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).
Motoring tests analyzing engine frictional and pumping losses.
| Identifier | ExFiles\Box 54\4\ Scan050 | |
| Date | 25th September 1924 | |
| R.R. 493a (50a) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. Expl. No. REF Hs {Lord Ernest Hives - Chair} /Am/LG5.9.24. C O P Y. MOTORING TESTS. It was observed that at 500 r.p.m. the frictional and pumping losses of this engine amounted to 39 lbs/sq.in. M.E.P. An analysis was made of these losses by motoring the engine under the following conditions :- (a) As run at 500 r.p.m. scavenging 3 lbs/sq.in. (b) Same conditions scavenging air pipe 'H' removed. (c) All valve caps and plugs removed. (d) Rotary valve bodily removed. The water jacket temperature was maintained at 80°C., if the temperature of the jacket was reduced at all, the motoring losses at once increased, confirming that the piston friction is considerable. The test was repeated at 1000 r.p.m. when the losses were found to be 45.5 lbs/sq.in. M.E.P. The most noticeable feature of these figures is the amount of work required to draw in and expel the scavenging and working charge through the rotary valve. The scavenging, though only at 3 lbs/sq.in., absorbs almost 5 lbs/sq.in. M.E.P. While removing the valve caps only increases the motoring losses by 2 lbs/sq.in. M.E.P., further removing the rotary valve makes a difference of 5½ lbs. M.E.P. On examining the rotary valve to account for these losses, it was observed that all the ports are necessarily restricted owing to the dimensions of the valve. In particular, the contd :- | ||