R-value: An index of the ability of a substance or material to retard the flow of heat, higher numerical values correspond to higher insulating ability.
RA size: One of a series of sizes to which untrimmed paper is manufactured, for reels of paper, the standard sizes in millimeters are 430, 610, 860, and 1220, for sheets of paper, the sizes are RA0, 860 × 1220, RA1, 610 × 860, RA2, 430 × 610, RA sizes correspond t
rabbet plane: NULL
radar station: The place, position, or location from which, or at which, a radar set transmits or receives signals.
radar surveying: Surveying in which airborne radar is used to measure accurately the distance between two ground radio beacons positioned along a baseline, this eliminates the need for measuring distance along the baseline in inaccessible or extremely rough terrain.
radar telescope: A large radar antenna and associated equipment used for radar astronomy.
radar theodolite: A theodolite that uses radar to obtain azimuth, elevation, and slant range to a reflecting target, for surveying or other purposes.
radar threshold limit: For a given radar and specified target, the point in space relative to the focal point of the antenna at which initial detection criteria can be satisfied.
radar tracking: Tracking a moving object by means of radar.
radar tracking station: A radar facility which has the capability of tracking moving targets.
radar triangulation: A radar system of locating targets, usually aircraft, in which two or more separate radars are employed to measure range only, the target is located by automatic trigonometric solution of the triangle composed of a pair of radars and the target in which a
radar wind system: Apparatus in which radar techniques are used to determine the range, elevation, and azimuth of a balloon-borne target, and hence to compute upper-air wind data.
radarscope overlay: A transparent overlay placed on a radarscope for comparison and identification of radar returns.
radial acceleration: NULL
radial band pressure: The pressure which is exerted on the rotating band by the walls of the gun tube, and hence against the projectile wall at the band seat, as a result of the engraving of the band by the gun rifling.