From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Explanation of a diagram showing speed and braking measurements over sequential periods.
| Identifier | ExFiles\Box 113\2\ scan0171 | |
| Date | 11th November 1930 guessed | |
| -7- the drop H-J at the end of No. 19 measurement period. The height J-K corresponds to the average speed of the 19th M.P. Again in this case it cannot be determined exactly the actual point at which braking commenced, only ½ a second for this first measurement period of braking must therefore be counted. The point J corresponds to the position of the measuring mechanism at the end of the 19th M.P. This point is a little behind the inter-section of the vertical H-K and the prolongation of the horizontal corresponding to the average speed of the 19th M.P. The drop in speed from one measurement period to the other is not absolutely vertical, owing to the fact that during this time the diagram advances a certain amount. The vertical must, therefore, be drawn from the point of drop of the preceding period. This displacement is of no practical importance. At the end of the 19th M.P. at the point H, at the moment when the measuring mechanism relapses to zero, another organ commences the measurement of the 20th M.P. at the point K.{Mr Kilner} The height reached during this 20th M.P. is less than that of the 19th, owing to there being braking. In the present case, the mechanism attains the point L. At the end of this 20th M.P. the curve, maintained during the 19th M.P. at the corresponding height, falls to the height corresponding to the 20th M.P. i.e. to the point L. It remains at this height during the whole duration of the 21st M.P. i.e. for one second. This is repeated second by second, until stoppage occurs. It may now be that the average speed of the M.P. just before stoppage is, for example, 5 km/hr. whereas the speed at the end of this same period is zero. The stylus will record at the end of this M.P. 5 km/hr. As the diagram paper will no longer advance, since the vehicle has come to a stop, this speed is no longer represented by a horizontal, but by an invisible point on the vertical line. We may determine this point in the following manner (Fig. 5). At the end of the 24th M.P. at the point M, the curve falls to the height corresponding to the average speed of this M.P. say | ||