Flight, March 7, 1914.
SOME AMERICAN FLYING BOATS.
The Christofferson Flying Boat.
THE flying boat built by Silas Christofferson, and equipped with one of the new Hall Scott 100 h.p. engines, normally carries three passengers at a speed of 60 m.p.h., but it would probably carry another passenger if extra seating accommodation had been provided.
In its arrangement of the engine, placed down in the hull instead of between the planes, the Christofferson flying boat resembles the Benoist, and, like that craft, despite the low centre of gravity, flies very well. The boat itself, which measures 24 ft. 6 in. in length, is built up of 1/2 in. by 1/2 in. spruce ribs, reinforced by 1/2 in. longitudinal spruce stringers. The planking consists for the bottom of 1/4 in. cedar. The sides, up to a height of 14 in. from the bottom, are covered with cedar 3/14 in. thick whilst from this point to the gunwales the sides are covered with cedar 1/8 in. thick. The wind shield in front of the pilot's seat is covered with 1/8 in. mahogany. The single seat in front is occupied by the pilot, whilst the two passengers sit side by side in another seat on a level with the leading edge of the wings. Immediately behind the passengers' seats is the engine, which, through a 18-24 chain gearing, drives the propeller mounted 14 ins. below the rear spar of the upper main plane. The propeller-shaft is of hollow chrome nickel steel, and has a diameter of 2 ins. at the propeller, tapering to 1 1/2 ins. at the front. The radiator is placed behind the engine, while the petrol and oil tanks, which have a capacity of 20 gallons, are placed in the bottom of the hull under the engine.
It will be noticed that the upper main plane has a very pronounced overhang, the weight of which is taken, when the machine is at rest, by cables passing over king posts or cabanes situated above the outer pair of plane struts. In order to provide clearance for the propeller, the trailing edges of the planes have been cut away for a short distance from the hull. The ailerons fitted to the upper plane have a greater chord than the remainder of the trailing part of the wing, in order, no doubt, to render them more efficient. Constructionally, the wings consist of two main spars of I section formed by a web having three laminations, 3/4 in. thick, mortised into the flanges. The ribs are built up in the usual way of webs, bored out for lightness, mortised into the flanges, and glued and nailed.
The leading edge is composed of two strips, of which the front one is sharply pointed, whilst the trailing edge is formed by a strip of spruce with an oval leaving edge. Mounted on the upturned rear portion of the boat is the fixed tail plane, to the trailing edge of which is hinged the divided elevator. The rudder, which is partly balanced, is hinged to an extension of the stern post of the hull. The bottom of the boat, which is of the flat non-stepped type, is protected by two runners of spruce hollowed out for lightness and canvas-covered and waterproofed. Mounted under the tips of the lower plane are two floats cylindrical in front and flattened out at the rear.
The dimensions of the Christofferson flying boat, two of which it is stated have been ordered by the Norwegian explorer Amundsen, who intends to utilise them on his next expedition, are :-
Span of upper plane 49 ft. Gap 5 ft. 5 in.
,, lower plane 33 ft. 6 in. Weight 1,200 lbs.
Length over all 28 ft. Speed with 100 h.p. Hall Scott engine 60 m.p.h.
Chord 5 ft. 6 in.