See constellation.
Each year exactly divisible by 4 is a leap year, except century years (1800, 1900, etc.), which must be exactly divisible by 400 (2000, 2400, etc.) to be leap years. The calendar year is based on the tropical year. Also called civil year.
A unit of heat originally defined as the amount of heat required to raise the temperature of 1 gram of water through 1° C (the gram-calorie or small calorie).
Several calories are now in use: International Steam Table calorie = 4.1868 joules, mean calorie = 4.19002 joules, thermochemical calorie = 4.184 joules, 15° C calorie = 4.18580 joules, 20° C = 4.1890 joules. The kilogram calorie or kilocalorie is 1000 times as large as a calorie.
Calorimeters are used in some pyrheliometers.
See constellation.
See constellation.
The luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 * 1012 hertz and that has a radiant intensity in that direction of (1/683) watt per steradian (16th CGPM (1979), Resolution 3).
The previous is an excerpt from WWW version of the National Institute of Standards and Technology: Physics Laboratory's International System of Units (SI)
Also called candle.
See constellation.
See constellation.
See constellation.
Capabilities belong to people, organized forces, or things.
See constellation.
2. A small, sealed, pressurized cabin with an internal environment which will support life in a man or animal during extremely high altitude flight, space flight, or emergency escape. See ejection capsule.
The term spacecraft is preferred to capsule for any man-carrying vehicle.
3. A container carried on a rocket or spacecraft, as an instrument capsule holding instruments intended to be recovered after a flight.
2. Acquisition or absorption of an additional particle by an atomic nucleus.
This cycle, first suggested by Bethe in 1938, gets its name from the fact that carbon plays the role of a kind of catalyst in that it is both used by and produced by the reaction, but is not consumed itself. Four protons are, in net, converted into an alpha particle and two positrons (with accompanying neutrinos); and three gamma-ray emissions are emitted directly in addition to the two gamma emissions that ensue from annihilation of the positrons by ambient electrons. This cycle sets in at stellar interior temperatures of the order of 5 million degrees Kelvin.
An even simpler reaction, the proton-proton reaction, is also believed to occur within the sun and may be of equal or greater importance.
Standard punched cards are 7.375 x 3.250 x 0.007 inches, containing either 80 columns in each of which any of 12 positions may be punched or 90 columns in each of which any combination of 6 places may be punched.
2. Any card adapted for the storage of information.
3. A printed-circuit board, usually before other parts are mounted therein. See module, package.
An automatic card punch punches cards according to a stored program.
In a Carnot cycle, the net work done is the difference between the heat inputQ1at higher temperatureT1and the heat extractedQ2at the lower temperatureT2.
2. In modulation of a signal, a wave suitable for being modulated as a sine wave, a recurring series of pulses, or a direct current.
A wave generated at a point in the transmitting system and modulated by the signal.
The three planes intersect in three straight lines, called coordinate axes. The coordinate planes and coordinate axes intersect in a common point, called the origin. From any point P in space three straight lines may be drawn, each of which is parallel to one of the three coordinate planes. If A, B, C denote these points of intersection, the Cartesian coordinates of P are the distances PA, PB, and PC. If the coordinate axes are mutually perpendicular, the coordinate system is rectangular; otherwise, oblique.
The cascaded series usually serves to amplify the effect.
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A vacuum tube consisting essentially of an electron gun producing a concentrated electron beam (or cathode ray) which impinges on a phosphorescent coating on the back of a viewing face (or screen). The excitation of the phosphor produces light, the intensity of which is controlled by regulating the flow of electrons. Deflection of the beam is achieved either electromagnetically by currents in coils around the tube, or electrostatically by voltages on internal deflection plates.
A light so concentrated by means of refracting lenses or prisms is a dioptric light.
