreign contaminants such as ice or bird nests on the inside of the spinner are another concern as they can cause dangerous engine vibration or damage.
For more information on spinners, see Mike Collins’ article in the October 2011 edition of AOPA Flight Training magazine.