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).
Comparative table of radiator types and their boiling temperatures at specified speeds.
| Identifier | ExFiles\Box 16\2\ Scan013 | |
| Date | 21th April 1931 | |
| TYPE OF RADIATOR MATRIX. Figures given Ats. Temp. at which the car will eventually boil if driven for sufficiently long under conditions specified. 30 M.P.H. | 45 M.P.H. --- Small Hexagon Ended American Tube. Hexagon .305 across Flats Centre .255 Round No. of Dents 18. 36.5 | 37.5 --- Large Hexagon ended American Tube. No. of Dents. 20. Hexagon .360 across Flats. Centre .309 dia. round. 33.5 | 34. --- C.m.m. Parallel Square Tube E.81385. figures from previous tests. 30.25 | 34. --- Square Tube E.81389. 6.m.m. Square Centre. Ends expanded to 7 1/2 m.m horizontally only i.e. vertical waterways only. | --- Present Standard. 6/7 1/2 m.m. round E.79448 4 dents/Tube. X. 21.5 | X 24.5 X. these figures are lower than some we have previously attained. --- Tests on 19-EX. Conditions as in Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/KT. 21.4.31 All tests taken with bonnet having vertical louvres. These tests are very susceptible to the direction of the wind and are therefore not always exactly comparable from day to day. | ||