Curtiss “Cruiser”.
Top Speed: n.a.
Engine: two Curtiss eight-cylinders
Wingspan: 75.8 feet
Weight: over 4,000 pounds
Specifications from “Practical Aviation,” by Charles Hayward, 1919
Designed for sporting rather than for military use, the design and equipment of the Curtiss “cruiser”, afford an indication of the trend that development undoubtedly will take once the war is over. It is a twin- motor flying boat of the pusher type with a speed range of 65-48 miles per hour and weighs over 2 tons fully loaded. The equipment includes a Sperry gyroscope, searchlight, marine running lights, lights at the top of each strut, and electric starters for the motors. Current for all these purposes is developed by two small fan-driven generators located on the inner end of the outrigger which supports the tail unit.
These generators produce 2 amperes at 22 volts when driven at 4000 r.p.m. and their driving propellers are located in the slip stream of the machine’s propellers so that they get the full benefit of the air current set up by the latter ¡ storage batteries having a capacity of 2 ampere hours are floate n the line to absorb any excess current as well as to operate the instrument lights and the trouble-hunting lamp when the engines are not running.
Planes
The machine has a span of 75 feet 10 inches oil the upper wing, the lower wings measuring but 48 feet. A modified R.A.F. No. 6 wing curve is employed set at a dihedral angle of degree and with an angle of incidence of 4 degrees. The chord is feet and the gap 7 feet 6 inches, the total supporting surface 853 square feet. Flat steel tubing is employed for the leading edge of the wings, the upper plane consisting of five sections. The wing beams are of I-section spruce, the compression are of solid pine, and the remaining ribs are of pine, birch, and spruce. Ailerons are used on the upper wings only and measure feet 3 inches long with a maximum width of 4 feet. Each has area of 46.8 square feet. To prevent side slipping, vertical fins placed above the outer pair of struts on each of the upper These fins, or keels, have an area of 12 1/2 square feet each. The lower planes are built in four sections, each of the outboard sections measuring 19 feet in length. The central sections consist of extensions projecting 3 feet from either side of the hull and are built rigid enough to walk on. They are covered with rubber matting and are designed to give access to the motors. The inter-plane struts are streamlined sections of heavy spruce, 4 1/2 by 1 1/2 inches, of the same thickness throughout, though the supporting struts for the motors are tapered from the ends toward the center.
Tail Unit
The stabilizing plane, the elevators, and the rudder re carried on an outrigger supported at its outer end by struts rising from the stern of the hull. The horizontal stabilizer measures 16 feet across its trailing edge and has a chord of 6 feet x inches, giving it an area of 63.9 square feet. It is of the non-lifting type, being in the neutral position when the machine is horizontal, and is placed at the center of propeller thrust. The elevators have an area of 49.8 square feet, while the tail fin has an area of 34.9 square feet. The rudder is of the unbalanced type, an area of 31.2 square feet, and has a height above the keel of 8 feet 9 inches.
Controls
While the hull has accommodation for five- people, two cockpits are fitted and they have dual Depcrdussin control, the control bridge being of the usual inverted U type and made of ash. The control wheels are 16 inches in diameter. One and one-quarter revolutions of the control wheel move the ailerons through an arc of GO degrees, one-half above and one-half below the upper wing line. The rudder has equal range of movement, but through the multiplying gear employed this is reduced to are of 40 degrees at the rudder controlling bar.
Power Plant
Two Curtiss eight-cylinder V type water-cooled 100-h.p. motors drive 8-feet 8-inch propellers in opposite directions. Both motors are provided with electric starters, tin1 pinions of which engage an I8-inch gear wheel just back of the propeller hub, though cranks are also fitted for hand star; The latter protrude through the radiators, and are mounted inches forward of the in struts on brackets attached to them. Each radiator weighs 70 pounds and 80 pounds of water are carried. The hull has an over-all length of 34 feet 3 inches with a maximum beam of 4 feet just at the leading edge of the planes. A 6-inch step is placed 14 feet 1 inch aft of the forward perpendicular, the center line of the forward main beam of the lower plane coming just 20 inches forward of the step. Ash framing and keel with sides of mahogany and cedar and a covering of canvas arc used in the construction of the hull. The cockpit is about 7 long and is divided into two sections. The forward section contains seats for the two pilots and the instrument board, while tin after section seats two passengers. About 4 feet farther aft another one-man cockpit for the accommodation of a mechanic. The wing floats are 7 feet long, I8 inches wide, and 19 inches- deep and are built up of ash frames internally braced by wire and covered with light veneer. Their displacement in water when completely immersed is 800 pounds.
Instrumentation. The instruments include air aneroid registering up to 12,000 feet, a compass attached to and synchronized with a drift indicator, an air-speed indicator, a gasoline-supply gage, oil gages, a banking indicator, an angle of incidence indicator, inclinometer. In addition, there is a chart board hinged, so as to be let down out of the way when desired, instead of duplicating the throttle control for governing the speed of the motors, this is placed amidships just between the two pilots.
Weight
The machine proper weighs 2240 pounds while the power plant adds an additional 1316 pounds; fuel and oil for flight of five hours represent a weight of 620 pounds; and the eight of the electrical equipment is but 70 pounds. Complete with seats, instruments, and accessories, the hull weighs 885 pounds, the net weight of the complete machine is 3556 pounds and it is capable of carrying a useful load of 1100 pounds. The loading per foot of lifting surface is approximately 5.5 pounds while loading per brake horsepower 21.6 pounds. The machine can climb 2000 feet in 10 minutes.