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).
Report discussing engine cooling, radiator airflow, and bonnet ventilation at various speeds and conditions.
Identifier | ExFiles\Box 24\4\ Scan194 | |
Date | 25th August 1924 | |
- 2 - BY17/H.{Arthur M. Hanbury - Head Complaints} 25.8.24. not under direct fan control normally will replace the covered area and no serious inconvenience is suffered so long as enough radiator area to meet fan area, and therefore fan requirements, is available. From the last paragraph on first page of PN{Mr Northey}2/DN. 22.8.24. it would appear that FN. has taken my demand for "air speed" to be synonymous with "fan speed" but I was particularly careful to avoid the term "fan speed" all through my report, as being an ambiguous term, and replaced it by one which is accurate; but more than that, I carefully pointed out that increased air speed does not necessarily mean increased fan speeds at all but :- a/- increased efficiency of the fan itself, b/- giving free vent from bonnet to the air handled by the fan, more especially the latter, precisely as urged by FN. So far I have dealt with hill-climbing conditions. I now propose to deal with criticism that my deductions are'all put"out of court" when the car is driven along the road. Whilst admittedly some change takes place at certain speeds, at high speeds the conditions are not materially altered owing to the fact, repeatedly pointed out in my report, that there is a totally inadequate area provided to allow the air to escape from the bonnet, and therefore it would appear that the fan in adding to the pressure of air in bonnet set up by speed of car, practically prevents air flowing through radiator at any reasonable speed except where matrix is beneath the influence of the fan. This point is clearly indicated by the fact that at any speed above 50 MPH. the bonnet if unsecured will lift up under the internal pressure set up, and since pressure of this magnitude would oppose the pressure on the matrix face set up by car speed, obviously little, if any, air can be flowing through radiator except where fan controlled. The increased undershield clearances arranged on latest 40/50 do not prevent boiling even with shutters on bonnet open at full speed level road conditions if temperature is at or above 30oC. Contd. | ||