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supersonic diffuser
defences. Now it is seen as a possibility for Sonic Cruise
type aircraft to exceed Mach 1 in recovering from upsets.
supersonic diffuser Contracting duct (see supersonic flow).
supersonic flow Flow which relative to immersed body or
surrounding walls is supersonic. In contracting duct decelerates
and compresses; in expanding duct accelerates and
rarefies.
supersonic inlet Air inlet designed for supersonic flow
both past and through it for at least part of flight; ideally
has centrebody or side wedge to create attached oblique
shock and various forms of variable geometry and auxiliary
doors.
supersonic jet 1 Propulsive jet from rocket, ramjet or
afterburner whose velocity relative to source is supersonic.
2 Supersonic aeroplane (colloq.).
supersonic nozzle Propulsive or wind-tunnel nozzle
through which relative flow velocity is supersonic. Ideally
of con/di form with variable profile and area.
supersonic propeller Propeller whose blades are designed
to operate with supersonic relative velocity over major
portion of surface. Noise problem appears insoluble.
supersonic tunnel Wind tunnel capable of supersonic
speed in working section (either brief or sustained).
supersonic turbine Turbine of any kind designed to
operate with flow velocity relative to rotor blades supersonic
(rare).
superstall Progressive stall attainable by certain aeroplanes,
eg T-tail with rear-mounted engines, in which
(partly because at low speeds drag increases faster than lift
when pilot pulls nose up) decay of speed and increasing
AOA leads to stable condition in which aeroplane descends
in approximately constant attitude (not far removed from
level flight) but with decaying speed and AOA increasing
continuously so that after long period it approaches 90°.
Root cause is combination of nose-up pitching moment
plus immersion of horizontal tail in wing wake, destroying
effectiveness. If not recoverable, called locked-in stall.
superstandard propagation Propagation with superrefraction.
superstructure 1 Secondary structure built above main
fuselage or other part of aircraft (rare; eg not used for
AWACS radar aerial).
2 Secondary fairing structure to streamline box-like
truss.
supervised operator experience Total of 25 hours flown
with a type-rated pilot, required before a pilot can have
SOE restriction removed from logbook and fly VLJ solo
[intended FAA.JAA, 2005–] (Int.).
SUPP Supplemental.
supplemental carrier US air carrier operating under
supplemental certificate, normally authorizing services of
various kinds other than scheduled.
Supplemental Type Certificate, STC Authorizes alteration
to aircraft, engine or other item operating under
approved type certificate (US).
supplementary aerodrome One designated for use by
aircraft unable to reach its regular or alternate aerodrome
(BS, suggest arch.).
supply balloon Flexible container for storing gas at low
pressure ready for aerostats; normally too heavy to fly even
if free. Hence supply main, supply tube, links * with aerostat
needing supply of gas.
supply chain The complete network of subcontractors to
surface
a major company or programme, especially arranged hierarchically.
support 1 All services and material needed or provided to
assist operator after delivery (see * items).
2 Action taken to assist friendly unit in battle.
3 Part of force or unit held back at start of action as
reserve.
4 Underpinning of new programme by R&D effort to
ensure answers are available to technical problems.
supporting aircraft All active aircraft other than unit
aircraft (DoD).
supporting surfaces Those aerofoil surfaces whose chief
function is to provide lift for aerodyne; can be fixed or
rotating.
support items For support (1) typically publications,
training, simulator and instructional rigs, auxiliary ground
equipment, spare parts, testing, warranty provisions and
field modification kits.
support zone Designated surface area for airlanding or
other operations in direct support of battle (no longer used
DoD, NATO).
suppressant Active ingredient for suppressing an action,
normally fire, esp. one automatically released by sensitive
pressure sensors in fuel tanks or similar regions; passive
suppressing methods, eg reticulated foam, are not *.
suppressed 1 Installed so that item does not project
beyond skin of aircraft; thus * aerial is synonymous with
flush aerial.
2 Emitter, especially engine(s), designed or installed to
minimize emissions; for civil aircraft noise predominates,
for military aircraft IR radiation.
suppressive Intended to suppress hostile defensive fire by
offensive action, eg direct attack with weapons and offensive
ECM; hence * attack, * support, * weapons (eg
ARMs).
suppressor 1 Jet-engine nozzle either configured for
minimum noise or shielded by additional surrounding duct.
2 Various additions to electrical or electronic devices or
circuits to reduce unwanted leakages, emissions or other
phenomena, eg extra grids in thermionic valves (tubes) to
stop secondary emission and large series resistors in HT
circuits to eliminate sparking.
suppressor pulse Sent out to disable L-band [original
meaning, 0.39-1.55 GHz] avionics during transmitting
period of other equipment on similar wavelength, to
prevent interference or damage.
SUPPS Regional supplementary procedures.
Supra Support for the use of presently unserved airspace
(Euret).
supra-aural Fitting over the ear.
Supral Superplastic aluminium alloy marketed for
SPFDB applications (British Alcan).
suprathermal ion detector One of ALSEP experiments left
on Moon; measures energetic ions impacting suface to
determine solar-wind energies.
SUPT Specialized undergraduate pilot training.
SURE, Sure Sensor update and refurbishment effort
(USN).
surf Verb, see surfing.
surface 1 Aerofoil, esp. large, eg wing (not small rotating,
eg compressor blade).
2 Exterior of aircraft, eg * friction drag.
3 2-D layer corresponding to particular pressure altitude.
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