GB683710A - Improvements in or relating to radio navigation aids for aircraft - Google Patents

Abstract

683,710. Radio navigation. MARCONI'S WIRELESS TELEGRAPH CO. Ltd. Dec. 15, 1950 [March 15, 1950], No. 6548/50. Class 40 (vii). A radio aircraft landing aid comprises an installation providing a hyperbolic equi - phase contour pattern with foci on a substantially horizontal line at right angles to the desired approach path and providing also a second contour pattern with foci on a line which is slightly inclined to the vertical and is to one side of the approach line the intersection of one of the second contour surfaces with one of former defining the desired glide path in the desired app embodiment where the installation is arranged to assist landing on the runway R of an aerodrome X stations AA<SP>1</SP> and B are provided at the ends of a line which is at right angles to the desired glide path and bisected by it. These stations may radiate signals providing any form of hyperbolic path-defining system, but a C.W. system such as is described in Specification 683,687 or 683,688 is preferred. Hyperbolic equi-phase contours are provided by the radiations of these stations intersecting the ground plane as shown by the lines consisting of dashes and single dots, in particular the plane 2 containing the required glide path is defined and a crafts' relation to it may be shown on a left-right meter. An additional pair of aerials radiating different frequency signals defining a second hyperbolic contour system are situated at AA<SP>1</SP> one aerial being above the other and being nearer the plane 2. The hyperbolic contours of this pattern cut the plane 2 in such manner as shown by the dash and double dotted lines, the straight line intersection being below ground level. By adjusting the position of the upper aerial in a plane parallel to plane 2 it can be arranged that one of these contours defines a suitable asymptotic glide path 1 and an instrument on a craft using the landing path can be designed to indicate " too high " or " too low " in respect of the glide path. Preferably a third hyperbolic system is included, with stations B and MB roughly in the direction of the approach path, from the contours of which (shown with dashes and triple dots in the Figure) distance along the approach path can be determined. Certain of the aerials may be common to two or even all three of the hyperbolic systems. It is pointed out that the aid may be adjusted to bring an aircraft under the control of an autopilot down to the " critical height " and then, if the pilot does not take control to land, automatically fly the craft up and away again.