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).
Explaining the use of a Nomogram for calculating engine performance metrics.
| Identifier | ExFiles\Box 77\5\ scan0126 | |
| Date | 18th May 1918 | |
| To R.{Sir Henry Royce} from EFC. c. to CJ. To E.{Mr Elliott - Chief Engineer} To EY. To EP.{G. Eric Platford - Chief Quality Engineer} To Da.{Bernard Day - Chassis Design} To EH. X.3290 - RE NOMOGRAMS. Herewith please receive blueprint of a Nomogram we have constructed connecting the working volume, revolutions per minute, brake mean pressure, and brake horse power, for a four stroke cycle internal combustion engine. The graphical relation between these four quantities is obtained as follows:- A straight line drawn from the working volume point to the revolution per minute point, intersects the reference line at a third point. A straight line drawn to the right through this third point on the reference line, intersects the brake horse power and the brake mean pressure scales at corresponding points, so that if either one of these two is known the other one may be determined by the ruling of this line. Further if it is desired to find the speed at which a given engine will give a certain Brake Horse Power at a certain brake mean pressure, a line may be drawn connecting the two points on the corresponding scales of B.H.P. and B.M.P. and produced to the left to meet the reference line. Another line may then be drawn from the working volume point through the point where this first line meets the reference line and on being produced will intersect the R.P.M. scale at the required R.P.M. figure. The points on the working volume scale corresponding to the Contd. | ||