The tail section of an airplane is called the empennage. It has a tail cone, fixed surfaces called stabilizers, and movable surfaces: a rudder for yaw and an elevator for pitch. The surfaces can be arranged in several ways, and each layout changes how the airplane handles.
This guide covers the conventional tail, T-tail, V-tail, stabilator and the canard, using the FAA's pilot and maintenance handbooks, plus what each layout costs the pilot in handling.
Key Takeaways
A conventional tail uses a horizontal stabilizer with an elevator and a vertical stabilizer with a rudder.
A T-tail puts the horizontal surfaces on top of the fin, above most propeller downwash effects. It needs a stiffer fin and is more prone to deep stall.
A V-tail has two slanted fixed surfaces with movable ruddervators. The FAA describes its control system as more complex and its total drag reduction as minimal.
A stabilator is a one-piece horizontal tail that pivots. A canard puts the horizontal surface ahead of the wing, where it creates lift instead of pushing down.
What the Tail Is Made Of
The FAA's maintenance handbook says most empennage designs have a tail cone, fixed stabilizers and movable surfaces. The tail cone closes and streamlines the rear fuselage. It's built from the same kinds of members as the fuselage but is usually lighter, because it sees less stress.
The stabilizers are built much like wings, with spars, ribs, stringers and skin. Bending, torsion and shear from air loads pass from one member to another, each absorbing some and passing the rest along, and in the end the spar transmits any overload to the fuselage. The rudder sits at the back of the vertical stabilizer and the elevator at the back of the horizontal stabilizer. Trim tabs on these surfaces are small movable parts of the trailing edge. They're controlled from the flight deck and reduce the control pressure the pilot has to hold.
What the Tail Does
The elevator controls pitch about the lateral axis. The rudder controls yaw about the vertical axis, using the left and right rudder pedals. The horizontal tail also does a second job. On a conventional airplane it normally pushes down. That downward force balances the airplane around its center of gravity, which is why the center of gravity limits matter so much at the tail.
Pulling the control column back raises the elevator's trailing edge. That increases the downward force on the tail, the tail moves down and the nose pitches up. Pushing forward does the opposite: the elevator camber increases, the tail produces more lift, which means less tail-down force, and the nose pitches down.
The rudder is a speed-dependent control. Its effectiveness increases with speed, so the FAA says large deflections can be needed at low speed and small ones at high speed. In propeller-driven aircraft, slipstream flowing over the rudder makes it more effective.
Why center of gravity shows up at the tail
Center of gravity too far aft: there might not be enough elevator nose-down force at low stall speed to get the nose down and recover.
Center of gravity too far forward: there won't be enough elevator nose-up force to flare for landing. In the flare, power is usually reduced and speed is low, so airflow over the empennage drops and the elevator gets less effective just when you need it.
Tail Configurations Compared
Tail designs (FAA Pilot's Handbook, Chapters 3 and 6)
Design
Arrangement
Strengths
Drawbacks
Conventional
The horizontal tail is attached near the bottom of the vertical stabilizer or at its midpoint.
Propeller downwash helps the elevator raise the nose at low speed.
The elevator works in disturbed air from the propeller, fuselage and wing.
T-tail
The horizontal stabilizer sits at the top of the vertical stabilizer.
The elevator works in undisturbed air, above most propeller downwash effects in normal flight, and away from the exhaust of aft fuselage-mounted engines. Reduced noise and vibration inside. Common with aft fuselage-mounted engines, and on seaplanes, to keep the surfaces away from the water.
The elevator must move farther and with more force at slow speed. Needs a stiffer fin and brings a weight penalty. More susceptible to deep stall.
V-tail
Two slanted surfaces do the work of a horizontal and a vertical tail. The movable surfaces are ruddervators.
Fewer surfaces.
A more complex control system, more susceptible to Dutch roll, and the FAA calls the total reduction in drag minimal.
Stabilator
A one-piece horizontal stabilizer pivots about a central hinge instead of having a separate elevator.
The whole surface moves, controlled by the control wheel like an elevator.
Extremely sensitive to control inputs and aerodynamic loads. Needs an antiservo tab and usually a balance weight.
Canard
A horizontal surface in front of the main wing.
It creates lift instead of a downward force, which should theoretically mean less drag for a given lift.
The handbook lists no specific drawbacks. It describes two types, one with a surface about the size of a normal tail and the tandem wing.
Conventional. The horizontal tail attaches near the bottom of the fin or at its midpoint. The rudder is on the fin and the elevator on the horizontal surface.T-tail. The horizontal surface sits on top of the fin, above most propeller downwash effects.V-tail. Two slanted surfaces act as horizontal and vertical stabilizers. Their movable parts are ruddervators.Stabilator. The whole horizontal surface pivots. A small antiservo tab on the trailing edge makes it less sensitive.
T-Tail Details
The T-tail's selling point is clean air. The elevator sits above most of the downwash from the propeller and the airflow around the fuselage and wings, so control movements feel consistent through most flight conditions. The FAA says T-tails have become popular on many light and large aircraft, especially those with engines mounted on the aft fuselage, because the layout takes the tail out of the exhaust blast. Seaplanes and amphibians often have them to keep the horizontal surfaces as far from the water as possible.
