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helipad
complete Earth coverage, each pass having the same illumination
angle.
helipad Prepared area designated as take-off/landing
area for helicopters; need have no facilities other than
painted markings.
heliport Facility for operating, basing, housing and
maintaining helicopters; if civil, includes passenger facilities
and usually mail/cargo channels.
heliport acquisition beacon Marks landing pad[s] by
white flashing Morse H.
helistat Aerostat with added helicopter rotor(s).
helistop Helipad served by civil helicopter.
helitanker Large firefighting helicopter.
helitow Towing by helicopter, normally applies to
minesweeping.
helium Inert gaseous element, He, density 0.0001785
(0.1785 gl -1 ), 0.01114 lb/ft 3 , BPt 3.2°, 4.2° K (two
isotopes), helium 3 (three atomic nuclei) being important
as lunar-source material for fusion power.
helix angle 1 Of gear, measured between line tangent to
tooth helix at PCD and shaft axis.
2 Of propeller, see effective*.
3 Of wingtip in steady roll, P b [roll rate × span] 2V
[TAS].
HELJTO High-energy laser joint technology office.
Hellads High-energy liquid laser area-defense system
[airborne].
Hellas Helicopter laser [radar].
helmet Individual fairing over piston-engine cylinder,
hence helmeted cowl.
helmet sight Any of several systems which attempt to
interface between human aircrew looking at surface (or
other) target and aiming of armament system; usually
wearer’s head is in some way accurately aligned with rigid
flight helmet whose orientation is then automatically
monitored to give output signals fed to weapon-aiming
system.
Helmholtz resonator Hollow volume connecting with
outside via small orifice, single-frequency output.
Helmore light Powerful air-to-air searchlight [RAF, not
adopted, 1940].
Helms Helicopter malfunction system.
helo Helicopter (colloq.).
HELP, Help Hybrid electronic lightweight packaging.
Helps Helicopter protection and support.
Helraps Heliborne long-range active [acoustic-path]
sonar.
Helras Helicopter long-range sonar.
HELS, Hels High-energy-laser system [TF adds test
facility] (USA).
HELSTF High-energy-laser system test facility, at
WSMR (USA).
Heltads High-energy-laser tactical air-defense system
(USA).
Heltas Helicopter towed-array support.
Helweps High-energy laser weapon system (TRW/
USN).
HEMA Heavy maintenance.
Hem-bird Helicopter electromagnetic probe, suspended
magnetometer for measuring thickness and other
parameters of surface layers.
HEMC High-explosive medium-capacity.
Hemes Helicopter Hospital Emergency Medical
Evacuation Service (USAF, USA).
HETE
hemispherical engine Piston engine whose combustion
spaces at TDC are hemispherical.
hemispherical radar Mounted at nose and tail of aerial
platform to provide complete 360º (2 180º) azimuth
coverage.
hemispherical resonator gyro Senses changes in vibration
patterns in thin-wall glass shell when subject to acceleration.
hemispheric rule For IFR, and VFR between FL30-290,
altitude assignments are determined by magnetic bearing.
Hemloc Helicopter emitter/locator countermeasures.
Hemp Name of khaki-ochre colour [BS.4800-10B-21] of
large patrol and tanker aircraft (RAF).
Hems Helicopter emergency medical service.
HEMT High electron mobility transition.
HEND High-energy-neutron detector.
He-Ne Helium/neon laser.
henry, H SI unit of inductance, that of closed circuit in
which 1 V is generated when current varies at steady 1 A/s;
in other units H=kg.m 2 s -2 A -2 ; plural henrys.
HEOB Hostile electronic order of battle.
HEO Highly elliptical [Earth] orbit; P adds payload.
HEP High-explosive plastic.
HEPA High-efficiency particulate air, or arrester.
HEPL High-energy-pulse laser.
heptane Basic member of straight-chain (alkane) hydrocarbons
(see paraffin series) with seven carbon atoms and
thus 16 of hydrogen; zero-octane reference fuel.
HER 1 Harsh [or high] environment recorder.
2 Helicopter experimental radar.
Herald Helicopter equipment for radar and laser
detection.
Herbst manoeuvre Post-stall [70° AOA] 180° turn using
vectored thrust (X-31).
Hercules Large range of fibre-reinforced materials [US
company name].
Herid High-energy railgun integration demo, (USAF).
Hermes Helicopter energy/rotor management system;
automatically computes limiting payload.
Hermit Harsh-environment robust micromechanical
technology.
HERO, Hero Historical evaluation and research
organization.
herringbone gear Double-helical (see helical).
HERT Headquarters emergency relocation team.
Hertz, Hz SI unit of frequency, = cycles per second;
hence kHz, mHz, GHz etc.; in the US, increasingly hertz.
Hertz pressure Contact pressure between mating gear
teeth.
Hesh High-explosive squash-head.
hesitation roll Aerobatic rolling manoeuvre, normally
based on slow roll, in form of succession of quick aileron
applications between which rate of roll is suddenly
arrested; positions of arrest called points, and common **
are 4-point, 8-point or 16-point, 16 being difficult and
rare.
HESSI, Hessi High-energy solar spectroscopic imager.
HeSTOR Helicopter simulator for technology
operations and research.
HET 1 Helicopter environmental technique, to increase
safety and reduce disturbance by avoiding dwellings, and
certainly urban areas.
2 Hall-effect thruster.
HETE High-energy transient Explorer.
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