CHAPTER XIX. OPERATION AND TRAINING.

CHAPTER XIX. OPERATION AND TRAINING.Self-Training. In the early days of aviation, there were few schools, and these were so expensive to attend that the majority of the aeronautical enthusiasts taught themselves to fly on home-made machines. While this was a heroic method, it had the advantage of giving the student perfect confidence in himself, and if his funds were sufficient to outlast the crashes, it resulted in a finished and thorough flyer. In general, this process may be described as consisting of two hours of practice followed by a week or more of repairing.The present-day beginner has many advantages. He has the choice of many excellent schools that charge a reasonable tuition, and where the risk of injury is small. He has access to the valuable notes published in the aeronautical magazines, and the privilege of consulting with experienced aviators. The stability and reliability of the planes and the motors have also been improved to a remarkable degree, and the student no longer has to contend with a doubtful aeroplane construction nor with the whims of a poorly-constructed motor.Training Methods. In the majority of American schools, the instructor accompanies the student in the first flights. The controls are "Dual," or interconnected, so that the instructors’ controls act in unison with those of the student, thus giving the latter an accurate knowledge of the movements necessary for each flight condition. After the first few flights the instructor can relax his controls at times so that the student can take charge. This continues until the student has shown the ability to handle the machine alone under ordinary conditions and is then ready for his first "Solo" or flight alone. The first solo is a critical period in his training, for when once in flight he is beyond all human aid.At the navy training school at Pensacola, the student is first taken for a ride with one of the instructors without giving him access to the controls. This is simply to give the student an experience in the sensation of flight. After this he is taken for a series of short flights on a dual control machine, the instructor gradually allowing him to take charge to a greater and greater extent as he develops the "Air feel." During this time the intricacies of the maneuvers are also gradually increased, so that after about ten hours of this sort of work he is allowed to take his first solo. It has been found that the average student will require from 10 to 20 hours of dual control instruction before he is fit to fly alone. When his work has proven satisfactory he is then allowed to fly in rough weather, execute spirals, and attempt high altitude and long distance flying.Some instructors believe in showing what can be performed in the air from the very beginning. During the first dual flights, the pilot indulges in dives, vertical banks, side slip, or even looping. After an experience of this sort, the student is far more collected and easy during the following instructions in simple straight flying. If this preliminary stunt flying has a very material effect on the nerve of the student it may be taken for granted that he is not adapted for the work and can be weeded out without further loss of time. If he is of the right type, this "rough stuff" has a beneficial influence on his work during the succeeding lessons. During this time numerous landings are made, for it must be understood that this is one of the most difficult features of flying. With 15 minute lessons, at least 6 landings should be made per lesson.A second method of instruction, and to the author's mind the most desirable, is by means of the "Penguin" or "Roller." This is a low-powered machine with very small wings—so small that it cannot raise itself from the ground. By running the penguin over the ground, the student learns how to manage his engine and to steer with his feet. In this way he obtains a certain delicacy of touch without endangering either himself or an expensive machine. After he has progressed satisfactorily on this machine he graduates to a faster penguin or else to a very slow aeroplane with which he can actually leave the ground. Since the second penguin, or the slow aeroplane are much faster than the first machine, the student finds that the sensitiveness of the rudder and controls are greatly increased. They require more careful handling than in the first instance, and the slightest mistake or delay will send the machine skidding. The aeroplanes used at this stage are very low-powered, and are capable of rising only a few feet from the ground, but they give the student an opportunity of learning the aileron and tail controls in comparative safety. The same result can be obtained with a standard aeroplane by a permanent set in the throttle control, and by adjusting the stabilizer surface. The beginner is allowed to work only during calm weather, as the low speed and small lifting capacity is likely to cause an accident if the machine is caught by a side or following gust. He only learns how to get the machine off the ground, to keep the tail up and hold it in a straight line for a few seconds.The man taught by the penguin method is alone when he first leaves the ground, and hence is generally more self-reliant than one who has been "Spoon fed." His experience in handling the controls has made his movements instinctive, so that when he first actually flies he is in a better position to analyze the new problems before him. It is a better and cheaper method for the school as the breakage is less expensive and allows the unfit students be weeded out before they cause damage to themselves or to the school property.Ground Instruction. Before attempting flight, the student should be thoroughly versed in the principles an constructional details of the aeroplane and the aeronautic motor. He should know how to take down, time and repair every type of motor with which he is likely to come into contact. He should be able to tell at a glance whether the machine is rigged or trued up properly, and have a general knowledge of the underlying principles of aerodynamics. The study of these subjects is the function of the ground school. At this school the student should learn the assembling and adjusting of the aeroplane structure and its balance.Types Suitable for Pilots. There is a great diversity of opinion as to the type of man best suited for flying. In this country the government requirements regarding age and physical condition are very exacting, while in Europe it has been found that physical condition is not an index to a man's ability as a pilot. Many of the best French pilots were in such bad shape as to be rejected by the other branches of the army. Our men are well under 30 years of age, while in European service there are many excellent pilots well over 40. It is almost impossible to tell from external appearances whether a man can become a good pilot.In general he must be more intelligent and better educated than the average infantryman. He should not be subject to an attack of "Nerves," nor become easily rattled, for such a man courts disaster in flying. Many exhibition flyers of reputation have proved absolute failures in military service. A knowledge of mechanics will be of great benefit and has been the salvation of many a pilot in active service. Automobile or motorcycle experience is particularly valuable. Recklessness, or a dare-devil sort of a disposition, are farthest from being qualifications for an aviator. Such a man should not be permitted to fly, for he is not only a constant menace to himself but to everyone else concerned.Learning to Fly Alone. It is with the greatest hesitancy that the author enters into a "Ground course" of flight instruction. I can, however, list the principal things to avoid and some of the things to do, but this will never take the place of actual field instruction and experience. The first and last thing to remember is to "Proceed slowly and with caution." Never try a new stunt until you are absolutely sure that you have thoroughly mastered the preliminary steps in straight flying. Over-confidence at the beginning is almost as bad as no confidence at all, and the greatest difficulty met with by instructors during the first solo flights is to keep the student from imitating the maneuvers of the more experienced flyers. Spend plenty of time rolling or "Grass-cutting" before attempting to leave the ground. Be sure that you can handle the rudder with accuracy, and at fairly high speeds before attempting to lift. A few days spent in sitting in the machine (motor dead), and acquainting yourself with the controls is excellent practice and certainly is not a loss of time. With the machine in the hangar, move the controls for imaginary turns, dips and other maneuvers so that the resistance, reach and limit of control movement will come more naturally when the machine is moving.During the ground rolling period, the elevator or stabilizer should be set so that it is impossible to leave the ground, and the motor should be adjusted so that it cannot develop its