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stalled pressure
(variable-sweep at max. sweep) wings exhibit no * even at
AOA beyond 60°.
2 Sudden breakdown in fluid flow previously attached
to solid surface, caused by changed angle of either surface
or flow, violent pressure pulse in flow (esp. travelling
upstream) or other severe disturbance, eg flutter.
3 Point at which opposing linear force or torque overcomes
that of driving member (eg PFCU, hydraulic
motor, airbrake or tailplane actuator), causing a
commanded movement to be arrested.
stalled pressure Delivery pressure at which delivery from
variable-stroke fluid pump, centrifugal compressor or
certain other pumps falls to zero; also called reacted
pressure.
stall fence Fence whose purpose is primarily to improve
behaviour at stall.
stalling angle AOA at which flow suddenly separates
from upper surface; probably that at which C L is a
maximum
stalling flutter 1 Flutter in one or more degrees of
freedom near angle of stall (1).
2 In particular, flutter of any stalled aerofoil [eg,
compressor blade] drawing energy from surrounding
flow.
stalling speed Any speed at which stalling AOA is
reached, esp. that at 1 g when ** is at lowest value (when
depends on aircraft weight, aircraft configuration and air
density, among other variables). Usually assumptions
include SL ISA, gear/flaps down, power off.
stall-limited bank angle Maximum angle at which a coordinated
turn can be sustained at maximum power, φ =
cos -1 M/C Lmax S W ½ρV 2 .
stall line Boundary between acceptable operating conditions
for gas turbine and stall zone for any given altitude
as plotted on compressor map.
stall margin Difference, normally expressed as available
spread of rpm, between gas-turbine operating line (at any
altitude and for transient slam accelerations, etc) and stall
line.
stall out To stall as result of attempting too steep a climb
or for any other reason, esp. when chasing opponent, thus
leaving manoeuvre incomplete or failing to get into firing
position.
stall protection system Aeroplane flight-control
subsystem sensitive to AOA (sometimes sensed at points
on either side of centreline to cater for rapid-roll AOAs)
which at given value triggers positive action to prevent
stall; obvious example is stick-pusher, but stick-shaker is
sometimes considered for inclusion.
stall quality Pilot’s subjective opinion of behaviour of
aircraft (normally fixed-wing aerodyne) at stall, assessed
for all types of stall (eg accelerated) and configurations (eg
dirty).
stall recovery Urgent action to restore normal airflow
over the wings. The objective is to reduce angle of attack
as rapidly as possible, with minimum loss of height.
Astonishingly, different methods of Standard Stall
Recovery have been taught. Many authorities still insist
on: Stck – Power – Pedal – Rudder if required. Today’s
RAF teach: Power – Stick – forget rudder.
stall strip Transverse ridge or other projection added to
skin of aeroplane, usually in spanwise direction along
leading edge, to serve as stall-promoter, create warning
buffet and ensure stall (1) occurs first at that point.
standard atmosphere
stall tolerance Generally non-quantified quality of gasturbine
fan and/or compressor to accept distorted airflow
or other disturbance (eg gun gas, ingested jet gas, birds,
hail or pressure pulses moving upstream) without stalling.
stall turn Flight manoeuvre in which aircraft (aeroplane
or glider) is pulled up into very steep climb, usually with
engine cut well back, until on point of stall full rudder is
applied to cause rapid rotation in yaw, with wings rotating
in near-vertical plane; ends in dive and pullout on to
desired heading (generally on to reciprocal). In US
hammerhead stall (also see wingover).
stall warning Anything giving pilot warning of
impending stall, eg natural buffet, inbuilt ** system
sensing AOA and giving visible or aural warning, or stickshaker
with or without knocker.
stall warning and identification system SWIS, system
commanded by AOA vane (12) whose signals are analysed
for AOA and rate; because of natural lag or hysteresis in
system, trigger is fired progressively earlier as rate is
increased by building in a phase advance giving protection
at all rates.
stall zone Region beyond stall line of gas turbine at any
altitude where attempted pressure ratio is too great for
rpm and airflow.
stalo Stabilized local oscillator.
Staloc Self-tracking automatic lock-on circuit.
stamo Stabilized master oscillator.
Stamp 1 Small tactical aerial mobility platform
(USMC).
2 Single-tube auto multipoint.
3 Also written STAMP, Strike Air Management
Programme [RN] (UK).
4 Stabilized miniature payload (UAV).
STAN Sum total and nose gear.
Stanag, STANAG Standard NATO, or Standardization,
agreement. There are hundreds, e.g., *3838
repeats MIL-STD-1553B.
stand 1 Place for parking one aircraft, especially at
airport terminal.
2 Fixed or mobile mounting for item undergoing
inspection, test, maintenance or repair.
stand-alone Generalized term meaning equipment, eg
radar, is not integrated directly into existing system of
radars or other sensors, computers and com. network.
Increasingly being used for fixed-based weapon systems
and even vehicle-mounted (eg airborne) equipments.
Thus * ASW helicopter operates autonomously, without
needing senors or other platforms.
standard acceleration due to gravity See gravity.
standard aerodrome “An aerodrome suitable for the
operation of regular day and night services” [BS.1940].
Now arch.
standard air munitions package Conventional air/
ground munitions required for 30-day support of one
aircraft of specific type, air-transportable in three equal
increments.
standard atmosphere Model atmosphere defined in
terms of pressure, density and temperature for all heights,
assuming perfect gas, devoid of any form of water or
suspended matter; approximates to real atmosphere and
taken as reference for aircraft performance and all other
quantitative measures. First NACA 1925 (see model
atmosphere), later refined 12 times, current 1980 ICAO
Doc 7488. Physical constants; P 0 10,132.5 Pa; T 0
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