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).
Options to weaken the Phantom III chassis frame by either lightening it or reducing its cost.
| Identifier | ExFiles\Box 94\4\ scan0097 | |
| Date | 2nd November 1937 | |
| To Rm.{William Robotham - Chief Engineer} from D.Clapham. 2 327 2.11.37. Re. Phantom III. Chassis frame. The P.III. frame is considered to be unnecessarily strong. There are two ways in which it can be made weaker, (a) by lightening it or (b) by cheapening it. (a) The present frame is .114" thick, weighs 410 lbs. and has a torsional stiffness of 2080 lbs/ft/degree. The thickness could be reduced to .080" when the weight would be 305 lbs. and the torsional stiffness 1450 lbs.ft./degree. (b) The present cost is in the region of £50. By reverting to a channel section frame the cost could be reduced to about £20. and the weight would be about 350 lbs. The layout should be generally similar to Bentley III. except that we recommend that the channel sections of the cruciform should be the other way round and merge into the frame at either end, thus making a box section without the necessity for a gusset. The front end should be similar to Wraith. Suggested thickness .114" If the gearbox is still to be separately mounted scheme (a) is the more suitable but scheme (b) could be applied by moving the cruciform back to clear the gearbox and putting a good stiff crossmember between the engine and gearbox similar to the one amidships in the present P.III. The frame should be all welded instead of bolted. Rm{William Robotham - Chief Engineer}/D.Clapham. | ||