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).
Radiator core specifications, steam pocket formation, and heat dissipation improvements.
| Identifier | ExFiles\Box 149a\3\ scan0185 | |
| Date | 21th September 1936 | |
| -2- Hs{Lord Ernest Hives - Chair}/Std.19/KW.21.9.36. With reference to the weight of our radiator core, we note that you have got the weight of the core down to as low a figure as 41 1/2 lbs., and Messrs. John Marston state that in their opinion the difference between your core and our own is due to the different thickness of strip employed. We shall test a matrix using the same thickness of strip as your core. We also rather suspect that our Mark VI core is not up to your 20 x 55 constant core in dissipation, and would like you to send us a matrix to attached drawing E.88288 in your 18 x 62 constant core if possible. Failing that, in your 20 x 55 constant core. We are forwarding an official order for same. We are going to try out the various suggestions which you have made and are particularly interested in your idea for using glass outlet pipes from the engine to observe steam formation. Thermo couple exploration of our cylinder head does indicate some steam pocket formation, and we are at present endeavouring to rectify this - a difficult matter without complete redesign of the engine, unfortunately. One of our minor troubles has been excessive water loss (unless a steam-tight radiator blow-off valve is fitted), and we note that you say this is often an effect of bad head design, resulting in formation of steam pockets. This confirms a suspicion of ours that these two features were interconnected, particularly as we were unable to reproduce the water loss on a rig with water heating by gas flame. With regard to increasing the depth of our core, we note that you advise two 2 1/2" cores: we should like you to make it clear whether you consider this combination to give greater heat dissipation than a 4" core, or whether it is suggested as a means for us to get production stock readily. Actually we have no difficulty in obtaining a 4" core from Messrs. John Marston. We are anxious to avoid using a deeper block than 3.300" if this is at all possible, in order to avoid weight increase and increase of under-bonnet temperature. Our main line of attack at the moment is to use a more effective fan, running at a higher speed. Tests have shown that we can gain considerably in this way. | ||