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).
Investigation into the causes and potential solutions for overheating in the interior of closed Phantom cars.
| Identifier | WestWitteringFiles\P\July1926-September1926\ Scan026 | |
| Date | 14th July 1926 | |
| R.R. 235A (100 T) (S.H. 159 11-8-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2800 TO HS.{Lord Ernest Hives - Chair} FROM DA{Bernard Day - Chassis Design}/EV.{Ivan Evernden - coachwork} c. to LHS.{Lord Herbert Scott} ORIGINAL DA{Bernard Day - Chassis Design}/EV{Ivan Evernden - coachwork}1/M14.7.26. X8230 X5908 X3003 X8109 RECEIVED OVERHEATING IN THE INTERIOR OF CARS. For some while now the C.S.C. has brought to our notice complaints of overheating in the rear compartments of closed Phantoms. EV.{Ivan Evernden - coachwork} discussed this matter with the C.S.C. when in London, and on examination of a car complained of it was evident that the temperature on the top of the floorboards over the rear exhaust box was such that one could not a hand on them. The coachbuilders have done something towards alleviating the trouble by ensuring that the floorboards are gastight, that the roof is covered with sorbo rubber and then carpet, and that ventilation holes are drilled vertically through the wooden runner communicating with the air space in the valance. Also we understand owners are instructed to drive with certain windows open, and certain closed, to avoid any vacuum effect. We wonder whether you have had any experience of this trouble on the closed cars you have tested. We suggest that this trouble may have come up on the Phantom for the following reasons - (1) Engine has increased power. (2) The radiating area of the rear silencer is larger. (3) The heat transmitted to the exhaust gases may be slightly greater. (4) The lagging has been left off the rear exhaust silencer. It is understood that this trouble of overheating occurs at speeds round about 40 MPH. There appear to us to be 2 causes contributing to the heating - (a) Hot air from the engine and convection currents from the silencer heating up the floorboards, and possibly passing through into the body when the boards have shrunk, this condition being assisted by the partial vacuum in the interior of the body. To overcome this it would appear to be necessary to lag the forward end of the silencer for at least half its length. (b) Heat by radiation from the top of the silencer may heat up the underside of the floorboards. This would be cured by lagging the top half of the silencer. We have suggested to the coachbuilders that a sheet metal tray about 1" below the floorboards, having its periphery turned up all round so as to imprison a quantity of still air, would be an effective means of preventing the heat of either convection or radiation (1) | ||