The Aeroplane Speaks. H. L. Barber
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the Letter to The Technical Editor, “Daily Mauler,” London.
And a League was formed, and there were Directors with Fees, and several out-of-service Tin Hats, and the Man-who-takes-the-credit, and a fine fat Guinea-pig, and all the rest of them. And the Inventor paid his Tailor and had a Hair-Cut, and is now a recognized Press Expert—but he is still waiting for those Mechanics!
“I'm afraid,” said the Slide-rule, who had been busy making those lightning-like automatic calculations for which he is so famous, “it's quite impossible to fully satisfy all of you, and it is perfectly plain to me that we shall have to effect a Compromise and sacrifice some of the Lift for Speed.”
Thud! What was that?
Efficiency had fainted dead away! The last blow had been too much for her. And the Principles gathered mournfully round, but with the aid of the Propeller Slip1 and a friendly lift from the Surface she was at length revived and regained a more normal aspect.
Said the Stagger with a raffish air, “My dear young lady, I assure you that from the experiences of a varied career, I have learned that perfection is impossible, and I am sure the Designer will be quite satisfied if you become the Most Efficient Compromise.”
“Well, that sounds so common sense,” sighed Efficiency, “I suppose it must be true, and if the Designer is satisfied, that's all I really care about. Now do let's get on with the job.”
So the Chalk drew a nice long slim body to hold the Engine and the tanks, etc., with room for the Pilot's and Passenger's seats, and placed it exactly in the middle of the Biplane. And he was careful to make its position such that the Centre of Gravity was a little in advance of the Centre of Lift, so that when the Engine was not running and there was consequently no Thrust, the Aeroplane should be “nose-heavy” just to the right degree, and so take up a natural glide to Earth—and this was to help the Pilot and relieve him of work and worry, should he find himself in a fog or a cloud. And so that this tendency to glide downwards should not be in evidence when the Engine was running and descent not desired, the Thrust was placed a little below the Centre of Drift or Resistance. In this way it would in a measure pull the nose of the Aeroplane up and counterbalance the “nose-heavy” tendency.
And the Engine was so mounted that when the Propeller-Thrust was horizontal, which is its most efficient position, the Angle of Incidence and the Area of the surfaces were just sufficient to give a Lift a little in excess of the Weight. And the Camber was such that, as far as it was concerned, the Lift-Drift Ratio should be the best possible for that Angle of Incidence. And a beautifully simple under-carriage was added, the outstanding features of which were simplicity, strength, light-weight, and minimum drift. And, last of all, there was the Elevator, of which you will hear more by-and-by. And this is what it looked like then:
And Efficiency, smiling, thought that it was not such a bad compromise after all and that the Designer might well be satisfied.
“Now,” said she, “there's just one or two points I'm a bit hazy about. It appears that when the Propeller shaft is horizontal and so working in its most efficient attitude, I shall have a Lift from the Surfaces slightly in excess of the Weight. That means I shall ascend slightly, at the same time making nearly maximum speed for the power and thrust. Can't I do better than that?”
“Yes, indeed,” spoke up the Propeller, “though it means that I must assume a most undignified attitude, for helicopters2 I never approved of. In order to ascend more quickly the Pilot will deflect the Elevator, which, by the way, you see hinged to the Tail. By that means he will force the whole Aeroplane to assume a greater Angle of Incidence. And with greater Angle, the Lift will increase, though I'm sorry to say the Drift will increase also. Owing to the greater Drift, the Speed through the air will lessen, and I'm afraid that won't be helpful to the Lift; but I shall now be pointing upwards, and besides overcoming the Drift in a forward direction I shall be doing my best to haul the Aeroplane skywards. At a certain angle known as the Best Climbing Angle, we shall have our Maximum Margin of Lift, and I'm hoping that may be as much as almost a thousand feet altitude a minute.”
“Then, if the Pilot is green, my chance will come,” said the Maximum Angle of Incidence. “For if the Angle is increased over the Best Climbing Angle, the Drift will rush up; and the Speed, and with it the Lift, will, when my Angle is reached, drop to a point when the latter will be no more than the Weight. The Margin of Lift will have entirely disappeared, and there we shall be, staggering along at my tremendous angle, and only just maintaining horizontal flight.”
“And then with luck I'll get my chance,” said the Drift. “If he is a bit worse than green, he'll perhaps still further increase the Angle. Then the Drift, largely increasing, the Speed, and consequently the Lift, will become still less, i.e., less than the Weight, and then—what price pancakes,3 eh?”
“Thank you,” from Efficiency, “that was all most informing. And now will you tell me, please, how the greatest Speed may be secured?”
“Certainly, now it's my turn,” piped the Minimum Angle of Incidence. “By means of the Elevator, the Pilot places the Aeroplane at my small Angle, at which the Lift only just equals the Weight, and, also, at which we shall make greater speed with no more Drift than before. Then we get our greatest Speed, just maintaining horizontal flight.”
“Yes; though I'm out of the horizontal and thrusting downwards,” grumbled the Propeller, “and that's not efficient, though I suppose it's the best we can do until that Inventor fellow finds his Mechanics.”
“Thank you so much,” said Efficiency. “I think I have now at any rate an idea of the Elementary Principles of Flight, and I don't know that I care to delve much deeper, for sums always give me a headache; but isn't there something about Stability and Control? Don't you think I ought to have a glimmering of them too?”
“Well, I should smile,” said a spruce Spar, who had come all the way from America. “And that, as the Lecturer says, `will be the subject of our next lecture,' so be here again to-morrow, and you will be glad to hear that it will be distinctly more lively than the subject we have covered to-day.”
PART II. THE PRINCIPLES, HAVING SETTLED THEIR DIFFERENCES, FINISH THE
JOB
Another day had passed, and the Flight Folk had again gathered together and were awaiting the arrival of Efficiency who, as usual, was rather late in making an appearance.
The crowd was larger than ever, and among the newcomers some of the most important were the three Stabilities, named Directional, Longitudinal, and Lateral, with their assistants, the Rudder, Elevator, and Ailerons. There was Centrifugal Force, too, who would not sit still and created a most unfavourable impression, and Keel-Surface, the Dihedral Angle, and several other lesser fry.
“Well,” said Centrifugal Force, “I wish this Efficiency I've heard so much about would get a move on. Sitting still doesn't agree with me at all. Motion I believe in. There's nothing like motion—the more the better.”
“We are entirely opposed to that,” objected the three Stabilities, all in a breath. “Unless it's in a perfectly straight line or a perfect circle. Nothing but perfectly straight lines or, upon occasion, perfect circles satisfy us, and we are strongly suspicious of your tendencies.”
“Well, we shall see what we shall see,” said the Force darkly. “But who in the name of blue sky is this?”
And in tripped Efficiency, in a beautifully “doped” dress of the latest fashionable shade of khaki-coloured fabric, a perfectly stream-lined bonnet, and a bewitching little Morane parasol,4 smiling as usual, and airily exclaiming, “I'm so sorry I'm late, but you see the Designer's such a funny man. He objects to skin friction,5 and insisted upon me changing my fabric for one of a smoother surface, and