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Aviation History
1921
1921 - 0831.PDF
DECEMBER 15, 1921 condition was excellent. The engine was then re-erected and a further power curve taken. Fig. I, Curve C, shows the power developed, the maximum being 462 at 1,840. These figures are no.t snatch readings, but the power that can be sustained. The engine was then run for two hours as follows :— 440 h.p. at 1,775 r.p.m. 450 h.p. at 1,840 r.p.m. " These figures show that the engine has an ample margin of power, and that the main components of the engine are not over-stressed, although the revolutions are excessive for this type of engine for long periods—the normal rating being 380 h.p. at 1,57.5 r.p.m. The Type Test also included half an hour's slow-running test at 393 r.p.m.—the engine accele- rating to normal revolutions within five seconds." " The author is of the opinion that the provision of proper test plant is a matter of the utmost importance, and has been sadly neglected in the past. Fig. 2 shows a test bed for multi-cylinder engines up to 600 b.h.p., and Fig. 3 a similar plant for testing single-cylinder units ur> to 65 b.h.p. Reference to Fig. 2 will show that the engine is mounted on ~ a bearer plate, and is spigoted thereto just as in the aeroplane • fuselage. This bearer plate is attached to a stand which is mounted on rollers, the torque reaction being taken by spring buffers. The engine is coupled by means of two universal joints and a cardan shaft to a Heenan and Froude water dynamometer. The tail-shaft of the dynamometer is coupled through a dog-clutch to a 100 h.p. variable-speed motor. This motor is used for ' running in ' and starting the engine." „ " A 65-in. fan located in a pit outside the test-house, and direct-driven by a 270 h.p. shunt-wound* motor, supplies air at an average velocity of 85 m.p.h. This air flow can be varied at will. A no-gall, tank supplies petrol to the engine through three flowmeters for measuring the fuel consumption. A 9-gall. electrically heated tank supplies oil, the tank being heated to 50° C. to represent flying conditions. Special apparatus is arranged for measuring the temperature of the cylinders and valves while the engine is running." " Fig. 3 shows the single-cylinder bed, which is a replica of the main stand in all details. Figs. 4 and 5 show front and back views of the Bristol ' Jupiter ' engine." " Fig. 6 shows a detailed view of the cylinder and head, and the patented valve-rocker mechanism. It will be noted that the valve-rocker mechanism is mounted on a bracket which is independent from the cylinder head. This rocker fulcrum bracket is anchored by an eye-bolt to the centre of the head, and by a tie rod to the crank-case of the engine. As the cylinder heats up and grows, this fulcrum bracket is automatically drawn down by the tie rod from the crank- case, and so allows the valve clearances to remain con- stant." " Fig. 7 shows the crankshaft, connecting rod and piston assembly complete. The rigid construction of the crank and connecting rod will be noted. Attached to the webs of the cranks will be seen two trailing spouts for taking away the surplus oil from the big-end bearing. These spouts rotate in two concentric slots in the sides of the crank-case-from which the oil drains away into the isolated sump. " Fig. 8 shows the back-cover assembly complete, readyto bolt to the rear end of the crank-case, and demonstrates what a compact unit this may be made. On this cover aremounted the two magnetos, two oil pumps, two strainers, oil relief valve, tachometer drive, and distributor for thegas starter." " Fig. 9 is a view of the rear end of the crank-case showingthe patented spiral induction system. This consists of a three-" start " spiral casting fitted to an annular chamber inthe back half of the crank-case. Each of the three " starts " in the spiral is fed by one carburettor, which in turn feedsthree cylinders. There is therefore in effect three separate insulated spiral-induction systems, fed by three separatecarburettors. This arrangement supplies an absolutely even mixture throughout the engine. Further, should one cylinderfail for any cause, the whole carburation system is not upset and the engine cut out, as has been the case on other typesof engines. Instead, with this triple spiral-induction system only the number of cylinders (viz., three) fed by the particularspiral are cut out, and these cylinders being equally disposed, the balance of the engine is not materially affected. Toprove out this scheme, a one-hour test has been run under