full thrust. This will provide against an accidental lift. Be easy and gentle in handling the controls, for they work easily, and have powerful effect at high speeds. The desperate fervor with which the beginner generally yanks at the "joystick" is generally the very reason for his accidents. Do not start off at full speed without first getting used to the effect of the controls. Learn to find the location of the various devices so that you can reach them without looking or without fumbling.The First Straight. By adjusting the stabilizer and elevators so that the latter has a greater degree of freedom, and by changing the motor so that it can be run at a slightly higher speed, we are in a position to attempt our first flight. Be careful that the adjustment will limit the climb of the machine, and choose only the calmest of weather. It should be remembered that the aeroplane will get off the ground at a lower speed than that required for full flight at higher altitudes, this being due to the cushioning effect between the wings and the earth. A machine traveling at a speed capable of sustaining flight at a few feet above the earth will cause it to stall when it is high enough to lose this compression. The adjustment should be such that the machine cannot rise above this "Cushion," and in this condition it is fairly safe for the beginner.In making the first runs under the new conditions of adjustment, the student should learn to manipulate the elevators so that they will hold the tail up in the correct position, that is, with the chord of the wings nearly horizontal. Do not allow the tail skid to drag over the ground further than necessary. At this point the student should be strapped in the seat by a quick-detachable safety belt.Now comes the test. Get under full headway with the tail well up, taking care to run against the breeze. The speed increases rapidly, then the motion and jar seem softer, and the motor ceases to roar so loudly. There is now a very distinct change in the note of the motor. You are off. At this point a very peculiar illusion takes place, for your elevation of a few feet seems about a thousand times greater than it really is. With this impression the student usually tries to correct matter by a sudden forward push on the control lever causing fine dive and a smash. It must be borne in mind that only the slightest movement of the controls should be made, and if this does not prove sufficient after a moment or so, advance them still further but very gently. Sudden movements must be avoided. At first the "Hops" should not extend over a hundred yards or so until the student is sure of his controls. Little by little they can be increased in length and height. He should practice for some time before attempting a flight of more than a mile. By this time, the student will have learned that the landing is by far the most difficult feature in flying, and he should practice this incessantly before trying flights in windy weather.The machine should be headed directly into the wind, both in getting off and in landing, especially in the latter case, as a sudden following gust will tend to stall a machine or upset it. With a head wind, the lift is maintained at a low speed and hence is an aid in a safe landing. When flying in still air there is little if any use for the ailerons, but in gusts the student will need their aid in maintaining lateral balance. After the rudder and elevator controls have been well learned the effect of the ailerons can be tried. Gusty or squally weather must be avoided at this point in the training, and no turns should yet be attempted.When the student attains heights greater than a few feet he should take great care in obtaining a sufficient ground speed before trying to get off, for if lifted before the full flying speed is attained it is likely to stall. Fast climbing at sharp angles is dangerous unless a sufficient ground speed has been attained. Sustentation is due to forward speed, and this must not be forgotten. The quickest climb for getting over trees and other obstructions is obtained by gaining full speed on the ground before the climb begins, as the power of the engine is aided by the momentum of the machine.In landing in small fields it is necessary to bring the machine to rest as soon as possible, and this stopping distance depends to a great extent upon the attitude of the machine when it first touches the ground. If it is landed so that the chassis wheels and tail skid strike the ground simultaneously, the incidence is so great that the wings act as air brakes. On landing, the angle in any case should be quickly increased past the angle of maximum lift. The lift is much reduced and the drag is increased by quickly pulling the control toward the aviator. This also reduces the tendency toward nosing over.A normal landing in a large field can be affected by first starting down at the normal gliding angle, and when from twenty to thirty feet above the ground the elevator control is pulled back so that the machine will describe a curve tangent to the ground. In student's practice the curve should not be exactly tangent to the ground, but tangent to a level two or three feet above the ground. The machine is now losing speed, and to prevent settling the elevator should be pulled back a trifle. The speed continues to decrease until it settles down through the small remaining distance with the elevator full back. The points of support should strike simultaneously. It is difficult for the beginner to make this sort of a landing, as there always seems to be an uncontrollable desire to jam the machine down on the ground. If a puff of wind happens to strike the machine when a few feet off, the student becomes rattled by the suddenly increased elevation and jams her down doubly hard.Wind Flying. The nature of wind at low altitudes is determined to a great extent by the contour of the ground. Eddies are caused by trees, embankments, fences, small hills, etc., which tend to disturb the equilibrium or change the course of the aeroplane. As the altitude increases, the effects of these obstructions are less pronounced, until at from 2000 to 3000 feet the effect is practically negligible. Winds that may be "Bumpy" near the ground are fairly regular when 3000 feet is attained. At the higher altitudes the velocity increases, and if the machine is flying against the wind the progress will naturally be much slower at the higher altitudes. When starting in a strong wind it is advisable to attain an altitude of at least 300 to 400 feet before turning. Turning in with the wind carries the possibility of a drop or stall.A short gust striking the machine, head on, tends to retard the velocity in regard to the earth, but in reality increases the relative air speed and thus causes the machine to climb momentarily. A prolonged head gust may produce a stall unless corrected by the elevator or met with by reserve power. A rear gust reduces the relative wind velocity and tends to make the machine stall, although there are a few cases where the gust velocity has been great enough to cause a precipitate drop. The higher the speed, the less the danger from rear gusts.The gusts are much more pronounced with low winds, say winds of about 5 to 15 miles per hour, and hence it is usually more tricky to fly in a wind of this velocity than with a higher wind. It is not the speed of the wind so much as it is its variation from the average velocity. One should start to work on a "bump" at the moment it first starts to appear.When flying with the wind, the total speed in regard to the earth is the sum of the wind speed and the aeroplane speed. When flying against it is the difference between the aeroplane and air speeds. Thus, if the air speed of the aeroplane is 60 miles per hour, the speed in regard to the ground will be 75 miles per hour with a following wind of 15 miles per hour, and 45 miles per hour when flying against a 15-mile wind. The speed when flying across the wind would be represented by the diagonal of a parallelogram, one side of which represents the aeroplane speed, and the other side the wind speed. The angle of the diagonal is the angle at which the machine must be pointed. When viewed from the ground, an aeroplane in a cross wind appears to fly sideways.Turning. After the beginner is able to maintain longitudinal and lateral balance on straight away flights, he next attempts turns. At first, the turns must be of great radius. As the radius is gradually shortened, the effects of centrifugal force become greater, increasing the tendency toward skidding or outward side slip. To prevent skidding, the outer wing tip must be raised so that the lift will oppose the centrifugal force. The shorter the turn, and the faster it is made, the greater will be the banking angle. Should the bank be too steep, the gravitational force will pull the machine down, and inwardly in a direction parallel to the wings. This is known as an "Inner side slip." The banking may be performed by the natural banking tendency of the aeroplane or may be assisted by depressing the aileron on the outer wing