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).
Composite piston design for aero work and the use of magnesium alloys for weight reduction.
| Identifier | ExFiles\Box 142\4\ scan0013 | |
| Date | 20th March 1928 | |
| - 2 - The weight of the small piston is 1 lb. 1 1/4 ozs. I am attaching photostat prints of the two types of piston. Piston for Aero work. The piston which Mr. Goodwin said the German Co. were most interested in for car work was a composite piston made up with a separate head and skirt, which were joined together by the non-expanding iron nickel alloy known as 'Inva'. The largest piston of this type they have made is 4" diameter. The skirt and the head are joined together by two strips of 'Inva', one on each side of the piston when looked at from the side of the engine, the gudgeon pin passing through the two pieces of metal through a clearance hole produced for this purpose. The head of the piston is produced in a soft magnesium alloy of high conductivity, the skirt is produced from a harder magnesium alloy, which however has a lower conductivity, and for this reason is not suitable for use in the head. The scheme from the description seems to be rather fanciful, but Mr. Goodwin assured me that a number of people in the States were using the piston in question, and that the patents were U.S.A. which had been bought by the Electron Co. in Germany. General Mr. Goodwin seemed to be very interested in impressing upon us the value of magnesium for crankcases and gearbox work with the object of reducing weight on the chassis. As to whether you are interested in having some castings produced in Electron for car work is a point I am not clear upon. The material is of course very much more difficult to handle, every precaution having to be taken in the Foundry, and whilst Mr. Goodwin stated that they would be willing to give us a licence for casting in our own Foundry and show us how to obtain the results, he pointed out that this would only take place when we were handling the material in large quantities. In regard to die castings in special magnesium alloys, these Mr. Goodwin emphatically stated were far from satisfactory, although many of them were being used for small engines. Here again he was very emphatic that he felt certain the results would not be anything like up to our standards of quietness. BY.{R.W. Bailey - Chief Engineer} | ||