2. Short for celestial navigation.
The horizon, celestial equator, ecliptic, and galactic systems of celestial coordinates are based on the celestial horizon, celestial equator, ecliptic, and galactic equator, respectively, as the primary great circle. See coordinate, Table VI, for a comparison of the systems.
The expression usually refers to the upper branch, that half of the great circle from pole to pole which passes through the zenith; the other half being the lower branch. The celestial meridian coincides with the hour circle through the zenith and the vertical circle through the elevated pole.
Celestial navigation usually refers to the process as accomplished by a human operator. The same process accomplished automatically by a machine is usually termedcelestial guidanceor sometimes automatic celestial navigation.
The expression may also be applied to the data obtained by such measurement.
Instrument aboard SOHO which analyzes the constituents of the solar wind.
Same as centigrade temperature scale.
The Ninth General Conference on Weights and Measures (1948) replaced the designation degree centigrade by degree Celsius.
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A prefix meaning one-hundredth.
A temperature scale with the ice point at 0° and the boiling point of water at 100°. Now called Celsius temperature scale.
Conversion to the Fahrenheit temperature scale is according to the formula
One-hundredth of a meter; approximately 0.3937 U.S. inch, exactly 1/2.54 inch.
A system of units based on the centimeter as the
A unit of viscosity. See poise.
2. Usually capitalized. The place, facility, or activity from which this control is exercised; specifically, at Cape Canaveral or at Vandenberg AFB, the place, facility, or activity at which the whole action incident to a test launch and flight is coordinated and controlled, from the make-ready at the launch site and on the range, to the end of the rocket flight downrange.
For a few seconds during the actual launch, control of a missile is exercised from the blockhouse, but it almost immediately reverts to Central Control for guidance and tracking, with two men in essential control. One of these is the supervisor of range operations, the other is the range safety officer.
Gravitation is considered as a central force in celestial mechanics.
2R,
where is the angular
speed of rotation; and R is the radius of curvature of the path. This
magnitude may also be written as V2/R, in terms of the linear
speed V. This force (per unit mass) is equal and opposite to the centripetal
acceleration. Also called centrifugal acceleration. The centrifugal force on the earth and atmosphere due to rotation about the earth's axis is incorporated with the field of gravitation to form the field of gravity.
This phenomenon is analogous to the generation of a shock wave when an object is traveling faster than the sound velocity of the medium. A bow wave is set up which radiates energy into the medium and slows down the object.
The angle that the cone of luminescence makes with the direction of motion of the particle can be used to measure the velocity of the particle.
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Chadless punching is used where it is undesirable to mutilate information written or printed on the punched medium.
This recovery time provides the possibility of simultaneously interrogating and tracking the beacon by as many radars as required so long as they are phased, synchronized, or the sum total pulse recurrence frequency does not exceed the maximum pulse recurrence frequency characteristics of the beacon.
In the neutron-fission chain reaction, a neutron striking a fissionable atom causes a fission releasing neutrons which cause other fissions.
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The pressure of gases within the combustion chamber of a rocket engine.
The volume of the rocket combustion chamber including the convergent portion of the nozzle up to the throat.
2. In computer operations: (a) That portion of a storage medium which is accessible to a given reading station. See track. (b) A path of flow, usually including one or more operations.
Some of the basic assumptions used to develop the equation were that the ionizing radiation from the sun is essentially monochromatic, that the ionized constituent is distributed exponentially (with a constant scale height), and that there is an equilibrium condition between the creation of free electrons and their loss by recombination.
For example, a decimal digit (0 to 9), a letter (A to Z), or a symbol (comma, plus, minus, etc.).
The characteristics of an aircraft are (1) qualities such as stability, maneuverability, and strength; (2) features such as number, kind, or power of engines, and size, shape, or number of wings; and (3) capabilities such as range, speed, and payload.
The length of a straight cylindrical tube having the same volume as the chamber of a rocket engine would have if it had no converging section.
2. A linear algebraic equation determining the eigenvalues or free waves of a boundary value problem. See characteristic value problem.
