H. Barber

“ It is five o'clock of a fine calm morning, when the Aeroplane is wheeled out of its shed on to the greensward of the Military Aerodrome. There is every promise of a good flying day, and, although the sun has not yet risen, it is light enough to discern the motionless layer of fleecy clouds some five thousand feet high, and far, far above that a few filmy mottled streaks of vapour. ”

“ But, as the Lift increases with the Speed, the complaints of the Under-carriage are stilled, and then, the friendly Lift becoming greater than the Weight, the Aeroplane swiftly and easily takes to the air.
Below is left the Earth with all its bumps and troubles. Up into the clean clear Air moves with incredible speed and steadiness this triumph of the Designer, the result of how much mental effort, imagination, trials and errors, failures and successes, and many a life lost in high endeavour. ”

“ Every city and town you must know has its distinct individuality to the Pilot's eye. Some are not fairy places [45] at all, but great dark ugly blots upon the fair countryside, and with tall shafts belching forth murky columns of smoke to defile clean space. Others, melancholy-looking masses of grey, slate-roofed houses, are always sad and dispirited; never welcoming the glad sunshine, but ever calling for leaden skies and a weeping Heaven. ”

“ Oh, where is he who will invent a contrivance to keep me supplied with air of right density and quality? It should not be impossible within certain limits."
"We fully agree," said the dying Power and Thrust. "Only maintain Us and you shall be surprised at the result. For our enemy Drift decreases in respect of distance with the increase of altitude and rarity of air, and there is no limit to the speed through space if only our strength remains. And with oxygen for pilot and passengers and a steeper pitch11 [35] for the Propeller we may then circle the Earth in a day!" ”

“ The air of this early dawn is distinctly chilly, and the A.M.'s are beginning to stamp their cold feet upon the dewy grass, 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." ”

“ A propeller screws through the air, and the distance it advances during one revolution, supposing the air to be solid, is known as the pitch. The pitch, which depends upon the angle of the propeller blades, must be equal to the speed of the aeroplane, plus the slip, and if, on account of the rarity of the air, the speed of the aeroplane increases, then the angle and pitch should be correspondingly increased. Propellers with a pitch capable of being varied by the pilot are the dream of propeller designers. ”

“ A brand new, rakish, up-to-date machine it is, of highly polished, beautifully finished wood, fabric as tight as a drum, polished metal, and every part so perfectly "stream-lined" to minimize drift, which is the resistance of the air to the passage of the machine, that to the veriest tyro the remark of the Pilot is obviously justified. ”

“ And now does the burden of work fall upon the Lift and Drift Wires, and they scream to the Turnbuckles whose business it is to hold them in tension, "This is the limit! the Limit! The Limit! Release us, if only a quarter turn." But the Turnbuckles are locked too fast to turn their eyes or utter a word. Only the Locking Wires thus: "Ha! ha! the Rigger knew his job. He knew the trick, and there's no release here." For an expert rigger will always use the locking wire in such a way as to oppose the slightest tendency of the turnbuckle to unscrew. ”

“ Now the distant drone of the engine can be heard, but not for long, for suddenly it ceases and, the nose of the Aeroplane sinking, the craft commences gliding downwards.
"Surely too far away," says a subaltern. "It will be [53] a wonderful machine if, from that distance and height, it can glide into the Aerodrome." And more than one express the opinion that it cannot be done; but the Designer smiles to himself, yet with a little anxiety, for his reputation is at stake, and Efficiency, the main reward he desires, is perhaps, or perhaps not, at last within his grasp! ”

“ And the Drift has hopes of reaching the Maximum Angle of Incidence and vanquishing the Thrust and the Lift. And he grows very bold as he strangles the Thrust; but the situation is saved by the Propeller, who is now bravely helicopting skywards, somewhat to the chagrin of Efficiency. ”

“ I will now, by means of the following illustration, try to explain how the longitudinal dihedral secures stability:
First, imagine the aeroplane travelling in the direction of motion, which coincides with the direction of thrust T. The weight is, of course, balanced about a C.P., the resultant of the C.P. of the main surface and the C.P. of the stabilizing surface. For the sake of illustration, the stabilizing surface has been given an angle of incidence, and therefore has a lift and C.P. In practice the stabilizer is often set at no angle of incidence. ”