tip. Unless the speed is well up to normal, the machine will be likely to stall and drop on a turn, as the head resistance is much greater under these conditions. For safety one should take a short downward glide before starting the turn, so that the speed will surely be sufficient to carry it around the turn. A turn should never be attempted when climbing unless one has a great reserve power. The combined effects of the turning resistance, and absorption of energy due to the climb, will be almost certain to stall the machine. There are banking indicators on the market which will prove of great service. These operate on the pendulum principle and indicate graphically whether the aeroplane is being held at the correct angle of bank.Proper Flight Speed. An aeroplane should always be provided with an air speed meter, giving the speed of the machine in relation to the air. When flying with the wind the pilot is likely to be confused by the tremendous ground speed at which his machine is flying. While the machine may be moved at a fast clip in regard to the earth, it may be really near the stalling speed. This error is particularly dangerous when one turns in with the direction of the wind, after flying against it for some time. The sudden increase in the earth speed, when fully in with the wind, always creates a sudden desire to throttle down at the very time when the relative air speed has already been greatly reduced by the turn. Stalling due to this cause has resulted in many accidents, and the beginner should always attain an altitude of a least 500 feet before he tries turning in with a strong wind. An accurate speed indicator eliminates this danger to a great extent, but it should be proved that the instrument itself is accurate before too much reliance is placed on it.Before the advent of the indicator, pilots were compelled to estimate the speed by the sense of feel, some depending upon the feel of the wind pressure on their faces, and others by the relative resistance offered to the movement of the control surfaces. The sense of "Air feel" developed by the late Lincoln Beachey was marvelous, for without instruments he would repeatedly climb nearly into a stall when only 50 feet from the ground, and then recover with his chassis nearly dragging in the weeds.Gliding (Fr. Vol Plan). "Gliding" is a descent along an inclined path without power, and is possible with any aeroplane. By suitably inclining the wings with the horizontal, gravity is made to produce a forward propelling component that moves the machine forward at the expense of a loss in altitude. The angle of the gliding path made with the horizontal is known as the "Gliding angle," and indicates the efficiency of the aeroplane, for with machines having very low head resistance the angle is very "flat," and more nearly approaches the horizontal. The best or flattest gliding angle is an inherent feature of the aeroplane design, and this cannot be exceeded by any effort on the part of the pilot. It is generally expressed in terms of the ratio of the descent to the forward distance traveled, thus a gliding angle of 10 means that the aeroplane travels 10 feet horizontally for every foot of descent. Any angle steeper than the flattest angle can be produced by pushing forward on the elevator controls, thus depressing the elevator tips.A very flat gliding angle is a most important feature from the standpoint of safety, as it determines the extent of the area within which a landing can be made with a dead engine. If the gliding angle is taken as 12, and the height is 2000 feet, then the radius of the circular area in which a landing is possible is 2000 × 12 = 24000 feet, and the diameter is twice this or 48,000 feet, so that we can land anywhere within a distance of over 9 miles. If the best gliding angle of the machine were only 10, this will be reduced to 2000 × 10 = 20000 feet, hence our chance of choosing a safe landing space would be cut down in proportion. The best gliding angle corresponds to a certain speed and wing angle, and must be determined by experiment, but in many machines the adjustment of the weight is such that the machine automatically picks up the best glide as soon as the motor is cut off, and needs but little correction by the elevators. Such a machine is dived slightly when the motor is cut out, and then after a few oscillations settles down and travels steadily along the proper gliding path. In trying to improve this performance, the speed indicator and incidence indicator should be carefully watched so that neither the stalling angle nor the stalling speed are approached. The best glide angle corresponds to the best flight speed and will be increased if the incidence is much below or above the incidence for the most economical flight speed.Vertical Nose Dive. When the aeroplane is diving vertically, nose down, the center of pressure movement in some machines may oppose the elevators, thus making it difficult to straighten out into the horizontal. If pulling full back on the elevator control does not remedy matters, the control should then be quickly reversed so that there is a momentary tendency to throw the machine over on its back. This breaks up the lock, and when accomplished, the controls should be again pulled back to bring the machine into the horizontal with the elevators in the original straightening out position. The momentum swings the machine out and against the locking position, thus aiding the controls in overcoming the moment of the C. P.Typical Gliding Angle Diagram Showing Path Inclination of Deperdussin Monoplane.Typical Gliding Angle Diagram Showing Path Inclination of Deperdussin Monoplane.Tail Spin (Spinning Nose Dive). Spinning is due to side slipping or stalling, and sooner or later every pilot gets into this position either through accident or intention. If an accident, it may be due to the design of the aeroplane through an improper distribution of the vertical surfaces, or again it may be caused by very steep banking without an equivalent rate of turning. Incorrect manipulation of the ailerons when the machine is near stalling speed, or when gliding in a spiral of gradually decreasing radius, also causes this result. At any rate, the side slip and stall are the final cause of spin. In "Stunt flying," where a spin is desired, one of the quickest methods of getting a spin is to pull the controls all the way back and push the rudder hard over in the desired direction of spin with the motor shut off. Another way to get a spin with lots of "Pep" in it, is pull the stick clear back with the motor on, and climb until the machine is stalled, then rudder over hard with the controls still held back. The aeroplane will now fall over on its side in the direction of the rudder, and assisted by the motor which has again cut in after the peak of the climb, will give all the spin that any critic could ask for. After the stall occurs, the motor should be throttled down for it is likely to strain the plane or even break it.There are several ways of coming out of the spin. Probably the best way, and the one that causes the least loss of altitude, is to keep the controls pulled back all the way, and rudder in the opposite direction to the spin (Motor cut out). The rudder will stop the spin, and the elevator will cause the plane to level out of the dive simultaneously, but the controls should be put into neutral as soon as leveled out or there will be another spin started in the opposite direction. A very common method used by exhibition flyers is first put the controls into neutral, and rudder opposite to the spin until it stops turning and it is then put into a nose dive. The straight nose dive can then be easily corrected by pulling back on the controls until it levels out. This latter method develops an excessive speed and requires a high altitude.When the aeroplane is overbanked at normal speed, and the turn is not correspondingly rapid, the plane will slip down sideways into an "Inside side slip." The strong upward wind against the side of the body will turn the nose into a dive, the nose drops, and the tail will then start to swing around in a circle larger than the circle described by the nose—the dive continuing. When much below the normal flight speed, or near the stalling point, the inner ailerons are not as effective when making a sharp turn for their velocity is much reduced. When fully depressed, the inner ailerons give very little lift toward righting the machine but add to the drag and tend to spin the machine around with the inner tips acting as a center of rotation. The outer ailerons are very effective and because of the high speed of these tips, there is a strong banking tendency that eventually will result in side slip and a spin if the pilot is not experienced. Either the spin due to overbanking, or that due to low speed may be straightened out according to instructions already given.When a turn is attempted at low speed near the ground, the student generally fails to bank up sufficiently through fear of striking the ground with the lower wing tip, and therefore gets into an outward