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 the performance of three different types of radiator cores for slow-speed cooling.
| Identifier | ExFiles\Box 24\5\ Scan338 | |
| Date | 24th September 1930 guessed | |
| TYPES OF RADIATOR CORE FOR SLOW SPEED COOLING 'C' .078 .250 ZIG ZAG RIBBON WITH INDIRECT COOLING 'B' .405 'A' TUBES .250 DIA EXPANDED TO HEXAGON ENDS Y-Axis: H.P. DIS. PER SQ. FT FRONTAL AREA. PER 100° DIFF. IN TEMP. X-Axis: AIR SPEED THROUGH MATRIX M.P.H. Graph data: DALBY 7 M.M. TUBES 4-0" LONG, 1 M/M GAP Table: WT EMPTY | WT FULL | SQ. FT SURFACE | FREE AIR AREA % | % DIRECT | DEPTH A | 11.0 | 15.6 | 33.8 | 61.6% | 93% | 4.0 B | 12.3 | 14.4 | 37.2 | 72.7% | 28.0% | 3.250 C | 14.5 | 18.9 | 51.5 | 64.2% | 54% | 4.0 | ||