The price shows up at slow speed. A conventional tail gets propeller downwash pushing down on it, which helps raise the nose. A T-tail doesn't, so its elevator must move farther to raise the nose a given amount, and the required control force is higher. Longitudinal stability of a trimmed aircraft is the same for both layouts, but the FAA says pilots should expect heavier forces on takeoff, landing and in stalls.
The structure pays too. The horizontal surfaces sit on the top of the fin, and their weight at the end of that long arm loads the fin and can lead to flutter. Engineers answer by stiffening the vertical stabilizer, which usually costs weight compared with a conventional tail.
Deep stall
Deep stall is the major caution. At a very high angle of attack with low airspeed and an aft center of gravity, the wake of a fully stalled wing can blanket the horizontal tail, making the elevator or stabilator almost ineffective and recovery difficult. Deep stalls can happen on any aircraft, but the FAA says they're more likely on T-tails. The distance between the wings and the tail and the position of the engines, such as tail-mounted ones, can increase the risk, and these features may make it more prevalent on transport aircraft than on general aviation ones.
Designers fight it with several devices, from control stops to elevator down springs, and transport jets commonly use stick pushers. An elevator down spring puts a mechanical load on the elevator that tends to move it nose-down. The trim tab normally balances that spring. If the trim tab stops being effective, the spring drives the elevator to nose-down, the speed builds and the stall is prevented.
V-Tail and Ruddervators
A V-tail replaces the horizontal and vertical stabilizers with two slanted surfaces, which are fixed surfaces that act as both. The handbook's photo is a Beechcraft Bonanza V35. The movable parts are called ruddervators. They connect through a special linkage that lets the control wheel move both together, working as an elevator, while the rudder pedals move them differentially for directional control.
When a pilot asks for pitch and yaw at the same moment, a mixing mechanism moves each ruddervator the appropriate amount. That linkage is the first drawback. The second is that a V-tail is more susceptible to Dutch roll than a conventional tail. The FAA's glossary defines Dutch roll as a combination of rolling and yawing oscillations that's usually dynamically stable but objectionable in an airplane. And the total drag reduction, the handbook says, is minimal.
Stabilators and Trim
A stabilator replaces the fixed stabilizer and elevator with one surface that pivots from a central hinge. It's moved with the control wheel like an elevator. Pull back, the trailing edge rises, the aerodynamic tail load increases and the nose goes up.
Because the whole surface pivots, a stabilator is extremely sensitive to control inputs and aerodynamic loads. An antiservo tab on the trailing edge tames it. The tab deflects in the same direction as the stabilator, which raises the force needed to move it and makes the pilot less likely to overcontrol. It also works as a trim tab, relieving control pressure and holding the stabilator where it's set. A balance weight, usually in front of the main spar, may project into the empennage or sit on the forward part of the stabilator tips.
Canards
A canard puts the horizontal surface in front of the main wing. It's an airfoil like the horizontal surface on a conventional tail, with one difference: the canard actually creates lift and holds the nose up, where an aft tail pushes down to stop the nose pitching forward. The handbook calls this theoretically more efficient, since using the horizontal surface to help carry the weight should mean less drag for a given amount of lift.
The idea is old. It was used on the Wright Flyer, and the FAA says it has regained popularity on newer aircraft. Two types exist: one with a horizontal surface about the size of a normal aft tail, and a tandem wing, where the front surface has about the same size and airfoil as the aft-mounted wing. The handbook's example is the Piaggio P180, which has a variable-sweep canard that gives longitudinal stability about the lateral axis.
Tailless and Combined Surfaces
The maintenance handbook lists other ways to combine controls. Elevons perform the combined functions of ailerons and elevators. A ruddervator combines rudder and elevator. Flaperons are ailerons that can also act as flaps. For the wing-mounted ones, see our guide to flaps, and for the fuselage the tail bolts onto, fuselage types.
Frequently Asked Questions
What's the tail of an airplane called?
The empennage. Most designs have a tail cone, fixed surfaces called stabilizers, and movable surfaces: a rudder and an elevator.
What's a T-tail?
A tail design with the horizontal stabilizer mounted on top of the vertical stabilizer. It keeps the elevator above most propeller downwash effects, but it needs a stiffer fin and is more susceptible to deep stall.
What's a ruddervator?
A movable surface on a V-tail. The pair of ruddervators do the work of an elevator and a rudder, moving together for pitch and differentially for yaw.
What's a stabilator?
A one-piece horizontal stabilizer that pivots about a central hinge instead of having a separate elevator. An antiservo tab makes it less sensitive.
What's a canard?
A horizontal surface mounted in front of the main wing. Unlike a conventional tail, it creates lift and holds the nose up, instead of exerting a downward force.
What's a deep stall?
A condition at very high angle of attack and low airspeed where the wake of a stalled wing blankets the horizontal tail and makes the elevator almost ineffective. It's more likely on T-tails, especially with an aft center of gravity.
Does a V-tail reduce drag?
Only slightly. The FAA says the total reduction in drag is minimal, and the control system is more complex.