side slip. In the frantic effort to keep the low wing up and off the ground he depresses the low aileron to the full, thus increasing the drag on the low side and starting the spin. Very much to his surprise he finds that this actually drops the low tip further instead of raising it as the outer tip is now speeding around at a tremendous clip, and the outer lift is increasing the bank against his will. Given time, and altitude, the plane will bank up until it stands on end, and in any event a bad side slip results, and the fun is on. If near the ground as assumed, either the side slip or the resulting nose dive will soon terminate matters. The moral to be derived from this experience is to keep up to speed in making a turn, to maintain a safe altitude, and in case the speed should fall off, to depress theouter aileron. The outer aileron will resist the spin if depressed, as the drag acts against the spin, and the bank thus obtained will act against the outer side slip, without destroying the velocity of the machine as a whole. In turning at stalling speed, the aileron effects are reversed, and as soon as straightened out the engine should be opened up so that the speed will be increased and the landing made as easy as possible.If the fin and rudder surface is not sufficient for the machine, little is gained by turning the rudder to an angle greater than 15°, and in such cases it is much more effective when held parallel to the wind. If correction has been started before the spin has developed great rapidity, the rudder can first be turned to check the rotation and then turned back parallel to the wind. It is always best to shut off the engine when getting out of a tail spin, especially if the engine rotation is in the direction of the spin, since the motor torque aids the spin and acts against the controls. In case of a smash there is no danger from fire with the engine cut out.Stunt Flying. When the student has had 20 hours or more of solo flying, and is capable of performing the ordinary maneuvers with confidence and accuracy, he is in a position to undertake stunt flying under the directions of a good instructor in a dual control machine. This tremendously increases the confidence of the student if gone about in the right way, and in his after flying experience enables him to get out of tight places that would otherwise often prove impossible. There is no doubt but what stunt flying has decreased the percentage of accidents when properly taught, and that Pegoud's original stunt of looping the loop has been one of the greatest steps in the advancements of aeronautics that we have had, if only for the fact that it taught the flyer that there was no flying attitude so bad but what there was a solution for it.Flying Upside Down. With the machine on its back, then wings are very inefficient, and it is impossible to maintain horizontal flight in this position, and the machine is also very unstable. It should really be called gliding instead of flying since the aeroplane constantly loses altitude along an inclined gliding path. The distance that a machine can be glided in this way depends upon the skill of the pilot, and it will also be found that upside down flight with a large dihedral is more difficult than with straight wings. The upside down flight begins with a glide to gain speed, the path being about 20° with the horizontal, and this speed gain is imperative since it requires both the power of the motor and the momentum of the machine to overcome the sharp climb for the turnover.Upside Down Glide Diagram, Showing Successive Positions of Aeroplane.Upside Down Glide Diagram, Showing Successive Positions of Aeroplane.After sufficient speed has been attained, the controls are pulled back for a climb at about a 60° angle, as between (A) and (C), this maneuver being best performed with the gliding path (C-D) against the wind. With the control pulled back at (A), the rudder is thrown over sharply in the desired direction of the turnover, and this will turn the machine over as indicated by at (B), the machine finally getting on its back at the peak of the climb (C). With the machine on its back, reverse rudder to stop the overturning, and when the wings are horizontal, the rudder should be put in neutral to hold it in this position. At (C) the motor is shut off, and the glide continued to (D) where it is leveled out by a backward pull on the controls. This should always be performed at an altitude well over 2000 feet.Looping Diagram Showing Successive Positions of Machine.Looping Diagram Showing Successive Positions of Machine.Looping. This is probably the easiest of all stunts outside of the spiral glide. It starts with about a 20° glide as at (A) to increase the velocity (Motor on), and at the beginning of the loop at (B), the control lever is pulled back slowly. The controls must be pulled back faster and faster as the plane approaches the top of the loop, a steady pull producing nearly the correct effect because of the decreasing elevator resistance as the machine reaches the top of the loop at (C). At the top, the lever should be clear back and must be held in this position until at the bottom (D) where the machine leaves the loop along the inclined path (D-E) At (D), the stick is pushed slowly forward to neutral, gradually bring the machine into the horizontal. The loops must always be made when flying into the wind, and the faster they are made the better, for there is less strain on the frame and speed also prevents the motor from cutting out at the top of the loop.A Few Straight Loops and Backward Reverse Loops Performed by Niles.A Few Straight Loops and Backward Reverse Loops Performed by Niles.Photograph of Night Looping by Charles Niles.Photograph of Night Looping by Charles Niles. The Machine was Provided with Railroad Flares which Left the Trace or Path of the Aeroplane on the the Dry Plate.Immelmann Turn. This maneuver was originated by the German flyer Immelmann, and is much used in combat by both the Allied and German armies, for it subjects the enemy to a maximum field of fire and enables the machine to make a quick getaway with a single seat machine. With the enemy machine at (X), and with our machine provided with two machine guns, it will be seen that the enemy is under the fire of either the rigid front gun or the pivoted cock-pit guns through nearly three-quarters of the twisting loop. The pivoted gun which fires over the top wing is the most effective as it can reach the enemy machine (X) at (A), (B), (D) and (E), the only blind spots occurring during the climb from (B) to (D) as indicated by the partly rolled over position at (C).Successive Positions in Immelmann Turn.Successive Positions in Immelmann Turn, Enemy Machine Either Being at Y or X.It begins with the usual power glide (Motor on) at (A) in order to gain speed, and at the beginning of the 60° at (B) the elevator controls are pulled back and the rudder given a quick turn to the extreme position in the direction of the desired turnover. The rudder action turns the machine over on its back at the peak of the climb at (D) without the use of ailerons. At the top (D), the rudder is thrown to the opposite direction to stop the roll over and is then brought back to neutral to hold the machine flat on its back. The elevator controls are held back until the machine comes out of the reverse loop extending from (D) to (E) and until it leaves on the horizontal at (F). As the object is to get away quick, the finish along (E-F) should be made with the wind, and preferably should be started across wind. Motor should be throttled down from (D) to (E) to prevent coming out with excessive speed.Positions in "Turn Over," the Machine Continuing to Rotate in the Same Direction from B to D.Positions in "Turn Over," the Machine Continuing to Rotate in the Same Direction from B to D.The Roll-Over. The start of this stunt is exactly like the start of the upside down glide or the Immelmann, while the finish is a sort of reversed Immelmann, the machine being straightened out without going around a loop. When at the top of the turnover climb, the rudder is not reversed and straightened out as in the Immelmann, but a little rudder is kept on so as to continue the turnover and bring the plane out on the horizontal. The rudder action is assisted by a slight application of the aileron while the elevator control is pushed forward after the machine leaves the peak of the climb. I am indebted to Lieutenant Charles W. Keene for suggestions on the Immelmann and roll over, and to the late Lieutenant R. C. Saufly of the U. S. Navy for other items on training.Flying Upside Down With a Bleriot Monoplane.Flying Upside Down With a Bleriot Monoplane. The Plane is Far Too Low to Recover Its Normal Position, and as a Result, the Glide Ended Fatally.An Aeroplane Equipped with the Light Boat Hull Shown, in this Figure is Known as a "Flying Boat".An Aeroplane Equipped with the Light Boat Hull Shown, in this Figure is Known as a "Flying Boat". It Differs from the "Seaplane," as the Floats or Pontoons of the Latter Do Not Enclose the Passenger and Pilot.

