Glossary — T

t Tonne, 1 Megagram, 1 000 kg.

T Trainer (UK and US designator).

tab Small auxiliary surface hinged (flight-adjustable) or attached in a fixed position (ground-adjustable) to trailing-edge of control surface for trimming, balancing (reducing hinge moment: force needed to operate main surface) or in other way assisting pilot. Compare anti-balance tab.

tabbed flap Fitted with narrow-chord tab along trailing-edge which deflects to greater angle than main surface.

TAC Tactical Air Command.

TACAMO Take Charge And Move Out – USN AVLF relay system.

Tacan Tactical air navigation, UHF navaid giving bearing and distance to ground beacons; distance element (see DME) can be paired with civil VOR.

taileron Left and right tailplanes used as primary control surfaces in both pitch and roll.

tailplane Horizontal stabiliser; main horizontal tail surface, originally fixed and carrying hinged elevator(s) but today often a single ‘slab’ serving as control surface (see stabiliser, stabilator).

TANS Tactical air navigation system: Decca Navigator or Doppler-based computer, control and display unit.

TARPS Tactical Airborne Reconnaissance Podded System.

TAS True airspeed, EAS corrected for density (often very large factor) appropriate to aircraft altitude.

TBAP Tyazhelyy Bombardirovochnyy Aviatsionnyy Polk = heavy bomber aviation regiment.

TBO Time between overhauls.

t/c ratio Ratio of the thickness (aerodynamic depth) of a wing or other surface to its chord, both measured at the same place parallel to the fore-and-aft axis.

TCAS Traffic-alert and collision-avoidance system.

Tercom Terrain-comparison (or contour-matching), navigation aid which compares relief of terrain with profile stored in memory.

TERPROM TERrain PROfile Matching. (Same as Tercom).

TFR Terrain-following radar (for low-level attack).

TFW Tactical Fighter Wing.

thickness Depth of wing or other aerofoil; maximum perpendicular distance between upper and lower surfaces.

thrust vectoring Rotation of a vehicle's thrust axis to control its trajectory or support its weight.

TIALD Thermal imaging and laser designation (pod).

tiltrotor Aircraft with fixed wing and rotors that tilt up for hovering and forward for fast flight.

TINS Tactical Inertial Navigation System.

T-O Takeoff

T-0 noise EPNdB measure of aircraft taking off, at point directly under flight path 3.5 n miles from brakes-release.

TOGW Take-off gross weight (not necessarily MTOW).

TOW Tube-launched, Optically-tracked, Wire-guided (anti-tank guided missile). Designation = BGM-71.

ton Imperial (long) ton = 1 016 t or 2 240 Ib, US (short) ton = 0.9072 t or 2 000 lb.

track Distance between centres of contact areas of main landing wheels measured left/right across aircraft (with bogies, distance between centres of contact areas of each bogie).

transceiver Radio transmitter/receiver.

transformer-rectifier Device for converting AC to DC at a different voltage.

transponder Radio transmitter triggered automatically by a particular received signal, as in secondary surveillance radar (SSR).

TsENTROSPAS (in Russian Federation) Ministry for Civil Defence, Emergencies and Elimination of the Consequences of Natural Disasters.

TTH Troop Trnasport Helcopter (NH-90 variant).

Tu Tupolev (Russian design bureau).

turbofan Gas-turbine jet engine generating most thrust by a large-diameter cowled fan, with small part added by jet from core.

turbojet Simplest form of gas turbine comprising compressor, combustion chamber, turbine and propulsive nozzle.

turboprop Gas turbine in which as much energy as possible is taken from gas jet and used to drive reduction gearbox and propeller.

turboshaft Gas turbine in which as much energy as possible is taken from gas jet and used to drive high-speed shaft (which in turn drives external load such as helicopter transmission).

twist Progressive change of angle of incidence of a wing, rotor blade or other aerofoil from root to tip.

Type Certificate Airworthiness licence granted to enable a manufacturer to produce and market a specified type of aircraft (compare C of A).

tyre sizes Five systems of classification are in current use; Type I, consisting of a single figure indicating nominal diameter in inches, is obsolete. See adjacent table and also ‘ply’.

Tyre classification