FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1920
1920 - 0765.PDF
JULY 15, 1920 the features are that the nickel chrome steel connecting rods are alternately forked at their big ends over their opposites on the same crank-pin ; thus bringing the cylinder masses into direct opposition : and that dry sump dualised lubrica- tion is employed, as from two pumps also driven from the nickel chrome-ste el crank-shaft by skew gearing. One of these pumps clears the oil from the base chamber and returns' it to the oil tank to be cooled, while the other is duplicated At the Aero Show : Valve gear detail of the unit of the 600 h.p. "Condor." It will be seen that the four valves are set in diagonally into four quarters of the domed combustion space, and have their four rockers v - actuated from two centralised cams and so geared internally that the high-velocity part force- feeds the oil drawn from the outside oil tank to the main bearings and big ends through the hollows in the webs and straights of the crank-shaft, while the low-velocity part lubricates the cam-shaft and all auxiliary bearings : the cylinder surfaces being lubricated by the oil-mist from the high-velocity circuit excess. The design of the crank- chamber itself has been specially devised to give greater strength and to allow the bearing caps to take a larger share of the side thrust under the usual working stresses. The same description applies to the 300 h.p. six-cylinder Sikh vertical engine : except that the single water-pump is mounted on the tail of the crank-shaft vertically, and that only two magnetos are fitted; to which the main drive is by spur-gearing from the cam-shaft end, and then by helical gearing, as before, from the driven spindle to the laminated blade couplings. This smaller engine is shown with direct drive to the propeller: but the 800-900 h.p. model has the same design of spur-gear reduction as in previous Sunbeam V- type models, but proportionately enlarged, and with a ratio of 1,400 r.p.m. to 920 r.p.m. on the propeller, in a clock- wise rotation. The total weight, empty, of the larger Sikh is 1,952 lbs., and that of the smaller a little over half that weight. The 500 h.p. Vee-type twelve-cylinder Siddeley •• Tiger," now exhibited for the first time on Stand 51, has apparently been largely re-designed from the original model; chiefly tcu follow known Continental air-ship engine practice as regards the mounting of units with open sides butted together with circular rubber unions to give a complete end-to-end flush around the combustion heads and valve-jacketing, as from two water-inlet branches from a centrifugal high-output pump mounted on the tail of the crank-shaft as illustrated. The bore and stroke are 160 mm. and 180 mm. respectively. The overhead valve gear is mounted in two blocks with access panels at the side, over each bank, which is set at a 6o° angle to its opposite. The valves, two inlets and two exhausts to each cylinder, are set in diagonally and bell- crank operated. A feature is that the cam-shafts are helically splined through the driven skew gear so as to move lengthwise through it, and also carries lever armed collars, likewise inter- nally threaded on a quick pitch, to give that end-long move- ment to engage ramp-extensions of the exhaust valve cams, a d relieve the compression for starting : the lever arms being interconnected. The induction is of the omnibus bar-type—: four bars feeding three cylinders each—and mounted inwards of the V : but is supplied by way of four long trunks curved over the top of the banks to suspend as many Claudel car- burettors outside the V, at crank-chamber level. The lubrication is of the dry sump type, quadrupled : the central supply pump, which is driven from the crank-shaft, drawing from an outside tank, and delivering to a triple distributing pump feeding three of the main bearings. There the oil enters the hollows of the crank-shaft, passes to the crank-pins, up the hollow connecting rods to the cylinder surfaces by way of the gudgeon pins, in the usual force-feed manner ; but an equal volume of it goes to the four other main bearings and thence escapes to the sump, where two return or scavenge pumps are submerged at either end. The usual drive-gear—a bevel train—is located at the rear end of the crank-shaft, both for the valve gear drive and for a transverse drive to the two twelve-point magnetos placed aft. In addition, a starting motor of Lucas make, mounted transversely, gives a bevel gear drive to an encased vertical spindle, which at its lower end has a bevel meshing up with the main drive bevel on the crank-shaft. One of these bevels is understood to contain a free-wheel clutch connection with its spindle, which overruns as soon as the start is effected. The mass-construction follows the usual Siddeley practice '•' « At the Aero Show : Three- quarter forward view of the most highly ela- borated Rolls-Royce model—the 12-cylinder 600 h.p. " Condor." The harmony of all detail and freedom from encum- brance despite the thorough fashion of the distribution of water supply and induction, are specially displayed. Other points are the four-way valve control from two cams in each case, and the harmonious modelling of the epieyclic propeller- shaft reducing - gear en- casement with the crank chamber
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