Self-Training. In the early days of aviation, there were few schools, and these were so expensive to attend that the majority of the aeronautical enthusiasts taught themselves to fly on home-made machines. While this was a heroic method, it had the advantage of giving the student perfect confidence in himself, and if his funds were sufficient to outlast the crashes, it resulted in a finished and thorough flyer. In general, this process may be described as consisting of two hours of practice followed by a week or more of repairing.

The present-day beginner has many advantages. He has the choice of many excellent schools that charge a reasonable tuition, and where the risk of injury is small. He has access to the valuable notes published in the aeronautical magazines, and the privilege of consulting with experienced aviators. The stability and reliability of the planes and the motors have also been improved to a remarkable degree, and the student no longer has to contend with a doubtful aeroplane construction nor with the whims of a poorly-constructed motor.

Training Methods. In the majority of American schools, the instructor accompanies the student in the first flights. The controls are "Dual," or interconnected, so that the instructors’ controls act in unison with those of the student, thus giving the latter an accurate knowledge of the movements necessary for each flight condition. After the first few flights the instructor can relax his controls at times so that the student can take charge. This continues until the student has shown the ability to handle the machine alone under ordinary conditions and is then ready for his first "Solo" or flight alone. The first solo is a critical period in his training, for when once in flight he is beyond all human aid.

At the navy training school at Pensacola, the student is first taken for a ride with one of the instructors without giving him access to the controls. This is simply to give the student an experience in the sensation of flight. After this he is taken for a series of short flights on a dual control machine, the instructor gradually allowing him to take charge to a greater and greater extent as he develops the "Air feel." During this time the intricacies of the maneuvers are also gradually increased, so that after about ten hours of this sort of work he is allowed to take his first solo. It has been found that the average student will require from 10 to 20 hours of dual control instruction before he is fit to fly alone. When his work has proven satisfactory he is then allowed to fly in rough weather, execute spirals, and attempt high altitude and long distance flying.

Some instructors believe in showing what can be performed in the air from the very beginning. During the first dual flights, the pilot indulges in dives, vertical banks, side slip, or even looping. After an experience of this sort, the student is far more collected and easy during the following instructions in simple straight flying. If this preliminary stunt flying has a very material effect on the nerve of the student it may be taken for granted that he is not adapted for the work and can be weeded out without further loss of time. If he is of the right type, this "rough stuff" has a beneficial influence on his work during the succeeding lessons. During this time numerous landings are made, for it must be understood that this is one of the most difficult features of flying. With 15 minute lessons, at least 6 landings should be made per lesson.

A second method of instruction, and to the author's mind the most desirable, is by means of the "Penguin" or "Roller." This is a low-powered machine with very small wings—so small that it cannot raise itself from the ground. By running the penguin over the ground, the student learns how to manage his engine and to steer with his feet. In this way he obtains a certain delicacy of touch without endangering either himself or an expensive machine. After he has progressed satisfactorily on this machine he graduates to a faster penguin or else to a very slow aeroplane with which he can actually leave the ground. Since the second penguin, or the slow aeroplane are much faster than the first machine, the student finds that the sensitiveness of the rudder and controls are greatly increased. They require more careful handling than in the first instance, and the slightest mistake or delay will send the machine skidding. The aeroplanes used at this stage are very low-powered, and are capable of rising only a few feet from the ground, but they give the student an opportunity of learning the aileron and tail controls in comparative safety. The same result can be obtained with a standard aeroplane by a permanent set in the throttle control, and by adjusting the stabilizer surface. The beginner is allowed to work only during calm weather, as the low speed and small lifting capacity is likely to cause an accident if the machine is caught by a side or following gust. He only learns how to get the machine off the ground, to keep the tail up and hold it in a straight line for a few seconds.

The man taught by the penguin method is alone when he first leaves the ground, and hence is generally more self-reliant than one who has been "Spoon fed." His experience in handling the controls has made his movements instinctive, so that when he first actually flies he is in a better position to analyze the new problems before him. It is a better and cheaper method for the school as the breakage is less expensive and allows the unfit students be weeded out before they cause damage to themselves or to the school property.

Ground Instruction. Before attempting flight, the student should be thoroughly versed in the principles an constructional details of the aeroplane and the aeronautic motor. He should know how to take down, time and repair every type of motor with which he is likely to come into contact. He should be able to tell at a glance whether the machine is rigged or trued up properly, and have a general knowledge of the underlying principles of aerodynamics. The study of these subjects is the function of the ground school. At this school the student should learn the assembling and adjusting of the aeroplane structure and its balance.

Types Suitable for Pilots. There is a great diversity of opinion as to the type of man best suited for flying. In this country the government requirements regarding age and physical condition are very exacting, while in Europe it has been found that physical condition is not an index to a man's ability as a pilot. Many of the best French pilots were in such bad shape as to be rejected by the other branches of the army. Our men are well under 30 years of age, while in European service there are many excellent pilots well over 40. It is almost impossible to tell from external appearances whether a man can become a good pilot.

In general he must be more intelligent and better educated than the average infantryman. He should not be subject to an attack of "Nerves," nor become easily rattled, for such a man courts disaster in flying. Many exhibition flyers of reputation have proved absolute failures in military service. A knowledge of mechanics will be of great benefit and has been the salvation of many a pilot in active service. Automobile or motorcycle experience is particularly valuable. Recklessness, or a dare-devil sort of a disposition, are farthest from being qualifications for an aviator. Such a man should not be permitted to fly, for he is not only a constant menace to himself but to everyone else concerned.

Learning to Fly Alone. It is with the greatest hesitancy that the author enters into a "Ground course" of flight instruction. I can, however, list the principal things to avoid and some of the things to do, but this will never take the place of actual field instruction and experience. The first and last thing to remember is to "Proceed slowly and with caution." Never try a new stunt until you are absolutely sure that you have thoroughly mastered the preliminary steps in straight flying. Over-confidence at the beginning is almost as bad as no confidence at all, and the greatest difficulty met with by instructors during the first solo flights is to keep the student from imitating the maneuvers of the more experienced flyers. Spend plenty of time rolling or "Grass-cutting" before attempting to leave the ground. Be sure that you can handle the rudder with accuracy, and at fairly high speeds before attempting to lift. A few days spent in sitting in the machine (motor dead), and acquainting yourself with the controls is excellent practice and certainly is not a loss of time. With the machine in the hangar, move the controls for imaginary turns, dips and other maneuvers so that the resistance, reach and limit of control movement will come more naturally when the machine is moving.

During the ground rolling period, the elevator or stabilizer should be set so that it is impossible to leave the ground, and the motor should be adjusted so that it cannot develop its full thrust. This will provide against an accidental lift. Be easy and gentle in handling the controls, for they work easily, and have powerful effect at high speeds. The desperate fervor with which the beginner generally yanks at the "joystick" is generally the very reason for his accidents. Do not start off at full speed without first getting used to the effect of the controls. Learn to find the location of the various devices so that you can reach them without looking or without fumbling.

The First Straight. By adjusting the stabilizer and elevators so that the latter has a greater degree of freedom, and by changing the motor so that it can be run at a slightly higher speed, we are in a position to attempt our first flight. Be careful that the adjustment will limit the climb of the machine, and choose only the calmest of weather. It should be remembered that the aeroplane will get off the ground at a lower speed than that required for full flight at higher altitudes, this being due to the cushioning effect between the wings and the earth. A machine traveling at a speed capable of sustaining flight at a few feet above the earth will cause it to stall when it is high enough to lose this compression. The adjustment should be such that the machine cannot rise above this "Cushion," and in this condition it is fairly safe for the beginner.

