Flight, March 1934

THE STINSON "MODEL A" TRANSPORT

   THERE are, in the U.S.A., several large towns which, although they lie on the main trunk air routes, are inadequately served by air. The reason for this is that the high speed aircraft working the long range services are not justified in stopping at these towns owing to the consequent reduction in speed over their route and the extra cost involved. On reviewing this situation the Stinson Aircraft Corporation decided to build a fast three-engined high performance passenger aircraft to sell at less than the large types and to operate at less cost per passenger mile.
   Design was begun in 1932 and the aircraft will be put into production early this spring. A new type of wing is used, but the fuselage follows standard practice, as it is of chrome-molybdenum tubing.
   As may be seen from the G.A. drawings, for which we are indebted to our contemporary Aero Digest, the wings, in plan form, resemble somewhat those of our "Monospar" S.T.4. The centre sections taper both in plan form and thickness towards the fuselage. The two outboard engines are mounted in a fashion recommended by the N.A.C.A. for maximum efficiency, but we are inclined to think that the nose engine must be comparatively inefficient owing to the large size of fuselage. It must be remembered, however, that the "Stinson Model A" is not the only triple-engined low-wing passenger aircraft being built in the U.S. to-day, for we call to mind the G.A.38, a drawing of which was published in FLIGHT for February 1, 1934. M. Wibault has demonstrated in his type 282 T12 that a triple-engined machine with comparatively large fuselage which is by no means of ideal streamline shape can be made extraordinarily efficient by the suppression of extraneous excrescences.
   In the new Stinson, close attention has been given to seating arrangements, vision, quietness, ventilation and heating. Eight hammock-type chairs are provided in the cabin, and four of these may face a common centre for luncheon or card games. A large baggage compartment in the rear of the cabin is loaded from the outside but is easily accessible from the inside. A lavatory is also located to the rear of the cabin. Additional mail is carried in the nacelles.
   A cockpit for two pilots (if two pilots are needed on short feeder line services) is located forward of the cabin where, it may be gathered from the drawings, vision is excellent. A large mirror for rear vision for use while taxying is mounted over the cockpit.
   The engines are three Lycoming nine-cylinder radials rated at 240 h.p. at 2,000 r.p.m., driving Smith controllable-pitch aircrews. These airscrews are operated in unison by a device which is practically automatic after take-off, if the pilot so desires. This simplifies synchronisation of engine revolutions. Sperry Horizon and Sperry Gyro are fitted as standard and such refinements as Goodrich "de-icer" equipment and heated pitot head are optional.

THE STINSON "MODEL A" TRANSPORT
Three 240-h.p. Lycoming

   Wing span 60 ft. (18,29 m).
   Length 36 ft. 10 in. (11,21 m).
   Height (including radio mast) 14 ft. 2 in. (4,57 m).
   Total power 720 h.p.
   Power available for cruising 540 h.p.
   Gross weight 8,750 lb.
   Pay load 1,860 lb. (3 968,67 kg).
   Wing loading 17-5 lb./sq.ft. (85,3 kg/m2).
   Power loading 12-2 lb./h.p. (5,53 kg/h.p.).
   Wing area 500 sq. ft. (46,45 m2).
   Ailerons 53-5 sq. ft. (4,97 m2).
   Flaps (at 60 deg.) 41-6 sq. ft. (3,87 ms).
   Horizontal tail surfaces 105 sq. ft. (9,75 m2).
   Vertical tail surfaces 35 sq. ft. (3,25 m2).
   Cruising speed at 5,000 ft. 150m.p.h. (241,4 km/hr.).
   Cruising speed at 1,000 ft. 146 m.p.h. (234,96 km/hr.).
   Climb at sea level (wheels up) 1,060 ft./min. (323 m/min.).
   Climb at sea level (wheels down) 935 ft./min. (294 m/min.).
   Range with 35 per cent. excess fuel 370 miles (595,5 km).