The vertical stabilizers, vertical stabilisers, 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 and provide
direction stability. It is analogous to a skeg on boats and ships.
On aircraft, vertical stabilizers generally point upwards. These are
also known as the vertical tail, and are part of an aircraft's
empennage. This upright mounting position has two major benefits: The
drag of the stabilizer increases at speed, which creates a nose-up
moment that helps to slow down the aircraft that prevent dangerous
overspeed, and when the aircraft banks, the stabilizer produces lift
which counters the banking moment and keeps the aircraft upright at
the absence of control input. If the vertical stabilizer was mounted
on the underside, it would produce a positive feedback whenever the
aircraft dove or banked, which is inherently unstable. 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 all known trijets (jet aircraft with 3
engines), the vertical stabilizer houses the central engine or engine
Vertical stabilizers, or fins, have also been used in automobiles,
specifically in top level motor sports, with the concept making a
resurgence in both
Formula 1 and
Le Mans Prototype
Le Mans Prototype racing.
A few aircraft models have a ventral fin under the rear end. Normally
this is small, or can fold sideways, to allow landing. Both the North
American X-15 supersonic/hypersonic experimental aircraft, and the
late World War II German twin-engined
Dornier Do 335
Dornier Do 335 heavy fighter
used differing forms of the cruciform tail stabilizing surface format.
1.1.1 Conventional tail
1.1.3 Cruciform tail
1.2 Multiple stabilizers
1.2.1 Twin tail
1.2.2 Triple tail
3 Automotive/motorsports use
4 See also
The conventional tail of an Airbus A380, with the vertical stabilizer
Tails of Iberia aircraft at Madrid Barajas Airport.
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.
Main article: T-tail
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, the Fokker 70, the Boeing 727, the Vickers
VC10 and Douglas DC-9, and most high-performance gliders.
T-tails are often incorporated on configurations with fuselage mounted
engines to keep the horizontal stabilizer away from the engine exhaust
T-tail aircraft are more susceptible to pitch-up at high angles of
attack. This pitch-up results from a reduction in the horizontal
stabilizer's lifting capability as it passes through the wake of the
wing at moderate angles of attack. This can also result in a deep
T-tails present structural challenges since loads on the horizontal
stabilizer must be transmitted through the vertical tail.
Main article: Cruciform tail
The cruciform tail is arranged like a cross, the most common
configuration having 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
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.
Falconjets from Dassault always have cruciform tail.
Main article: Twin tail
The twin tail of a Chrislea Super Ace, built in 1948
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
Beechcraft Model 18 and many modern
military aircraft such as the American F-14, F-15, and F/A-18 use this
configuration. The F/A-18, F-22 Raptor, and F-35 Lightning II 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. A twin tail may be either H-tail, twin fin/rudder construction
attached to a single fuselage such as North American
B-25 Mitchell or
Avro Lancaster, or twin boom tail, the rear airframe consisting of two
separate fuselages each sporting one single fin/rudder, such as
P-38 Lightning or
Lockheed Constellation with a triple tail
A variation on the twin tail, it has three vertical stabilizers. An
example of this configuration is the Lockheed Constellation. On the
Constellation it was done to give the airplane maximum vertical
stabilizer area while keeping the overall height low enough so that it
could fit into maintenance hangars.
Main article: V-tail
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.
Winglets served double duty on Burt Rutan's 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.
Fin is an alternative name for the vertical stabilizer.
The vertical stabilizer often employs a small fillet or "dorsal fin"
at its forward base which helps to increase the stall angle of the
vertical surface (thanks to vortex lift) and to prevent a phenomenon
called rudder lock or rudder reversal.
Rudder lock occurs when the
force on a deflected rudder (in a steady sideslip) suddenly reverses
as the vertical stabilizer stalls. This may leave the rudder stuck at
full deflection with the pilot unable to recenter it.
While vertical stabilizers have also been used in some race cars, such
as the 1955 Jaguar D-type, the concept has seen sparing use until
recently when the concept has seen a resurgence in
Formula 1 and Le
Mans endurance racing. The ostensible purpose of this is primarily to
reduce sudden high speed yaw induced blow overs that would cause the
cars to flip due to aerodynamic lift when subject to extreme yaw
angles during cornering or in a spin. In addition to this, some
Formula 1 teams utilized the wing as a way to disrupt the airflow to
the rear wing reducing drag, the most radical system being the
"F-duct" found in the MP4-25 (and later copied by Ferrari in the
Ferrari F10), which could divert air from a duct in the front of the
car, on demand by the driver, through a tunnel in the vertical fin
onto the rear wing to stall it and reduce drag on the straights on
which downforce wasn't needed. The system has since been banned for
Formula 1 season. For Le Mans Prototypes, the vertical
stabilizer, dubbed the "Big Honking Fin" by some fans has become
mandatory for all newly homologated sports prototypes.
Ferrari F10 with large rear vertical fin sprouting out of the airbox
and leading into the rear wing.
^ Kumar, Bharat (2005). An Illustrated Dictionary of Aviation. New
York: McGraw Hill. p. 272. ISBN 0 07 139606 3.
^ NASA Flight Education website Archived February 27, 2009, at the
^ "The New Audi R18 LMP1". 2010-12-13. Retrieved