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).
Letter from W. H. Colt Ltd. discussing observations on a bonnet device and a new self-adjusting fan being sent for testing.
| Identifier | ExFiles\Box 135\1\ scan0019 | |
| Date | 16th March 1932 | |
| W. H.{Arthur M. Hanbury - Head Complaints} COLT, LTD. [Header Left] BETHERSDEN NEAR ASHFORD - KENT - TELEPHONE BETHERSDEN 6 TELEGRAMS COLT BETHERSDEN KENT [Header Right] BUSH HOUSE ALDWYCH LONDON. W.C.2 LONDON DIRECTOR: I. J.{Mr Johnson W.M.} O'HEA, F.C.I.S. TELEPHONE AND TELEGRAMS TEMPLE BAR 5112 [Handwritten Top] γ 1509. WHC/KH/K [Handwritten] LID{A. J. Lidsey} March 16th, 1932. Messrs Rolls-Royce Ltd., Derby [Stamp] RECEIVED MAR 17 1932 Dear Sirs, For the attention of Mr. Lidsey. With regard to the bonnet device we are obliged for your letter enclosing blueprint giving details of your observations during tests. Your chart clearly reveals that the device does not clearly yield in practice what we have reason to anticipate from wind tunnel tests. There is obviously a very big neutral sphere around bonnet sides devoid of velocity, thus reducing suction through our device, the performance of which is entirely depending on area opening and pressure difference between bonnet interior and outside. This neutral zone is particularly pronounced in the case of your make where the radiator is sharp edged, whereas round edges would permit more flow passed bonnet sides with greater extraction through our device. Whilst this circumstance is disappointing the bonnet device will prove of some use as a pressure release when combined with our self-adjusting fan, and we venture to put forward that its appearance is also an improvement on that of the ordinary flip flap device. Our Self-Adjusting Fan. We are now ready to despatch this to you tomorrow. We have converted only the larger of the two fans kindly sent to us and we should be much obliged if you could fit this up for a test and favour us with your observations. The only means at our disposal for driving this fan was an electromotor of only 1/4 h.p. with which we obtained the following results. | ||