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).
20-hour endurance test of an F.XI supercharged engine, detailing performance, consumption, and detonation.
| Identifier | ExFiles\Box 36\2\ scan 201 | |
| Date | 1st March 1929 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/VH. c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to HU. E.{Mr Elliott - Chief Engineer} c. to BY.{R.W. Bailey - Chief Engineer} 42934 Hs{Lord Ernest Hives - Chair}/VH2/LGS.3.29. X3996 RR.F.XI. FULL S/C. ENGINE. 20 hrs. endurance running at 1850 r.p.m. and boost of 16.5 lbs/sq.in. abs. with 6/1 compression ratio. Engine F.XI-3-25. Fuel 80/20 Aviation/Benzol (Shell). Sparking plugs Lodge A.40. B.HP. at gate and 1850 r.p.m. 453 HP. (uncorrected) Fuel consumption (average) .510 pts/B.HP/hr. Oil consumption (average) 3 pts/hr. GENERAL CONDITION AT END OF RUN - VERY GOOD. With 5.5/1 comp. ratio pistons it was found that the performance of machines fitted with our F.S. engines could be considerably reduced at high altitudes (at 10,500 ft., power reduced from 503 HP. to 467 B.HP.) In view of our decision to retain the 6/1 comp. ratio on the full s/c. engines, a 20 hrs. run was carried out at a boost of 16.5 lbs/sq.in. abs. and 1850 r.p.m. This is the maximum boost we allow for setting the gate throttle position in a machine. See attached curve for reduction of boost with increase in r.p.m. Detonations were audible at some distance from the engine (approx. 10 ft.) under these conditions. By changing over to 100% Benzol fuel, and not detonating, we gained 4 B.HP. - the loss due to detonation representing less than 1%. contd :- | ||