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ultimate stress
“flappable” parts of structure, esp. wing. Hence, ultimate
bending/compressive/tensile/torsional strength.
ultimate stress That in a member or piece of material at
moment of fracture; in theory that in structural member
loaded to ultimate strength.
Ult-Join Unit-level trainer, joint operations integrated
network.
ultra-bypass engine One name of unducted propfan,
with BPR from 20 to 50 (Boeing).
ultra-high bypass UHB, alternative to above
(McDonnell Douglas).
ultra-high-density seating Seating configuration for
maximum number of passengers (invariably greater than
original certification limit) with minimal pitch and no
galley.
ultra-high frequency 300–3,000 MHz, see Appendix 2.
ultra-high magnetic field Generally, greater than 10 T
(100 kG).
ultra-high-speed photography Rate higher than 10 4
images/s.
ultra-high vacuum Previously below 10 –13 torr (not
apparently yet defined in SI, but this is 13.33 × 10 –11 N/m 2 );
density 3.2 × 10 3 mol/cc, mean free path (air 25°C)
3.8×10 10 .
ultralight aircraft Categories of small aeroplane. In
USA, 1-seat with empty weight 254 lb (115.2 kg); in
Australia, 1 or 2 seats, MTOW 540 kg (1,190.5 lb).
France, see ULM, UK, see microlight, SLA.
ultra-long-haul FDP exceeding 16 hours.
ultra-low airdrop Below 15 m (50 ft) AGL.
ultramicroscope Instrument for observing extremely
small particles by intense illumination causing diffraction
rings on dark background.
ultra-short takeoff Use of short forward run by aircraft
capable of VTO, normally called merely STO. Can
involve pilot-selectable operating modes.
ultrasonic Mechanical vibrations, eg sound waves, of
frequency too high to be audible to humans
(opposite = infrasonic). Generally frequencies above
15 kHz, usually generated by electro-acoustic transducer
and propagated through solids, liquids and gases.
ultrasonic bonding Techniques of joining materials with
ultrasonic energy, in some cases to cause local melting
(ultrasonic welding) and in others to cause either
enhanced local diffusion or merely heating to accelerate
curing or setting of adhesive.
ultrasonic cleaning The item to be cleaned is immersed
in liquid [water or various proprietary fluids] and
surrounded by small bubbles created by magnetostrictive
transducers. The collapse of the bubbles [implosion]
bombards the surface with shockwaves.
ultrasonic inspection NDT method in which cracks are
revealed by discontinuity in propagation of ultrasonic
waves through metal.
ultrasonic machining Techniques for shaping solids, esp.
those too hard or for any other reason not machinable by
conventional means. Most common method uses shaped
tool oscillated vertically above work at frequency about
20 kHz, with space between tool/work fed with hard
powder abrasive.
ultrasonic rolling Transducer (typically 20 kHz) placed
inside one (rarely both) of rolls in rolling mill with objective
of reducing rolling energy needed, reducing required
UMTS
temperature of metal being rolled and rolling to thinner
gauges.
ultrasonic welding Techniques in which ultrasonic vibrations
are used to join two metal (rarely, either or both is
non-metal) surfaces brought into contact. Surfaces
usually well mating, atomically clean and pressed together
under pressure. In some techniques ultrasonic rearrangement
of atoms is sufficient to cause melting at interface,
while in others there is diffusion between the two faces.
ultrasonic wind sensor Most have three sources
exchanging pulses between each pair, times being
precisely measured.
ultrasound Sound of ultrasonic frequency.
ultra-violet Band of EM radiation of frequency just too
high (ie wavelength too short) to be visible; links visible
violet at about 3.8 to 4 × 10 –7 m to limiting wavelength put
at from 1 to 1.36 × 10 –8 m (next major part of spectrum
is X-ray at appreciably shorter wavelength).
ultra-violet detector Material, eg single-crystal silicon
carbide, not triggered by sunlight or other incident
radiation but instantly responsive to UV.
ultra-violet imagery That produced by sensing UV
reflected from target (DoD).
ULV 1 Upper limit of video (HUD).
2 Ultra-low volume (crop spraying).
UM Rhymes with ‘come’, an unaccompanied minor
[passenger under 16].
UMA 1 Unmanned aircraft, = drone or RPV.
2 Uffici Meteorologici Aeronautica (I).
3 Unusual military activities.
Umark Unit maintenance aerial recovery kit.
umbilical 1 Connection between vehicle, esp. space
launcher, missile (esp. large ballistic) or RPV, and ground,
along which pass all necessary supplies and signals up to
moment of liftoff or launch, eg computer data-link,
telemetry, guidance programming, topping-up liquid
propellants, electrical/hydraulic/pneumatic power and
instrumentation. Generally grouped into one large
multiple conduit with pull-off connector. Occasionally
plural, when two serve one vehicle.
2 Jetway, loading bridge (colloq.).
umbilical cord See umbilical (1).
umbilical tower Tower carrying umbilical lines and
connector to an upper stage of a ballistic vehicle; often
called umbilical mast.
UMC Upgraded main computer.
UMD 1 Unrefuelled mission distance.
2 Unit manning document.
UMG Universal message generator.
umkehr Anomaly of relative zenith intensities of
scattered sunlight near UV as Sun nears horizon, often
cap U.
UML Unified modelling language.
UMLS Universal MLS.
UMR Unrefuelled mission radius.
umrust Modified, modification (G).
UMS 1 Unified message switch.
2 Utilities management system.
UMT 1 Universal military training.
2 Universal mount.
UMTE Unmanned threat emitter.
UMTS Universal mobile telecommunications system,
providing all previous facilities plus TV and videoconferencing
on mobile devices (2004 on).
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