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UGSS
UGSS Unmanned global strike system.
UGV Unmanned ground vehicle, usually controlled
from air.
UH UDMH
UHB Ultra-high bypass engine.
UHC Unburned hydrocarbons.
UHCA Ultra-high-capacity aircraft.
UHD Ultra-high density.
UHDT Unable higher, due traffic.
UHE Ultra-high energy; CR adds cosmic rays.
u.h.f. Ultra-high frequency, see Appendix 2.
UHH Ultra-high hardness [steel].
UHPT Undergraduate helicopter pilot training.
UHR Ultra-high resolution.
UHS Ultra-high-speed (logic).
UHV Ultra-high vacuum.
UI Unnumbered information.
UIAA See IUAI.
UIC Upper-airspace/information centre (ICAO).
UIF Unfavourable information file.
UIL User interface language.
UIP Upgrading instructor pilots.
UIR Upper-airspace flight-information region.
UIS Upper-airspace/information service, or system.
UIT 1 Union Internationale des Télécommunications.
2 UV imaging telescope.
UJT Unijunction transistor.
UK Training centre (USSR, R).
UKAATS UK Advanced Air Traffic System.
UKAB UK Airprox Board (CAA).
UKACC UK Air Cargo Club.
UKACCIS UK air command and control information
system.
UKAdge UK air-defence ground environment.
UKADR UK air-defence region.
UKAG UK Airports Group [organisations and
suppliers; office, Rugby CV21 1BU] (UK).
UKAPE The UK Association of Professional
Engineers [office, Bromley, Kent].
UKAS UK Accreditation Service.
UKATS UK Air Traffic Services, part of Nats.
UKcEB UK Council for Electronic Business.
UKF Unbemanntes Kampfflugzeug = UAV (G).
UKFSC UK Flight Safety Committee [office, Fairoaks
Airport, GU24 8HX] (UK).
UKIRCM UK IR countermeasures.
UKISC UK Industrial Space Committee [FEI + SBAC,
office, Wisbech PE13 1JZ] (UK).
UKLF UK land forces.
UKMF UK Mobile Force.
UKMSCS UK military satellite communications
system.
UKN Unknown.
UKOOA UK Offshore Operators’ Association.
UKRAOC UK Regional Air Operations Centre.
UKSCC UK Satellite-navigation Co-ordinating
Committee.
UKSEDS UK Students for the Exploration and
Development of Space (RAeS).
UKTI UK Trade and Investment; DSO adds Defence
and Security Organisation [1 April 2008] (UK).
UKWMO UK Warning and Monitoring Organization.
UL 1 Ultralight.
2 Unleaded.
ultimate strength
3 Uplink
ULA 1 Uncommitted logic array.
2 Ultra-light aircraft.
3 Fairbanks, AK, tracking station.
ULAA Ultra-Light Aircraft Association (Australia; in
UK became PFA in 1952).
Ulade Ultralight aeronautical diesel engine.
ULAIDS Universal locator airborne integrated data
system.
Ulana Unified local-area network architecture.
ULB Underwater locator beacon.
ULC Unit load container.
ULCE Unified life-cycle engineering.
ULCS Unit-level circuit switch.
ULD 1 Unit load device.
2 Underwater locating device.
ULDB Ultra-long-duration balloon.
ULD Carrier See Dolly.
ULEA Ultra-long-endurance aircraft.
ULEV Unmanned long-endurance vehicle.
ULH Ultra-long-haul., generally taken to mean 8,000+
n.m. (14,816 km).
ULL Ullage (NASA).
ULLA Ultra-low-level airdrop.
ullage Volume above liquid in a tank; occasionally
misused to mean last dregs of liquid itself remaining in
tank.
ullage engine Rocket motor fired in ullage manoeuvre.
ullage manoeuvre Applying axial thrust to spacelauncher
stage or other liquid propellant tank(s) that are
nearly empty in order to collect remaining propellants
around delivery pipe connection.
ullage motor See ullage engine.
ullage space See ullage.
ullage washing Injecting gaseous nitrogen from ground
supply before takeoff.
ULM Ultra-leger motorisé = ultralight aircraft (F).
MTOW (1 seat) 300 kg (661.4 lb), (2 seat) 450 kg (992 lb),
stall 35 kt (65 km/h).
ULMS 1 Undersea-launch (or long-range) missile
system.
2 Unit-level message switch.
ULN Ultra-low Nox.
ULP Upper-level protocol.
ULR Ultra-long-range; loosely = ULH.
ULS Unimproved landing strip.
ULSA Ultra-low-sidelobe antenna.
Ultem Fire-blocking furnishing materials based on PEI,
seen as replacement for Lexan (GE).
ultimate factor of safety Number by which limit (or
proof) load is multiplied to obtain ultimate load; purely
arbitrary factor of safety, usually varying from 1.5 to 2,
representing best humanly attainable compromise
between economic structure weight and aircraft that will
not break.
ultimate load Greatest load that any structural member
is required to carry without breaking; that at which it may
legally be on verge of breaking, and permamently
deformed. Usually, limit load × UFS.
ultimate strength Strength required to bear ultimate
loads, or product of greatest load considered possible in
service multiplied by UFS. Gust requirements, in which
structure oscillates, can be superimposed on maximum
static load to demand even greater design strength in
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