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).
Comparison of radiator and bonnet efficiencies, including weight, ventilation, and cost considerations.
| Identifier | Morton\M19\ img071 | |
| Date | 19th May 1931 | |
| - 2 - we cannot get the English manufacturers to produce hexagon tubes as cheaply as we can buy them in the States, but we have at least an alternative source of supply with which to threaten them. We anticipate that the small hexagon tube would in any case shew a saving over standard both in detail and building up because there are approx. 750 less tubes per radiator. WEIGHT. The small hexagon tube radiator complete with shutters and water weighs 23 lbs. less than the standard radiator and 17 lbs. less than the best square tube radiator. We attribute this to - (1) Smaller number of tubes. (2) Hexagon ends hold less solder than round ends. (3) Smaller water spaces. BONNET VENTILATION. We compared a bonnet having three of the new shutters/side, closed dimensions 10.9" X 4" with a standard louvred bonnet having 29 louvres/side. The total area for air escape of the louvres is 326.25 sq.in. and of the shutters open 189.66 sq.in. Shutters to N.Sch.3232 Louvres to E.79291. The results shew that the shuttered bonnet makes rather less than half the difference of the louvred bonnet at both high and low speeds. [Diagram with dimensions 2.2", 1.1", 2.9" and text 'SHUTTER OPEN DIMENSIONS'] SUMMARY. With the radiator efficiencies attained in these tests we consider that there need be no more over-heating complaints. We should recommend that, subject to a confirmatory test in France, shuttered bonnets should be abolished and that the standard should be plain bonnets, with louvres for tropical climates. In saying this we would point out that the small hexagon tube without bonnet ventilation is as efficient as our four dented tube (1931 standard) with a louvred bonnet. To this we have | ||