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).
Test results for Wraith calorstats under varying shutter tensions and temperatures.
| Identifier | ExFiles\Box 9\3\ 03-page081 | |
| Date | 31th January 1938 | |
| TESTS ON WRAITH CALORSTATS. (i) RIG TESTS. Wraith radiator rigged up so that water at varying temperatures could be passed through the top tank. Temperatures for shutters to commence opening, reach full open and be fully closed were noted as given below. All shutters adjusted to have some end play and be perfectly free in operation. Calorstat spring was shortened by two coils and calorstat guide was shortened by .200. Note - All temperatures measured at cylinder head outlet. Condition. | Temp. for commence open-ing. °C. | Temp. for full open. °C. | Temp. for full closed. °C. --- | --- | --- | --- Shutters set as standard. No initial tension. | 77.5 | 90 | 55 Shutters set with .100 initial tension. | 81.5 | 93.5 | 62 Shutters set with .200 initial tension. | 85.5 | 96 | 67 RM{William Robotham - Chief Engineer}/Std.9/MH.{M. Huckerby}31.1.38. | ||