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).
Comparative analysis of different cooling system radiator tube configurations and their performance.
| Identifier | WestWitteringFiles\U\2January1930-September1930\ Scan256 | |
| Date | 24th August 1929 | |
| HS{Lord Ernest Hives - Chair}/RM.{William Robotham - Chief Engineer} FROM DA.{Bernard Day - Chassis Design} C to RY F [Handwritten] COOLING SYSTEMS. DA{Bernard Day - Chassis Design}2/M24.8.29 ORIGINAL [Stamp] N250 [Handwritten] N766 [Handwritten] With reference to HS{Lord Ernest Hives - Chair}/RM{William Robotham - Chief Engineer}2/MJ21829. we think there is still something mysterious about the choking up: (1) The gap seems to have always been 1 mm. (2) Though the length of the gaps has been reduced the number of gaps has been increased owing to the reduced dia. of the swelled up ends. Since the length of enlarged end is the same on all the tubes we have been able to examine, the following comparative figures obtain: TABLE 1 Area of one gap. | No. of gaps from width of matrix. | Total area sq. ins. --- | --- | --- V.{VIENNA} series. | .0394 X 4.25 = .1674 | 77 | 12.81 F.2.B. | .0394 X 3.75 = .1476 | 88 | 13.00 SS.{S. Smith} 7/6 tubes. | .0394 X 3.50 = .1379 | 87 | 12.00 SS.{S. Smith} 7/5½ " | .0591 X 3.5 = .207 | 87 | 18.00 [Handwritten notes next to Table 1] so that the UNSATISFACTORY F2B IS ACTUALLY LARGER THAN THE SATISFACTORY V.{VIENNA} .81 X 100 / 12.81 = 6.32% less than V.{VIENNA} series 5.19 / 12.81 = 40.5% more than V.{VIENNA} series So that though SS.{S. Smith} with 7/6 tubes has some 6½% less area than V.{VIENNA} series, with 7/5½ tubes the SS.{S. Smith}area is much more. Comparative hydraulic mean depths are: TABLE 2 Hydraulic mean depth. --- V.{VIENNA} series. | .01925 F.{Mr Friese} 2. B. | .01955 SS.{S. Smith} (7/6 tubes.) | .0195 SS.{S. Smith} (7/5½ tubes.) | .0291 [Handwritten note next to Table 2] Restriction Inversely proportional to radiator hydraulic mean depth. Cross section of channel ÷ perimeter touched by fluid from which it would appear that while there is no appreciable difference in the first 3 radiators, the advantage is with SS.{S. Smith} The reference in para. 1. of your memo. to the top tube space on SS.{S. Smith} being 25% less than on V.{VIENNA} series we cannot entirely understand. The reduction in length is .750, and .750 / 4.25 = 17.65%. If you refer to the rectangular hole made by the bottom of the top tank the difference in area is of the order of 29%, but this does not seem an important matter as the hydraulic resistance of this rectangle cannot be a serious factor in itself. As regards the bottom of the top tank overlapping the tubes more in SS.{S. Smith} than in previous radiators, there does not appear to be any necessity for this, and we suggest that the flange along the bottom of the tank should experimentally be made wide enough for the 7 mm. tubes only. The large tube through which the shutter control passes, which appears at the moment to be controlling the width of the flange, we think should not matter. We will discuss the question of a filter in the top tank with R.{Sir Henry Royce} and if he is agreed we will send you a scheme as soon as possible. We will also discuss with him the shape of the bottom outlet. DA.{Bernard Day - Chassis Design} [signature] | ||