GB758614A - Apparatus for the direct indication of the product of an instantaneous speed and another factor - Google Patents

Abstract

758,614. Speed product calculators. GENOUILLAC, J. DU V. DE. Oct. 1, 1954 [Oct. 2, 1953; March 12, 1954], No. 28391/54. Class 106 (3). In an apparatus for indicating the product of a speed v and a factor q which may be variable, a movable reference system is provided whose movement is an exponential function of 1 - with time and the speed vector is transferred q along a fixed axis of the reference system, the product qv being ascertained by the distance from the origin of the point where the speed of the movable reference marks is equal to v. As applied to fire control where the factor q is T the time of flight of the shell to the target an exponential spiral 1, Fig. 1, which is rotated 1 with an angular velocity of - so that the move- T ment of the points of intersection of the spiral with the axis RR<SP>1</SP> can be expressed as x = e<SP>-t/T</SP> or dx/dt = -x/T and an image M of the target is caused to move along the axis RR<SP>1</SP> with the velocity v so that where the spiral appears to move with the same velocity as the image x v = - or x = vT and the then distance x of M T from the origin is equal to the desired product, this being the point at which to fire the gun. In the embodiment in Fig. 3 the invention is utilized to ascertain the specific fuel consumption c of an engine where c = dE/dt. 1/Cα, E being the quantity of fuel, C the torque and a the engine revolution speed. The factor q in this embodiment is 1/Cα and is generated by a cylinder 5 rotated by a gear 6 from the engine 7 so that the cylinder rotates at a speed proportional to C.a. The cylinder 5 has an exponential helix 8 of the formula z = e# on its surface so that dz - = z.C.α. A second cylinder 9 has a simple dt helix 10 traced thereon for which z = # and this cylinder is rotated by a fuel meter 11 whereupon z = E and dE/dt = dz/dt. The two helices will have a common point along the axis RR<SP>1</SP> where they appear to have the same speed, at this point z.Cα dE/dt and hence the longitudinal co-ordinate at this point will be proportional to c the specific consumption. In Fig. 4 the instantaneous speed v is measured, the factor q being made equal to unity. A cylinder 12 bearing a simple helix 15 of formula z = # is rotated at a speed proportional to v so that dz/dt = d#/dt = v. A second transparent cylinder 16 outside the cylinder 12 is driven by clockwork 17 and bears an exponential helix 18 of dz formula z = e# whence 0 = t and - = z. At dt the point on the scale RR<SP>1</SP> where the speeds of the helices 15, 18 are equal, z = v.