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).
Analysis of car chassis dimensions and engine configurations, considering alternatives for future models.
| Identifier | WestWitteringFiles\Q\December1926-January1927\ 80 | |
| Date | 1st December 1926 guessed | |
| contd :- -2- As our alternative for U.S. conditions we have the 20 HP. which is a 'medium-length' car with a 'small' engine, and is about 5" too short from the dash to the rear axle for adequate body space. Apparently 90" from the tip of the pedals to the rear axle is about a practical figure to accommodate all ideas in coachwork. Any consideration of the eight-in-line, as far as I can see, would mean a still longer bonnet and therefore longer wheelbase, or a still more restricted body space. It appears to me therefore that, to meet future conditions in this country and wherever traffic is heavy, every effort should be made to shorten the distance from front wheels to the pedals, and if a greater number of cylinder is to be considered, the balanced-V-eight like the Cadillac is the only thing so far designed which enters into the field of possibilities. This could give us a dimension of about 40" from the front wheels to the dash, and we could get 95" body space with a 135" wheelbase. It has other advantages, namely :- Greatly reduced bearing loads. Theoretical balance equal to straight-eight. Actual possibilities of smoothness greater than straight-eight, because of more rigid construction. No slipper flywheel. No reaction dampers. Possibly no spring drive. Better distribution from a single carburetter. The engine weight being grouped more nearly over the axle would tend towards a greater amount of inertia of the complete car, and therefore better riding for a given spring deflection. (See my note to R.{Sir Henry Royce} of Nov. 10th. on inertia tests). We think that a basic defect of the long car is its inadequate moment of inertia. What this would amount to is a slightly enlarged version of the 20 HP. with nearly twice the available horsepower in about the same length of bonnet, and about 5" more body space from the dash to the rear axle. It appears to me that the major difficulty is to get overhead Phantom valve gear in a reasonable width of bonnet. Overhead tappet adjustment like the Phantom is contd :- | ||