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).
Experimental results for determining the moment of inertia and centre of gravity of the 28.G model.
| Identifier | ExFiles\Box 9\5\ 05-page246 | |
| Date | 10th July 1939 | |
| 646 + 600, Rm{William Robotham - Chief Engineer}/HFP.2/MH.{M. Huckerby}10.7.39. MOMENT OF INERTIA OF 28.G. Experiments were carried out to determine the Moment of Inertia of 28.G. and the height of the centre of gravity above the line of the wheels. The following figures were obtained - Weight on front wheels - 2182 lbs. Weight on rear wheels - 2254 lbs. Total weight - 4436 lbs. Wheel base - 136" This gives a Centre of Gravity 66" from rear axle. The car was made to pivot about a point 4.5" below the centre line of the wheels and 45" in front of the rear axle. The front of the car was supported on a spring whose rate was 270 lbs/inch. and whose point of action was 98.3" from the point about which the car was made to pivot. The periodic time under these conditions was .782 secs. This gives a moment of inertia about this axis of 108,900 lb/ft2. The front of the car was placed on scales and weighed, the back was then raised through 20° 10' and a weight transference of 114 lbs. was obtained. This was repeated with the rear of the car on the scales and a weight transference of 126 lbs. was obtained for an angular movement of 20° 30'. The mean of these results gives the centre of gravity 9.9" above the centre line of the wheels. This gives the moment of inertia of 88,000 lb.ft2 about the centre of gravity. All these figures are indicated on the accompanying sketch with the following additional data - Inertia of Wheels 41.85 lb.ft.2 Weight of unsprung mass including wheels front - 270 total. rear - 430 " | ||