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).
Conclusions from tests on different radiator matrix types, grilles, shutters, and fans for a Bentley.
| Identifier | ExFiles\Box 87\1\ scan0086 | |
| Date | 14th September 1934 | |
| -2- Conclusions. (a) From consideration of sheet 1 it is seen that the Marston Mark V type of matrix (Harrison Vee bonded type) is much more efficient than the Marston Mark III type. Also the 58 m.m. thick Marston Mark V matrix is more than adequate for cooling the Bentley car, since it is approx. 12% more effective than present standard 84 m.m. Marston Mark III matrix (i.e., raises air temperature to boil by approx. 12%). (b) From sheet 2 it is seen that the standard shutters reduce the efficiency of the standard matrix by approximately 3%, while the radiator grille to Lec.3865 results in a corresponding reduction of approximately 12%. Further, by comparing results obtained with the grille before modification (see report HB{C. E. Harcombe}/Std.2/MA. 16.5.34) it is seen that the modification - which consisted of removing alternate horizontal bars from grille - has resulted in the loss of cooling efficiency falling from approx. 17% to approx. 12%. This, combined with the fact that the deflecting slats fitted on vertical ribs of grille to trap air and prevent it flowing off the grille, have reduced rather than improved the grille's cooling efficiency (see sheets 2 & 6), indicates that the grille acts as a normal restriction to fluid flow of the air through the matrix and does not deflect the air flow in any way. (c) Sheet 5 shows the variation of air intake temperature with variation of water temperature during warming up period, with shutters fully closed. (d) From the following results it is seen that the two fans tested result in drops in maximum speed of 1.8 and 2.8 M.P.H. This indicates that the fans are needing quite a large horsepower to drive them. In view of this some form of variable pitch fan should be worth developing :- (e) From sheet 6, it is seen that under conditions specified in test the bonnet temperature is approximately 8° lower with bypass system than with shutter system. | ||