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).
Analysis of a braking diagram, summarizing speed, distance, time, and deceleration.
| Identifier | ExFiles\Box 113\2\ scan0172 | |
| Date | 11th November 1930 guessed | |
| -8- 9 km. per hour. As the speed at the end of this 24th M.P. is not yet zero, this speed is marked during the duration of the distance travelled in the 25th M.P. by a horizontal N-O.{Mr Oldham} At the point O, the speed curve falls suddenly to zero. However, as a certain distance has been traversed during the 25th M.P. (N-O), a certain average speed has been realised. This can be determined by dropping a vertical from the point M, and drawing from the point P thus obtained an oblique line parallel to C-D and K-L. These obliques are all parallel, for they are functions of the forward feed of the paper and of the speed - proportional values. The intersection Q of the oblique and of the vertical O-R gives the average speed of the last second's running, at the end of which stoppage took place. This average speed is, in the present case, 5 km. per hour. The effective running time during the last M.P. is not determinable, and as for the first second it will be fixed as half a second only. To sum up the braking diagram indicates - 1. - That braking has taken place from a speed of 79 km/hr to zero. 2. - That the course traversed during braking (K-R) is 50.5 metres + 11 metres (value of the table for the speed of 79 km/hr) since we have allowed ½ second for the 19th M.P. = total 61.5 metres. 3. - That the time necessary for the braking of the vehicle running at 79 km/hr. to stopping point has been 6 seconds on a course of 61.5 metres. This time corresponding to 7 measurement periods, the 19th and 25th (the first and the last) being only taken as half seconds. 4. - That the deceleration can be determined for each second by proceeding in the same manner as when determining the acceleration per second. The values are naturally, negative. The braking graph can be constructed in the same manner as indicated for the acceleration graph. This graph is represented on Fig. 5., on the right. | ||