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).
Bursting tests and safety recommendations for a Phantom III cast iron flywheel.
| Identifier | ExFiles\Box 129\4\ scan0192 | |
| Date | 9th April 1938 | |
| To EJJ. c. to Hs.{Lord Ernest Hives - Chair} c. to By.{R.W. Bailey - Chief Engineer} c. to W.Bell. 1110. Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler}1/JH.9.4.38. PHANTOM III. Testing Cast Iron Flywheel. At 4,700 r.p.m. the rim velocity is 307 ft.sec. this is about three times the speed recommended for ordinary cast iron flywheels. According to one published formula, even if we assume high tensile iron of 18 tons ultimate, the wheel should burst at about 5,520 r.p.m. and this makes no allowance for variation or cooling stresses in the casting. We therefore recommend that bursting tests be carried out by spinning a wheel at high speed. If we provide a maximum of 7,000 r.p.m. the stress would be 2.2. times that at 4,700 and we do not consider this an excessive margin of safety. Attached is a rough diagramatic sketch of the rig we have in mind, the wheel being mounted on a vertical shaft in a pit for safety. We suggest that an intermediate shaft between the bevel gearbox and the flywheel shaft be fitted with aluminium driving sleeves pinned on so that they would break away in the event of the flywheel shaft flying adrift and thereby protect the driving unit from damage also the bearing housings of the flywheel shaft might be made of aluminium (or mounted on a aluminium plate) so as to save the steel structure. Will EJJ. please prepare a scheme from which the cost can be estimated. Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler} | ||