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).
Preliminary cooling tests for the 7.B.V. car, comparing matrix sizes and performance against the B.III and B.50 models.
| Identifier | ExFiles\Box 99\4\ scan0057 | |
| Date | 29th March 1938 | |
| To Hy.{Tom Haldenby - Plant Engineer} from Rm{William Robotham - Chief Engineer}/Std. c. Hs.{Lord Ernest Hives - Chair} c. Da.{Bernard Day - Chassis Design} c. Da{Bernard Day - Chassis Design}/Ev.{Ivan Evernden - coachwork} Rm{William Robotham - Chief Engineer}/Std.10/MH.{M. Huckerby}29.3.38. 440 also 1044 MATRIX SIZE - B.III AND B.50. We have carried out preliminary cooling tests on 7.B.V. in order to determine the adequacy or otherwise of the matrix fitted to same, and in order to get an idea of the size of matrix suitable for B.50. As the car is fully occupied with other work, we have not been able to run full speed and low speed full throttle tests at Brooklands as usual, but have run a full throttle full speed and idling test on a stretch of road between Nottingham and Doncaster on which we are in the habit of making such tests. As mentioned in our report on Wraith cooling, we have found that figures obtained in this way can be related to the absolute ones obtained by continuous running on Brooklands. As a general rule the critical air temperature determined by this road test by taking mean of runs in opposite directions (readings every mile over a 20 mile stretch each way) is approx. 5°C better than the absolute figure determined on the track. Further, if a car is adequately cooled under maximum speed full throttle conditions it is usually satisfactorily cooled at low speed full throttle conditions provided the fan is a reasonably effective one, (this can be checked from the idling figures). Accordingly, the results of our tests indicate that the B.III car is more than adequately cooled as it stands (since the critical air temperature under the road conditions mentioned is 46°C while that under the absolute track condition will, therefore, be 41°C) except under idling conditions. Idling tests indicate a critical air temperature of less than 13°C - at this air temperature 7.B.V idled for 33 minutes before boiling - in this respect it is a little better than the standard B.II car. Opening one bonnet side of 7.B.V made a big difference to the idling critical air temperature, raising it to approx. 23°C. It is obvious, therefore, that bonnet louvres or shutters would help this condition, and that the fan is effective. The latter would be expected since it is identical with Wraith fan already tested. | ||