Government supervision, with the petrol turned off from thecentre carburettor. The engine ran quite steadily the whole time and developed 193 b.h.p., and within five seconds ofturning on the petrol the engine picked up to full load." In conclusion Mr. Fedden said a few words about mountingradial air-cooled engines :—" In the past many radial air- cooled engines have never had a proper chance owing tobad mounting. The author is strongly of the opinion that . engine-designers are the right people to design the engine-mounting for all types of engines—no matter whether they be air-cooled or water-cooled—and that the sooner this factis established the better it will be for the development of aeronautics generally." " The mounting of air-cooled radials has been so verymuch abused in the past, and this type of engine offers such unique opportunities for unit mounting, that it is consideredthat all air-cooled radials should be supplied complete by the engine-makers with mounting and cowling, and actuallytested with these components. Fig. 10 shows the Bristol ' Jupiter' engine correctly mounted as a complete unit.The illustration is self-explanatory, and is, the author submits, worth careful investigation. This mounting eliminates firerisk, and enables a 380 h.p. engine to be changed in the field in comfortably under two hours—a matter of the greatestimportance both for civil and military work." " At the present time, 45 h.p. per cylinder is the limit whichhas been attained for air-cooled cylinders at suitable r.p.m. and to maintain really first-class reliability. It is, however,believed that this is by no means the limit for this type of cylinder, and that in the next few years it may be expectedthat satisfactory air-cooled radials up to 1,000 h.p. and weighing under 2 lbs./b.h.p. will be an established fact." Resignation of Sir C. F. Lambert, K.C.B. VICE-ADMIRAL SIR C. F. LAMBERT, K.C.B., having been placed on the retired list of the Navy, at his own request, as already announced, is also relinquishing his appointment of Director of Personnel at the Air Ministry, and his position as additional member of the Air Council. M. Michelin Retires OWING to the state of his health, M. Michelin has felt compelled to resign the Presidentship of the Aero Club of France. M. Michelin has been a valuable asset to aviation from the earliest days, and his resignation must prove a severe loss to the French Club. Germany and War 'Planes FROM Berlin the figures given for aircraft destroyed, etc., up to October 1 last are 127,471 aeroplanes and 20,364 aero engines destroyed and 629 aeroplanes and 3,632 aero engines surrendered. Gordon-Bennett Balloon Race IT has been decided—until such time as they may alter their views—by the Aero Club of Geneva that the 1922 Gordon-Bennett Balloon Race is to be held on September 2 and start from Geneva. Zurich in this connection proposes to organise an aviation meeting. R.A.F. Club THE R.A.F. Club will shortly be housed in its new club- house in Piccadilly, one time the home of the Lyceum Club, and next door to the Cavalry Club. Like the R.A.C., theR.A.F. Club has j.ts own swimming bath. A Ford Aeroplane FROM New York comes the announcement that Mr. Ford proposes to launch out into aeroplane-building—presumably for commercial purposes. As the names of Admiral Sims and Mr. Edison are coupled with the new departure, there may be possibilities in it. But turning out safe 'planes is hardly one to conduct on the same lines as the launching of " Tin Lizzies " by the 100,000, more or less, per day, *A Message from F. Warren MerriamWE have received from our old friend, Captain F. Warren Merriam, the allowing message, which we publish in the hopethat it may reach those concerned :— " To my numerous pupils and friends : As I am about topublish a book embracing the flying career of my pupils and self—from the early days of flying, and on—and which willat the same time record in it facts relating to the Great War, so far as the Air Services are concerned—I should deem it agreat and personal favour if any of you would be so kind as to forward to me (c/o The Royal Aero Club, 3, Clifford Street,W. 1) any anecdotes or incidents that you know of in connec- tion with the above. In fact, any information relating toflying and administration in the Services, that would help to make this volume a success as an educative power, inhumour and interest, would be welcome. " Wishing one and all the Compliments of the Season.Yours very sincerely, F. WARREN MERRIAM.'' 831
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