Patent GB-401339-A (GB)
Title: Speed indicating arrangement for moving bodies, principally aerial moving bodies
IPC: G01P3/52
Filed: 1932-05-05
Abstract: 401,339. Electrical speed-indicators. MICHAUD, F., 28, Rue Monge, Paris. May 5, 1932, No. 12981. Convention date, May 16, 1931. Addition to 380,084. [Class 106 (iii).] The arrangement described in the parent Specification is modified in that the E.M.F. produced in the conducting wire intersecting the vertical component of the earth's magnetic field is rendered operative by connecting the ends of the wire to the cathode filament and to one electrode of an electric vacuum discharge tube, with the insertion in the circuit of the wire of means causing the effect of this E.M.F. to appear in said circuit. The conducting wire 1 cutting the vertical component of the earth's field is connected at one end to the cathode filament 2 and at the other end through the battery 5 and resistance 6 to the plane anode 3 of the vacuum tube 4 distant several centimetres from the filament 2. The ends of the resistance 6 are connected to a continuous current amplifier 7 connected to a measuring apparatus 8. The arrangement is mounted on a support capable of being moved about a vertical axis. This enables measurements to be taken in two different azimuths and enables parasitic effects to be eliminated. The vacuum tube 4 alone may be movable, the support remaining fixed. In the modification shown in Fig. 2 two vacuum tubes 4, 4a and two resistances 6, 6a are used. A single source 9 for the two filaments is used to eliminate parasitic disturbances due to variations of the heating current. In the modification shown in Fig. 3 two anodes 3, 3a and a single filament 2 are combined in one vacuum tube. In the modifications shown in Figs. 4 and 5 gaps AB, CD are formed in the conductor cutting the earth's magnetic field and the vacuum tube 10 includes a grid 11 or 15 several centimetres distant from the filament 12 or 14. The potentials of the points C and D are equalised. By making the distance CD very large the E.M.F. generated is increased. The arrangement of Figs. 4 and 5 can be carried out with a triode of the ordinary or current type, i.e. with the normal distance between the filament and grid ; notably in Fig. 5 a triode having concentric electrodes is utilised. One arrangement for equalising the potentials of the points C and D is shown in Fig. 6 in which a rotatable insulating plate 17 has fixed on it conducting bodies 16 rubbing alternately on brushes 18 and 19 constituting the points C and D respectively. Another arrangement for equalising the potentials of the points C and D is shown in Fig. 7 and is similar to a Wimshurst machine arrangement. Two pairs of conductors 20, 21 and 20a, 21a are mounted respectively on superposed conical plates 22 and 23 rotating in opposite directions. The conductors rub against brushes 18, 18a constituting the point C and brushes 19, 19a constituting the point D. The conductors 20 and 20a are mounted in such a manner on their respective plates 22 and 23 that during the whole time that the conductor 20 is in contact with the brush 18, the conductor 20a is not in contact with the brush 18a. An equivalent arrangement is made for the conductors 21 and 21a and their respective brushes 19 and 19a. The potentials of the points C and D may be equalised by leading the electric charges located there, by means of a liquid spray projected mechanically, from one extremity to the other of the gap or by particles, ions or electrons travelling in a vacuum tube. Fig. 8 shows an arrangement for ascertaining the direction of travel. The lead-out wires of the system according to any of the arrangements described above are connected to two contacts 24 and 25 fixed on an insulating cylinder 26 mounted on the axis of rotation 27 of the system. Two diametrically opposed brushes 28 and 29 make connection with the contacts at each half turn and are so mounted that they can be turned about the axis 27 and can then be fixed. By utilising two systems rotated with equal and opposite angular speeds, the two contacts can be replaced by rings ensuring constant electrical connection as described and shown in the parent Specification. In order to ascertain the speed in magnitude and direction the components of the speed are measured according to two different orientations of the support. The speed and its direction can be deduced from these measurements by calculation or by a geometrical construction.