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).
Graphs comparing under-bonnet air pressure for plain versus louvered bonnets at various road speeds and gears.
| Identifier | ExFiles\Box 131\1\ scan0025 | |
| Date | 16th September 1931 | |
| CHASSIS 19 EX. AIR PRESSURE UNDER BONNET (RECORDED BY U TUBES) STANDARD UNDERSHIELDS. RESULTS GIVEN ARE AVERAGE OF FOUR READINGS, TWO ON EACH SIDE OF ENGINE, HALF WAY BETWEEN BONNET SIDE HINGE AND BOTTOM OF SIDE PANEL, ONE AT FRONT END, ONE AT REAR OF ENGINE. TOP GEAR PLAIN BONNET: -----o LOUVERED BONNET: -----x PRESSURE UNDER BONNET (INCHES OF WATER) ROAD SPEED (M.P.H.) LBS/SQ IN. 3RD. GEAR PRESSURE UNDER BONNET (INCHES OF WATER) ROAD SPEED (M.P.H.) LBS/SQ IN. 2ND. GEAR PLAIN BONNET : -----o LOUVERED BONNET: -----x PRESSURE UNDER BONNET (INCHES OF WATER) ROAD SPEED (M.P.H.) LBS/SQ IN. RADIATOR USED WAS FITTED WITH 6x7.5MM MATRIX TUBES WITH 4 INDENTATIONS. | ||