Part 3 (1/2)
”Whatever do you mean?” asked Efficiency ”What can the Rudder have to do with you?”
”It's like this,” they replied: ”e are deflected doards we gain a larger Angle of Incidence and also enter an area of compressed air, and so produce more Drift than those of us on the other side of the Aeroplane, which are deflected upwards into an area of rarefied air due to the _suction_ effect (though that term is not academically correct) on the top of the Surface If there is more Drift, _ie_, Resistance, on one side of the Aeroplane than on the other side, then of course it will turn off its course, and if that difference in Drift is serious, as it will very likely be if there is no wash-out, then it willthe Aeroplane on its course, besides creating extra Drift in doing so”
”I think, then,” said Efficiency, ”I should prefer to have that wash-out,[7] and th of construction for light weight, I' the price in Lift And now let me see if I can sketch the completed Aeroplane”
[Illustration]
”Well, I hope that's all as it should be,” she concluded, ”for to-morrow the Great Test in the air is due”
[Footnote 4: Morane parasol: A type of Moranesurfaces are raised above the pilot in order to afford hiood view of the earth]
[Footnote 5: Skin friction is that part of the drift due to the friction of the air with roughness upon the surface of the aeroplane]
[Footnote 6: Banking: When an aeroplane is turned to the left or the right the centrifugal force of its momentum causes it to skid sideways and outwards away from the centre of the turn To minimize such action the pilot banks, _ie_, tilts, the aeroplane sideways in order to oppose the underside of the planes to the air The aeroplane will not then skid outwards beyond the slight skid necessary to secure a sufficient pressure of air to balance the centrifugal force]
[Footnote 7: An explanation of the way in which the wash-out is combined with a wash-in to offset propeller torque will be found on p 82]
PART III
THE GREAT TEST
It is five o'clock of a fine cal, when the Aeroplane is wheeled out of its shed on to the greensward of the Military Aerodroh the sun has not yet risen, it is light enough to discern the h, and far, far above that a few fil beloved of pilots
A brand new, rakish, up-to-date hly polished, beautifully finished wood, fabric as tight as a drum, polished metal, and every part so perfectly ”stream-lined” to minie of the machine, that to the veriest tyro the re 'bus, looks alht to have a turn for speed with those lines”
”Yes,” replies the Flight-Commander, ”it's the latest of its type and looks a beauty Give it a good test A special report is required on this machine”
The AM's[8] have now placed the Aeroplane in position facing the gentle air that is just beginning tomade sure of a sufficiency of oil and petrol in the tanks, is standing by the Propeller; the Rigger, satisfied with a job well done, is critically ”vetting” the machine by eye; four AM's are at their posts, ready to hold the Aeroplane fro the blocks which have been placed in front of the wheels; and the Flight-Sergeant is awaiting the Pilot's orders
As the Pilot approaches the Aeroplane the Rigger springs to attention and reports, ”All correct, sir,” but the Fitter does not this ine, for well he knows that this pilot always personally looks after the preli boots and goggled, climbs into his seat, and now, evenappearance, as if straining to be off and away First heis clear, for soround the control lever or ”joy-stick” is lashed fast to prevent the wind fro them
The air of this early dawn is distinctly chilly, and the AM's are beginning to starass, but very careful and circumspect is the Pilot, as he mutters to himself, ”Don't worry and flurry, or you'll die in a hurry”
At last he fumbles for his safety belt, but with a start re it to zero, sruff voice, ”Well, I should think so, twenty reen pilot to stall the Aeroplane Pancake, they call it” And the Pilot, who is an old hand and has learned a lot of things in the air thatabout, distinctly heard the Pitot Tube, whose mouth is open to the air to receive its pressure, staoodness the Rigger blowsair simply fills me with e I'm not sure of my rubber connections either”
”Oh, shut up!” cry all the Wires in unison, ”haven't we got our troubles too? We're in theour Factor of Safety, and hoe can possibly stand it e get the Lift only the Designer knows”
”That's all right,” squeak all the little Wire loops, ”we're that accoate a bit and so relieve your tension” For the whole Aeroplane is braced together with innumerable wires, many of which are at their ends bent over in the fors on the spars and elsewhere--a cheap and easy way of ate, you little devils, would you?” fairly shout the Angles of Incidence, Dihedral and Stagger, aroans fro to happen to us then? How are we going to keep our adjust depends?” ”butt us and screw us,”[9] wail the Wires ”butt us and screw us, and death to the Loops That's e sang to the Designer, but he only looked sad and scowled at the Directors”
”And who on earth are they?” asked the Loops, tre for their troublesome little lives