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).
Graph comparing poppet valve and Aspin engine port areas against timing angle in degrees.
| Identifier | ExFiles\Box 134\1\ scan0221 | |
| Date | 21th June 1940 | |
| DES. 8874 A.{Mr Adams} PORT AREA D' ASPIN PROPOSAL 14/11/40 FOR 5.4 ENGINE VERTICAL INCREASE OF PORT BY 25% ASPIN INLET & EXHAUST EXE 'DC' EXHAUST SCALED UP TO MERLIN THROAT AREA 4.500 D' THROAT AREA 3.310 D' MERLIN INLET EXE 'DC' INLET SCALED UP TO MERLIN MERLIN EXHAUST TIMING ANGLE - DEGREES. KEY. MERLIN INLET MERLIN EXHAUST ASPIN PROPOSAL 14/11/40 FOR 5.4 ENGINE VERTICAL INCREASE OF PORT BY 25% ASPIN INLET AND EXHAUST EXE 'DC' EXHAUST SCALED UP TO MERLIN EXE 'DC' INLET SCALED UP TO MERLIN. ALL AREAS SHOWN ABOVE HAVE BEEN INCREASED TO SUIT A 5.4 DIA. BORE ENGINE. COMPARISON OF POPPET VALVE AND ASPIN ENGINE PORT AREAS ROLLS-ROYCE LTD. PRINT ROOM 22 JUN 1940 DERBY DES. 8874 A.{Mr Adams} SHAW 21.6.40 | ||