Vertical stabilizer
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The vertical stabilizers, or fins, of aircraft, missiles or bombs are typically found on the aft end of the fuselage or body, and are intended to reduce aerodynamic side slip.
On aircraft, vertical stabilizers generally point upwards. These are also known as the vertical tail, and are part of an aircraft's empennage. The trailing end of the stabilizer is typically movable, and called the rudder; this allows the aircraft pilot to control yaw.
Often navigational radio or airband transceiver antennas are placed on or inside the vertical tail. In most aircraft with three jet engines, the vertical stabilizer houses the central engine or engine inlet duct, as in the Lockheed L-1011, McDonnell Douglas DC-10, McDonnell Douglas MD-11, Boeing 727, BAe Trident, Tupolev Tu-154, and the Yakovlev Yak-40.
Types of vertical stabilizers
Single
Conventional tail
The vertical stabilizer is mounted exactly vertically, and the horizontal stabilizer is directly mounted to the empennage (the rear fuselage). This is the most common vertical stabilizer configuration.
T-tail
A T-tail has the horizontal stabilizer mounted at the top of the vertical stabilizer. It is commonly seen on rear-engine aircraft, such as the Bombardier CRJ200 or Douglas DC-9, as well as the Silver Arrow small airplane, and most high performance gliders. The only operational fighter aircraft to use the T-tail configuration were the McDonnell F-101 Voodoo and the Lockheed F-104 Starfighter.
T-tails are often incorporated on configurations with fuselage mounted engines to keep the tail away from the engine exhaust plume.
T-tail aircraft are more susceptible to pitch-up at high angles of attack. This pitch-up results from a reduction in the horizontal tail's lifting capability as it passes through the wake of the wing at moderate angles of attack.
T-tails present structural challenges since the horizontal tail loads must be transmitted through the vertical tail.
Cruciform tail
The cruciform tail is arranged like a cross, the most common configuration has the horizontal stabilizer intersecting the vertical tail somewhere near the middle. The PBY Catalina uses this configuration. The "push-pull" twin engined Dornier Do 335 World War II German fighter used a cruciform tail consisting of four separate surfaces, arranged in dorsal, ventral, and both horizontal locations, to form its cruciform tail, just forward of the rear propeller.
Multiple stabilizers
Twin tail
Rather than a single vertical stabilizer, a twin tail has two. These are vertically arranged, and intersect or are mounted to the ends of the horizontal stabilizer. The Beechcraft Model 18 and many modern military aircraft such as the American F-14, F-15, and F-18 use this configuration. The F-18 and F-22 Raptor have tailfins that are canted outward, to the point that they have some authority as horizontal control surfaces; both aircraft are designed to deflect their rudders inward during takeoff to increase pitching moment.
Triple tail
A variation on the twin tail, it has three vertical stabilizers. The best example of this configuration is the Lockheed Constellation. On the Constellation it was done to give the airplane maximum vertical stabilizer area, but keep the overall height low enough so that it could fit into maintenance hangars.
V-tail
A V-tail has no distinct vertical or horizontal stabilizers. Rather, they are merged into control surfaces known as ruddervators which control both pitch and yaw. The arrangement looks like the letter V, and is also known as a butterfly tail. The Beechcraft Bonanza Model 35 uses this configuration, as does the F-117 Nighthawk, and many of Richard Schreder's HP series of homebuilt gliders.
Winglet
Winglets served double duty on Burt Rutan's rear wing forward canard pusher configuration VariEze and Long-EZ, acting as both a wingtip device and a vertical stabilizer. Several other derivatives of these and other similar aircraft use this design element.