envelope /env.l.υp/ noun 1. the set of limitations within which a techno-logical system, especially an aircraft, can perform safely and effectively .
The boundaries of flight envelopes vary between aircraft categories and per-formance groups but in each case, there is a speed which must not be exceeded which is called the Vne (never-exceed speed). 2. a cover . The atmosphere is the gaseous envelope surrounding the earth.
environment /.nva.r.nm.nt/ noun
1. nearby conditions or circumstances .
A body of air warmer than its environ-ment will rise. . a non-computer envi-ronment a computer-free working situ-ation 2. the natural world in which people, animals and plants live . People are interested in issues to do with the environment, such as global warming.
environmental /.nva.r.n
ment(.)l/ adjective referring to the immediate surroundings . environmen-tal conditions
environmental control system
/.nva.r.nment(.)l k.ntr.υl
s.st.m/ noun an air-conditioning sys-tem for the aircraft. Abbreviation ECS
environmental lapse rate
/.nva.r.nment(.)l lps re.t/ noun
the rate at which the temperature of the air falls as one rises above the earth .
Although there is an average ELR of 1.98°C per 1,000 feet, in practice the ELR varies considerably with space and time. Abbreviation ELR
epoxy-based primer /.p.ksi be.st pra.m./ noun a primer contain-ing epoxy resin, a substance which, with the addition of hardeners, becomes very strong and hard after a time at nor-mal temperatures
equal /ikw.l/ adjective having the same quantity, measure, or value as another . For every action, there is an equal and opposite reaction. . verb to be the same in value as . Two plus two equals four (2 + 2 = 4).
equalise /ikw.la.z/, equalize verb
to become the same in quantity, meas-ure or value . Fluid pressure and gas
pressure equalise at normal system pressure.
equate /.kwe.t/ verb to be the same as . In an electrical circuit, an increase in length equates to an increase in resistance.
equation /.kwe.(.)n/ noun a state-ment, usually in symbols, that two quantities or mathematical expressions are equal . X2 + Y2 = Z2. . The equa-tion Vg = P can be used to find the geos-trophic wind.
equator /.kwe.t./ noun the imagi-nary great circle around the Earth’s sur-face, equidistant from the poles and per-pendicular to the Earth’s axis of rotation which divides the Earth into the north-ern hemisphere and the southern hemi-sphere . Every point on the equator is equidistant from the poles.
equatorial /ekw.t.ri.l/ adjective
referring to the equator or to conditions that exist at the Earth’s equator . equa-torial heat . equatorial climate
equilibrium /ikw.l.bri.m/ noun a
state of physical balance . When an air-craft is in unaccelerated straight and level flight at a constant speed, the forces of lift, thrust, weight and drag are in equilibrium.
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