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).
Outlining modifications to improve the slow running speed of Kestrel Supercharged engines for float planes.
| Identifier | ExFiles\Box 179b\2\ img029 | |
| Date | 19th October 1932 | |
| ORIGINAL To R.{Sir Henry Royce} From Ha/Lov.{Mr Lovesey} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to Rg.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} EP.{G. Eric Platford - Chief Quality Engineer} c. to Lr.{Mr Ellor} Lp.{Mr Lappin} Ha/Lov.{Mr Lovesey}1/WJ.19.10.32 X1908 X3933 X4657 SLOW RUNNING - KESTREL SUPERCHARGED ENGINES. We have had considerable criticism of the slow running of the Kestrel engines from the Fleet Air Arm and have actually observed that the slow running has been too fast to permit the safe manoeuvring of float plane on the water in order to pick up the hoisting tackle. We shew up badly in this respect compared with the Napier and the air cooled engines, the latter which hold considerable favour in this branch of the service. The present slow running speed is 420 RPM. which is not objectionable on land planes but is too fast for float planes. If the speed is adjusted lower the engine is very liable to stop which greatly increases the danger of drifting into the side of the ship, also the metering over the idling range is upset. With the object of overcoming this defect we have carried out extensive tests on the full supercharged Kestrel in the Fairey lll F.{Mr Friese} at Tollerton and by means of comparatively simple modifications to the carburetter have effected considerable improvement. We can now give a slow running speed of 300 RPM. with no danger of stopping the engine and a very uniform mixture is obtained over the whole idling range. The modifications are as follows:- (1) The slow running sliders have the throttle edge discharge alo deleted and a plain discharge hole .125 dia. substituted. (2) The slow running air hole is drilled part of the way down with air discharge holes in the form of a simple diffuser. The lower part of the tube is plugged to reduce the fuel capacity of the well. (3) A simpler scheme of slow running jet which is of the "straight through" type and should be less liable to stoppage. A filter is also employed below this jet. It must not be imagined that the fitting of these parts allow greater latitude for the finish and final adjustment of the carburetter. It is absolutely essential for the obtaining of good slow running to have a hundred per cent job made of the throttle, discharge sliders, controls etc. | ||