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).
Recommendation to revise the 'Standard of Cooling' by changing radiator matrix specifications for models B.III and B.50.
| Identifier | ExFiles\Box 112\1\ scan0040 | |
| Date | 27th September 1930 | |
| -2- We have considered the question of revising our "Standard of Cooling" and particularly in the light of experience with 15,000 miles tests in hot weather in France etc., and with a view to minimising weight and cost of radiator matrices. As a result we think that a system which gives an absolute track critical air temperature of 35°C (or 95°F) with a corresponding actual critical air temperature under hard driving road conditions of 40°C (or 104°F) and an idling critical air temperature of approx. 25°C. should be satisfactory in service. The only conditions under which it is likely to give trouble are extreme tropical ones, and the proportion of cars operating under these conditions is sufficiently small to make it worth while supplying a specially large matrix (increased depth) and fan, if necessary, to them. Accordingly, we recommend that on B.III we should use a 58 M.M. Mk.VI matrix in place of the present 65 M.M. one and reduce the height of matrix by .9". This will give us our 35°C absolute critical air temperature. B.50, owing to its taller radiator will then have a matrix identical with B.III but 1½" greater in height. The extra area so obtained will, we think, about counterbalance the reduction in air flow which may be caused by a more restricted grille on B.50. We have already arranged that the B.III bottom tank tools (which are combination tools with Wraith ones) shall be suitable for a 58 M.M. bottom tank if desired. The frontal areas of B.III and B.50 matrices will then be 383 sq.in. and 412 sq.in. respectively, while the depths will both be 58 M.M. The same tanks can then be used on both radiators. As the use of a steam valve is a matter on which we have not finally decided yet, the above sizes of matrix do not take into account the use of same. If a valve is used a further small reduction in matrix cost will be possible by omitting tinning of the air way strip of same. Rm{William Robotham - Chief Engineer}/Std. | ||