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Aviation History
1938
1938 - 1325.PDF
MAY 12, 1938. FLIGHT. a A "FLAT" ENGINED TRANSPORT The Alcor Junior : Un- usual Motor Arrangement and Composite Construction In a side view the Alcor C-6-1 does not appear to be unusual, although the forward position of the two airscrews is apparent. The Alcor Junior Transport seats eight. THE latest Alcor C-6-1, designed by Alan H. Lockheed,is an entirely new model, although as far back asi93o-3i the same designer had produced a machine based on the Lockheed Vega with a substantially similar and unorthodox type of engine installation. In 1934 the first high-wing Alcor appeared and this, too, had the same "prone" twin-engined arrangement. The construction of the new Alcor Junior Transport, as it is termed, is composite. Laminated spruce, steel tubing and alloy sheet are each used where it can have a definite ad- vantage. The spruce is used for control surfaces and in the "V fi 1 ~ ex-- ii / /I \ outer wing sections, while chrome-molybdenum steel tubing isemployed at the points of heavy local stresses such as landing gear attachment, engine mounting and at the wing roots. Thewing, which is fully cantilever, has two spars and is covered with a three-ply skin except around the fuel tanks, where sheetDuralumin is at1 ached by screws as a protection and to facilitate inspection. Hydraulically operated trailing-edge flaps are provided andthe ailerons are of Frisc type with ball bearings. The under- carriage is, of course, retractable, and turns aft through a90 deg. arc into wheel wells in the underside of the wing. In the semi-monocoque fuselage the nose portion and pilot'scockpit are made up of steel tuning covered with alloy sheet, which is easily detachable. The main section is a two-plyshell of Alcor manufacture moulded under pressure, the longerons and formers being of spruce. The tail surfaces arefully cantilever and similar in construction to the control sur- faces. The whole of the machine is covered with lightweightfabric and lacquered to give an aerodynamically efficient finish. The cabin can be arranged to carry four or six passengers,and full dual control is provided for the crew of two. The unorthodox engine installation is designed to give mini-mum head resistance and to secure high efficiency on one engine in case of a motor failure. Two 250 h.p. superchargedMenasco C6S-4 inverted, in-line, air-cooled, six-cylinder engines are mounted on their sides, cylinder banks inboard. Cowlingsand air-cooling scoops are faired into the front structure of the fuselage as well as into the wing, top and bottom. The main engine mountings are secured to the front wingspar, and extensions of the steel tube cradles pass back to the rear spar. Cantilever torque arms restrain each engine atapproximately its mid-point. Constant-speed Hamilton Standard airscrews are used, withArens controls. The tip clearance between the two airscrews is only twelve inches and their thrust line, in reference to thecentre line of the machine, is toed out 4 deg. Behind the cabin are the toilet and baggage compartments.The radio equipment is also carried, entirely enclosed, in the rear section of the fuselage. The single-engine performance of the Alcor is said to be quiteexceptional, and the particular type of engine mounting makes it possible to fly the machine '' hands off " on one motor. Theperformance in these circumstances includes a ceiling of 12,oooft., climb of 300ft./min. and speed of 174 m.p.h. The track of the Alcor is wide for the machine (13ft. 2jin.)and the general ground handling is said to be very good. ALCOR C-6-1 TRANSPORT. (Two 250 h.p. Menasco C6S-4). Empty Weight ~ 4,141 !b. Gross Weight ^ 0,200 1b. Wing Area -•--• 318 sq. ft. Wing Loading — 19.5 lb./sq. ft Power Loading = 12.2 lb. sq. ft. Range = 675/835 miles. Max. sea level speed" 196 m.p.h. at 2,300 r.p.m., 240 h.p.( Max. speed at 5,500 ft. = 211 m.p.h. at 2,300 r.p.m., 250 h.p. Cruising speed at 5,500 ft. = 11)1 m.p.h. at 2,000 r.p.m., 187 h.p. Cruising Consumptions : fuel=- 37 gal./hr., oil= 1.25 qt./hr. Cruising speed at 10,000 ft. — 200 m.p.h. at 2,000 r.p.m., 187 h.p. Max. sea level climb = 1,350 ft./min. Ceiling = 20,000 ft.
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