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shock spectrum
boundary layer; ie increase in thickness of shock (1) from
about 10 -3 mm by several orders of magnitude.
shock spectrum Plot of peak amplitude of response of
single-degree-of-freedom system to various single applied
shocks (3).
shock stall Gross breakdown of flow behind shockwave
on wing (esp. one of large t/c ratio or for any other reason
causing large airflow acceleration) at about critical Mach
number, causing symptoms of loss of lift and turbulent
wake resembling stall, but at normal AOA.
shock strut Main energy-absorbing member of landing
gear; may or may not be main structural member but
(unlike shock absorber) is always part of structure.
shock tube Wind tunnel for hypersonic studies in which
fluid at high pressures, usually involving rapid combustion
to increase energy, is released by rupturing
diaphragm and accelerates through evacuated working
section containing model. Many varieties, most having
stoichiometric gas mixture as driver and large-expansionratio
(over 200) supersonic nozzle upstream of working
section, giving M up to 30 and T around 18,000° K.
shockwave 1 Surface of discontinuity between freestream
fluid and that affected by body moving at relative
velocity greater than speed of sound in surrounding fluid.
As fluid accelerates round body, if it eventually reaches
local Mach 1 a weak shock forms perpendicular to flow,
called a normal shock. Pressure difference (p 1 -p 0 )/p 0 is
zero and flow downstream is subsonic. As M increases,
shock leans back, becoming an inclined shock, at angle
α = sin -1 1/M, or 1-M 2 , pressure ratio and velocity of
propagation V 0 increase according to M and angle of
deflection, a property of geometry of body; for 15° deflection
(ie wedge or cone of 15° semi-angle) at Mach 3 static
and (p 1 -p 0 )/p 0 and V 0 /a 0 = 2.1, ie * moves at twice speed of
sound.
2 Continuously propagated pressure pulse formed by
blast from explosion in air by air blast, underwater by
water blast and underground by earth blast (DoD,
NATO).
Shodop Short-range Doppler.
shoe Detachable interface between pylon or hardpoint
and store, often specific to latter.
Shols, SHOL Ship/helicopter operational limit[s].
shoot bolt Linear bolt type of panel latch.
shooter 1 Aircraft detailed to attack a target, as distinct
from one whose task is to mark or designate.
2 The catpult control officer.
shooting the breeze Engaging in casual shoptalk (US).
shoot up 1 To attack a surface target with gunfire.
2 To simulate this at an airshow.
shop head End of rivet upset when rivet is used.
shop visit Removal of item from aircraft for repair or
other attention in specially equipped workshop, usually of
customer.
shop-visit rate Frequency, measured on occasions per
unit of flight-time [eg, per 10 5 h] with which particular
item [eg, engine] is removed from aircraft for repair or
overhaul; often a global fleet average.
Shorad Short-range air-defense; S adds system (USA).
Shoran From short-range navigation, precision radio
navaid based on timing pulsed transmissions from two or
more fixed stations; in conjunction with suitable
computer used for blind bombing.
shore Strut supporting airship during manufacture.
shot-peening
shoreline Line drawn straight across all inlets less than
55.6 km (30 nm) wide (ICAO).
short-distance navaid One usable within 320 km/200
miles (NATO).
short field Limiting field or runway demanding special
takeoff procedure.
short final[s] 1 Last part of approach, usually defined as
that commencing at inner marker.
2 Radio call made from aircraft 2 n.m. (3,706 m) from
threshold, or on final approach from shortened circuit.
short-haul Several definitions, eg maximum-payload
range (knee of graph) 1,609 km (1,000 statute miles) or
less; see also short-range transport.
short hundredweight US unit of mass = 100 lb = 45.3592
kg.
short-life engine One designed for single flight or any
other purpose not requiring prolonged use, and normally
qualified for running time of 50 h.
short lift Use of STO to enable powered-lift aircraft to
carry enhanced payload.
short-lift rating Thrust rating permitted for [usually] 15 s
for VTO or VL.
short period In assessment of factors such as lateralcontrol
damping of fighters, usually means 1.5 s.
short-range attack missile ASM launched at range not
exposing launch aircraft to terminal defences (USAF).
short-range ballistic missile Up to about 600 nm (1,112
km, 691 miles) (DoD).
short-range clearance Authorizes IFR departure to
proceed to a fix short of destination pending further clearance.
short-range Doppler Trajectory measurement using
Dovap plus Elsse.
short-range transport Range at normal cruising conditions
not to exceed 1,200 nm (2,224 km, 1,382 miles).
short round 1 Round of ammunition deficient in length
(DoD ‘in which projectile has been seated too deeply’),
causing stoppage.
2 Ordnance delivered on friendly troops.
short stacks Briefest form of piston engine exhaust for
cowled engine.
short takeoff and landing, STOL Usually defined as able
to take off or land over 50 ft screen (note, not 35 ft) within
total distance of 1,500 ft (457 m).
short ton US ton of 2,000 lb, = 907.185 kg.
short trail Towing position for sleeve (presumably other
forms) of target in which target is immediately astern of
towing aircraft.
short wave 1 Not defined and rare in aerospace:
traditional radio meaning is decametric (10-100 m)
corresponding to 30-3 MHz; FAA meaning is frequencies
7.7–2.8 MHz; for IR means wavelength 1-2.5µ; scientific
is 0.4-1µ wavelengths.
2 In spectrometry, band 2.5-45 µ.
shot 1 Commercial lead * for shotguns, normally used
as cheap variable mass.
2 Tailored hardened steel balls of graded sizes.
3 Solid-projectile ammunition, eg for air-firing practice
or AP type.
4 Report indicating a gun has been fired (DoD).
5 Single flight of unguided ballistic rocket, eg probe.
shotgun wind Appearing to come from all points of the
compass.
shot-peening Bombarding metal surface with air-
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