Of a rocket engine, a descriptive parameter,
) A convenient reference length (usually constant) of a given configuration, such as overall length of an aircraft, the maximum diameter or radius of a body of revolution, a chord or span of a lifting surface, etc.
An important example of a physical problem which leads to a characteristic value problem is the determination of the modes and frequencies of a vibrating system. In this case the dependent variable of the differential equation represents the displacements of the system and the parameter represents the frequencies of vibration.
The use of these lines or surfaces may facilitate the solution of the equations and is known as the method of characteristics. The method has been particularly successful, for example, in the problem of finite-amplitude expansion and shock waves.
This phenomenon, which is sometimes called electrical neutrality, is a result of the extremely large electric space charge fields that would arise if the densities were not equal. Although the positive and negative charge densities are seldom exactly equal, their percentage difference is so small as to be negligible. It is not difficult to maintain this condition in an active plasma since ionization or recombination always produces or destroys an ion pair together.
2. A familiarization flight in an aircraft, or a flight in which a pilot or other aircrew member or members are tested or examined for proficiency.
2. The sequence of steps taken to familiarize a person with the operation of an airplane or other piece of equipment.
In sense 1, a checkout is usually taken at a transition point between one phase of action and another. To shorten the time of checkout, automation is frequently employed.
Chemical changes, according to the nature of the materials entering into the change, may be induced by heat (thermochemical), light (photochemical), and electric (electrochemical) energies.
2. A fuel that uses special chemicals, such as the fuel once projected for the afterburner of the B-70.
This entire region is the seat of a number of important photochemical reactions involving atomic oxygen O, molecular oxygen O2, ozone O3, hydroxyl OH, nitrogen N2, sodium Na, and other constituents to a lesser degree.
The formula for chi square (x2) depends upon intended use, but is often expressible as a sum of terms of the type (f - h)2 / h where f is an observed frequency and h is its hypothetical value.
2. (symbol c). In aeronautics, a straight line intersecting or touching an airfoil profile at two points; specifically, that part of such a line between two points of intersection.
This line is usually a datum line joining the leading and trailing edges of an airfoil, joining the ends of the mean line of an airfoil profile, from which the ordinates and angles of the airfoil are measured. As such a datum line, it is sometimes called the geometric chord, to distinguish it from a chord established on the basis of any other considerations.
3. = chord length.
In sense 3, points or stations along a chord are designated in percentages or fractions of the chord or chord length from the leading edge, as, a point at 25 percent, or one-quarter, chord.
For many airfoils, the chord is established intersecting the airfoil profile at its extremities, and the chord length is equal to the length of the chord between the points of intersection; for airfoils where the chord is established by a point or points of tangency or intersection not at the extremities, however, the chord length is considered to extend beyond either or both points, as necessary, to equal the maximum length of the profile. See chord, senses 2 and 3.
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A measure of the accuracy with which a rocket or missile can be guided; the radius of the circle at a specific distance in which 50 percent of the reliable shots land. Also called circular error probable, circle of probable error.
Circular area = 1.2733 * true area.
True area = 0.785398 * circular area.
In rocketry, the diameter of a circle within which 75 percent of the events under study occur. CD = 3.330
where
= standard deviation. Circular dispersion is most often used as a measure of error of the accuracy with which rockets reach their intended target.
).
One circular mil = 7.85 x 10-7 square inch.
A circularly polarized wave is equivalent to two super-posed plane polarized waves of sinusoidal form in which the displacements have the same amplitude, lie in perpendicular planes, and are in quadrature.
This term is usually applied to transverse waves.
2. A precise measure of the average flow of fluid along a given closed curve. Mathematically, circulation is the line integral.
By Stokes theorem, the circulation about a plane curve is equal to the total vorticity of the fluid enclosed by the curve.
The given curve may be fixed in space or may be defined by moving fluid parcels.