In making the first runs under the new conditions of adjustment, the student should learn to manipulate the elevators so that they will hold the tail up in the correct position, that is, with the chord of the wings nearly horizontal. Do not allow the tail skid to drag over the ground further than necessary. At this point the student should be strapped in the seat by a quick-detachable safety belt.

Now comes the test. Get under full headway with the tail well up, taking care to run against the breeze. The speed increases rapidly, then the motion and jar seem softer, and the motor ceases to roar so loudly. There is now a very distinct change in the note of the motor. You are off. At this point a very peculiar illusion takes place, for your elevation of a few feet seems about a thousand times greater than it really is. With this impression the student usually tries to correct matter by a sudden forward push on the control lever causing fine dive and a smash. It must be borne in mind that only the slightest movement of the controls should be made, and if this does not prove sufficient after a moment or so, advance them still further but very gently. Sudden movements must be avoided. At first the "Hops" should not extend over a hundred yards or so until the student is sure of his controls. Little by little they can be increased in length and height. He should practice for some time before attempting a flight of more than a mile. By this time, the student will have learned that the landing is by far the most difficult feature in flying, and he should practice this incessantly before trying flights in windy weather.

The machine should be headed directly into the wind, both in getting off and in landing, especially in the latter case, as a sudden following gust will tend to stall a machine or upset it. With a head wind, the lift is maintained at a low speed and hence is an aid in a safe landing. When flying in still air there is little if any use for the ailerons, but in gusts the student will need their aid in maintaining lateral balance. After the rudder and elevator controls have been well learned the effect of the ailerons can be tried. Gusty or squally weather must be avoided at this point in the training, and no turns should yet be attempted.

When the student attains heights greater than a few feet he should take great care in obtaining a sufficient ground speed before trying to get off, for if lifted before the full flying speed is attained it is likely to stall. Fast climbing at sharp angles is dangerous unless a sufficient ground speed has been attained. Sustentation is due to forward speed, and this must not be forgotten. The quickest climb for getting over trees and other obstructions is obtained by gaining full speed on the ground before the climb begins, as the power of the engine is aided by the momentum of the machine.

In landing in small fields it is necessary to bring the machine to rest as soon as possible, and this stopping distance depends to a great extent upon the attitude of the machine when it first touches the ground. If it is landed so that the chassis wheels and tail skid strike the ground simultaneously, the incidence is so great that the wings act as air brakes. On landing, the angle in any case should be quickly increased past the angle of maximum lift. The lift is much reduced and the drag is increased by quickly pulling the control toward the aviator. This also reduces the tendency toward nosing over.

A normal landing in a large field can be affected by first starting down at the normal gliding angle, and when from twenty to thirty feet above the ground the elevator control is pulled back so that the machine will describe a curve tangent to the ground. In student's practice the curve should not be exactly tangent to the ground, but tangent to a level two or three feet above the ground. The machine is now losing speed, and to prevent settling the elevator should be pulled back a trifle. The speed continues to decrease until it settles down through the small remaining distance with the elevator full back. The points of support should strike simultaneously. It is difficult for the beginner to make this sort of a landing, as there always seems to be an uncontrollable desire to jam the machine down on the ground. If a puff of wind happens to strike the machine when a few feet off, the student becomes rattled by the suddenly increased elevation and jams her down doubly hard.

Wind Flying. The nature of wind at low altitudes is determined to a great extent by the contour of the ground. Eddies are caused by trees, embankments, fences, small hills, etc., which tend to disturb the equilibrium or change the course of the aeroplane. As the altitude increases, the effects of these obstructions are less pronounced, until at from 2000 to 3000 feet the effect is practically negligible. Winds that may be "Bumpy" near the ground are fairly regular when 3000 feet is attained. At the higher altitudes the velocity increases, and if the machine is flying against the wind the progress will naturally be much slower at the higher altitudes. When starting in a strong wind it is advisable to attain an altitude of at least 300 to 400 feet before turning. Turning in with the wind carries the possibility of a drop or stall.

A short gust striking the machine, head on, tends to retard the velocity in regard to the earth, but in reality increases the relative air speed and thus causes the machine to climb momentarily. A prolonged head gust may produce a stall unless corrected by the elevator or met with by reserve power. A rear gust reduces the relative wind velocity and tends to make the machine stall, although there are a few cases where the gust velocity has been great enough to cause a precipitate drop. The higher the speed, the less the danger from rear gusts.

The gusts are much more pronounced with low winds, say winds of about 5 to 15 miles per hour, and hence it is usually more tricky to fly in a wind of this velocity than with a higher wind. It is not the speed of the wind so much as it is its variation from the average velocity. One should start to work on a "bump" at the moment it first starts to appear.

When flying with the wind, the total speed in regard to the earth is the sum of the wind speed and the aeroplane speed. When flying against it is the difference between the aeroplane and air speeds. Thus, if the air speed of the aeroplane is 60 miles per hour, the speed in regard to the ground will be 75 miles per hour with a following wind of 15 miles per hour, and 45 miles per hour when flying against a 15-mile wind. The speed when flying across the wind would be represented by the diagonal of a parallelogram, one side of which represents the aeroplane speed, and the other side the wind speed. The angle of the diagonal is the angle at which the machine must be pointed. When viewed from the ground, an aeroplane in a cross wind appears to fly sideways.

Turning. After the beginner is able to maintain longitudinal and lateral balance on straight away flights, he next attempts turns. At first, the turns must be of great radius. As the radius is gradually shortened, the effects of centrifugal force become greater, increasing the tendency toward skidding or outward side slip. To prevent skidding, the outer wing tip must be raised so that the lift will oppose the centrifugal force. The shorter the turn, and the faster it is made, the greater will be the banking angle. Should the bank be too steep, the gravitational force will pull the machine down, and inwardly in a direction parallel to the wings. This is known as an "Inner side slip." The banking may be performed by the natural banking tendency of the aeroplane or may be assisted by depressing the aileron on the outer wing tip. Unless the speed is well up to normal, the machine will be likely to stall and drop on a turn, as the head resistance is much greater under these conditions. For safety one should take a short downward glide before starting the turn, so that the speed will surely be sufficient to carry it around the turn. A turn should never be attempted when climbing unless one has a great reserve power. The combined effects of the turning resistance, and absorption of energy due to the climb, will be almost certain to stall the machine. There are banking indicators on the market which will prove of great service. These operate on the pendulum principle and indicate graphically whether the aeroplane is being held at the correct angle of bank.

Proper Flight Speed. An aeroplane should always be provided with an air speed meter, giving the speed of the machine in relation to the air. When flying with the wind the pilot is likely to be confused by the tremendous ground speed at which his machine is flying. While the machine may be moved at a fast clip in regard to the earth, it may be really near the stalling speed. This error is particularly dangerous when one turns in with the direction of the wind, after flying against it for some time. The sudden increase in the earth speed, when fully in with the wind, always creates a sudden desire to throttle down at the very time when the relative air speed has already been greatly reduced by the turn. Stalling due to this cause has resulted in many accidents, and the beginner should always attain an altitude of a least 500 feet before he tries turning in with a strong wind. An accurate speed indicator eliminates this danger to a great extent, but it should be proved that the instrument itself is accurate before too much reliance is placed on it.

