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tulip valve
burner at fuel pressure not high enough to atomize continuous
film but too high for it to converge as bubble.
tulip valve Piston-engine exhaust valve shaped in side
elevation like tulip.
Tumav Tactical unmanned multirole air vehicle.
tumble 1 To rotate about lateral axis, ie end over end;
rare in aircraft but not uncommon in spacecraft.
2 To rotate metal parts in drum, often with powder
abrasive, to remove flash or burrs and obtain polished
surface.
3 Of gyro wheel, to precess to limit after toppling.
tumblehome Distance measured parallel to transverse
axis from vertical line through widest extremity of
seaplane or flying-boat hull to any point on skin above.
tumblehome line Abrupt change of curvature of mould
line, buttock line or water-level contour at end of contour
[marine aircraft].
tumble limit Angular displacement in pitch or roll at
which traditional gyro instrument is on gimbal stops.
tumbler Drum in which metal parts are tumbled (2).
tumbler switch Snap-action electrical switch with short
operating lever.
tumbling To tumble (1, 2, 3); to be in that condition.
tunable beam approach Pre-ILS landing system (BABS,
SBA) in which pilot tuned receiver to particular airfield
(arch.).
tundra tyre Low-pressure tyre suitable for operations
from snow.
tuned-bandpass transformer Typically, primary winding
forms anode load of one stage and secondary drives grid
of succeeding stage.
tuned circuit Oscillatory circuit with capacitance and
inductance selected or tuned to resonate at frequency of
applied signal.
tuned-grid circuit Parallel resonant circuit linking grid
and cathode with maximum response at resonant
frequency; similar resonant response for tuned anode
circuit.
tuner Subcircuit or device in RF receiver which selects
desired frequency and rejects all others.
tungsten Silver-grey metal, symbol W, density 19.3, MPt
3,407°C; one of densest, hardest, strongest and most
refractory metals known.
tungsten inert-gas welding DC current is passed through
cathode of 4% thoriated tungsten and through workpiece
with high-purity argon fed to both sides of weld and to
form gas lens from torch.
Tungum Corrosion-resistant alloy of copper with 14.6%
zinc and small amounts of other metals.
tuning 1 Fine adjustment over continuous analog range
of values to obtain that desired, eg RF frequency/wavelength
or optimum operating condition of engine or other
device.
2 See airframe *.
tunnel 1 See wind tunnel.
2 Axial fairing along body, eg to cover pipes, cables and
other lines routed outside skin.
3 Channel along which baggage passes through
screener.
tunnel diode Semiconductor device having single p-n
junction across which electrons flow by quantum
tunnelling; when biased to centre of a negative-resistance
mode can operate as amplifier, oscillator or switch.
tunnel shock That occurring immediately downstream
turbine temperatures
of supersonic working section in wind tunnel when Mach
number falls below unity; intense if no second throat.
tunnel vision Inability to perceive anything outside an
extremely small angular range of FOV, as if one were in a
tunnel; caused by disease or high g.
TUP Technology utilization program (NASA, technology
transfer).
turb, TURBC Turbulence (ICAO).
turbidity Any condition of atmosphere which reduces its
transparency to radiation, esp. optical; term normally
applied to cloud-free sky where * is caused by suspended
matter, scintillation and other effects.
turbine 1 Gas-turbine shaft power, ie turboshaft or
turboprop; eg helicopter can be said to have * power.
2 Prime mover whose power is obtained by action of
working fluid (water, steam, cold or hot gas, etc) to give
tangential circumferential forces reacting on blades or
shaped passages which rotate a shaft. At redline speed a
modern turbofan blade can move at 460 m (1,500 ft) s -1 ,
under 60,000 g. One or more are source of power in all gas-
* engines and in turbochargers, turbopumps and many
other rotary machines.
turbine-airscrew unit See turboprop.
turbine bearing Bearing supporting turbine shaft.
turbine blade Radial aerofoil mounted in edge of turbine
disc whose tangential force rotates turbine rotor. Each
turbine stage has many blades, occasionally fabricated in
groups of two or more. Called bucket in US. Inwardsradial
turbine does not have *.
turbine disc Central member upon which turbine rotor
blades are mounted; in some modern engines the blades
and disc are monolithic. In many multistage turbines there
are no flat discs, first and last stages being conical and
intervening stages being rings gripped between them.
turbine entry temperature See turbine temperatures.
turbine gas temperature See turbine temperatures.
turbine rotor Complete turbine rotating assembly with
1–6 stages; stators are excluded.
turbine shroud Shroud around periphery of turbine
rotor stage, formed by * section on tip of each blade.
turbine stage Single turbine disc or ring with inserted
blades; for completeness should be associated with
preceding stator (IGV) stage.
turbine stator Ring of fixed blades, also called inlet guide
vanes, upstream of each turbine rotor stage, on to whose
blades ** directs gas with optimum distribution of V and
pressure for maximum turbine work and efficiency (eg
changes radial pressure/V, previously uniform, so that
with increasing radius pressure increases while V falls).
turbine temperatures This entry describes temperatures
in gas-turbine engines. Alphabetically, these are: CET,
CIT, COT, EGT, RIT, SOT, TDT, TET, TGT and TIT.
Following a particle through an engine, CIT is
compressor inlet temperature, which is that of the ambient
atmosphere corrected for any ram effect. COT is
compressor outlet temperature, measured immediately
behind the final stage of compression. CET, combustor
exit temperature (also called combustion chamber outlet
temperature, giving a second meaning for COT) is the
temperature of the gas at the entry to the first-stage
turbine stator. SOT is stator (first-stage) outlet temperature.
The gas is then cooled 20°–120°C by injection of
cooling air from the turbine disc (whose temperature TDT
is cooled by the airflow) and other sources to give the RIT
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