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).
Comparison of cost, weight, and convenience between orthodox and Rover type bonnets.
| Identifier | ExFiles\Box 119\4\ scan0117 | |
| Date | 21th September 1938 | |
| -2- (4) From a weight and cost point of view there is little to choose between the orthodox and Rover bonnets provided both are in steel and that the latter is made as simple and inexpensive as possible. A little consideration will show that the top plates, top hinge and side plates of each will cost approximately the same, while the cost of fitting the rest strip (Ferodo) and securing stiffener of the Rover type will be more than offset by the cost of the side hinges on the orthodox type. With regard to bonnet fasteners - the four fasteners which would be used on the orthodox bonnet (Wraith type) would cost 7/-d.{John DeLooze - Company Secretary}, while even if the six fasteners shown on the present B.50 Rover bonnet scheme were used their cost would be 13/-d.{John DeLooze - Company Secretary}, an increase of 6/-d.{John DeLooze - Company Secretary} - we do not propose, however, to use all the fasteners shown on the B.50 scheme. Just as many, if not more, stiffeners etc. will be required on the orthodox as on the Rover bonnet sides so that the only other extra cost of the Rover bonnet will be that of the supporting brackets off the dash and radiator which obviously will only be a minor cost item. In any case, in view of the fact that the economy effected by making the bonnet in steel is only possible by using the Rover type, a small cost increase with this type due to construction could be tolerated. The above facts also will indicate that there will not be much difference in weight between the two types - in point of fact, the orthodox bonnet on 8.B.V. weights 63 1/4 lbs. while the Rover type on 1.B.50 weights 60 1/2 lbs. (includes top plates, hinges, side plates and all fittings, fasteners etc., but not bonnet rest plates or angles and fittings). (5) From the owners' point of view the Rover bonnet is much more convenient than the orthodox type - it permits one to inspect water level, oil level, etc. without the effort of lifting the whole side plate and with much greater speed. On the occasions when the opening of the top plates only will not permit sufficient accessibility to the engine the extra trouble involved in removing the side plates will be of small moment. | ||