Before the advent of the indicator, pilots were compelled to estimate the speed by the sense of feel, some depending upon the feel of the wind pressure on their faces, and others by the relative resistance offered to the movement of the control surfaces. The sense of "Air feel" developed by the late Lincoln Beachey was marvelous, for without instruments he would repeatedly climb nearly into a stall when only 50 feet from the ground, and then recover with his chassis nearly dragging in the weeds.

Gliding (Fr. Vol Plan). "Gliding" is a descent along an inclined path without power, and is possible with any aeroplane. By suitably inclining the wings with the horizontal, gravity is made to produce a forward propelling component that moves the machine forward at the expense of a loss in altitude. The angle of the gliding path made with the horizontal is known as the "Gliding angle," and indicates the efficiency of the aeroplane, for with machines having very low head resistance the angle is very "flat," and more nearly approaches the horizontal. The best or flattest gliding angle is an inherent feature of the aeroplane design, and this cannot be exceeded by any effort on the part of the pilot. It is generally expressed in terms of the ratio of the descent to the forward distance traveled, thus a gliding angle of 10 means that the aeroplane travels 10 feet horizontally for every foot of descent. Any angle steeper than the flattest angle can be produced by pushing forward on the elevator controls, thus depressing the elevator tips.

A very flat gliding angle is a most important feature from the standpoint of safety, as it determines the extent of the area within which a landing can be made with a dead engine. If the gliding angle is taken as 12, and the height is 2000 feet, then the radius of the circular area in which a landing is possible is 2000 × 12 = 24000 feet, and the diameter is twice this or 48,000 feet, so that we can land anywhere within a distance of over 9 miles. If the best gliding angle of the machine were only 10, this will be reduced to 2000 × 10 = 20000 feet, hence our chance of choosing a safe landing space would be cut down in proportion. The best gliding angle corresponds to a certain speed and wing angle, and must be determined by experiment, but in many machines the adjustment of the weight is such that the machine automatically picks up the best glide as soon as the motor is cut off, and needs but little correction by the elevators. Such a machine is dived slightly when the motor is cut out, and then after a few oscillations settles down and travels steadily along the proper gliding path. In trying to improve this performance, the speed indicator and incidence indicator should be carefully watched so that neither the stalling angle nor the stalling speed are approached. The best glide angle corresponds to the best flight speed and will be increased if the incidence is much below or above the incidence for the most economical flight speed.

Vertical Nose Dive. When the aeroplane is diving vertically, nose down, the center of pressure movement in some machines may oppose the elevators, thus making it difficult to straighten out into the horizontal. If pulling full back on the elevator control does not remedy matters, the control should then be quickly reversed so that there is a momentary tendency to throw the machine over on its back. This breaks up the lock, and when accomplished, the controls should be again pulled back to bring the machine into the horizontal with the elevators in the original straightening out position. The momentum swings the machine out and against the locking position, thus aiding the controls in overcoming the moment of the C. P.

Typical Gliding Angle Diagram Showing Path Inclination of Deperdussin Monoplane.Typical Gliding Angle Diagram Showing Path Inclination of Deperdussin Monoplane.

Typical Gliding Angle Diagram Showing Path Inclination of Deperdussin Monoplane.

Tail Spin (Spinning Nose Dive). Spinning is due to side slipping or stalling, and sooner or later every pilot gets into this position either through accident or intention. If an accident, it may be due to the design of the aeroplane through an improper distribution of the vertical surfaces, or again it may be caused by very steep banking without an equivalent rate of turning. Incorrect manipulation of the ailerons when the machine is near stalling speed, or when gliding in a spiral of gradually decreasing radius, also causes this result. At any rate, the side slip and stall are the final cause of spin. In "Stunt flying," where a spin is desired, one of the quickest methods of getting a spin is to pull the controls all the way back and push the rudder hard over in the desired direction of spin with the motor shut off. Another way to get a spin with lots of "Pep" in it, is pull the stick clear back with the motor on, and climb until the machine is stalled, then rudder over hard with the controls still held back. The aeroplane will now fall over on its side in the direction of the rudder, and assisted by the motor which has again cut in after the peak of the climb, will give all the spin that any critic could ask for. After the stall occurs, the motor should be throttled down for it is likely to strain the plane or even break it.

There are several ways of coming out of the spin. Probably the best way, and the one that causes the least loss of altitude, is to keep the controls pulled back all the way, and rudder in the opposite direction to the spin (Motor cut out). The rudder will stop the spin, and the elevator will cause the plane to level out of the dive simultaneously, but the controls should be put into neutral as soon as leveled out or there will be another spin started in the opposite direction. A very common method used by exhibition flyers is first put the controls into neutral, and rudder opposite to the spin until it stops turning and it is then put into a nose dive. The straight nose dive can then be easily corrected by pulling back on the controls until it levels out. This latter method develops an excessive speed and requires a high altitude.

When the aeroplane is overbanked at normal speed, and the turn is not correspondingly rapid, the plane will slip down sideways into an "Inside side slip." The strong upward wind against the side of the body will turn the nose into a dive, the nose drops, and the tail will then start to swing around in a circle larger than the circle described by the nose—the dive continuing. When much below the normal flight speed, or near the stalling point, the inner ailerons are not as effective when making a sharp turn for their velocity is much reduced. When fully depressed, the inner ailerons give very little lift toward righting the machine but add to the drag and tend to spin the machine around with the inner tips acting as a center of rotation. The outer ailerons are very effective and because of the high speed of these tips, there is a strong banking tendency that eventually will result in side slip and a spin if the pilot is not experienced. Either the spin due to overbanking, or that due to low speed may be straightened out according to instructions already given.

When a turn is attempted at low speed near the ground, the student generally fails to bank up sufficiently through fear of striking the ground with the lower wing tip, and therefore gets into an outward side slip. In the frantic effort to keep the low wing up and off the ground he depresses the low aileron to the full, thus increasing the drag on the low side and starting the spin. Very much to his surprise he finds that this actually drops the low tip further instead of raising it as the outer tip is now speeding around at a tremendous clip, and the outer lift is increasing the bank against his will. Given time, and altitude, the plane will bank up until it stands on end, and in any event a bad side slip results, and the fun is on. If near the ground as assumed, either the side slip or the resulting nose dive will soon terminate matters. The moral to be derived from this experience is to keep up to speed in making a turn, to maintain a safe altitude, and in case the speed should fall off, to depress theouter aileron. The outer aileron will resist the spin if depressed, as the drag acts against the spin, and the bank thus obtained will act against the outer side slip, without destroying the velocity of the machine as a whole. In turning at stalling speed, the aileron effects are reversed, and as soon as straightened out the engine should be opened up so that the speed will be increased and the landing made as easy as possible.

If the fin and rudder surface is not sufficient for the machine, little is gained by turning the rudder to an angle greater than 15°, and in such cases it is much more effective when held parallel to the wind. If correction has been started before the spin has developed great rapidity, the rudder can first be turned to check the rotation and then turned back parallel to the wind. It is always best to shut off the engine when getting out of a tail spin, especially if the engine rotation is in the direction of the spin, since the motor torque aids the spin and acts against the controls. In case of a smash there is no danger from fire with the engine cut out.

