AVIATION

Dominion, Volume 23, Issue 55, 28 November 1929, Page 16

AVIATION

HIGH SPEED ’PLANES

DIFFICULTY OF VERTICAL

BANK

(By

“Tail-Skid.")

The greatest difficulty o£ all to be met by the designer arises from the necessity of making vertical back turns at frequent intervals along the course. No pilot can stand the enormous forces temporarily imposed upon botli man and machine when a sudden vertical bank is attempted at anything like the extreme speed of which the machine is capable. There is, intleed, very little difficulty in travelling at 300 m.p.h., or even more, on a straight course, provided the acceleration or deceleration is gentle; but when a pilot suddenly changes course a new set of forces comes into operation. Here we have in a very acute form the unpleasant sensation experienced in a lift which suddenly ascends or descends. A simple illustration of the increased gravity strain on mart and machine is possible from a gauge of the varying pressure in the fuel quantity which is carried, in the case of the seaplanes, in the floats. Assuming for the sake of argument that .the pressure of the petrol on the bottom of the float tank is 1001 b., and the machine, travelling at 300 m.p.h., suddenly changes direction, the fuel weight might be temporarily increased as much as 4001 b., and the fuel tends to push its way through the bottom of the float. Should the turn be sharp enough the pressure might rise to about 6001 b. This is what is known as subjecting something to a force of four or six time gravity, and the same laws are applicable to the pilot. The force that is normally responsible for the pumping of the blood to the pilot’s brain is in abeyance, and the blood tends to be drained awav from the brain into the body. If he attempts to turn too sharply everything will momentarily go black before his eyes. The number of times a man can withstand the force of gravity thus imposed is of vital importance not, only to him personally, but also to the designer, who must eventually build aircraft that will withstand weight for the reasons already given. The human element may be hard to gauge as it varies from time to time and with different pilots, and is probably the most difficult factor to cope with in the high speed aircraft construction. The effect of this increased gravity does not end with the pilot, hut the mechanical heart of the engine also feels the strain. The petrol in a vertical bank tends to run away from the carburettor and the engine, and if not fed by an extremely strong force, will tend to cut out.

Fuel Consumption. The motorist, accustomed to run something like 25 miles to the gallon, will be startled to learn that the Schneider Trophy engines may consume as much as two gallons of fuel per minute, and the heat, units absorbed by the lubricating oil alone, if translated into terms of power, would exceed the highest .power of any car on the road to-day. Oil docs not. part with its heat quickly, and so it is 'tliat an elaborate system of oil coolers is necessary. The Supermarine seaplane actually pumps the lubricating oil from the engine in the nose to the hollow fin at the tail, where it is sprayed against the thin metal surface in order to reduce its’ temperature; while the Gloster racer uses the skin of the fuselage by the cockpit, the float struts and even the surface of the floats themselves to keep the oil from losing its properties from overheating.

WELLINGTON’S PAGEANT REPRESENTATIVE

SOMETHING ABOUT THE MONOCOUPE Many who went to the Wellington pageant were quite impressed with the little black and orange Monocoupe recently assembled by Mr. O. Cottrell, of Lower Hutt, and the good impression was strengthened when the little machine gained second place-in the landing competition. Accommodation in the Monoeoupo is in the form of an enclosed cabin under the wing, with side-by-side seating, slightly staggered. The dimensions of the cabin are: 32in. wide by 43iu. high by 30in. deep. Sides and front are provided with windows that open. A door is provided on the left-hand side, and the controls arc placed on the same side. Dual control can be put in if required. Controls are of conventional cable and pulley type, with stick control of elevator and* ailerons and pedal control for rudder. . Wings are of the braced highwing type. The fuselage is of welded steel-tube structure with an internal wire bracing, very deep under the wing, with a sharp reduction in depth and width forward and aft’ of the cabin to the engine-bearer and rudder-post respectively. The power is provided by a 60-7 o h.p. Velie five-cylinder radial air-cooled engine. Other engines may be fitted. Dimensions are as follow: Span, 30ft.; chord, sft.; length, 19ft. 9in.; height, Oft. 3in.: weight, empty. 7001 b.; weight loaded, 11751 b. Details of the aeroplane's performance are as follow: Maximum speed, 102 m.p.h.; cruising speed, 87 m.jhh.; landing speed, 35 m.p.h.; initial rate, of dim, 700 ft. per minute; normal range, 400 miles.