“ The Control Cables of twisted wire, a bit tight before, have slightly lengthened by perhaps the eighth of an inch, and, the Controls instantly responding to the delicate touch of the Pilot, the Aeroplane, at the will of its Master, darts this way and that way, dives, loops, spirals, and at last, in one long, magnificent glide, lands gently in front of its shed. ”

“ For the whole Aeroplane is braced together with innumerable wires, many of which [29] are at their ends bent over in the form of loops in order to connect with the metal fittings on the spars and elsewhere—a cheap and easy way of making connection.
"Elongate, you little devils, would you?" fairly shout the Angles of Incidence, Dihedral and Stagger, amid a chorus of groans from all parts of the Aeroplane. "What's going to happen to us then? How are we going to keep our adjustments upon which good flying depends?" ”

“ The sun is rising quicker than ever mortal on earth witnessed its ascent. Far below is Mother Earth, wrapt in mists and deep blue shadows, and far above are those light, filmy, ethereal clouds now faintly tinged with pink. ”

“ At three thousand feet altitude the Pilot is satisfied that he is now sufficiently high to secure, in the event of engine failure, a long enough glide to earth to enable him to choose and reach a good landing-place; and, being furthermore content with the steady running of the engine, he decides to climb no more but to follow the course he has mapped out. Consulting the compass, he places the Aeroplane on the A–E course and, using the Elevator, he gives his craft its minimum angle of incidence at which it will just maintain horizontal flight and secure its maximum speed. ”

“ The pilot must then learn to know just the angle of bank at which the margin of lift is lost, and, if a sharp turn necessitates banking beyond that angle, he must "nose-down."
In this matter of banking and nosing-down, and, indeed, regarding stability and control generally, the golden rule for all but very experienced pilots should be: Keep the aeroplane in such an attitude that the air pressure is always directly in the pilot's face. The aeroplane is then always engaging the air as designed to do so, and both lifting and controlling surfaces are acting efficiently. ”

“ Nearly all the wood in an aeroplane is designed to take merely the stress of direct compression, and it cannot be bent safely. Therefore, in packing an aeroplane up from the ground, or in pulling or pushing it about, be careful to stress it in such a way as to produce, as far as possible, only direct compression stresses. For instance, if it is necessary to support the lifting surface, then the packing should be arranged to come directly under the struts so that they may take the stress in the form of compression for which they are designed. ”

“ The sun rises and they take on all colours, blending one with the other, from dazzling white to crimson and deep violet-blue. Lakes and rivers here and there in the enormous expanse of country below refract the level rays of the sun and, like so many immense diamonds, send dazzling shafts of light far upwards. ”

“ Like a living thing it responds, and instantly leaves the ground, clearing the hedge like a—well, like an Aeroplane with an excellent margin of lift. Upwards it climbs with even and powerful lift, and the familiar scenes below again gladden the eyes of the Pilot. Smaller and more and more squat grow the houses and hills ”

“ This is, in practice, a far more efficient arrangement than the helicopter, i.e., the air-screw revolving about a vertical axis and producing a thrust opposed to gravity. If, when climbing, the propeller thrust is at such an angle as to tend to haul the aeroplane upwards, then it is, in a measure, acting as a helicopter, and that means inefficiency. The reason of a helicopter being inefficient in practice is due to the fact that, owing to mechanical difficulties, it is impossible to construct within a reasonable weight an air-screw of the requisite dimensions. ”

“ Invading the realms of fancy? Well, perhaps so, but at any rate it is possible that extraordinary speed through space may be secured if means are found to maintain the impulse of the engine and the thrust-drift efficiency of the propeller at great altitude. ”

“ Do tell us what we can do to help you to overcome Gravity and Drift with the least possible Power. That obviously seems the game to play, for more Power means heavier engines, and that in a way plays into the hands of our enemy, Gravity, besides necessitating a larger Surface or Angle to lift the Weight, and that increases the Drift. ”

“ The margin of lift decreases with altitude, owing to the decrease in the density of the air, which adversely affects the engine. Provided the engine maintained its impulse with altitude, then, if we ignore the problem of the propeller, which I will go into later on, the margin of lift would not disappear. Moreover, greater velocity for a given power would be secured at a greater altitude, owing to the decreased density of air to be overcome. ”

“ The A.M.'s8 have now placed the Aeroplane in position facing the gentle air that is just beginning to make itself evident; the engine Fitter, having made 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 A.M.'s are at their posts, ready to hold the Aeroplane from jumping the blocks which have been placed in front of the wheels; and the Flight-Sergeant is awaiting the Pilot's orders. ”