Stunt Flying. When the student has had 20 hours or more of solo flying, and is capable of performing the ordinary maneuvers with confidence and accuracy, he is in a position to undertake stunt flying under the directions of a good instructor in a dual control machine. This tremendously increases the confidence of the student if gone about in the right way, and in his after flying experience enables him to get out of tight places that would otherwise often prove impossible. There is no doubt but what stunt flying has decreased the percentage of accidents when properly taught, and that Pegoud's original stunt of looping the loop has been one of the greatest steps in the advancements of aeronautics that we have had, if only for the fact that it taught the flyer that there was no flying attitude so bad but what there was a solution for it.

Flying Upside Down. With the machine on its back, then wings are very inefficient, and it is impossible to maintain horizontal flight in this position, and the machine is also very unstable. It should really be called gliding instead of flying since the aeroplane constantly loses altitude along an inclined gliding path. The distance that a machine can be glided in this way depends upon the skill of the pilot, and it will also be found that upside down flight with a large dihedral is more difficult than with straight wings. The upside down flight begins with a glide to gain speed, the path being about 20° with the horizontal, and this speed gain is imperative since it requires both the power of the motor and the momentum of the machine to overcome the sharp climb for the turnover.

Upside Down Glide Diagram, Showing Successive Positions of Aeroplane.Upside Down Glide Diagram, Showing Successive Positions of Aeroplane.

Upside Down Glide Diagram, Showing Successive Positions of Aeroplane.

After sufficient speed has been attained, the controls are pulled back for a climb at about a 60° angle, as between (A) and (C), this maneuver being best performed with the gliding path (C-D) against the wind. With the control pulled back at (A), the rudder is thrown over sharply in the desired direction of the turnover, and this will turn the machine over as indicated by at (B), the machine finally getting on its back at the peak of the climb (C). With the machine on its back, reverse rudder to stop the overturning, and when the wings are horizontal, the rudder should be put in neutral to hold it in this position. At (C) the motor is shut off, and the glide continued to (D) where it is leveled out by a backward pull on the controls. This should always be performed at an altitude well over 2000 feet.

Looping Diagram Showing Successive Positions of Machine.Looping Diagram Showing Successive Positions of Machine.

Looping Diagram Showing Successive Positions of Machine.

Looping. This is probably the easiest of all stunts outside of the spiral glide. It starts with about a 20° glide as at (A) to increase the velocity (Motor on), and at the beginning of the loop at (B), the control lever is pulled back slowly. The controls must be pulled back faster and faster as the plane approaches the top of the loop, a steady pull producing nearly the correct effect because of the decreasing elevator resistance as the machine reaches the top of the loop at (C). At the top, the lever should be clear back and must be held in this position until at the bottom (D) where the machine leaves the loop along the inclined path (D-E) At (D), the stick is pushed slowly forward to neutral, gradually bring the machine into the horizontal. The loops must always be made when flying into the wind, and the faster they are made the better, for there is less strain on the frame and speed also prevents the motor from cutting out at the top of the loop.

A Few Straight Loops and Backward Reverse Loops Performed by Niles.A Few Straight Loops and Backward Reverse Loops Performed by Niles.

A Few Straight Loops and Backward Reverse Loops Performed by Niles.

Photograph of Night Looping by Charles Niles.Photograph of Night Looping by Charles Niles. The Machine was Provided with Railroad Flares which Left the Trace or Path of the Aeroplane on the the Dry Plate.

Photograph of Night Looping by Charles Niles. The Machine was Provided with Railroad Flares which Left the Trace or Path of the Aeroplane on the the Dry Plate.

Immelmann Turn. This maneuver was originated by the German flyer Immelmann, and is much used in combat by both the Allied and German armies, for it subjects the enemy to a maximum field of fire and enables the machine to make a quick getaway with a single seat machine. With the enemy machine at (X), and with our machine provided with two machine guns, it will be seen that the enemy is under the fire of either the rigid front gun or the pivoted cock-pit guns through nearly three-quarters of the twisting loop. The pivoted gun which fires over the top wing is the most effective as it can reach the enemy machine (X) at (A), (B), (D) and (E), the only blind spots occurring during the climb from (B) to (D) as indicated by the partly rolled over position at (C).

Successive Positions in Immelmann Turn.Successive Positions in Immelmann Turn, Enemy Machine Either Being at Y or X.

Successive Positions in Immelmann Turn, Enemy Machine Either Being at Y or X.

It begins with the usual power glide (Motor on) at (A) in order to gain speed, and at the beginning of the 60° at (B) the elevator controls are pulled back and the rudder given a quick turn to the extreme position in the direction of the desired turnover. The rudder action turns the machine over on its back at the peak of the climb at (D) without the use of ailerons. At the top (D), the rudder is thrown to the opposite direction to stop the roll over and is then brought back to neutral to hold the machine flat on its back. The elevator controls are held back until the machine comes out of the reverse loop extending from (D) to (E) and until it leaves on the horizontal at (F). As the object is to get away quick, the finish along (E-F) should be made with the wind, and preferably should be started across wind. Motor should be throttled down from (D) to (E) to prevent coming out with excessive speed.

Positions in "Turn Over," the Machine Continuing to Rotate in the Same Direction from B to D.Positions in "Turn Over," the Machine Continuing to Rotate in the Same Direction from B to D.

Positions in "Turn Over," the Machine Continuing to Rotate in the Same Direction from B to D.

The Roll-Over. The start of this stunt is exactly like the start of the upside down glide or the Immelmann, while the finish is a sort of reversed Immelmann, the machine being straightened out without going around a loop. When at the top of the turnover climb, the rudder is not reversed and straightened out as in the Immelmann, but a little rudder is kept on so as to continue the turnover and bring the plane out on the horizontal. The rudder action is assisted by a slight application of the aileron while the elevator control is pushed forward after the machine leaves the peak of the climb. I am indebted to Lieutenant Charles W. Keene for suggestions on the Immelmann and roll over, and to the late Lieutenant R. C. Saufly of the U. S. Navy for other items on training.

Flying Upside Down With a Bleriot Monoplane.Flying Upside Down With a Bleriot Monoplane. The Plane is Far Too Low to Recover Its Normal Position, and as a Result, the Glide Ended Fatally.

Flying Upside Down With a Bleriot Monoplane. The Plane is Far Too Low to Recover Its Normal Position, and as a Result, the Glide Ended Fatally.

An Aeroplane Equipped with the Light Boat Hull Shown, in this Figure is Known as a "Flying Boat".An Aeroplane Equipped with the Light Boat Hull Shown, in this Figure is Known as a "Flying Boat". It Differs from the "Seaplane," as the Floats or Pontoons of the Latter Do Not Enclose the Passenger and Pilot.

An Aeroplane Equipped with the Light Boat Hull Shown, in this Figure is Known as a "Flying Boat". It Differs from the "Seaplane," as the Floats or Pontoons of the Latter Do Not Enclose the Passenger and Pilot.

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