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).
Front engine support, engine vibration, engine roar, and battery ignition.
| Identifier | Morton\M1.4\ img014 | |
| Date | 1st November 1921 | |
| To BY.{R.W. Bailey - Chief Engineer} from R.{Sir Henry Royce} -2- R7/GS/11/21 Contd. (5) FRONT ENGINE SUPPORT. This shows the wisdom of not attempting to hold the frame by the engine, greater strength and rigidity would do harm. We must have more elasticity or uniformity of stress or real three point suspension by the use of a balancing beam inside the cross member. We are sending instructions for improved tubes, as simplicity and some contribution to the torsional rigidity is desired. We should cancel the brazing and make the tubes out of solid. This should improve the section of the material and its condition. If necessary, we must join the supporting tubes with a cross member, and carry it centrally round the steering shaft support. Mr. Hives might make a test on the existing "Goshawk" chassis with one supporting tube only. (6) ENGINE VIBRATION. The engine on this first "Goshawk II" does not now vibrate as badly as when seen at Thetford, possibly because of the lighter aluminium pistons, but I have asked Mr. Hives to run the engine by electro-motor of another engine, and add and remove piece by piece to detect if any parts are not in perfect running balance. Nothing should cause the engine to vibrate until the couple set up by the two sets of three cylinders bends the crankshaft. This ought not to be felt until more than 3000 r.p.m., but I thought some parts such as the flywheel, front or back clutch ring was out of running balance, which is very necessary should be perfect in an engine running normally above 2000 r.p.m. (7) ROAR ON "GOSHAWK" ENGINE. X4227 The so called roaring of "Goshawk II" has now disappeared by timing the valves later. The power curves and other things suggest that some improvement in power may be possible by altering the camshaft so that the exhaust opens later, and in closing overlaps the inlet, and permits the inlet to be closed earlier and so give more power at low speed, without altering the power curve much at high speed, i.e. reducing the angle between the cams, so as to permit making the exhaust later without making the inlet too late in closing. This experiment can be carried out on "Goshawk I" but this engine may not be quite like "Goshawk II" so we must finally get exactly the best timing of "GOSHAWK II" on "Goshawk II". X.3485 (8) BATTERY IGNITION. (See also item 12 later) One has not to handle "Goshawk II" long before one finds that it (like other engines of its size and class) requires the ignition timing to be exactly correct for the speed at which the engine is running (possibly the Bosch governor is moving the ignition the wrong way) and points out the wonderful advantage an engine derives from an automatic advanced battery ignition such as we are fitting, and I suggest that we make our automatic governor spring so that it does not start to advance the ignition until about 1000 crankshaft revs., then it advances it rather more quickly than the correct amount found experimentally. The exact reason for this was explained. it is based upon a less | ||