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Aviation History
1949
1949 - 1765.PDF
FLIGHT, 20 October 1949 benefit (and complication) of the usual fairing doors. In our opinion, Mooney's brightest contribu- tion to light-aircraft imagineering is the unique longitudinal-trim control and co-ordination device—a safety feature not yet seen on more adult (and expensive) aircraft. In the first place, Mooney has scorned anything as simple as trim tabs on the trailing edge of the elevators and has reverted to an adjustable horizontal tail, but without the more usual screw-gear complications of the past. The whole tail-unit, complete with vertical surfaces, is pivoted about the top longerons of the fuselage and can be rocked in pitch through an arc of about 7 deg by a fore-and-aft movement at the bottom longerons. One of the incidental advantages of this arrangement (which, in itself, is not new) is the structural homogeneity of the complete tail unit as a component assembly for attach- ment to the fuselage. The really unique and useful part of the job lies in the automatic co-ordination of the wing- flap setting with the tail trim. As a matter of historical fact, again, even this basic idea is not new, for we dimly recall a similar tie-up on a Fairey seaplane (we think) a good quarter- century ago; however, Mooney has gone much further with his "Safe-Trim" scheme and, moreover, he seems to have made it work quite nicely on a previous design—the Culver Cadet. In the M-18L the pilot sets a single trim control against a scale reading for take-off, climb, cruising, or land- ing, by so doing, both the flaps and stabilizer are auto- matically aligned in their correct relationship for optimum performance at the desired flight condition. But this is not all; in order to take care of trim changes between power off and on, the designer has introduced a spring interconnection between the fiap-cum-tail trim sys- tem and the engine throttle, so that the latter can be opened or closed suddenly without drastic change of flight attitude. This obviates that nasty feel on the stick after pushing open the throttle in a baulked landing. (As a vin- tage World War I pilot we recall the powerful idiosyn- crasies of the infamous R.E.8 in that respect—one needed three hands for throttle, stick and trimming wheel!). And so we heartily commend the Mooney "Safe-Trim" device as an excellent safety feature for aircraft in the personal- aircraft category. Constructionally, the M-18L is a judicious mixture of metal, wood and fabric, the aim being a sturdy, lightweight and low-cost structure. Thus the wings, stabilizer and fin are single-spar, wood construction with a "D "-section plywood leading edge for torsional strength and ease of maintenance and repair. Ailerons, split flaps, elevators and rudder are welded steel tubing with fabric covering. The rear part of the fuselage, aft of the cockpit, is a plywood monocoque with fabric covering for weather protection ; the front half, comprising the engine mount and cockpit, is a welded steel-tube structure with aluminium-alloy sheet covering. Standard flight instruments include air-speed indicator, altimeter, and compass; engine instruments provided are tachometer, oil pressure, oil temperature, and fuel gauges. Optional equipment at extra cost includes cabin heater MOONEY M-I8L SPECIFICATION Power Plant Lycoming Model 0-I45-B2. »ir-cooled flat-four ; normal rating, 65 h.p. at 2,550 r.p.m. at sea-level. Dimensions Span, 26ft 11 in ; length, 17ft 7in ; height, 6ft 3m ; wing area, 95 sq ft ; aspect ratio, 7.6. „ ,. . . Weights and Loadings.—Gross weight, 780 Ib ; empty weight, 500 Ib: useful load, 280 Ib (includes pilot, baggage 40 Ib, fuel II U.S. gal and oil (I U.S. gal); wing loading, 8.2 Ib/sq ft ; power loading, 12 Ib/h.p. Performance Stalling speed (power off), 45 m.p.h. ; minimum speed (power on), 38 m.p.h.; optimum cruise speed (67 per cent power at. lO.UOOH) 125 m.p.h. ; economy cruising speed (50 per cent power at sea-level), 115 m.p.h. ; maximum speed, 138 m.p.h. ; initial rate of climb. l,090ft/mm : time °' <••'«"> co 10,000ft, 12 min ; service ceiling, 19.400ft; take-off run (over 50ft), 525ft; landing run (over 50ft), 860ft ; range (optimum cruise), 390 miles ; range (economy cruise), 440 miles ; fuel consumption, 35-40 m/gal. From Frisco to Perim. Interior of the 80-seater Boeing YC-97B military transport used by the Pacific Division of the U.S. Military Air Transport Service. Except for the triple seating it is similar in all other respects to the civil airline Stratocruiser. - - with summer cold-air attachments, airscrew-hub spinner, ash tray, carburettor air filter, extra seat cushion, electrical power supply, navigational and cockpit lighting, landing light, radio equipment, and stall-warning indicator. From a personal examination and flight demonstration, the Mooney M-18L appealed to us as a thoroughly practical job of personal-aircraft design and construction—with a number of ingenious, out-of-the-ordinary ideas thrown in for good measure. From a British petrol austerity stand- point, perhaps a 65-horse stable is a bit extravagant to keep up, but in America this is the usual trend, and it is obviously better to have some power in the throttle hand than in the bush or ditch because of a sticky take-off. In fact, "don't strain the horses" would be a good engineer- ing text for this study in light-plane imagineering. AERIAL CHARABANC CHIPS and trains have long catered for several classes *-^ ot passenger. Even the Marxian paradise of the U.S.S.R., where one might fairly expect the classless society, we understand that commissars and ballet dancers (an exciting combination) travel first-class; the military autocracy follow next in order of rank; and the proletariat hang on outside on the roof, running-board or buffer-beam. In England, until a few years ago, we still had first, second and third-class railway carriages ; while, to-day, in joint with the political times, we have abolished the middle- class and kept the upper and lower categories. When the twentieth-century renaissance sweeps over Britain some- time in the next decade, we may even get around to " upping " the thirds into seconds. This idea of second-class lower-fare travel for the masses is now beginning to catch on in the aeronautical firma- ment. Boeing have recently announced a proposal for a charabanc version of the Stratocruiser with accommoda- tion for 99 to 103 passengers in place of the standard, more spacious interior seating only 61 to 75. Second-class rail travel in the States is usually designated as a " coach-type '' fare and so the proposed addition to the Boeing family line will be known as the " Stratocoach." Triple chairs on the left side (in lieu of the standard double seats), smaller dressing rooms and elimination of the usual full-size rear galley characterize the 103-passenger interior. The 99- seater has the same general arrangement, but sacrifices four seats for a small midship galley if such extra service is desired. Considerable difference of opinion exists in the U.S.A. B 19
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