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Aviation History
1927
1927 - 0430.PDF
JUNE 16, 1927 shown by the curve marked " Full Throttle Best Setting."Hence, by the use of the mixture control, at full throttle, with the engine turning 1,800 r.p.m., the fuel consumptioncan be varied between 0-555 and 0-495 lb./h.p./hr. without losing any revolutions. An engine fitted with a propellerturning 1,800 r.p.m. at full throttle will, when throttled to any given speed, develop the power shown on the propellerload curve. If the full throttle power is not 1,800 r.p.m., the propeller load curve will start from the point on the powercurve corresponding to the maximum revolutions per minute, and will be similar in form to the propeller load curve drawnfrom 1.800 r.p.m. The fuel consumption on the propeller load curve is givenby the three curves marked " Propeller Load." The upper curve shows the consumption obtained when the mixturecontrol is left in the full rich position. The middle curve indicates the fuel consumption when the mixture control isset to the leanest possible position with the engine still turning maximum revolutions per minute, and left in thisposition while running at part throttle. The lowest curve gives the lowest petrol consumption at which the engine willoperate smoothly. To obtain these lowest readings, the throttle must be set with the mixture control at full rich togive a speed of 30 r.p.m. above the desired speed. The mixture control should then be pulled back until the engine loses 30 r.p.m. The fuel reading will then correspond to thelowest of the propeller load fuel consumption curves. The maximum revolutions per minute on the fuel consump-tion curve must correspond with the full throttle revolutions per minute of the propeller load curve. From this point, thefuel consumption curves will be similar in form to the curves drawn from 1,800 r.p.m. To convert the specific fuel consumption into gallons perhour, multiply the specific consumption (in pounds per horse-power hour) by the horse-power which the engine isdeveloping, and divided by 6, the weight in pounds of one gallon of petrol. (This refers, of course, to American petroland American gallons. The American gallon is 0-83254 of our own.) Specification of J-5C and J-5CA Models Type: 9-cylinder, radial air cooled ; bore, 4-5 ins.; stroke, 5-5 ins.; Capacity, 788 cub. ins.; compression ratio, 5-2: 1. Guaranteed power at sea level, 200 b'.h.p. at 1,800 r.p.m. Weight, dry, 508 lbs. (average). Length overall, 34 ins. ; overall diameter, 45 ins. Distance from mounting flange to end of propeller hub, 27-^J ins. Guaranteed fuel consumption, not more than 0-60 lbs./h.p./hr. at rated power. Guaranteed oil consumption, not more than 0-025 lbs./h.p.'hr. at rated power. THE PRAGUE AERO SHOW Some of the Czechoslovak Exhibits (Continued from page 384.) LAST week we briefly described some of the V A via " machinesexhibited at the Prague Aero Show, and this week we conclude with particulars of the other " Avia " typesexhibited by the firm of Milos Bondy. Following this we give some notes and illustrations of the " Aero " exhibits,constructed by the Aero Aircraft Factory of Prague. The "Avia" Commercial and Military Machines For commercial work there is the B.H.25, which is a 5-8passenger cabin biplane that has been specially designed to meet the requirements for passenger transport in CentralEurope. It can be equipped with any make of engine of from 400 to 600 h.p., either of the broad arrow water-cooledtype or the radial air-cooled type, as the engine unit forms a separate unit, built up of steel tubes with removable cowling,so designed to accommodate either type. It is a single bay biplane of orthodox wood, plywood andfabric construction. The top plane is in three sections— two outer, carrying the petrol tanks, and a centre sectionmounted on the fuselage—while the lower plane is in two sections attached direct to the lower longerons of the fuselage.Ailerons are fitted to all four wings, and the tail plane is adjustable as to incidence from the pilot's cockpit. Allcontrol surfaces are of wood and fabric construction, and the cables are mainly outside, and are thus easily accessible. The fuselage is of wood construction with plywood covering,and without wire bracing. The pilot's cockpit is located in front of the wings, immediately behind the engine,from which it is separated by a fire-proof wall. On the pilot's right is a seat for a mechanic or wireless operator (orpassenger), while behind is a small sliding window communi- cating with the passengers' cabin. The latter is roomy andcomfortable, accommodating six persons, seated in rockinjr chairs at the walls of the cabin, where a good outlook isobtained through circular windows (sliding " Triplex "). The interior is upholstered, and entrance is gained by meansof a door at the rear (on the left), which is close to the ground when the machine is at rest.In the roof is a " Ccllon " skylight which can also by used as an emergency exit, while light luggage racks arealso provided. Behind the cabin is a lavatory and luggage compartment, extra luggage being stored below the pilot'scockpit. A sturdy undercarriage is provided, fitted with enclosedrubber disc shock-absorbers. The latter work in compression and provide for long travel and good recoil, so that themachine will not bounce when roughly landed. The tail skid is also strong, and consists of a steel tube carrying aninterchangeable shoe of mild steel, and a strong spiral spring. The B.H. 25 is very stable at every angle or speed, being THE PRAGUE AERO SHOW: The Aero A-ll two-seater reconnaissance biplane (240 h.p. constructed by Aero Tovarna Letadel, of Prague. 392 Walter),
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