Lane Pearman

The Cessna 172 may be the most ubiquitous training plane made, and it dwarfs any other plane's production run. Most pilots have flown one - and it's usually the swept tail version.

Cessna introduced the 172 in 1956 with a straight tail - essentially a rectangle sticking straight up from the fuselage. Between 1956 and 1960, Cessna produced 4,195 straight-tailed 172s.

In 1960, Cessna released the redesigned 172A - with a swept vertical tail. That tail, with minor modifications, has stayed on the 172 line ever since. It looks faster - but is it?

Boldmethod

A Swept Tail Flies Like A Swept Wing

A swept vertical tail is no different than a swept wing. On a straight wing, the relative wind flows parallel to the chord lines; but on a swept wing, the relative wind flows across the chord lines at an angle.

Only the wind component flowing parallel to the chord line accelerates and produces lift. On a high-speed aircraft, this decreases the airflow's acceleration over the airfoil - preventing supersonic flow and wave drag. But, at low speeds, the sweep decreases the amount of lift that the airfoil generates.

Boldmethod

Boldmethod

On a slow-flying aircraft like a Cessna 172, you don't have to worry about supersonic airflow over the wing or tail. (You'd have much bigger problems by that point...) But, the 172's swept tail still "sees" only a component of airflow - and generates less force than a straight tail. So, a swept tail must be larger than a straight tail, which increases drag.

The increase in drag isn't massive, and the swept shape looks fast. It's one case where marketing and aesthetics wins out over aerodynamics.