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Aviation History
1917
1917 - 0947.PDF
SEPTEMBER the obstruction would be 4 ft. x 9 ins. x 9 ins., with a pro-jected area to the wind of 3 ft., which would be roughly com- parable with the dimensions of a honeycomb radiator. Thetests were carried out with the centre of the block placed at one-fifth of the chord from the leading and trailing edges,on the upper and lower surfaces at the centre section of the wing. ,As experiments at the National Physical Laboratory have shown, it is the centre section of a wing which develops thegreatest lift and efficiency, both lift and L D falling off progressively towards the tip. If we consider also a typicalpressure diagram as shown in the figure, the possibility of important losses becomes apparent. Since we are concernedwith qualitative results only, the actual lifts and drifts on the model have been plotted in the curves. The lift in posi-tion A is considerably less throughout the working range of angles than in any other arrangement. If we consider that the block is then placed at that pointon the wing where the maximum suction pressure is developed, we can see that this loss in lift is to be reasonably expected.In other positions the loss in lift is not appreciable, and when as at C the block is placed on the lower side toward the reartrailing edge, the lift is actually increased ; the obstruction apparently increases the pressure on the lower face, of courseat the expense of some addijjonal drift. The drag and L D are poor for the combination A andB on the upper surface of the wing. D and C have smaller values of L D than the wing alone, but then the obstruc-tion is a real one, which would produce drift wherever it was placed on the machine.It is also noteworthy that the increase in drag of the com- bination C over the wing alone is so small. If the block weretreated as a flat plate normal to the wind, with a coefficient K = .0028 in 1b. ft./sec. units, its resistance would amountto .0282 lb. At o° the drift of the wing alone is .0280 lb., that of com-bination A is "0540, or a difference of .0260, practically equivalent to the flat plate figure. y"At the same angle the difference between the drag .0370 of combination C and the .0280 of the wing alone is only.0090. Something like 60 per cent, decrease in drag is there- fore gained at small angles by placing the block at C ascompared with the drag of the block placed either at A at anywhere else on the machine where it would not be skelteredby the wing. At bigger angles this gain would also maintain a high percentage. It would seem advantageous, therefore, to place an obstruc-tion of this nature on the lower surface of the wing towards the trailing edge rather than anywhere else on the wing.— "Aviation and Aeronautical Engineering." AN UNSINKABLE MOTHER-SHIP FOR AEROPLANES. THE following interesting description of a mother-ship foraeroplanes appears in our American contemporary Aerial Age •:—" The submarinejias a deadly enemy—the aeroplane. For every poison there is "an antidote seems to be a law of nature.The aeroplane can carry bombs capable of being set to ex- plode either at contact with the water or so many feet underthe water. The submarine under th% water cannot see above the water, but the aeroplane, like a gigantic fish hawk, canand does see the shadow of the submarine many feet under the water, just as the bird sees the fish. The hawk swoopsand div_es, to reappear with the fish; the aeroplane swoops t to a short distance above the long dark cigar shape shadowin the water, and lets drop bomb after bomb. Lucky the U-boat that escapes. She must either go down so far that-not the faintest indication shows up from below, or come up and fight with such anti-aircraft guns as she may be possessedof. But what chance has she if not one but several aero- planes are circling over her, and if an unsinkable ship is buta short distance away wiih three 6-in. rapid" firing rifles trained on the spot-where she must emerge ? - The U-boatthat elects to attack has no chance. Now the questions. If an aeroplane can spot and bomb a submarine, why don'tthey go out to sea every day on this kind of work ? Answer : An aeroplane has but a limited carrying capacity, even whenconstructed of the largest size, with immense area of wings and great horse-power. When equipped with engines ofnearly 300 h.p. the fuel consumption is some 30 gallons of gasoline per hour, and the fuel tanks rarelv carry more thanfive hours' fuel at full power. Then, too ; machine guns mustbe carried. So, though the lifting power of the rdachine may be over 5,000 lbs., it can only fly while it has fuel, and mustreturn for fresh supplies every few hours. If the aeroplane can fly at the rate of 80 m.p.h., and the U-boats are operating200 miles out from the coast, all the aeroplane can do is to go out, spend a short while looking round and then fly back.That is why the unsinkable ' mother '-ship is needed, some floating base of supplies, some sure landing stage and starting' take off.' So a long vessel with a broad upper deck, free from all obstructions of any kind—no funnels, no masts, nocranes, no ordinary deck houses, no boats, no rafts, no wire- less, no anything that might interfere with the alighting ofthe aeroplane or its launching. One of the original and clever features of this invention is the way in which theserequirements are met. The boats, the cranes, the masts for signalling and wireless, are all stowed below the upper deck,the masts and cranes being turned round horizontal thwart- ship axes by electric motors^ geared with worm and wormwheel gearing. The same is true of the" smoke-stacks, funnels and exhaust pipes. All ventilators project horizon-tally below the upper deck. The top of the pilot-house—for this ship can carry no navigator's bridge—is inclined aft, so -o-- -\.^. °r* o i ° * o \ o j o to I o ! o ( o I o O \ I O I O 1 O I C I O £ T o t^ An unsinkable mother-ship for aeroplanes, suggested by Mr. John L. Borger. 947 • • i
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