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otor force
of being dangerous, with vertical gusts of 30 m (100 ft)/s
(see rotor streaming).
rotor force Resultant imparted by lifting rotor, analysed
into lift and drag, or thrust (perpendicular to disc) and inplane
(H-) force.
rotor governing mode Control mode in which rotor (1)
speed is held constant.
rotor head Complete assembly of rotating components
at centre of lifting rotor of helicopter or autogyro,
including hub, blade attachments and pivot bearings, if
any, and complete control mechanism, as well as such
adjuncts as anti-icing, electrics and pressurization instrument
leads rotating with hub.
rotor hinge In a non-rigid [articulated] rotor, the drag
and flapping hinges.
rotor hub Primary structure connecting blades of helicopter
or autogyro rotor. Some authorities define hub to
mean same as head, which is unhelpful.
rotor incidence Angle between plane normal to axis of
rotation and relative wind (BSI).
rotor inlet temperature Assumed equal to SOT (gas
turbine).
rotor kite Towed engineless autogyro.
rotor mast Pylon carrying rotor in small rotorcraft.
rotorplane See rotorcraft.
rotor power cofficient Symbol C P , = P/ρA [Ω R] 3 .
rotor slap Noise, often almost explosive, caused by
interaction between each helicopter main rotor blade and
the vortex from its predecessor.
rotor streaming Shedding of turbulent rotors (3) downstream,
often near ground and very dangerous to aircraft.
rotor tip drive, tip jet Tip jet.
rotor torque That imparted to airframe by helicopter
rotor, esp. main lifting rotor of hub-driven type, which
has to be countered by tail rotor or use of two main rotors.
ROTR Rate of temperature rise.
Rotte Fighter aircraft in loose pair (G).
rough-air speed Recommended speed for flight in turbulence,
V RA (hence rough-air Mach, M RA ); lies between V A
and V C and usually near V B .
rough field Defined by standard categories of surface
profile, including post-attack damage repair: A, single
blister up to 1.5 in H (height) over aircraft-travel distance
of 80 ft; B, H up to 3 in; C/D, two 3 in blisters within 80 ft;
E, two up to 4.5 in; 2E, two up to 9 in.
roughness Criterion affecting surface finish: irregularities
that are closely spaced (see next entry).
roughness factor Rayleigh criterion ∆ h = λ/8 sin ψ where
λ wavelength and ψ angle of incidence.
roughness width cutoff Maximum width of surface
irregularities to be included in measure of surface height;
in Imperial measure usually 0.03 in, but occasionally
0.003, 0.010 or 0.10.
roulement 1 Rotation of aircraft through front-line
squadrons (RAF).
2 Short tours of duty, typically split into six four-month
cycles (UK Army).
rouleur Ground trainer with wing too small for flight
(F).
round 1 Single munition, missile or device to be loaded
on or in delivery platform (USAF).
2 Parachute with circular canopy [smokejumper term].
round-down Rear terminator of aircraft carrier flight
deck, usually normal to landing direction (term derives
row
from older ships where deck fell away over stern in largeradius
curve).
rounded trailing edge Aerofoil designed for flow attachment
by Coanda-effect blowing to give very high (10+) lift
coefficients.
roundel National marking for military aircraft in form
of concentric rings.
round-head rivet Usual rivet for thin sheet where
countersinking is not required; head OD larger than
button-head.
round-trip time For radar, see ranging time.
route 1 Defined path, consisting of one or more courses,
which aircraft traverses in horizontal plane over surface
of Earth (FAA).
2 Published route linking traffic points of air carrier
and used in traffic and rights negotiations.
3 Path followed by channel of AFTN network.
route flight 1 One from A to B.
2 Military mission, usually transport, over established
route.
route package Geographical division of enemy landmass
for purposes of air-strike targeting.
router Rhyming with doubter, machine tool having
high-speed cutter, usually rotating about vertical axis,
capable of being positioned anywhere over horizontal
work; cutter can be side or end-cutting and in large
machines may be NC.
router Pronounced rooter, seamlessly connects wireless
networks on land/sea/air cellular [Wi Fi] satellite systems.
route sector Route (1) between two traffic points.
route segment Route (1) between two way-points or
[ICAO] consecutive significant points.
route speed En route speed, usually synonymous with
block speed.
route stage Stage (4).
routine 1 Series of step-by-step EDP (1) instructions
forming part of program; hence portions of same are
subroutines.
2 Complete sequence of aerobatic manoeuvres planned
by competitor or airshow participant.
routing Itinerary followed by message in AFTN.
routing list That showing AFTN centre which outgoing
circuit to use for each addressee.
ROV Remotely operated vehicle.
Rover 1 Armed reconnaissance, usually against shipping
(RAF, WW2).
2 Remote operations, or operated, video enhanced
receiver [ground-to-air].
rover Self-propelled explorer of planetary or lunar
surface.
roving Traditional meaning was slightly twisted hank of
textile fibre; modern meaning in aerospace is continuous
fibre (eg carbon, graphite, boron, glass) for filament
winding, or continuous raw material for ECM chaff to be
cut to required response length in dispenser.
roving aerodynamic test system System for measuring
flow quality and other parameters at various points (eg
vane sets) in wind tunnel.
ROW 1 Rest of world.
2 Right of way.
row Group of cylinders of radial engine in one plane, all
driving one crankpin (strictly, not a row but planar array);
hence two-* engine has two planes one behind the other.
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