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 into the causes of radiator tubes collapsing, suggesting internal water pressure is to blame and that round brass tubes are superior.
| Identifier | ExFiles\Box 181\M11\ img141 | |
| Date | 12th February 1919 | |
| To EH. from R.{Sir Henry Royce} Copy to Mr. D 12th February, 1919. R12/G12219. RECEIVED 15 FEB 1919 X.3456.RE 49 GB. RADIATOR COLLAPSING. This is not as serious as at first sight. The collapse of tubes is not caused by suction of the pump, and is not caused by mechanical stress of carrying the weight of the radiator. I think it also shews the value of round tubes. The collapse has been due to internal water pressure, i.e. pressure on the outside of the middle of the tubes, either through the water boiling (as suggested by Mr. Elliott) with insufficient vent, i.e. water in the overflow pipes which are probably small, and not our standard, or possibly the water pressure may be due to vibration and the inertia of the water. This is rather a far fetched suggestion of mine, but when the radiator is thrown about the water would tend to stay behind and give heavy fluid pressure in the corners. Assume some reasonable acceleration in feet per second, test or calculate what rise of pressure. Get Mr. Clark to calculate, and you can rig up a test. It shews that small round brass tubes are probably better than square or hexagon copper tubes, copper being more ductile, i.e. has very low yield point when annealed. If these tubes are pressed out of round, say with the fingers during manufacture, any fluid pressure on the outside will tend to make it worse, finishing with a sudden collapse. Generally, if pressure is steady as in boiling, it will collapse all at once. This is most likely the cause, because you have been testing carburation with different water temperatures. R.{Sir Henry Royce} | ||