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).
Instructions and test results for a modified slow running scheme, focusing on throttle adjustments and performance.
| Identifier | ExFiles\Box 179b\2\ img030 | |
| Date | 19th October 1932 | |
| -2- He/Lov.{Mr Lovesey}1/MW.19.10.32. Cont'd.{John DeLooze - Company Secretary} Considerable care must be taken to see that the throttles are a good fit in the carb. bore because at very low idling speeds the throttles are only open a few thousandths of an inch. The throttle operating rods must permit the throttles to be perfectly synchronised in the closed position and no slack must exist in the jaws of these controls. The throttles must not, although a perfect fit when closed, bind on the sides near the spindle as this gives a 'springy' action. The slow running sliders must be a good fit both sideways in the bore to prevent air leaking from one side to the other of the throttles and also bed down well on the sliding face. We have found on several production engines outside the Works that the throttles could not be completely shut - i.e. with the stops screwed back - due to the magneto contact breakers coming on to their stops. This must not be permitted and it must be possible to completely close the throttles. When slow running adjustments are made it is particularly important that the slow running sliders have both the same position relative to the throttle edge. A start should be made with both sliders in the full rich position and exactly the same number of turns made on both adjusting screws until the correct position is obtained. The same applies to the throttle stops which should be adjusted so that both throttle levers come on to the stops simultaneously. This guards against springing one throttle relative to the other if the pilot pulls the throttle lever hard back. We have carried out numerous taxying and flight trials on the lll F.{Mr Friese} fitted up with this modified slow running scheme. The engine runs particularly smoothly over the idling range and responds to the throttle immediately. When gliding either fast or slow, when the engine may be motored over from 1200 R.P.M. to 550 R.P.M. with the throttle right back, there is no banging of the exhaust which is nearly always evident with the standard scheme. Some tests were made in which the machine was glided at the lowest safety speed and when about to touch the ground the nose was pulled up and the throttle pushed open quickly to imitate the condition of a mis-judged approach on to the deck of a ship. In every case the engine responded instantly. Even with land machines it was found that appreciably shorter landings could be made with the engine running at the lower revs. | ||